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Dissolved and particulate partitioning of trace elements and their spatial–temporal distribution in the Changjiang River
Dissolved and particulate partitioning of trace elements and their spatialtemporal distribution in the Changjiang River Zhongfang Yang, Xueqi Xia, Yubo Wen, Junfeng Ji, Changping Mao, Qingye Hou, Tao Yu PII: DOI: Reference:
S0375-6742(14)00179-4 doi: 10.1016/j.gexplo.2014.05.013 GEXPLO 5389
To appear in:
Journal of Geochemical Exploration
Received date: Revised date: Accepted date:
28 December 2012 13 May 2014 19 May 2014
Please cite this article as: Yang, Zhongfang, Xia, Xueqi, Wen, Yubo, Ji, Junfeng, Mao, Changping, Hou, Qingye, Yu, Tao, Dissolved and particulate partitioning of trace elements and their spatial-temporal distribution in the Changjiang River, Journal of Geochemical Exploration (2014), doi: 10.1016/j.gexplo.2014.05.013
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ACCEPTED MANUSCRIPT Dissolved and particulate partitioning of trace elements and their spatial-temporal distribution in the Changjiang River
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Zhongfang Yanga,b, Xueqi Xiaa,*, Yubo Wena,c, Junfeng Jib, Changping Maoc,d,
School of Earth Sciences and Resources, China University of Geosciences,
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a
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Qingye Houa, Tao Yua
National Research Center for Geoanalysis, Key Laboratory of Ecological
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b
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100083, Beijing, People’s Republic of China; E-mail: [email protected];
Geochemistry, Ministry of Land and Resources, Beijing, 100037, China Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing
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c
University 210093, Nanjing, China
School of Earth Sciences and Engineering, Hohai University 210098, Nanjing,
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d
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China
Corresponding Author: X. Xia
School of Earth Sciences and Resources, China University of Geosciences, 100083, Beijing, People’s Republic of China; E-mail: [email protected]; TEL: +86-10-82320527
ACCEPTED MANUSCRIPT ABSTRACT Samples of raw water, 0.45 μm filtrated water, 0.20 μm filtrated water, and
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0.45 μm filtrated suspended sediments were obtained and analyzed for trace elements (e.g., Se, As, Cd, Pb, Zn, and Cu) at 76 locations in the main channels
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and tributaries of the Changjiang river. The partitioning of the trace elements in
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the particulate and dissolved load, as well as their spatial and seasonal
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distributions, was investigated. We found that the concentrations of As, Se, Pb,
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and Zn in the dissolved phase (<0.20 μm) were much higher than those of the world averages, and Cd, As, Pb, and Se were highly enriched in the suspended
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sediments. Metals and metalloids differ in their partitioning characteristics. For the metal elements (e.g., Cd, Pb, Cu, and Pb), the particulate phase is the
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dominant form during transportation. The spatial and seasonal variation of the
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total metal loads and their partitioning are controlled by suspended sediment
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concentrations (SSCs) as well as water pH, which controls the absorbance of the metals by the suspended particles. The particulate phase of the metals is much higher during the flood season, when there is high SSC, especially in the upstream of the Three Gorges Dam (TGD), but the dissolved phase increases gradually down to the lower stream with the decreased water pH. For the typical metalloid elements, e.g., As and Se, the dissolved phase is the dominant form of transportation. In the flood season, the total loads of As and Se are higher with a higher spatial variation than those in the dry season. The highest total As load
ACCEPTED MANUSCRIPT occurres in the most upstream part of the river, and the highest Se load appeares in the section between Luzhou and the TGD. The results also indicate that large
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amounts of the heavy metals have deposited on the bottom of the Three Gorges reservoir. So, more work should been done to evaluate their potential
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environmental hazards as they may release suddenly with water acidification or
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other disturbances.
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KEYWORD: trace elements; dissolved phase; particulate phase; partitioning; the
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Changjiang (Yangtze) River
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1. Introduction
The Changjiang River (Yangtze River) is the world’s third-longest river (6300 km)
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and fourth largest in terms of water discharge (Chen et al., 2002). Covering an area of
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1.80×106 km2, the upper part of the Changjiang runs through the Tibetan Plateau, while
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its middle and lower parts run through one of the most populated and economically developed areas of the world. Consequently, the river receives many inputs of both natural and anthropogenic origin (Wang et al., 2010). Heavy metals (e.g., Cd, Pb, Cu, and Zn) and other trace elements (e.g., As and Se) are among the pollutants in Changjiang examined in former studies (Zhang and Selinus, 1997; Zhang, 1999; Che Y. et al. 2003; Wang and Liu, 2003; Koshikawa et al., 2007; Qiao et al., 2007; Xia et al. 2007; Müller et al. 2008, 2012; Shan et al. 2008; Zhang et al., 2008; Li and Zhang, 2010; Song et al., 2010; Wang et al., 2010). In aquatic
ACCEPTED MANUSCRIPT environments, trace elements exist in almost all the environmental media, including water, and suspended and bottom sediments. The trace elements in the river water of the
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Changjiang have been evaluated by Müller et al. (2008), Koshikawa et al. (2007), and Wang et al. (2011). Suspended sediment is another pathway of trace element
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transportation. Qiao et al. (2007) and Müller et al. (2012) investigated the seasonal trend
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of the trace element loads in suspended sediments based on the observation of Datong,
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one of the important hydrological stations at the lower reaches. Spatial distributions of
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trace elements in suspended sediments have been studied by Che et al. (2003) in the Changjiang estuary. Koshikawa et al. (2007) and Müller et al. (2008) have studied the
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same from the Three Gorges Dam to the estuary. Song et al. (2010) investigated the spatial variations of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in sediment and
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suspended solids for 75 locations distributed on the main channel and tributaries of the
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Changjiang and found that Panzhihua, the northeast of the Yunnan Province, and the
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Nanling mining area are the main sources of heavy metals, and that these metals are enriched in Poyang Lake and the Three Gorges Reservoir. There are various sources, including natural and anthropogenic, of trace elements in aquatic environments (Foster and Charlesworth, 1996). After entering surface waters, the trace elements are transported in very complexed forms or species (Gaillardet et al., 2003). Knowing the concentrations of the individual species of a given element in waters is of crucial importance to predicting their toxicity and bioavailability (Morel and Hering, 1993). However, it is rarely possible to measure the concentration of an
ACCEPTED MANUSCRIPT individual complex (Ammann, 2002). Therefore, the proportion of elements corresponding to the different chemical forms must be calculated, depending on the
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total concentration, pH, Eh conditions, the major element chemical composition of the water, and the complexation constants of the assumed complexes. There is another way
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to study the chemical form of trace elements, which is to operationally define
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“particulate” and “dissolved” fractions by filtration with 0.20μm or 0.45μm filters
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(Buffle and Van Leeuwen, 1992).
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For Changjiang, Zhang et al. (2008) studied the uptake and release of trace metals (Cu, Ni, Zn, Cd, and Co) in estuaries using river and sea end-member waters and
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suspended particulate matter. They demonstrated that dissolved concentrations of trace metals in the estuary can be modeled based on the metal concentration in suspended
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particulate matter (SPM), pH and salinity using a Kurbatov adsorption model. By
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sampling across a salinity gradient of 0.15‰ to 19.0‰ in surface waters of the
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Changjiang Estuary, Wang and Liu (2003) determined the concentrations of dissolved heavy metals and found that the distribution of acid-soluble heavy metals in the Changjiang estuary is mainly controlled by the concentration of suspended matter and salinity. It has been indicated by former studies (Gaillardet et al., 2003; Morel and Hering, 1993; Ammann, 2002; Zhang et al., 2008; Dai, 1994; Wang and Liu, 2003) that partitioning of the trace elements between the dissolved and particulate phase is influenced by many factors, including suspended sediment concentration (SSC), pH,
ACCEPTED MANUSCRIPT temperature, and salinity. Thus far, however, there is a lack of observations of the trace element partition of the whole Changjiang water system under the various water
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environment conditions. In 2007-2008, we carried out a survey of 76 locations in the main channel and
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tributaries from the Tuotuohe to the estuary of the Changjiang River. Samples of the
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raw water, 0.45 μm filtrated water, 0.20 μm filtrated water, and 0.45 μm filtrated
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suspended sediments were analyzed for trace elements (e.g., Se, As, Cd, Pb, Zn, and
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Cu). Samples of 0.45 μm filtrated water and suspended sediment were also collected monthly at Nanjing in the lower reaches of the river. Based on the observations, this
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paper aims to investigate the partitioning of the trace elements in the particulate and
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dissolved load transported in the river, especially their spatial and seasonal distributions.
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2.1 Sampling
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2. Materials and methods
Samples were collected during two 45-day periods from July to August 2007 (summer, the flood season) and November 2007 to February 2008 (winter, the dry season). Seventy-six sampling sites were assigned, with 36 located on the main channel labeled 1-36 and 40 on the tributaries labeled T01-T40 (Fig. 1). Three types of water samples were obtained: raw water samples and water samples filtrated through 0.45 μm and 0.20 μm filters. The raw water samples were collected in situ from the middle of the river using a boat with 50 ml disposable
ACCEPTED MANUSCRIPT polyethylene narrow-mouth bottles with screw caps. These samples were acidified to pH≈1.6 using high-purity HNO3. River water for filtration was collected using a 20 L
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washed plastic container after temperature (T) and pH were measured in situ using a thermometer and a portable pH-meter. These samples were then transported to a
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room and filtered in a few hours through pre-washed 0.45 μm cellulose membrane
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disc filters using an air pump. Then, 0.45 μm filtrated water samples were collected
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using 50 ml polyethylene bottles and then acidified with high-purity HNO3. The
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remainder was filtrated again with pre-washed 0.20 μm cellulose membrane disc filters, and the 0.20 μm filtrated water was also sampled using 50 ml bottles and
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acidified. The raw water, 0.45 μm filtrated water, and 0.20 μm filtrated water samples for laboratory trace element analysis were stored at approximately 4◦C
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before analysis. To provide reliable and accurate data, cleansing techniques were
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used for handling and analyzing the samples. All materials coming in contact with
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the samples were acid washed and stored in double polyethylene bags before use. The parallel samples included in these samples were taken at every six sampling sites to ensure the best results. Samples of suspended sediment were obtained from the 0.45 μm cellulose membrane disc filters after filtration. The suspended solid samples on the filter were removed in the laboratory using deionized water, and the solution containing the suspended solids was evaporated at 40 °C. Then, the solid residue was weighed and SSCs deduced by dividing the weight by the volume of the water having been
ACCEPTED MANUSCRIPT filtrated to obtain it. The volume of the water was measured by a measuring cup
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before filtration.
2.2 Chemical analysis
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The samples collected, including both the water and suspended sediments, were
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analyzed at the Ministry of Land and Resources P.R.C. Hefei Mineral Resources
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Supervision and Testing Center.
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For water samples, the determination of Ni, Co, Zn, Cu, Pb, Cd, and Cr was carried out by inductively coupled plasma-mass spectrometry (ICP-MS, IRIS
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Advantages, USA), in which Co were determined by the standard addition methods, while Ni, Zn, Cu, Pb, Cd, and Cr were monitored by standard sampling
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(multi-element standard, lot number GBW(E)080194). As and Se were determined
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by atomic fluorescence spectroscopy (AFS) using standard addition methods. A set
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of analytical quality control schemes was used with reference to the Specifications of the Multi-Purpose Regional Geochemical Survey carried out by the China Geological Survey (CGS, 2005). The relative errors for the analysis of the standard solution were less than 5%. The recovery of the standard addition was greater than 93% for Co and 95% for As and Se. Data below the analytical detection limits were set to a value of half the detection limit in constructing all plots and statistical calculations. For analysis of the suspended sediments, a small quantity (~1 g) of samples were ground to an 80-mesh size (0.2 mm) and then dissolved to HCl, HNO3, HClO4,
ACCEPTED MANUSCRIPT and HF under high pressure and temperature. As and Se were measured using an AFS 230E Atmospheric Fluorescence Spectrometer. Cd was measured using an AAS
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ZEEnit60 graphite-furnace atomic absorption spectrometer (Analytik Jena AG, Germany). Al2O3 was analyzed by ICP-OES. Co, Cr, Cu, Ni, Pb and Zn were
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measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) by
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Thermo ICP-MS X SERIES (Thermo Fisher Scientific, America). The analyzed data
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were assessed for accuracy and precision using a quality assurance and quality
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control (QA/QC) program that included reagent blanks and duplicate samples with 8% suspended solid samples, respectively, and using certified geochemical reference
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materials (GSS-2, GSS-3, GSS-4, GSS-6) with a deviation below 5%. 2.3 Assessment of sediment contaminations
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The enrichment factor (EF) was calculated for the trace elements using:
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EF [Ci / C Al ]sample /[(Ci / C Al )crust ] Where (Ci/CAl)
sample
(1)
is the ratio of the concentration of the element of concern
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(Ci) to that of Al (CAl) in the sample, and (Ci/CAl)crust is the same ratio in an unpolluted reference sample (Pekey, 2006). Elements that are naturally derived have an EF value of nearly unity, while elements of anthropogenic origin have EF values of several orders of magnitude. According to Sutherland (2000), six categories are recognized: <1 background concentration, 1-2 depletion to minimal enrichment, 2-5 moderate enrichment, 5-20 significant enrichment, 20-40 very high enrichment and > 40 extremely high enrichment. The Index of Geoaccumulation (Igeo) was also used as a quantitative measure of the degree of pollution in aquatic sediments (Müller, 1979; Förstner et al., 1990). Igeo
ACCEPTED MANUSCRIPT uses the relationship between the measured concentration (Ci) of the element in the sediment (<2 μm fraction) and the background concentration (Bi) in the shale
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sediment (Eq. (2)), and 1.5 is a correction factor due to lithogenic effluents.
