- Email: [email protected]
Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China
Marine Pollution Bulletin xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul
Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China Gang Xu a,b,⇑, Jian Liu a,b, Shaofeng Pei a,b,c, Xianghuai Kong a,b, Gang Hu a,b a
Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Ministry of Land and Resources, Qingdao 266071, China Qingdao Institute of Marine Geology, Qingdao 266071, China c Key Laboratory of Coastal Wetland Biogeosciences, China Geologic Survey, Qingdao Institute of Marine Geology, Qingdao 266071, China b
a r t i c l e
i n f o
Keywords: Heavy metals Distribution Source Surface sediments Near-shore area North Jiangsu Province
a b s t r a c t Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, 210Pbexcess and 137Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the Igeo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Sediments in the surface water are the most vulnerable to heavy metal pollution due to their open access to the disposal of terrestrial agricultural and industrial wastewater. Heavy metal contamination of the marine environmental media has received a great deal of world-wide attention because of their toxicity, persistence and non-biodegradable nature (Irabien and Velasco, 1999; Yu et al., 2008). Sediment quality has been recognized as an important environment indicator of water pollution (Jones and Turki, 1997; Feng et al., 2004; Marchand et al., 2006; Yu et al., 2008; Zhang et al., 2009) because marine sediment are the main sink for various pollutants, including heavy metals discharged into the environment (Dassenakis et al., 1997; Tam and Wong, 2000; Bettinetti et al., 2003; Singh et al., 2005), The natural source of heavy metals in marine sediments is mainly from the weathering and erosion of the lithosphere. Comparatively, anthropogenic sources are mainly from industrial processing, urban sewage and agricultural run-off (Kaushik et al., 2009). In order to make a more accurate assessment of heavy metal accumulation from anthropogenic source and the resultant environmental impact on sediments (Cuadrado and Perillo, 1997; ⇑ Corresponding author at: Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Ministry of Land and Resources, Qingdao 266071, China. Tel.: +86 532 857 55864; fax: +86 532 857 20553. E-mail address: [email protected] (G. Xu).
Loska and Wiechula, 2003; Zhang et al., 2009; Nobi et al., 2010), a complementary approach, which brings grain size effect, geoaccumulation index, correlation, enrichment factor together, is required. From 1128 to 1855, the Yellow River discharged into the South Yellow Sea, and contributed to the formation of the subaqueous old Yellow River Delta (Xu et al., 2010). After 1855, the river changed its channel and discharged into the Bohai Sea. The coast of north Jiangsu Province was eroded for the lack of sediment supply, and the eroded materials were redeposited partially in the near-shore area (Yu and Chen, 1986; Xue et al., 2004), partially in the subaqueous Yangtze River Delta (Liu et al., 2010) and partially in the mud area of South Yellow Sea (Yang and Youn, 2007). Many rivers surrounding the study area, such as the Guanhe River, the New Huaihe River, the Sheyang River, the Fanshen River, and the Beiba Tanqu and Subei Irrigation Channels, have provided a large amount of agricultural, residential and industrial wastewater. Heavy metals discharged into near-shore area by these rivers probably have exerted an effect on the marine environment. Therefore, the present study was carried out to meet the following objectives: (1) to study the characteristics of metal deposition in the surface sediments; (2) to determine the background values of heavy metals and Al by combination of 210Pb and 137Cs; (3) to assess the contamination status of heavy metals by geoaccumulation index; and (4) to distinguish the possible sources of heavy metals by correlation and enrichment factor.
http://dx.doi.org/10.1016/j.marpolbul.2014.03.041 0025-326X/Ó 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
2
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
2. Sampling and methods 2.1. Sampling In this study, 18 (B01-B18) surface sediment samples and one sediment core (Z01) were collected in the summer of 2008 in the near-shore area, north Jiangsu Province (Fig. 1). The surface sediment samples here conform to the top 5 cm of the center of the sampling box. Core sample was taken with a gravity corer with automatic clutch and reverse catcher. The bulk surface sediment samples were divided into two sub-samples for determination of heavy metals and grain size analysis. About 28 samples (at 2-cm intervals between 0 and 9.5 cm and at 4-cm intervals between 9.5 and 110 cm) were taken from Z01 core for further grain size, elements analysis and radionuclide measurement. 2.2. Analytical method 2.2.1. Grain size analysis The sediment samples were pretreated with 10% H2O2 to digest the organic matter. The excessive H2O2 solution was removed by
heating and evaporation. After that, 0.5% of sodium hexametaphosphate was added to the samples, making the sediments completely dispersed, and then the mixture was analyzed with a Mastersize-2000 laser particle size analyzer at the Qingdao Institute of Marine Geology, China. Grain-size parameter was calculated following the method of Folk and Ward (1957).