I geo log2 [Ci /(1.5 Bi )]
(2)
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where Ci is the measured concentration of heavy metal “i” and Bi is the background
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value of heavy metal “i”. Each heavy metal may be classified as unpolluted (Igeo<0),
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unpolluted to moderately polluted (0
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moderate to strongly polluted (25). Background values
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used in the Igeo and EF calculations were from Turekian and Wedepohl (1961). 2.4 Investigation of seasonal variation
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To investigate the seasonal variation of the element partitioning, a stationary
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sampling location was selected in Nanjing, which is at the lower reaches of the
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Changjiang river, and the water samples were collected monthly between Oct 2006 and Dec 2007. The raw water was sent to the laboratory in a few hours and filtrated with pre-washed 0.45 μm cellulose membrane disc filters. The filtrated water was analyzed for Cu, Pb, Zn and Cd with the methods described in section 2.2. Samples of suspended sediments were obtained from the filters and treated with the same procedure as in section 2.1 and were analyzed as described in section 2.2.
3. Results and discussion
ACCEPTED MANUSCRIPT 3.1 Trace element in water samples It is well known that trace element concentrations in continental waters depend
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on the size of the pore filters used to separate the particulates from the dissolved fraction. In the literature, trace element abundances in river waters are usually given
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by those filtrated using either 0.2 μm or 0.45 μm filters (Gaillardet et al., 2003).
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Summary statistics of the trace element concentrations in the raw water, 0.45 μm
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filtrated water, and 0.20 μm filtrated samples are shown in Tables 1, 2, and 3
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respectively. The statistical results in the flood season were based on the analytical data from 76 sampling locations both in the main channel and the tributaries, as
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shown in Fig. 1. Three samples (point 1, 3, 4) were absent in the dry season (November 2007 – February 2008) because of the frozen weather. It should be noted
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that the raw water samples in the study were acidified during collection, and the
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sediments were deposited in the bottles for several days before analysis of the
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supernatant. Thus, the data for the raw water samples are actually the labile fraction or acid soluble phase, including those dissolved in the water, absorbed by the suspended particles, in the carbonates and coatings, and in other forms that can be extracted by acid from the suspended matter. Thus, the data from the raw water samples are comparable to the acid-soluble heavy metal concentrations given by Wang and Liu (2003). The spatial variance of dissolved trace metals (i.e., the 0.45 μm filtrated metals) was reported by Wang et al. (2010), who showed that high concentrations of Cu, Ni,
ACCEPTED MANUSCRIPT Fe, Co, Sc, and Al were mostly in the upper reaches. Some tributaries, such as Puduhe, Xinjiang, Xiangjiang, Shun’anhe and Qingtonghe, also have high
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concentrations of dissolved Cd, Hg, Pb or As because of mining activities. Gaillardet et al. (2003) compiled the trace element concentrations in the dissolved loads of the
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world large rivers based on 0.20 μm filtrated data and determined the background
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values of the world average, which are appended in Table 3. From the table, it can be
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seen that the concentrations of As, Se, Pb and Zn in the Changjiang River were much
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higher than those of the world averages; and the concentrations of Co, Cu, Cd, Cr,
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and Ni are comparable to the world averages.
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3.2 Trace elements in the suspended sediments
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3.2.1 Summary statistics
Summary statistics of the trace element concentrations in the suspended
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sediments obtained for the 0.45 μm filters from the two sampling seasons is shown in Table 4. The statistics were based on the 76 samples in Fig. 1, but with the absence of points 1, 3, and 4 in the dry season. From Table 4, we can see that the concentrations for most trace elements have higher values in the dry season than those in the flood season. This result may be due to the higher water flux in the flood season that caused high SSC values with larger particle grains, which diluted the trace element concentrations absorbed in the smaller particles, e.g., hydrous oxides (Gaillardet et al., 2003). Additionally, the concentrations of Pb, Cd, As, Se, Zn, Cr,
ACCEPTED MANUSCRIPT and Cu in the suspended sediments generally have high variations (CV) compared
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with those of Co and Ni.
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3.2.2 EF and Igeo
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The EF values of the trace elements in the suspended sediments from the two seasons are shown in Table 5. From the table, we can see that the EF values of all the
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elements in the flood season are lower than those in the dry season. The slow water
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speed in the dry season induces smaller suspended particles with heavy absorbance of the trace elements. It was also shown that the EF values for most of the elements
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from the tributaries are much higher than those from the main channel, which
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indicates higher pollution in the tributaries. During the flood season, the Se from the
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tributaries is in the category of significant enrichment, and Pb, Cd, and As are in the category of moderate enrichment. During the dry season, the Se and Cd from the
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tributaries are in the category of significant enrichment, and As, Pb, Zn, Cu, and Cr are in the category of moderate enrichment. As shown in Table 5, the Igeo values of As, Se, Pb, Cu, and Cd from the tributaries are higher than those from the main channels both in the flood and the dry seasons. In the flood season, As is moderately polluted in the tributaries, when Se, Pb, and Cd are moderate to strongly polluted. In the dry season, As, Pb, Zn, and Cu are moderately polluted in the tributaries, and Se is moderately to strongly polluted; however, Cd is strongly polluted, with an Igeo=3.31.
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3.3 Seasonal variation of metal element partitioning
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The analytical results of the element concentrations for suspended sediment were given in mg/kg relative to the solid material, as shown in Table 6. It can be seen
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from the table that there are no clearly seasonal trends for the element concentrations
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in the suspended sediments. The data were multiplied by SSC to obtain the quantity
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of the element in the particulate phase relative to the volume of water. Thus, the data
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were transformed to units of μg/L to make them comparable to those in the dissolved phase (Fig. 2), which were from the analytical results of the 0.45 μm filtrated water.
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It is shown that the dominant phase of the elements is particulate, especially in the flood seasons, when there are high SSC values, and that the trace elements in the
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dissolved phase are relatively steady compared with those in the particulate phase.
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Thus, SSC is the dominant factor that controls the amount and seasonal variation of
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the trace elements transported in the Changjiang river.
3.4 Spatial variation of trace element partitioning Trace elements are transported in surface waters in complexed forms. Former studies (Buffle et al., 1992; Gaillardet et al., 2003) have shown that there is no clear boundary among dissolved, colloidal, and particulate fractions. However, authors generally operationally define a particulate fraction (>0.20 μm or 0.45 μm), a colloidal fraction (0.20 μm or 0.45 μm to 1 nm) and a truly dissolved fraction (<1 nm) (e.g.,
ACCEPTED MANUSCRIPT Buffle et al., 1992; Stumm, 1993). In this study, the element concentrations in the water samples were divided into three parts: 1) > 0.45 μm, 2) 0.20-0.45 μm, and 3) <
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0.20 μm. Conventionally, the third part was regarded as the dissolved fraction, with the first part the particulate fraction. The second part can be regarded as either the
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3.4.1 Partitioning difference among the elements
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dissolved or the particulate fraction, depending on the literature.
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The relative proportions of the > 0.45 μm, 0.20-0.45 μm, and < 0.20 μm fractions of the elements are shown in Fig. 3. 0.20-0.45 μm here demotes the
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concentration of an element in the 0.45 μm filtrated water subtracted by that in the
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0.20 μm filtrated one. The data in the figure were given by the average values of the
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samples located on both the main channel and the tributaries. It is shown that for most elements, especially the metals, the particulate fractions in the flood season are
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significantly higher than those in the dry season. The particulate fractions in the flood season are higher than 50% for most of the elements, except for As and Se. However, in the dry season the particulate fractions are usually lower. Only Cu, Pb, Al, and Fe have particulate fractions larger than 50% with the > 0.45μm part at 65.39%, 76.90%, 83.13%, and 84.63%, respectively. This result may be due to the higher water flux in the flood season, leading to improved concentrations of suspended particles, i.e., SSC, with trace elements absorbed on them. In the flood season, the ascending sequence of the particulate fractions for the
ACCEPTED MANUSCRIPT elements is Se
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clay minerals and oxides. Some metals, such as Pb, are easily absorbed by the clay minerals and hydrous oxides under the pH conditions of the natural ground water
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(Sigg et al., 2000). Being different from the metal elements, metalloids such as As and
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with little variation with the water flux and SSC.
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Se are transported mainly in the dissolved form both in the flood and the dry seasons
3.4.2 Spatial variation of metal element partitioning
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According to Fig. 3, metals (e.g., Cd, Pb, Cu, and Zn) and metalloids (e.g., As,
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and Se) have different forms of transportation. Fig. 4 shows the > 0.45 μm, 0.20-0.45
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μm, and < 0.20 μm fractions for the typical metals, e.g., Cd, Pb, and Zn, at the sampling locations in the main channel during the flood season. SSC and pH are also
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shown in the figure for comparison with the spatial distributions of the metal partitions. According to the spatial distribution of the metal fractions, two sections can be separated at the point of the Three Gorge Dam (TGD). In the section above the TGD, the particulate fractions were the dominant ones for all the metal elements. Moreover, the spatial variation of the total element load and the particulate proportions were mainly controlled by SSC. However, at the sampling locations near the TGD, i.e., points 15-19, both the total element load and the particulate proportions for all the metal elements decreased significantly due to the decreased
ACCEPTED MANUSCRIPT SSC as a result of the slow water flow into the TGD. The decreased water flow into the Three Gorges Reservoir promoted the sedimentation of the suspended particles.
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Thus, the absorbed metals sink with the suspended particles to form the bottom sediments. Therefore, at the sampling points near the TGD, the total element load
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and the particulate proportions was the lowest, and the total metal load was
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composed dominantly of the dissolved form. However, at the locations down to the
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TGD, the particulate proportions of the metals increased with the recovered
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suspended sediments, i.e., the SSC values. In addition, the dissolved proportions for the metals also increased from the TGD to the downstream of the river with gradual
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input from the pollution sources in the section. The lower reach of the Changjiang River is an economically developed region with all types of industries. The relative
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proportions of dissolved metals to the particulate ones in the downstream of the river
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are much higher than those in the upstream due to the lower pH value of the
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downstream water. Many studies have proved that the adsorption of metal cations by the suspended particles decreases with decreasing water pH (Sigg et al., 2000; Mouvet and Bourg, 1983; Brick and Moore, 1996; Erel et al., 1990). Fig. 5 shows the three fractions of the metals in the dry season compared with the SSC and water pH. Compared with those in the flood season, the particulate proportions of the metals decreased with the decreased SSC. Thus, the total loads of the metals were also much smaller than those in the flood season. The water pH in the dry season was lower than that in the flood season for most sampling locations.
ACCEPTED MANUSCRIPT The result was an enhanced relative proportion of the dissolved phase for the metals,
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which can be shown in Figs. 3 and 5.
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3.4.3 Spatial variation of metalloid element partitioning
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The three fractions for the typical metalloids, e.g., As and Se, during the flood season are shown in Fig. 6. From the figure, we can see that the dissolved fractions
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are the dominant form during the metalloid element transportation. The first point
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from Tuotuohe has the highest dissolved fractions and the highest total load of As. From points 2 to 15, i.e., the section that has a very high SSC, approximately half of
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the total As is in the particulate phase and the other half is in the dissolved phase. In
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the section downstream from point 15, the dissolved phase is the dominant form of
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As transportation, and the total load is relatively steady. For Se, the total load variation is also dominated by the dissolved phase. The maximum dissolved As
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appears at the section between points 11 and 12, i.e., Luzhou-Chongqing, and the minimum is between points 16 and 17, i.e., Wushan-Three Gorges Reservoir. The partitioning fractions for As and Se from the dry season are shown in Fig. 7, which also shows that the dissolved phase is the dominant form of As and Se transportation. It is also shown that the spatial variation of the load of the two elements is relatively smaller than that in the flood season.
4. Conclusion
ACCEPTED MANUSCRIPT Samples of the raw water, 0.45μm filtrated water, 0.20 μm filtrated water and 0.45μm filtrated suspended sediments were obtained and analyzed for the trace
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elements (e. g. Se, As, Cd, Pb, Zn, and Cu) in the 76 locations in the main channel and tributaries of the Changjiang river. The partitioning of the trace elements in the
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particulate and dissolved load transported into the Changjiang River and their spatial
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and seasonal distributions was studied, and the following was found:
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(1) The concentrations of As, Se, Pb and Zn in the dissolved phase (<0.20 μm)
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in the Changjiang River were much higher than those of the world averages, and for Co, Cu, Cd, Cr and Ni the concentrations are comparable to the world averages. Both
in the suspended particulates.
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the EF and Igeo values show that Cd, As, Pb, and Se are the elements highly enriched
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(2) The seasonal variation of total metal (e.g., Cd, Pb, Cu, and Pb) element
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loads is controlled by SSC with the particulate phase. The total loads of the metals
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increase with the increasing SSC in the flood season, and there are no clear seasonal trends for the element concentrations in both the suspended sediments and the filtrated waters.
(3) Metal and metalloid elements have different partitioning characteristics. For metal elements, the particulate phase is the dominant form during transportation, and the proportion is controlled by SSC and water pH. The particulate phase is much higher during the flood season when there is high SSC, especially in the upstream of the TGD.
ACCEPTED MANUSCRIPT (4) For the typical metalloid elements, e.g., As and Se, the dissolved phase is the dominant phase for transportation. The total loads are higher in the flood season
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than those in the dry season. And also, the spatial variation is little during the dry season.
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(5) Heavy metals absorbed on the particles deposited on the bottom of the
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Three Gorges reservoir may release suddenly with water acidification or other
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disturbance. So, more work should been done to evaluated their potential
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environmental hazards. Acknowledgement
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We thank the Land and Resources Survey Project of China Geological Survey (GZTR20060201, and 1212010511218) for financial support. The study was also
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financially supported by Key Laboratory of Ecological-geochemistry, Ministry of
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Land and Resources of the People's Republic of China. The financial support was
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gratefully acknowledged. Field assistance in collecting samples along Changjiang basin from Institute of surficial Geochemistry of Nanjing University, National Research Center for Geoanalysis of Hohai University, and China West Normal University are highly appreciated. We are also grateful to the anonymous reviewers whose constructive comments were critical to improving the scientific quality of our original manuscript. References Ammann, A. A., 2002. Speciation of heavy metals in environmental water by ion
ACCEPTED MANUSCRIPT chromatography coupled to ICP-MS. Anal. Bioanal. Chem. 372, 448–452. Brick, C. M., Moore, J. N., 1996. Diel variation of trace metals in the upper Clark
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Fork river, Montana. Environ. Sci. Technol. 30, 1953–1960. Buffle, J., Van Leeuwen, H. P., 1992. Environmental particles: 1. In Environmental
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Analytical and Physical Chemistry Series. Lewis Publishers, London, 554p.
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CGS (China Geological Survey), 2005. Specification of Multi-purpose Regional
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Geochemical Survey (DD2005-01) (in Chinese).
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Che, Y., He, Q., Lin, W.Q., 2003. The distributions of particulate heavy metals and its indication to the transfer of sediments in the Changjiang Estuary and
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Hangzhou Bay, China, Marine Pollution Bulletin 46(1), 123-131. Chen, J.S., Wang, F.Y., Xia, X.H., and Zhang, L.T., 2002. Major element chemistry
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of the Changjiang (Yangtze River). Chemical Geology, 187, 231-255.
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Dai, W. M., 1994. Species of Heavy Metals of Suspended Solids in Changjiang
AC
Estuary. Shanghai Environmental Science, 13(11), 7-9, 35 (in Chinese with English abstract). Erel, Y., Morgan, J. J., Patterson, C. C., 1990. Natural levels of lead and cadmium in remote mountain stream. Geochim. Cosmochim. Acta 55, 707–719. Förstner, U., Ahlf, W., Calmano, W., Kersten, M., 1990. Sediment criteria development, In: D. Helling, P. Rothe, U. Forstner, P. Stoffers (Ed.), sediments and environmental geochemistry. Springer Verlag. Foster, I. D. L., Charlesworth, S. M., 1996. Heavy metals in the hydrological cycle:
ACCEPTED MANUSCRIPT trends and explanation. Hydrol. Process. 10, 227–261. Gaillardet, J., Viers, J., Dupre, B., 2003. Trace elements in river waters. In: James I.
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Drever (Eds.). Holland, H., D., Turekian, K. K. (Executive Editors), Treatise on Geochemsitry Vol 5: Surface and Ground Water, Weathering, and Soils.
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Elsevier, pp.225-272.
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Koshikawa, M.K., Takamatsu, T., Takada, J., Zhu, M., Xu, B., Chen, Z., Murakami,
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elements in the yangtze estuary in 1997–2002: background data before the closure of the three gorges dam. Estuarine, Coastal and Shelf Science 71, 26-36.
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Li, S., Zhang, Q., 2010. Risk assessment and seasonal variations of dissolved trace elements and heavy metals in the upper han river, china. J. Hazard Mater. 181,
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Morel, F. M. M., Hering, J. G., 1993. Principles and Applications of Aquatic
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Chemistry. Wiley, New York. Mouvet, C., Bourg, A. C. M., 1983. Speciation (including adsorbed species) of copper, lead, nickel, and zinc in the Meuse River: observed results compared to values calculated with a chemical equilibrium computer program. Water Res. 6, 641–649. Müller, B., Berg, M., Yao, Z. P., Zhang, X. F.,Wang, D., Pfluger, A., 2008. How polluted is the Yangtze river? Water quality downstream from the Three Gorges. Sci. Total Environ. 402, 232-247.
ACCEPTED MANUSCRIPT Müller, B., M. Berg, B. Pernet-Coudrier, Qi W., Liu H., 2012. The geochemistry of the Yangtze River: seasonality of concentrations and temporal trends of loads.
Global
Biogeochemcial
Circles
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1971. Umsch. Wiss. Tech. 79 (24), 778-783.
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Müller, G., 1979. Schwermetalle in den Sedimenten des Rheins - Veranderungen seit
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Pekey, H., 2006. The distribution and sources of heavy metals in Izmit Bay surface
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sediments affected by a polluted stream. Marine Pollution Bulletin 52, 1197–1208.
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Qiao, S., Yang, Z., Pan, Y., Guo, Z., 2007. Metals in suspended sediments from the changjiang (Yangtze river) and huanghe (yellow river) to the sea, and their
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comparison. Estuarine, Coastal and Shelf Science 74, 539-548.
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Shan, L. L., Yuan, X. Y., Mao, C. P., Ji, J. F., 2008. Characteristics of heavy metals
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ACCEPTED MANUSCRIPT Stumm, W., 1993. Aquatic colloids as chemical reactants: surface structure and reactivity. Coll. Surf. A73, 1–18.
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Sutherland, R. A., 2000. Bed sediment associated trace metals in an urban stream Oahu. Hawaii. Environ. Geo. 39 (6), 611-627.
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Turekian, K.K., Wedepohl, K.H., 1961. Distribution of the elements in some major
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units of the earth’s crust. Geological Society of America Bulletin 72(2), 175-192.
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Wang, L., Wang, Y. P., Xu, C. X., An, Z. Y., Wang, S. M., 2010. Analysis and
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evaluation of the source of heavy metals in water of the River Changjiang. Environ. Monit. Assess. 173, 301-313.
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Wang, Z., Liu, C., 2003. Distribution and partition behavior of heavy metals between dissolved and acid-soluble fractions along a salinity gradient in the changjiang
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Xia, X. Q., Mao, Y. Q., Ji, J. F., Ma, H. R., Chen, J., Liao, Q. L., 2007. Reflectance
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spectroscopy study of Cd contamination in the sediments of the Changjiang River, China. Environmental Science Technology 41, 3449–3454. Zhang, C., Selinus, O., 1997. Spatial analyses for copper, lead and zinc contents in sediments of the Yangtze river basin. Sci. Total Environ. 204, 251-262. Zhang, Y. Y., Zhang, E. R., Zhang, J., 2008. Modeling on adsorption–desorption of trace metals to suspended particle matter in the Changjiang Estuary. Environmental Earth Sciences 53(8), 1751-1766. Zhang, J., 1999. Heavy metal compositions of suspended sediments in the
ACCEPTED MANUSCRIPT Changjiang (Yangtze River) estuary: Significance of riverine transport to the
AC
CE
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ED
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ocean. Continental Shelf Research 19, 1521–1543.
ACCEPTED MANUSCRIPT Table captions Table 1 Statistics of trace element concentrations in the raw water samples.
PT
Table 2 Statistics of trace element concentrations in the 0.45 μm filtrated water samples.
RI
Table 3 Statistics of trace element concentrations in the 0.20 μm filtrated water
SC
samples.
NU
Table 4 Summary statistics of the trace element concentrations in the suspended
MA
sediments.
Table 5 EF and Igeo values of the element concentrations in the suspended sediments.
ED
Table 6 Seasonal variation of SSC and the element concentrations in the suspended
AC
CE
PT
sediments.
ACCEPTED MANUSCRIPT Figure captions
PT
Fig. 1 Sketch map of the sampling locations Sampling locations of the main channel from upstream to downstream: 1-Tuotuohe, 2-Yushu, 3-Dege, 9-Qiaojia, 10-Yibin, 11-Luzhou,
RI
4-Batang, 5-Zhongdian, 6-Panzhihua, 7-Panzhihua, 8-Yuanmou,
19-Zhicheng,
20-Gong'an,
21-Yueyang,
22-Yueyang,
23-Jiayu,
24-Wuhan,
NU
18-Yichang,
SC
12-Chongqing, 13Chongqing, 14-Fuling, 15-Wanzhou, 16-Wushan, 17-Three gorge reservoir,
MA
25-Huangshi, 26-Jiujiang, 27-Pengze, 28-Anqing, 29-Tongling, 30-Wuhu, 31-Ma'anshan, 32-Nanjing,
ED
33-Zhenjiang, 34-Jiangyin, 35-Nantong, 36-Chongming Island.
PT
Fig. 2 Seasonal variation of element partitioning.
AC
CE
Fig. 3 Proportions of the trace element fractions.
Fig. 4 Cd, Pb and Zn in the three fractions compared with SSC and pH from the flood season. The sampling location numbers are the same as those in Fig. 1.
Fig. 5 Cd, Pb and Zn in the three fractions compared with SSC and pH from the dry season. The sampling location numbers are the same as those in Fig. 1, with the absence of points 1-3.
ACCEPTED MANUSCRIPT Fig. 6 As and Se in the three fractions from the flood season. The sampling locations
PT
are the same as those in Fig. 1.
Fig. 7 As and Se in the three fractions from the dry season. The sampling locations
AC
CE
PT
ED
MA
NU
SC
RI
are the same as those in Fig. 1, with the absence of points 1-3.
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
MA
NU
Figure1
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
Figure2
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
MA
NU
Figure3
AC
CE
PT
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure4
AC
CE
PT
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure5
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
Figure6
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
Figure7
ACCEPTED MANUSCRIPT
μg/L)
A s
Detectio n limit
S e
o
1 .0
C
P b
0
n
0
.2
.05
Z u
0 .1
C
0 .2
percentile
2 .91
25th
.80
0
.43
percentile
0.65
9
.27
9.26
0
2.23
4.96
.47
7.69
3 6.52
1 .53
1 .64
1 6.65
5 .35
1 7.43
2 .03
2
7
0
1
1 7.35
.28
.62
.35
1
0
1
6 .43
46.07
.30
5.63
7
5
1
2 .85
5.61
.19
1.58
2
.58
.67
0 .87
0
6
2
1
1
.71
43.09
.75
.33
9.91
1
.65
.30
0 .51
0
2
2
9
3
0
8.27
4.45
.26
5
0
0
1
0 .24
.09
.16
1.31
7
2
.62
.16
8.78
5.70
.88
2.97 2
1
0
3 CV (%)
3
0.41
2
0
0
5
0 .1
.46
.09
.30
.1
0
2
8
0
.05
.04
.21
1
7
.46
.35
2 Std. D
.31
.81
56.80
Mean
.63
1
2
AC
Maximu
.93
1
N i
0
.01
.34
2
3
2
.96
1
1
.52
.91
.72
.62
r
.05
0
1
.85
0
CE
90th
0
0
.79 6
percentile
.24
PT
75th
m
.42
0
0 .49
.82
0
4
percentile
.13
ED
50th
0
.29
.43
.42
0
3
percentile
.06
0
SC
10%
.16
0
NU
.90
0
MA
m
0
C
0
RI
The flood season (n=76) Minimu
d
0 .2
C
PT
Element(
6 .48
2 .40
1 .21
The dry season (n=73) Minimu m
0 .68
0 .06
0 .04
0 .05
1 .40
0 .33
0 .01
0 .88
0 .48
ACCEPTED MANUSCRIPT
2
percentile
.09
50th
75th
.50
Maximu m
4 .62
0
PT
.21
0
CE .40
3
.53
.88
.53
26.90 1 5.67
6 .12
3
3 2.75
1 .84
2 .09
8.67 2 .04 2
3.79 1
.87
2
1
3 .41
2 .31
Table 1 Statistics of trace element concentrations in the raw water samples.
AC
.75
0.28
.53
2
1
0
2 .29
2
0
1
2 .00
95.00
.29
6.08
1
2
7
1 .38
3.72
.78
.02
.65
0
1 14.70
2
3.19
.75
2
3
.32
1
0 .85
0
.23
0.38
1
0
4
0 .73
.63
.08
2
4
.24
.05
.45
4.59
4.66
.91
0
1
4
0
.60 6
CV (%)
7.41
ED
.86
.82
2
1
1
0
3
.28
4.09
.82
3
4
Std. D
1 .09
6
3 .03
0 .90
9.70
Mean
.60
1 .78
.23
0 .03
3
1
0
1 .24
.96
.93
0
7
percentile
.93
.39
.70
.41 0
0
.50
.33
90th
.16 0
5
percentile
0
.37
.88
.54
0
2
percentile
.08
2
PT
25th
.08
0
RI
.26
0
SC
percentile
0
NU
1
MA
10th
1 .67
ACCEPTED MANUSCRIPT
g/L)
S
s Detection
e
1
limit
C o
.2
Z
b
0
.0
P
0 .05
n 0
.1
0
.2
0
.48
25th
2
percentile
.38
50th
3
percentile
.65
75th
4
percentile
.83
90th
7
0
0
CE .30
AC
percentile
2
.05
.20 0 .41 0
0 .06
.72
.37
0
.11
0
.14
0
0
.29
.52 0
.95
3
3
.59 1
.75
0
1 .06
.03
.64
.07
.07
.13
.08
0
1
0
0
1 .61
.20
2
0
.97 0
6
0
.68 0
4
.1
.05 0
1
0
.05
.01
1 1.35
7
0
6 .94
0
.00
2 .54
1
.50
1
.62
.81
1
.49
0
0
0
C r
.05
1
.09
.52
0
.85
.43
NU
percentile
.02
MA
1
PT
10th
.05
ED
.34
.2
0
Minimum
d 0
SC
0
C
u
0
The flood season (n=76) 0
C
PT
A
RI
Element(μ
2 .46
0
2
N i 0 .1
0 .05 0 .32 0 .54 0 .93 2 .25 3 .08 4
Maximum
55.60 7
.35
.98
0
.87 0
2.13 1
0.26
4
.64 2
0.23 0
1
.28 1
Mean .86 2
.78
.31
0
.47 0
.55 1
.71
4
.09 2
.51 0
2
.45 1
Std. D 9.24 3
.59
.38
0
.62 1
.50 1
.33
0
.10 0
.56 1
1
.17 0
CV (%) .72
.75
.21
.10
.99
.86
.01
.70
.81
The dry season (n=73) 0 Minimum
.22
0 .02
0 .02
0 .05
0 .95
0 .14
0 .01
0 .59
0 .40
ACCEPTED MANUSCRIPT
percentile
.61
50th
2
percentile
.61
75th
4
percentile
.56
90th
6
percentile
.04 4
Maximum
8.70 4
Mean
.06
Std. D
.02
AC
CE
1
CV (%)
.28
.48
0 .06
.37
.08
.17
0 .48
0 .30 2 5.18
.77 2
.95
.12 5
.79
1 .46
.69
2
.81
0
.11 3
.68
0
4 4.51
.07 2
.43
.20
.12
.43 2
.11
.12
0 .78 1 .27 2 .02
2
2 6.55
6
1 .55
7 .56
2
.67
1
.34 0
0
1
9.82 0
5
.58
5.70 2
.58
1
1.78
.52
2 .52
0
0
1 .25
.06
2 4.10
0
1
0 .98
.03
9 .56
1
.93
1
49.10 0
.03
1
2.39
8
0
1
.06
1
.93
.51
6 .68
.52
0
.51
0
0
0
3 .58
.77
3 .58
0
0
.51
2 .60
.46
0 .78
0
0
0 .53
.71
.30
0
PT
6
0
.16
0
PT
1
.04
1
RI
25th
.06
0
SC
.02
0
NU
percentile
0
MA
1
ED
10th
3 .19
1 .19
2 .06
Table 2 Statistics of trace element concentrations in the 0.45 μm filtrated water samples.
ACCEPTED MANUSCRIPT
Table 3 Statistics of trace element concentrations in the 0.20 μm filtrated water samples. A
S
P
Z
Co Detection
e 1
limit
b 0
.0
.2
0.
n
05
0 .1
.2
The flood season (n=76)
.3
10th
.10 1
percentile
.2
.30
0
4
0
CE
75th
.61
.1
6
AC
90th
.81
Maximum
.7
.23 2
43.6
.58 7
Mean
.2
.68
Std. D
7.9
.47 3
CV (%)
.9
.69
0
.35 0 .59
.91
.32
.34
.86 0 .80
1.
0 .93
0 .90 1 .40
.51 4 .27
.13 2 .03 1 .55
.87
0 .76
0 .50
0 .28
0 .68
0 .46
0 .84
0 .74
1 .21
1 .78
2 .06
2 .72
1 8.16
4 .00
0
1 .42
1 .22
0
2 .50
1 .03
0 .954
0 .06
0
.090
0
.03
0
.094
0
0
0
.609
i
.1
0
.176 6
.1
0
.128
N
0
0
.074 2
r
0
.043
2 .84
.05
.008
3 .27
0.
.66
1 4.65
0
0
C
0
.001
7 .22
3
.34
4 .38
2
0
2 .24
0
.2
1 .26
0.
105
0
1
.01
1.
215 0
.26
0.
195 0
0
C d
0
.35
0.
163 0
2
126
493 2
.17
0.
180 1
0
0.
098
PT
.2
percentile
044
0
3
percentile
0.
ED
.0
50th
percentile
0
2
percentile
009
.20
25th
0.
NU
Minimum
0
MA
0
0
u
RI
s
SC
g/L)
C
PT
Element(μ
1 .75
0 .84
ACCEPTED MANUSCRIPT The dry season (n=73) 0
0
0.
0
0
0
0
0
0
Minimum
25th
.03 1
percentile
.5
0 .20
50th
2
percentile
.4
0
3 .8
90th
.40 5
percentile
.2
.60
3 Mean
.39
CE
.7
6
.0
AC
.24
0
0
.48
1
45
0 .41
2
0 .27
3
.18 5
1
7
0
.52
.40
.01
.78 1
.85
.41 0 .40 0
2 .08
.025
.92
3.74
.09 5 .03 2
.12
0 .61
1 .50
0 .72
1 1.08
1 .10
1 2.82
1 .87
2 3.33
2 5.91
0
5 .27
1 .40
0 .349
2
1
1
.159
0 .50
0
.967 2
.89
0
.296 4
0
0
.090 2
.33
0
.055
1 8.07
6.
.56
7 .06
2.
1
1 30.20
0
.73
.55
0 .025
0
.15
0.
83 1
.15
24
ED
.42
PT
8.1
0
0.
17
3
Maximum
Std. D
10 0
4
0.
.014
1 .45
0. 07
0
.07
0. 04
.30
75th percentile
03
0
.13
PT
.7
0.
.92
RI
percentile
0
.01
SC
0
01
NU
10th
.01
MA
.1
5 .99
3
2
.10 1
2
CV (%)
.6
Backgoun
.24
da
0 .62
a
28 0
.07
.96
0.
.56
148
0 .079
.41
0
.195
.60
1 .48
.14
0
.21
.080
Background values of the world average from Gaillardet et al. (2003).
0 .70
0 .801
ACCEPTED MANUSCRIPT Table 4 Summary statistics of the trace element concentrations in the suspended sediments.
(mg/kg)
A
S
s
e
C
P
o
Z
b
n
C u
Flood season (n=76) 3
0
5
2
6
7.55
50%
.32 2
percentile
3.07
75%
.59 3
9.43
Maximu m
1 .39
1 98.64
8
.76 3
Mean
.30
1
CV
AC
.08
.31
4.5
1
82.1
1
4
34.2
75.6
0
2 08.4
1 .34
0 .54
1 33.6
5 0.19
1 .70
1 06.28
2
0 .49
5 48.5
.99
5 6.30
2
8 8.29
1 41.1
9.54
5 0.21
2
2 92.50
1 86.7
.35
7
1 26.2
.49
4 0.98
1
1 07.03
1
307.0
1
2
1 07.2
.23
1 7.41
1
8 2.30
4 5.0
.00
N i
0
6
1.09
8
C r
.11
1
55.5
86.5
9.93
1
2.07
6.8
2
3.33
1
CE
6.05
4.01
5
2
0.23
PT
percentile
7.09 0
7.9
1
2
SC
percentile
0
5.7
NU
1
.02
MA
25%
.14
ED
.90
d
RI
Minimum
C
PT
Element
0 .52
0 .30
Dry season (n=73) 5
0
4
6
5
2
0
7
1
Minimum .19 25% percentile
1 7.54
50% percentile
.68
8.56
.21
1
5.09
4.15
4.57
4 9.13
2
0.06 1
.89
.66
4.33 1
4 7.02
.14 0
2
75% percentile
.25
1 85.51
2
63.46
2 02.47
5 6.84
8 .77
4 4.57
2
2 28.61
1 51.34
.21
3
2.46
1
1 05.94
54.40
0.34
.21
2
1 21.30
6 9.04
6 6.68
.51
3 45.91
6 6.05
ACCEPTED MANUSCRIPT Maximu m
4 93.9
6 .15
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7
0.95 1
1 445.5
2
3 510.3
1
9 73.31
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3
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1 272.8
2
6
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Mean .64 1
0.32 0
29.75 0
77.11 1
87.17 1
1
CV .79
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SC NU MA ED PT CE AC
69.88 1
.52
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.40
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4.37
8.60 0
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ACCEPTED MANUSCRIPT
Table 5 EF and Igeo values of the element concentrations in the suspended sediments. The flood season
Me
Me E
I geo
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Tributaries
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Main channel
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Tributaries
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Main channel
The dry season
ACCEPTED MANUSCRIPT Table 6 Seasonal variation of SSC and the element concentrations in the suspended sediments. Sam.
D
S
C
P
C
C
Zn
NJSS 0611
N ov-06
NJSS 06121
ec-06
06122
0701
ec-06
0703
AC NJSS
0705
0706 NJSS 0707
0708
PT 2.0
1
Ju
6
1
A
7 2.89
1 24.0
9.41
7.97 7
2.25
3.85
06.23 1 13.79 2
.74 17
1 09.66
1 .78
16 9.00
1
2
22
5
11.80
.01
9.50
1
1
28
5
18.48
.80
8.88
1
2
23
7
17.63
.24
6.38
1
2
25
5 9.24
6.59
52.0
ug-07
7
17.25
.42
7.13
1
1
37
6 3.54
4.62
04.2
l-07 NJSS
1
Ju n-07
6
1 27.75
.99
3.25
1 15.61
.68
1.38
6.41
2
2
83
6
20.40
.78
0.50
1
1
12
7
8.25
5.04
56.25
7
6
2
M
7
6.78
5.0
ay-07 NJSS
3
12
22.38
4.13
7.34
0.1
A
pr-07
6
1
.05
7
5.74
9.01
28
4.25
0.18
r
.96
7
6
1
M
ar-07
NJSS
1
1.3
CE
NJSS
2.43
5.78
3.1 Fe
b-07
7.16
31 0.50
9
6
1
Ja
NJSS
6
2
7.8
9 6.39
6.52
0.8
n-07
0702
1.0
D
NJSS
8.14 3
D
NJSS
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3.8
6
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ct-06
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d
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0610
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b
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NJSS
u
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SC
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ate
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No.
1 08.63
1 .63
2 32.38
ACCEPTED MANUSCRIPT NJSS 0709
Se p-07
6 1.8
NJSS
7 2.04
O
6 2.21
6
18 9.88
5
1 .77
20
1 08.36
1
1
ct-07 NJSS
7.62 N
8.86 7
9.63 6
22
ov-07 NJSS
3.92
D
4.79 6
6
ec-07
6.83
7.75
0.63
11.36 1
.57
24
SC
-
.38
1 10.39
1
1 16.13
CE
PT
ED
MA
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Note: SSC was given in mg/L with the element concentrations in mg/kg.
AC
0712
5.88
RI
0711
.54
PT
0710
ACCEPTED MANUSCRIPT Highlights Dissolved and particulate partitioning of trace elements in the
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Changjiang water system was studied. Metals and metalloids differ in their dissolved and particulate
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partitioning characteristics.
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For metals, the particulate phase is the dominant one varying with
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SSCs and water pH.
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The dissolved phase is the dominant form of transportation for
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metalloid elements.
S0375-6742(14)00179-4 doi: 10.1016/j.gexplo.2014.05.013 GEXPLO 5389
To appear in:
Journal of Geochemical Exploration
Received date: Revised date: Accepted date:
28 December 2012 13 May 2014 19 May 2014
Please cite this article as: Yang, Zhongfang, Xia, Xueqi, Wen, Yubo, Ji, Junfeng, Mao, Changping, Hou, Qingye, Yu, Tao, Dissolved and particulate partitioning of trace elements and their spatial-temporal distribution in the Changjiang River, Journal of Geochemical Exploration (2014), doi: 10.1016/j.gexplo.2014.05.013
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Dissolved and particulate partitioning of trace elements and their spatial-temporal distribution in the Changjiang River
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Zhongfang Yanga,b, Xueqi Xiaa,*, Yubo Wena,c, Junfeng Jib, Changping Maoc,d,
School of Earth Sciences and Resources, China University of Geosciences,
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a
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Qingye Houa, Tao Yua
National Research Center for Geoanalysis, Key Laboratory of Ecological
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b
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100083, Beijing, People’s Republic of China; E-mail: [email protected];
Geochemistry, Ministry of Land and Resources, Beijing, 100037, China Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing
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c
University 210093, Nanjing, China
School of Earth Sciences and Engineering, Hohai University 210098, Nanjing,
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d
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China
Corresponding Author: X. Xia
School of Earth Sciences and Resources, China University of Geosciences, 100083, Beijing, People’s Republic of China; E-mail: [email protected]; TEL: +86-10-82320527
ACCEPTED MANUSCRIPT ABSTRACT Samples of raw water, 0.45 μm filtrated water, 0.20 μm filtrated water, and
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0.45 μm filtrated suspended sediments were obtained and analyzed for trace elements (e.g., Se, As, Cd, Pb, Zn, and Cu) at 76 locations in the main channels
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and tributaries of the Changjiang river. The partitioning of the trace elements in
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the particulate and dissolved load, as well as their spatial and seasonal
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distributions, was investigated. We found that the concentrations of As, Se, Pb,
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and Zn in the dissolved phase (<0.20 μm) were much higher than those of the world averages, and Cd, As, Pb, and Se were highly enriched in the suspended
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sediments. Metals and metalloids differ in their partitioning characteristics. For the metal elements (e.g., Cd, Pb, Cu, and Pb), the particulate phase is the
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dominant form during transportation. The spatial and seasonal variation of the
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total metal loads and their partitioning are controlled by suspended sediment
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concentrations (SSCs) as well as water pH, which controls the absorbance of the metals by the suspended particles. The particulate phase of the metals is much higher during the flood season, when there is high SSC, especially in the upstream of the Three Gorges Dam (TGD), but the dissolved phase increases gradually down to the lower stream with the decreased water pH. For the typical metalloid elements, e.g., As and Se, the dissolved phase is the dominant form of transportation. In the flood season, the total loads of As and Se are higher with a higher spatial variation than those in the dry season. The highest total As load
ACCEPTED MANUSCRIPT occurres in the most upstream part of the river, and the highest Se load appeares in the section between Luzhou and the TGD. The results also indicate that large
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amounts of the heavy metals have deposited on the bottom of the Three Gorges reservoir. So, more work should been done to evaluate their potential
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environmental hazards as they may release suddenly with water acidification or
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other disturbances.
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KEYWORD: trace elements; dissolved phase; particulate phase; partitioning; the
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Changjiang (Yangtze) River
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1. Introduction
The Changjiang River (Yangtze River) is the world’s third-longest river (6300 km)
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and fourth largest in terms of water discharge (Chen et al., 2002). Covering an area of
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1.80×106 km2, the upper part of the Changjiang runs through the Tibetan Plateau, while
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its middle and lower parts run through one of the most populated and economically developed areas of the world. Consequently, the river receives many inputs of both natural and anthropogenic origin (Wang et al., 2010). Heavy metals (e.g., Cd, Pb, Cu, and Zn) and other trace elements (e.g., As and Se) are among the pollutants in Changjiang examined in former studies (Zhang and Selinus, 1997; Zhang, 1999; Che Y. et al. 2003; Wang and Liu, 2003; Koshikawa et al., 2007; Qiao et al., 2007; Xia et al. 2007; Müller et al. 2008, 2012; Shan et al. 2008; Zhang et al., 2008; Li and Zhang, 2010; Song et al., 2010; Wang et al., 2010). In aquatic
ACCEPTED MANUSCRIPT environments, trace elements exist in almost all the environmental media, including water, and suspended and bottom sediments. The trace elements in the river water of the
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Changjiang have been evaluated by Müller et al. (2008), Koshikawa et al. (2007), and Wang et al. (2011). Suspended sediment is another pathway of trace element
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transportation. Qiao et al. (2007) and Müller et al. (2012) investigated the seasonal trend
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of the trace element loads in suspended sediments based on the observation of Datong,
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one of the important hydrological stations at the lower reaches. Spatial distributions of
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trace elements in suspended sediments have been studied by Che et al. (2003) in the Changjiang estuary. Koshikawa et al. (2007) and Müller et al. (2008) have studied the
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same from the Three Gorges Dam to the estuary. Song et al. (2010) investigated the spatial variations of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in sediment and
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suspended solids for 75 locations distributed on the main channel and tributaries of the
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Changjiang and found that Panzhihua, the northeast of the Yunnan Province, and the
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Nanling mining area are the main sources of heavy metals, and that these metals are enriched in Poyang Lake and the Three Gorges Reservoir. There are various sources, including natural and anthropogenic, of trace elements in aquatic environments (Foster and Charlesworth, 1996). After entering surface waters, the trace elements are transported in very complexed forms or species (Gaillardet et al., 2003). Knowing the concentrations of the individual species of a given element in waters is of crucial importance to predicting their toxicity and bioavailability (Morel and Hering, 1993). However, it is rarely possible to measure the concentration of an
ACCEPTED MANUSCRIPT individual complex (Ammann, 2002). Therefore, the proportion of elements corresponding to the different chemical forms must be calculated, depending on the
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total concentration, pH, Eh conditions, the major element chemical composition of the water, and the complexation constants of the assumed complexes. There is another way
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to study the chemical form of trace elements, which is to operationally define
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“particulate” and “dissolved” fractions by filtration with 0.20μm or 0.45μm filters
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(Buffle and Van Leeuwen, 1992).
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For Changjiang, Zhang et al. (2008) studied the uptake and release of trace metals (Cu, Ni, Zn, Cd, and Co) in estuaries using river and sea end-member waters and
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suspended particulate matter. They demonstrated that dissolved concentrations of trace metals in the estuary can be modeled based on the metal concentration in suspended
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particulate matter (SPM), pH and salinity using a Kurbatov adsorption model. By
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sampling across a salinity gradient of 0.15‰ to 19.0‰ in surface waters of the
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Changjiang Estuary, Wang and Liu (2003) determined the concentrations of dissolved heavy metals and found that the distribution of acid-soluble heavy metals in the Changjiang estuary is mainly controlled by the concentration of suspended matter and salinity. It has been indicated by former studies (Gaillardet et al., 2003; Morel and Hering, 1993; Ammann, 2002; Zhang et al., 2008; Dai, 1994; Wang and Liu, 2003) that partitioning of the trace elements between the dissolved and particulate phase is influenced by many factors, including suspended sediment concentration (SSC), pH,
ACCEPTED MANUSCRIPT temperature, and salinity. Thus far, however, there is a lack of observations of the trace element partition of the whole Changjiang water system under the various water
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environment conditions. In 2007-2008, we carried out a survey of 76 locations in the main channel and
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tributaries from the Tuotuohe to the estuary of the Changjiang River. Samples of the
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raw water, 0.45 μm filtrated water, 0.20 μm filtrated water, and 0.45 μm filtrated
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suspended sediments were analyzed for trace elements (e.g., Se, As, Cd, Pb, Zn, and
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Cu). Samples of 0.45 μm filtrated water and suspended sediment were also collected monthly at Nanjing in the lower reaches of the river. Based on the observations, this
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paper aims to investigate the partitioning of the trace elements in the particulate and
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dissolved load transported in the river, especially their spatial and seasonal distributions.
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2.1 Sampling
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2. Materials and methods
Samples were collected during two 45-day periods from July to August 2007 (summer, the flood season) and November 2007 to February 2008 (winter, the dry season). Seventy-six sampling sites were assigned, with 36 located on the main channel labeled 1-36 and 40 on the tributaries labeled T01-T40 (Fig. 1). Three types of water samples were obtained: raw water samples and water samples filtrated through 0.45 μm and 0.20 μm filters. The raw water samples were collected in situ from the middle of the river using a boat with 50 ml disposable
ACCEPTED MANUSCRIPT polyethylene narrow-mouth bottles with screw caps. These samples were acidified to pH≈1.6 using high-purity HNO3. River water for filtration was collected using a 20 L
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washed plastic container after temperature (T) and pH were measured in situ using a thermometer and a portable pH-meter. These samples were then transported to a
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room and filtered in a few hours through pre-washed 0.45 μm cellulose membrane
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disc filters using an air pump. Then, 0.45 μm filtrated water samples were collected
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using 50 ml polyethylene bottles and then acidified with high-purity HNO3. The
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remainder was filtrated again with pre-washed 0.20 μm cellulose membrane disc filters, and the 0.20 μm filtrated water was also sampled using 50 ml bottles and
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acidified. The raw water, 0.45 μm filtrated water, and 0.20 μm filtrated water samples for laboratory trace element analysis were stored at approximately 4◦C
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before analysis. To provide reliable and accurate data, cleansing techniques were
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used for handling and analyzing the samples. All materials coming in contact with
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the samples were acid washed and stored in double polyethylene bags before use. The parallel samples included in these samples were taken at every six sampling sites to ensure the best results. Samples of suspended sediment were obtained from the 0.45 μm cellulose membrane disc filters after filtration. The suspended solid samples on the filter were removed in the laboratory using deionized water, and the solution containing the suspended solids was evaporated at 40 °C. Then, the solid residue was weighed and SSCs deduced by dividing the weight by the volume of the water having been
ACCEPTED MANUSCRIPT filtrated to obtain it. The volume of the water was measured by a measuring cup
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before filtration.
2.2 Chemical analysis
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The samples collected, including both the water and suspended sediments, were
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analyzed at the Ministry of Land and Resources P.R.C. Hefei Mineral Resources
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Supervision and Testing Center.
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For water samples, the determination of Ni, Co, Zn, Cu, Pb, Cd, and Cr was carried out by inductively coupled plasma-mass spectrometry (ICP-MS, IRIS
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Advantages, USA), in which Co were determined by the standard addition methods, while Ni, Zn, Cu, Pb, Cd, and Cr were monitored by standard sampling
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(multi-element standard, lot number GBW(E)080194). As and Se were determined
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by atomic fluorescence spectroscopy (AFS) using standard addition methods. A set
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of analytical quality control schemes was used with reference to the Specifications of the Multi-Purpose Regional Geochemical Survey carried out by the China Geological Survey (CGS, 2005). The relative errors for the analysis of the standard solution were less than 5%. The recovery of the standard addition was greater than 93% for Co and 95% for As and Se. Data below the analytical detection limits were set to a value of half the detection limit in constructing all plots and statistical calculations. For analysis of the suspended sediments, a small quantity (~1 g) of samples were ground to an 80-mesh size (0.2 mm) and then dissolved to HCl, HNO3, HClO4,
ACCEPTED MANUSCRIPT and HF under high pressure and temperature. As and Se were measured using an AFS 230E Atmospheric Fluorescence Spectrometer. Cd was measured using an AAS
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ZEEnit60 graphite-furnace atomic absorption spectrometer (Analytik Jena AG, Germany). Al2O3 was analyzed by ICP-OES. Co, Cr, Cu, Ni, Pb and Zn were
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measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) by
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Thermo ICP-MS X SERIES (Thermo Fisher Scientific, America). The analyzed data
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were assessed for accuracy and precision using a quality assurance and quality
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control (QA/QC) program that included reagent blanks and duplicate samples with 8% suspended solid samples, respectively, and using certified geochemical reference
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materials (GSS-2, GSS-3, GSS-4, GSS-6) with a deviation below 5%. 2.3 Assessment of sediment contaminations
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The enrichment factor (EF) was calculated for the trace elements using:
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EF [Ci / C Al ]sample /[(Ci / C Al )crust ] Where (Ci/CAl)
sample
(1)
is the ratio of the concentration of the element of concern
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(Ci) to that of Al (CAl) in the sample, and (Ci/CAl)crust is the same ratio in an unpolluted reference sample (Pekey, 2006). Elements that are naturally derived have an EF value of nearly unity, while elements of anthropogenic origin have EF values of several orders of magnitude. According to Sutherland (2000), six categories are recognized: <1 background concentration, 1-2 depletion to minimal enrichment, 2-5 moderate enrichment, 5-20 significant enrichment, 20-40 very high enrichment and > 40 extremely high enrichment. The Index of Geoaccumulation (Igeo) was also used as a quantitative measure of the degree of pollution in aquatic sediments (Müller, 1979; Förstner et al., 1990). Igeo
ACCEPTED MANUSCRIPT uses the relationship between the measured concentration (Ci) of the element in the sediment (<2 μm fraction) and the background concentration (Bi) in the shale
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sediment (Eq. (2)), and 1.5 is a correction factor due to lithogenic effluents.
I geo log2 [Ci /(1.5 Bi )]
(2)
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where Ci is the measured concentration of heavy metal “i” and Bi is the background
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value of heavy metal “i”. Each heavy metal may be classified as unpolluted (Igeo<0),
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unpolluted to moderately polluted (0
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moderate to strongly polluted (2
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used in the Igeo and EF calculations were from Turekian and Wedepohl (1961). 2.4 Investigation of seasonal variation
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To investigate the seasonal variation of the element partitioning, a stationary
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sampling location was selected in Nanjing, which is at the lower reaches of the
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Changjiang river, and the water samples were collected monthly between Oct 2006 and Dec 2007. The raw water was sent to the laboratory in a few hours and filtrated with pre-washed 0.45 μm cellulose membrane disc filters. The filtrated water was analyzed for Cu, Pb, Zn and Cd with the methods described in section 2.2. Samples of suspended sediments were obtained from the filters and treated with the same procedure as in section 2.1 and were analyzed as described in section 2.2.
3. Results and discussion
ACCEPTED MANUSCRIPT 3.1 Trace element in water samples It is well known that trace element concentrations in continental waters depend
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on the size of the pore filters used to separate the particulates from the dissolved fraction. In the literature, trace element abundances in river waters are usually given
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by those filtrated using either 0.2 μm or 0.45 μm filters (Gaillardet et al., 2003).
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Summary statistics of the trace element concentrations in the raw water, 0.45 μm
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filtrated water, and 0.20 μm filtrated samples are shown in Tables 1, 2, and 3
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respectively. The statistical results in the flood season were based on the analytical data from 76 sampling locations both in the main channel and the tributaries, as
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shown in Fig. 1. Three samples (point 1, 3, 4) were absent in the dry season (November 2007 – February 2008) because of the frozen weather. It should be noted
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that the raw water samples in the study were acidified during collection, and the
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sediments were deposited in the bottles for several days before analysis of the
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supernatant. Thus, the data for the raw water samples are actually the labile fraction or acid soluble phase, including those dissolved in the water, absorbed by the suspended particles, in the carbonates and coatings, and in other forms that can be extracted by acid from the suspended matter. Thus, the data from the raw water samples are comparable to the acid-soluble heavy metal concentrations given by Wang and Liu (2003). The spatial variance of dissolved trace metals (i.e., the 0.45 μm filtrated metals) was reported by Wang et al. (2010), who showed that high concentrations of Cu, Ni,
ACCEPTED MANUSCRIPT Fe, Co, Sc, and Al were mostly in the upper reaches. Some tributaries, such as Puduhe, Xinjiang, Xiangjiang, Shun’anhe and Qingtonghe, also have high
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concentrations of dissolved Cd, Hg, Pb or As because of mining activities. Gaillardet et al. (2003) compiled the trace element concentrations in the dissolved loads of the
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world large rivers based on 0.20 μm filtrated data and determined the background
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values of the world average, which are appended in Table 3. From the table, it can be
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seen that the concentrations of As, Se, Pb and Zn in the Changjiang River were much
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higher than those of the world averages; and the concentrations of Co, Cu, Cd, Cr,
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and Ni are comparable to the world averages.
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3.2 Trace elements in the suspended sediments
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3.2.1 Summary statistics
Summary statistics of the trace element concentrations in the suspended
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sediments obtained for the 0.45 μm filters from the two sampling seasons is shown in Table 4. The statistics were based on the 76 samples in Fig. 1, but with the absence of points 1, 3, and 4 in the dry season. From Table 4, we can see that the concentrations for most trace elements have higher values in the dry season than those in the flood season. This result may be due to the higher water flux in the flood season that caused high SSC values with larger particle grains, which diluted the trace element concentrations absorbed in the smaller particles, e.g., hydrous oxides (Gaillardet et al., 2003). Additionally, the concentrations of Pb, Cd, As, Se, Zn, Cr,
ACCEPTED MANUSCRIPT and Cu in the suspended sediments generally have high variations (CV) compared
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with those of Co and Ni.
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3.2.2 EF and Igeo
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The EF values of the trace elements in the suspended sediments from the two seasons are shown in Table 5. From the table, we can see that the EF values of all the
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elements in the flood season are lower than those in the dry season. The slow water
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speed in the dry season induces smaller suspended particles with heavy absorbance of the trace elements. It was also shown that the EF values for most of the elements
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from the tributaries are much higher than those from the main channel, which
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indicates higher pollution in the tributaries. During the flood season, the Se from the
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tributaries is in the category of significant enrichment, and Pb, Cd, and As are in the category of moderate enrichment. During the dry season, the Se and Cd from the
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tributaries are in the category of significant enrichment, and As, Pb, Zn, Cu, and Cr are in the category of moderate enrichment. As shown in Table 5, the Igeo values of As, Se, Pb, Cu, and Cd from the tributaries are higher than those from the main channels both in the flood and the dry seasons. In the flood season, As is moderately polluted in the tributaries, when Se, Pb, and Cd are moderate to strongly polluted. In the dry season, As, Pb, Zn, and Cu are moderately polluted in the tributaries, and Se is moderately to strongly polluted; however, Cd is strongly polluted, with an Igeo=3.31.
ACCEPTED MANUSCRIPT
3.3 Seasonal variation of metal element partitioning
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The analytical results of the element concentrations for suspended sediment were given in mg/kg relative to the solid material, as shown in Table 6. It can be seen
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from the table that there are no clearly seasonal trends for the element concentrations
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in the suspended sediments. The data were multiplied by SSC to obtain the quantity
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of the element in the particulate phase relative to the volume of water. Thus, the data
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were transformed to units of μg/L to make them comparable to those in the dissolved phase (Fig. 2), which were from the analytical results of the 0.45 μm filtrated water.
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It is shown that the dominant phase of the elements is particulate, especially in the flood seasons, when there are high SSC values, and that the trace elements in the
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dissolved phase are relatively steady compared with those in the particulate phase.
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Thus, SSC is the dominant factor that controls the amount and seasonal variation of
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the trace elements transported in the Changjiang river.
3.4 Spatial variation of trace element partitioning Trace elements are transported in surface waters in complexed forms. Former studies (Buffle et al., 1992; Gaillardet et al., 2003) have shown that there is no clear boundary among dissolved, colloidal, and particulate fractions. However, authors generally operationally define a particulate fraction (>0.20 μm or 0.45 μm), a colloidal fraction (0.20 μm or 0.45 μm to 1 nm) and a truly dissolved fraction (<1 nm) (e.g.,
ACCEPTED MANUSCRIPT Buffle et al., 1992; Stumm, 1993). In this study, the element concentrations in the water samples were divided into three parts: 1) > 0.45 μm, 2) 0.20-0.45 μm, and 3) <
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0.20 μm. Conventionally, the third part was regarded as the dissolved fraction, with the first part the particulate fraction. The second part can be regarded as either the
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3.4.1 Partitioning difference among the elements
SC
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dissolved or the particulate fraction, depending on the literature.
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The relative proportions of the > 0.45 μm, 0.20-0.45 μm, and < 0.20 μm fractions of the elements are shown in Fig. 3. 0.20-0.45 μm here demotes the
ED
concentration of an element in the 0.45 μm filtrated water subtracted by that in the
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0.20 μm filtrated one. The data in the figure were given by the average values of the
CE
samples located on both the main channel and the tributaries. It is shown that for most elements, especially the metals, the particulate fractions in the flood season are
AC
significantly higher than those in the dry season. The particulate fractions in the flood season are higher than 50% for most of the elements, except for As and Se. However, in the dry season the particulate fractions are usually lower. Only Cu, Pb, Al, and Fe have particulate fractions larger than 50% with the > 0.45μm part at 65.39%, 76.90%, 83.13%, and 84.63%, respectively. This result may be due to the higher water flux in the flood season, leading to improved concentrations of suspended particles, i.e., SSC, with trace elements absorbed on them. In the flood season, the ascending sequence of the particulate fractions for the
ACCEPTED MANUSCRIPT elements is Se
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clay minerals and oxides. Some metals, such as Pb, are easily absorbed by the clay minerals and hydrous oxides under the pH conditions of the natural ground water
RI
(Sigg et al., 2000). Being different from the metal elements, metalloids such as As and
MA
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with little variation with the water flux and SSC.
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Se are transported mainly in the dissolved form both in the flood and the dry seasons
3.4.2 Spatial variation of metal element partitioning
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According to Fig. 3, metals (e.g., Cd, Pb, Cu, and Zn) and metalloids (e.g., As,
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and Se) have different forms of transportation. Fig. 4 shows the > 0.45 μm, 0.20-0.45
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μm, and < 0.20 μm fractions for the typical metals, e.g., Cd, Pb, and Zn, at the sampling locations in the main channel during the flood season. SSC and pH are also
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shown in the figure for comparison with the spatial distributions of the metal partitions. According to the spatial distribution of the metal fractions, two sections can be separated at the point of the Three Gorge Dam (TGD). In the section above the TGD, the particulate fractions were the dominant ones for all the metal elements. Moreover, the spatial variation of the total element load and the particulate proportions were mainly controlled by SSC. However, at the sampling locations near the TGD, i.e., points 15-19, both the total element load and the particulate proportions for all the metal elements decreased significantly due to the decreased
ACCEPTED MANUSCRIPT SSC as a result of the slow water flow into the TGD. The decreased water flow into the Three Gorges Reservoir promoted the sedimentation of the suspended particles.
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Thus, the absorbed metals sink with the suspended particles to form the bottom sediments. Therefore, at the sampling points near the TGD, the total element load
RI
and the particulate proportions was the lowest, and the total metal load was
SC
composed dominantly of the dissolved form. However, at the locations down to the
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TGD, the particulate proportions of the metals increased with the recovered
MA
suspended sediments, i.e., the SSC values. In addition, the dissolved proportions for the metals also increased from the TGD to the downstream of the river with gradual
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input from the pollution sources in the section. The lower reach of the Changjiang River is an economically developed region with all types of industries. The relative
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proportions of dissolved metals to the particulate ones in the downstream of the river
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are much higher than those in the upstream due to the lower pH value of the
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downstream water. Many studies have proved that the adsorption of metal cations by the suspended particles decreases with decreasing water pH (Sigg et al., 2000; Mouvet and Bourg, 1983; Brick and Moore, 1996; Erel et al., 1990). Fig. 5 shows the three fractions of the metals in the dry season compared with the SSC and water pH. Compared with those in the flood season, the particulate proportions of the metals decreased with the decreased SSC. Thus, the total loads of the metals were also much smaller than those in the flood season. The water pH in the dry season was lower than that in the flood season for most sampling locations.
ACCEPTED MANUSCRIPT The result was an enhanced relative proportion of the dissolved phase for the metals,
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which can be shown in Figs. 3 and 5.
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3.4.3 Spatial variation of metalloid element partitioning
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The three fractions for the typical metalloids, e.g., As and Se, during the flood season are shown in Fig. 6. From the figure, we can see that the dissolved fractions
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are the dominant form during the metalloid element transportation. The first point
MA
from Tuotuohe has the highest dissolved fractions and the highest total load of As. From points 2 to 15, i.e., the section that has a very high SSC, approximately half of
ED
the total As is in the particulate phase and the other half is in the dissolved phase. In
PT
the section downstream from point 15, the dissolved phase is the dominant form of
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As transportation, and the total load is relatively steady. For Se, the total load variation is also dominated by the dissolved phase. The maximum dissolved As
AC
appears at the section between points 11 and 12, i.e., Luzhou-Chongqing, and the minimum is between points 16 and 17, i.e., Wushan-Three Gorges Reservoir. The partitioning fractions for As and Se from the dry season are shown in Fig. 7, which also shows that the dissolved phase is the dominant form of As and Se transportation. It is also shown that the spatial variation of the load of the two elements is relatively smaller than that in the flood season.
4. Conclusion
ACCEPTED MANUSCRIPT Samples of the raw water, 0.45μm filtrated water, 0.20 μm filtrated water and 0.45μm filtrated suspended sediments were obtained and analyzed for the trace
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elements (e. g. Se, As, Cd, Pb, Zn, and Cu) in the 76 locations in the main channel and tributaries of the Changjiang river. The partitioning of the trace elements in the
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particulate and dissolved load transported into the Changjiang River and their spatial
SC
and seasonal distributions was studied, and the following was found:
NU
(1) The concentrations of As, Se, Pb and Zn in the dissolved phase (<0.20 μm)
MA
in the Changjiang River were much higher than those of the world averages, and for Co, Cu, Cd, Cr and Ni the concentrations are comparable to the world averages. Both
in the suspended particulates.
ED
the EF and Igeo values show that Cd, As, Pb, and Se are the elements highly enriched
PT
(2) The seasonal variation of total metal (e.g., Cd, Pb, Cu, and Pb) element
CE
loads is controlled by SSC with the particulate phase. The total loads of the metals
AC
increase with the increasing SSC in the flood season, and there are no clear seasonal trends for the element concentrations in both the suspended sediments and the filtrated waters.
(3) Metal and metalloid elements have different partitioning characteristics. For metal elements, the particulate phase is the dominant form during transportation, and the proportion is controlled by SSC and water pH. The particulate phase is much higher during the flood season when there is high SSC, especially in the upstream of the TGD.
ACCEPTED MANUSCRIPT (4) For the typical metalloid elements, e.g., As and Se, the dissolved phase is the dominant phase for transportation. The total loads are higher in the flood season
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than those in the dry season. And also, the spatial variation is little during the dry season.
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(5) Heavy metals absorbed on the particles deposited on the bottom of the
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Three Gorges reservoir may release suddenly with water acidification or other
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disturbance. So, more work should been done to evaluated their potential
MA
environmental hazards. Acknowledgement
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We thank the Land and Resources Survey Project of China Geological Survey (GZTR20060201, and 1212010511218) for financial support. The study was also
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financially supported by Key Laboratory of Ecological-geochemistry, Ministry of
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Land and Resources of the People's Republic of China. The financial support was
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gratefully acknowledged. Field assistance in collecting samples along Changjiang basin from Institute of surficial Geochemistry of Nanjing University, National Research Center for Geoanalysis of Hohai University, and China West Normal University are highly appreciated. We are also grateful to the anonymous reviewers whose constructive comments were critical to improving the scientific quality of our original manuscript. References Ammann, A. A., 2002. Speciation of heavy metals in environmental water by ion
ACCEPTED MANUSCRIPT chromatography coupled to ICP-MS. Anal. Bioanal. Chem. 372, 448–452. Brick, C. M., Moore, J. N., 1996. Diel variation of trace metals in the upper Clark
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Fork river, Montana. Environ. Sci. Technol. 30, 1953–1960. Buffle, J., Van Leeuwen, H. P., 1992. Environmental particles: 1. In Environmental
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Analytical and Physical Chemistry Series. Lewis Publishers, London, 554p.
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CGS (China Geological Survey), 2005. Specification of Multi-purpose Regional
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Geochemical Survey (DD2005-01) (in Chinese).
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Che, Y., He, Q., Lin, W.Q., 2003. The distributions of particulate heavy metals and its indication to the transfer of sediments in the Changjiang Estuary and
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Hangzhou Bay, China, Marine Pollution Bulletin 46(1), 123-131. Chen, J.S., Wang, F.Y., Xia, X.H., and Zhang, L.T., 2002. Major element chemistry
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of the Changjiang (Yangtze River). Chemical Geology, 187, 231-255.
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Dai, W. M., 1994. Species of Heavy Metals of Suspended Solids in Changjiang
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Estuary. Shanghai Environmental Science, 13(11), 7-9, 35 (in Chinese with English abstract). Erel, Y., Morgan, J. J., Patterson, C. C., 1990. Natural levels of lead and cadmium in remote mountain stream. Geochim. Cosmochim. Acta 55, 707–719. Förstner, U., Ahlf, W., Calmano, W., Kersten, M., 1990. Sediment criteria development, In: D. Helling, P. Rothe, U. Forstner, P. Stoffers (Ed.), sediments and environmental geochemistry. Springer Verlag. Foster, I. D. L., Charlesworth, S. M., 1996. Heavy metals in the hydrological cycle:
ACCEPTED MANUSCRIPT trends and explanation. Hydrol. Process. 10, 227–261. Gaillardet, J., Viers, J., Dupre, B., 2003. Trace elements in river waters. In: James I.
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Drever (Eds.). Holland, H., D., Turekian, K. K. (Executive Editors), Treatise on Geochemsitry Vol 5: Surface and Ground Water, Weathering, and Soils.
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Elsevier, pp.225-272.
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Koshikawa, M.K., Takamatsu, T., Takada, J., Zhu, M., Xu, B., Chen, Z., Murakami,
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S., Xu, K., Watanabe, M., 2007. Distributions of dissolved and particulate
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elements in the yangtze estuary in 1997–2002: background data before the closure of the three gorges dam. Estuarine, Coastal and Shelf Science 71, 26-36.
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Li, S., Zhang, Q., 2010. Risk assessment and seasonal variations of dissolved trace elements and heavy metals in the upper han river, china. J. Hazard Mater. 181,
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Morel, F. M. M., Hering, J. G., 1993. Principles and Applications of Aquatic
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Chemistry. Wiley, New York. Mouvet, C., Bourg, A. C. M., 1983. Speciation (including adsorbed species) of copper, lead, nickel, and zinc in the Meuse River: observed results compared to values calculated with a chemical equilibrium computer program. Water Res. 6, 641–649. Müller, B., Berg, M., Yao, Z. P., Zhang, X. F.,Wang, D., Pfluger, A., 2008. How polluted is the Yangtze river? Water quality downstream from the Three Gorges. Sci. Total Environ. 402, 232-247.
ACCEPTED MANUSCRIPT Müller, B., M. Berg, B. Pernet-Coudrier, Qi W., Liu H., 2012. The geochemistry of the Yangtze River: seasonality of concentrations and temporal trends of loads.
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1971. Umsch. Wiss. Tech. 79 (24), 778-783.
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Müller, G., 1979. Schwermetalle in den Sedimenten des Rheins - Veranderungen seit
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Pekey, H., 2006. The distribution and sources of heavy metals in Izmit Bay surface
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sediments affected by a polluted stream. Marine Pollution Bulletin 52, 1197–1208.
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Qiao, S., Yang, Z., Pan, Y., Guo, Z., 2007. Metals in suspended sediments from the changjiang (Yangtze river) and huanghe (yellow river) to the sea, and their
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comparison. Estuarine, Coastal and Shelf Science 74, 539-548.
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Shan, L. L., Yuan, X. Y., Mao, C. P., Ji, J. F., 2008. Characteristics of heavy metals
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in sediments from different sources and their ecological risks in the lower reaches of the Yangtze River. Environmental Science 29, 2399–2404(in Chinese with English abstract). Sigg, L., Behra, P., Stumm, W., 2000. Chimie des Milieux Aquatiques, Dunod, Parris, 3rd edn. Song, Y., Ji, J., Mao, C., Yang, Z., Yuan, X., Ayoko, G.A., Frost, R.L., 2010. Heavy metal contamination in suspended solids of changjiang river-environmental implications. Geoderma 159, 286-295.
ACCEPTED MANUSCRIPT Stumm, W., 1993. Aquatic colloids as chemical reactants: surface structure and reactivity. Coll. Surf. A73, 1–18.
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Sutherland, R. A., 2000. Bed sediment associated trace metals in an urban stream Oahu. Hawaii. Environ. Geo. 39 (6), 611-627.
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Turekian, K.K., Wedepohl, K.H., 1961. Distribution of the elements in some major
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units of the earth’s crust. Geological Society of America Bulletin 72(2), 175-192.
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Wang, L., Wang, Y. P., Xu, C. X., An, Z. Y., Wang, S. M., 2010. Analysis and
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evaluation of the source of heavy metals in water of the River Changjiang. Environ. Monit. Assess. 173, 301-313.
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Wang, Z., Liu, C., 2003. Distribution and partition behavior of heavy metals between dissolved and acid-soluble fractions along a salinity gradient in the changjiang
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estuary, eastern china. Chem. Geol. 202, 383-396.
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Xia, X. Q., Mao, Y. Q., Ji, J. F., Ma, H. R., Chen, J., Liao, Q. L., 2007. Reflectance
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spectroscopy study of Cd contamination in the sediments of the Changjiang River, China. Environmental Science Technology 41, 3449–3454. Zhang, C., Selinus, O., 1997. Spatial analyses for copper, lead and zinc contents in sediments of the Yangtze river basin. Sci. Total Environ. 204, 251-262. Zhang, Y. Y., Zhang, E. R., Zhang, J., 2008. Modeling on adsorption–desorption of trace metals to suspended particle matter in the Changjiang Estuary. Environmental Earth Sciences 53(8), 1751-1766. Zhang, J., 1999. Heavy metal compositions of suspended sediments in the
ACCEPTED MANUSCRIPT Changjiang (Yangtze River) estuary: Significance of riverine transport to the
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ocean. Continental Shelf Research 19, 1521–1543.
ACCEPTED MANUSCRIPT Table captions Table 1 Statistics of trace element concentrations in the raw water samples.
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Table 2 Statistics of trace element concentrations in the 0.45 μm filtrated water samples.
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Table 3 Statistics of trace element concentrations in the 0.20 μm filtrated water
SC
samples.
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Table 4 Summary statistics of the trace element concentrations in the suspended
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sediments.
Table 5 EF and Igeo values of the element concentrations in the suspended sediments.
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Table 6 Seasonal variation of SSC and the element concentrations in the suspended
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sediments.
ACCEPTED MANUSCRIPT Figure captions
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Fig. 1 Sketch map of the sampling locations Sampling locations of the main channel from upstream to downstream: 1-Tuotuohe, 2-Yushu, 3-Dege, 9-Qiaojia, 10-Yibin, 11-Luzhou,
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4-Batang, 5-Zhongdian, 6-Panzhihua, 7-Panzhihua, 8-Yuanmou,
19-Zhicheng,
20-Gong'an,
21-Yueyang,
22-Yueyang,
23-Jiayu,
24-Wuhan,
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18-Yichang,
SC
12-Chongqing, 13Chongqing, 14-Fuling, 15-Wanzhou, 16-Wushan, 17-Three gorge reservoir,
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25-Huangshi, 26-Jiujiang, 27-Pengze, 28-Anqing, 29-Tongling, 30-Wuhu, 31-Ma'anshan, 32-Nanjing,
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33-Zhenjiang, 34-Jiangyin, 35-Nantong, 36-Chongming Island.
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Fig. 2 Seasonal variation of element partitioning.
AC
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Fig. 3 Proportions of the trace element fractions.
Fig. 4 Cd, Pb and Zn in the three fractions compared with SSC and pH from the flood season. The sampling location numbers are the same as those in Fig. 1.
Fig. 5 Cd, Pb and Zn in the three fractions compared with SSC and pH from the dry season. The sampling location numbers are the same as those in Fig. 1, with the absence of points 1-3.
ACCEPTED MANUSCRIPT Fig. 6 As and Se in the three fractions from the flood season. The sampling locations
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are the same as those in Fig. 1.
Fig. 7 As and Se in the three fractions from the dry season. The sampling locations
AC
CE
PT
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MA
NU
SC
RI
are the same as those in Fig. 1, with the absence of points 1-3.
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
MA
NU
Figure1
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
Figure2
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
MA
NU
Figure3
AC
CE
PT
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure4
AC
CE
PT
ED
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
Figure5
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
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Figure6
MA
NU
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
CE
PT
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Figure7
ACCEPTED MANUSCRIPT
μg/L)
A s
Detectio n limit
S e
o
1 .0
C
P b
0
n
0
.2
.05
Z u
0 .1
C
0 .2
percentile
2 .91
25th
.80
0
.43
percentile
0.65
9
.27
9.26
0
2.23
4.96
.47
7.69
3 6.52
1 .53
1 .64
1 6.65
5 .35
1 7.43
2 .03
2
7
0
1
1 7.35
.28
.62
.35
1
0
1
6 .43
46.07
.30
5.63
7
5
1
2 .85
5.61
.19
1.58
2
.58
.67
0 .87
0
6
2
1
1
.71
43.09
.75
.33
9.91
1
.65
.30
0 .51
0
2
2
9
3
0
8.27
4.45
.26
5
0
0
1
0 .24
.09
.16
1.31
7
2
.62
.16
8.78
5.70
.88
2.97 2
1
0
3 CV (%)
3
0.41
2
0
0
5
0 .1
.46
.09
.30
.1
0
2
8
0
.05
.04
.21
1
7
.46
.35
2 Std. D
.31
.81
56.80
Mean
.63
1
2
AC
Maximu
.93
1
N i
0
.01
.34
2
3
2
.96
1
1
.52
.91
.72
.62
r
.05
0
1
.85
0
CE
90th
0
0
.79 6
percentile
.24
PT
75th
m
.42
0
0 .49
.82
0
4
percentile
.13
ED
50th
0
.29
.43
.42
0
3
percentile
.06
0
SC
10%
.16
0
NU
.90
0
MA
m
0
C
0
RI
The flood season (n=76) Minimu
d
0 .2
C
PT
Element(
6 .48
2 .40
1 .21
The dry season (n=73) Minimu m
0 .68
0 .06
0 .04
0 .05
1 .40
0 .33
0 .01
0 .88
0 .48
ACCEPTED MANUSCRIPT
2
percentile
.09
50th
75th
.50
Maximu m
4 .62
0
PT
.21
0
CE .40
3
.53
.88
.53
26.90 1 5.67
6 .12
3
3 2.75
1 .84
2 .09
8.67 2 .04 2
3.79 1
.87
2
1
3 .41
2 .31
Table 1 Statistics of trace element concentrations in the raw water samples.
AC
.75
0.28
.53
2
1
0
2 .29
2
0
1
2 .00
95.00
.29
6.08
1
2
7
1 .38
3.72
.78
.02
.65
0
1 14.70
2
3.19
.75
2
3
.32
1
0 .85
0
.23
0.38
1
0
4
0 .73
.63
.08
2
4
.24
.05
.45
4.59
4.66
.91
0
1
4
0
.60 6
CV (%)
7.41
ED
.86
.82
2
1
1
0
3
.28
4.09
.82
3
4
Std. D
1 .09
6
3 .03
0 .90
9.70
Mean
.60
1 .78
.23
0 .03
3
1
0
1 .24
.96
.93
0
7
percentile
.93
.39
.70
.41 0
0
.50
.33
90th
.16 0
5
percentile
0
.37
.88
.54
0
2
percentile
.08
2
PT
25th
.08
0
RI
.26
0
SC
percentile
0
NU
1
MA
10th
1 .67
ACCEPTED MANUSCRIPT
g/L)
S
s Detection
e
1
limit
C o
.2
Z
b
0
.0
P
0 .05
n 0
.1
0
.2
0
.48
25th
2
percentile
.38
50th
3
percentile
.65
75th
4
percentile
.83
90th
7
0
0
CE .30
AC
percentile
2
.05
.20 0 .41 0
0 .06
.72
.37
0
.11
0
.14
0
0
.29
.52 0
.95
3
3
.59 1
.75
0
1 .06
.03
.64
.07
.07
.13
.08
0
1
0
0
1 .61
.20
2
0
.97 0
6
0
.68 0
4
.1
.05 0
1
0
.05
.01
1 1.35
7
0
6 .94
0
.00
2 .54
1
.50
1
.62
.81
1
.49
0
0
0
C r
.05
1
.09
.52
0
.85
.43
NU
percentile
.02
MA
1
PT
10th
.05
ED
.34
.2
0
Minimum
d 0
SC
0
C
u
0
The flood season (n=76) 0
C
PT
A
RI
Element(μ
2 .46
0
2
N i 0 .1
0 .05 0 .32 0 .54 0 .93 2 .25 3 .08 4
Maximum
55.60 7
.35
.98
0
.87 0
2.13 1
0.26
4
.64 2
0.23 0
1
.28 1
Mean .86 2
.78
.31
0
.47 0
.55 1
.71
4
.09 2
.51 0
2
.45 1
Std. D 9.24 3
.59
.38
0
.62 1
.50 1
.33
0
.10 0
.56 1
1
.17 0
CV (%) .72
.75
.21
.10
.99
.86
.01
.70
.81
The dry season (n=73) 0 Minimum
.22
0 .02
0 .02
0 .05
0 .95
0 .14
0 .01
0 .59
0 .40
ACCEPTED MANUSCRIPT
percentile
.61
50th
2
percentile
.61
75th
4
percentile
.56
90th
6
percentile
.04 4
Maximum
8.70 4
Mean
.06
Std. D
.02
AC
CE
1
CV (%)
.28
.48
0 .06
.37
.08
.17
0 .48
0 .30 2 5.18
.77 2
.95
.12 5
.79
1 .46
.69
2
.81
0
.11 3
.68
0
4 4.51
.07 2
.43
.20
.12
.43 2
.11
.12
0 .78 1 .27 2 .02
2
2 6.55
6
1 .55
7 .56
2
.67
1
.34 0
0
1
9.82 0
5
.58
5.70 2
.58
1
1.78
.52
2 .52
0
0
1 .25
.06
2 4.10
0
1
0 .98
.03
9 .56
1
.93
1
49.10 0
.03
1
2.39
8
0
1
.06
1
.93
.51
6 .68
.52
0
.51
0
0
0
3 .58
.77
3 .58
0
0
.51
2 .60
.46
0 .78
0
0
0 .53
.71
.30
0
PT
6
0
.16
0
PT
1
.04
1
RI
25th
.06
0
SC
.02
0
NU
percentile
0
MA
1
ED
10th
3 .19
1 .19
2 .06
Table 2 Statistics of trace element concentrations in the 0.45 μm filtrated water samples.
ACCEPTED MANUSCRIPT
Table 3 Statistics of trace element concentrations in the 0.20 μm filtrated water samples. A
S
P
Z
Co Detection
e 1
limit
b 0
.0
.2
0.
n
05
0 .1
.2
The flood season (n=76)
.3
10th
.10 1
percentile
.2
.30
0
4
0
CE
75th
.61
.1
6
AC
90th
.81
Maximum
.7
.23 2
43.6
.58 7
Mean
.2
.68
Std. D
7.9
.47 3
CV (%)
.9
.69
0
.35 0 .59
.91
.32
.34
.86 0 .80
1.
0 .93
0 .90 1 .40
.51 4 .27
.13 2 .03 1 .55
.87
0 .76
0 .50
0 .28
0 .68
0 .46
0 .84
0 .74
1 .21
1 .78
2 .06
2 .72
1 8.16
4 .00
0
1 .42
1 .22
0
2 .50
1 .03
0 .954
0 .06
0
.090
0
.03
0
.094
0
0
0
.609
i
.1
0
.176 6
.1
0
.128
N
0
0
.074 2
r
0
.043
2 .84
.05
.008
3 .27
0.
.66
1 4.65
0
0
C
0
.001
7 .22
3
.34
4 .38
2
0
2 .24
0
.2
1 .26
0.
105
0
1
.01
1.
215 0
.26
0.
195 0
0
C d
0
.35
0.
163 0
2
126
493 2
.17
0.
180 1
0
0.
098
PT
.2
percentile
044
0
3
percentile
0.
ED
.0
50th
percentile
0
2
percentile
009
.20
25th
0.
NU
Minimum
0
MA
0
0
u
RI
s
SC
g/L)
C
PT
Element(μ
1 .75
0 .84
ACCEPTED MANUSCRIPT The dry season (n=73) 0
0
0.
0
0
0
0
0
0
Minimum
25th
.03 1
percentile
.5
0 .20
50th
2
percentile
.4
0
3 .8
90th
.40 5
percentile
.2
.60
3 Mean
.39
CE
.7
6
.0
AC
.24
0
0
.48
1
45
0 .41
2
0 .27
3
.18 5
1
7
0
.52
.40
.01
.78 1
.85
.41 0 .40 0
2 .08
.025
.92
3.74
.09 5 .03 2
.12
0 .61
1 .50
0 .72
1 1.08
1 .10
1 2.82
1 .87
2 3.33
2 5.91
0
5 .27
1 .40
0 .349
2
1
1
.159
0 .50
0
.967 2
.89
0
.296 4
0
0
.090 2
.33
0
.055
1 8.07
6.
.56
7 .06
2.
1
1 30.20
0
.73
.55
0 .025
0
.15
0.
83 1
.15
24
ED
.42
PT
8.1
0
0.
17
3
Maximum
Std. D
10 0
4
0.
.014
1 .45
0. 07
0
.07
0. 04
.30
75th percentile
03
0
.13
PT
.7
0.
.92
RI
percentile
0
.01
SC
0
01
NU
10th
.01
MA
.1
5 .99
3
2
.10 1
2
CV (%)
.6
Backgoun
.24
da
0 .62
a
28 0
.07
.96
0.
.56
148
0 .079
.41
0
.195
.60
1 .48
.14
0
.21
.080
Background values of the world average from Gaillardet et al. (2003).
0 .70
0 .801
ACCEPTED MANUSCRIPT Table 4 Summary statistics of the trace element concentrations in the suspended sediments.
(mg/kg)
A
S
s
e
C
P
o
Z
b
n
C u
Flood season (n=76) 3
0
5
2
6
7.55
50%
.32 2
percentile
3.07
75%
.59 3
9.43
Maximu m
1 .39
1 98.64
8
.76 3
Mean
.30
1
CV
AC
.08
.31
4.5
1
82.1
1
4
34.2
75.6
0
2 08.4
1 .34
0 .54
1 33.6
5 0.19
1 .70
1 06.28
2
0 .49
5 48.5
.99
5 6.30
2
8 8.29
1 41.1
9.54
5 0.21
2
2 92.50
1 86.7
.35
7
1 26.2
.49
4 0.98
1
1 07.03
1
307.0
1
2
1 07.2
.23
1 7.41
1
8 2.30
4 5.0
.00
N i
0
6
1.09
8
C r
.11
1
55.5
86.5
9.93
1
2.07
6.8
2
3.33
1
CE
6.05
4.01
5
2
0.23
PT
percentile
7.09 0
7.9
1
2
SC
percentile
0
5.7
NU
1
.02
MA
25%
.14
ED
.90
d
RI
Minimum
C
PT
Element
0 .52
0 .30
Dry season (n=73) 5
0
4
6
5
2
0
7
1
Minimum .19 25% percentile
1 7.54
50% percentile
.68
8.56
.21
1
5.09
4.15
4.57
4 9.13
2
0.06 1
.89
.66
4.33 1
4 7.02
.14 0
2
75% percentile
.25
1 85.51
2
63.46
2 02.47
5 6.84
8 .77
4 4.57
2
2 28.61
1 51.34
.21
3
2.46
1
1 05.94
54.40
0.34
.21
2
1 21.30
6 9.04
6 6.68
.51
3 45.91
6 6.05
ACCEPTED MANUSCRIPT Maximu m
4 93.9
6 .15
4
7
0.95 1
1 445.5
2
3 510.3
1
9 73.31
5
3
4.89 1
1 272.8
2
6
03.68 2
5
Mean .64 1
0.32 0
29.75 0
77.11 1
87.17 1
1
CV .79
.53
.56
.33
.01
SC NU MA ED PT CE AC
69.88 1
.52
RI
.40
.47
PT
4.37
8.60 0
.71
0 .53
ACCEPTED MANUSCRIPT
Table 5 EF and Igeo values of the element concentrations in the suspended sediments. The flood season
Me
Me E
I geo
21.
o
39
P
11
b
0.70
Z
17
n
1.51
C
84.
u
07
C
1.1
d
6
C
12
r
2.13
N
51.
i
24
1 .38 0 .99 2 .32 1 .21 1 .34
45.
3
1
.74
04
.46
.56
0
2.1
6
2
.19
1
.84
.54
-
18.
0
-
0.28
59
.84
0
25
5
.94
6.86
0
24
.00 0
.49 1 .15 1
3
M
I
E
I
F
geo
ean
geo
(n=39)
2
1
5
4.
1
2.76
.59
.10
4.49
19
.84
1.
3
1
2.
6.
2
17
.93
.70
04
63
.50
2
1
-
1
0.
-
0.49
2.12
.03
0.23
8.75
85
0.47
2
9
2
0
1
3.
1
.24
.16
5.01
.00
.72
60.03
26
.48
1
0
3
2
0
4
2.
1
2.45
.66
.50
23.03
.27
.91
24.25
90
.30
92.
1
0
2
3
1
1
2.
1
19
.43
.29
16.20
.46
.52
61.86
51
.10
0
4.6
5
2
3.
3
1
9.
1
3
.30
8
.81
.31
10
.96
.71
41
1.67
.31
-
14
1
0
2
2
1
2
2.
1
0.08
4.23
.31
.16
84.36
.67
.14
57.25
34
.00
-
49.
1
-
5
1
0
5
1.
0
0.16
22
.01
0.22
9.83
.26
.06
7.54
18
.00
.15 1
.08
0
Tributaries
NU
C
.02
F
MA
1
2
ED
e
geo (n=34)
PT
0.4
F
CE
S
ean
(n=40)
AC
54
E
SC
F
s
I
an
(n=36) 25.
M E
an
A
Main channel
PT
Tributaries
RI
Main channel
The dry season
ACCEPTED MANUSCRIPT Table 6 Seasonal variation of SSC and the element concentrations in the suspended sediments. Sam.
D
S
C
P
C
C
Zn
NJSS 0611
N ov-06
NJSS 06121
ec-06
06122
0701
ec-06
0703
AC NJSS
0705
0706 NJSS 0707
0708
PT 2.0
1
Ju
6
1
A
7 2.89
1 24.0
9.41
7.97 7
2.25
3.85
06.23 1 13.79 2
.74 17
1 09.66
1 .78
16 9.00
1
2
22
5
11.80
.01
9.50
1
1
28
5
18.48
.80
8.88
1
2
23
7
17.63
.24
6.38
1
2
25
5 9.24
6.59
52.0
ug-07
7
17.25
.42
7.13
1
1
37
6 3.54
4.62
04.2
l-07 NJSS
1
Ju n-07
6
1 27.75
.99
3.25
1 15.61
.68
1.38
6.41
2
2
83
6
20.40
.78
0.50
1
1
12
7
8.25
5.04
56.25
7
6
2
M
7
6.78
5.0
ay-07 NJSS
3
12
22.38
4.13
7.34
0.1
A
pr-07
6
1
.05
7
5.74
9.01
28
4.25
0.18
r
.96
7
6
1
M
ar-07
NJSS
1
1.3
CE
NJSS
2.43
5.78
3.1 Fe
b-07
7.16
31 0.50
9
6
1
Ja
NJSS
6
2
7.8
9 6.39
6.52
0.8
n-07
0702
1.0
D
NJSS
8.14 3
D
NJSS
0704
3.8
6
PT
ct-06
2
d
RI
0610
O
b
NU
NJSS
u
SC
SC
MA
ate
ED
No.
1 08.63
1 .63
2 32.38
ACCEPTED MANUSCRIPT NJSS 0709
Se p-07
6 1.8
NJSS
7 2.04
O
6 2.21
6
18 9.88
5
1 .77
20
1 08.36
1
1
ct-07 NJSS
7.62 N
8.86 7
9.63 6
22
ov-07 NJSS
3.92
D
4.79 6
6
ec-07
6.83
7.75
0.63
11.36 1
.57
24
SC
-
.38
1 10.39
1
1 16.13
CE
PT
ED
MA
NU
Note: SSC was given in mg/L with the element concentrations in mg/kg.
AC
0712
5.88
RI
0711
.54
PT
0710
ACCEPTED MANUSCRIPT Highlights Dissolved and particulate partitioning of trace elements in the
PT
Changjiang water system was studied. Metals and metalloids differ in their dissolved and particulate
RI
partitioning characteristics.
SC
For metals, the particulate phase is the dominant one varying with
NU
SSCs and water pH.
MA
The dissolved phase is the dominant form of transportation for
AC
CE
PT
ED
metalloid elements.