2.2.2. Element analysis Element geochemistry of the samples was analyzed at the Center of Testing, Qingdao Institute of Marine Geology, China Geological Survey. Major elements and some trace elements (Al, Cu, Pb, Zn) were determined by X-ray fluorescence spectrometer (model Philips PW4400), following the method described by Xia et al. (2008). The trace element As was analyzed by atomic fluorescence spectrometry (AFS) and the element Cd measured by inductively coupled plasma mass spectrometry (ICP–MS), using the method described by Dai et al. (2007). All the sediment samples were analyzed in duplicates and the quality was controlled by stand reference materials (see Dou et al., 2013 for detail). The differences of the concentrations between the determined and
Fig. 1. Bathymetry and location of surface sediment and sediment core sampling stations in the near-shore area, north Jiangsu Province.
Table 1 Granularity and metal contents in the surface sediments in the near-shore area, north Jiangsu Province. Station
Mz (u)
Cu (mg/kg)
Pb (mg/kg)
Zn (mg/kg)
Cd (mg/kg)
As (mg/kg)
Al (%)
B01 B02 B03 B04 B05 B06 B07 B08 B09 B10 B11 B12 B13 B14 B15 B16 B17 B18 Min Max Mean SD
7.26 6.80 7.04 7.38 7.34 7.26 7.28 7.61 6.91 7.45 6.64 6.21 6.85 6.85 6.54 6.69 6.83 6.90 6.2 7.6 7.0 ±0.4
35.1 36.1 32.8 35.1 34 32.7 37 40.2 33.2 37.8 38 31.2 40 29 37.2 31.5 34.5 34.7 29.0 40.2 35.0 ±3.0
25.9 25.8 24.8 26 25.1 23.3 26.6 27.9 23.9 26.2 28 22.7 26.6 22.9 28.3 26.5 25.7 26.6 22.7 28.3 25.7 ±1.7
87.2 90.6 88.6 88.8 87.2 81.4 89.7 93.6 86.7 91.8 97.2 81.3 95.7 79.8 89.3 84.4 90.3 91.9 79.8 97.2 88.6 4.7
0.19 0.18 0.2 0.19 0.18 0.18 0.18 0.21 0.17 0.23 0.19 0.18 0.19 0.17 0.22 0.16 0.17 0.2 0.16 0.23 0.19 ±0.02
20.1 20.5 19.7 18.6 17.8 16.2 19.6 19.4 17.2 18.9 19.7 17.7 17.4 16.2 19 16.5 19.6 17.9 16.2 20.5 18.4 ±1.4
7.94 7.71 7.62 7.82 7.64 7.24 7.83 7.97 7.52 7.75 7.95 7.22 8.07 7.29 7.81 7.53 7.83 7.85 7.22 8.07 7.70 ±0.26
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
3
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx Table 2 Comparison of metals of surface sediments in the near-shore area, north Jiangsu Province and representative seas. Location Study area South Yellow Sea Coastal Bohai Bay East China Sea South China Sea
Range Mean Range Mean Range Mean Range Mean Range Mean
Cu
Pb
Zn
Cd
As
Al
Reference
29–40.2 35.0 6.0–32.9 16.9 20.1–62.9 38.5 4.3–42 15 5.29–122 38.1
22.7–28.3 25.7 6.2–39.3 17.8 20.9–66.4 34.7 10–49 27 4.18–58.7 23.6
79.8–97.2 88.6 24.6–244 93.7 55.3–457 131 18–114 60 10.7–346 87.4
0.16–0.23 0.19 0.06–1.54 0.3 0.12–0.66 0.22 No data
16.2–20.5 18.4 No data
This study Yuan et al. (2012)
No data
7.22–8.07 7.7 3.99–7.79 6.34 No data
No data
No data
Fang et al. (2009)
0.08–2.14 0.4
No data
No data
Zhu et al. (2011)
certified values were less than 5%, and the analytical precision for replicate samples was within ± 10%. 2.2.3. Radionuclide measurement 210 Pb, 226Ra and 137Cs were analyzed using the BE3830 gammaray spectrometer (made in Canberra Company of USA) at the Testing Center of Qingdao Institute of Marine Geology, China Geological Survey, following a procedure similar to that of Xia et al. (2011). And counting uncertainties associated with sample measurements were typically less than 10%. Supported 210Pb activities were assumed to be equal to the measured 226Ra activities, and 210Pb activities were calculated by subtracting supported 210 Pb activities from total 210Pb activities (San Miguel et al., 2004). The sediment accumulation rates were calculated by the constant initial concentration (CIC) model (Oldfield et al., 1978). 3. Results and discussion 3.1. 3.1 Metal Contents in the surface sediments Results of grain size and total metal concentrations of the surface sediment samples from the near-shore area, north Jiangsu Province are listed in Table 1. The total concentrations (mg kg1) vary from 29.0 to 40.2 (average 35.0 ± 3.0) for Cu, 22.7–28.3 (average 25.7 ± 1.7) for Pb, 79.8–97.2 (average 88.6 ± 4.7) for Zn, 0.16– 0.23 (average 0.19 ± 0.02) for Cd, 16.2–20.5 (average 18.4 ± 1.4) for As and 7.22–8.07 (average 7.70 ± 0.26) for Al. The spatial distributions of Cu, Pb, Zn and Al were similar to each other with high concentrations at stations B08, B11 and B13. However, Cd and As showed a different spatial distribution pattern from other metals with high concentrations at stations B10, B15, B08 for Cd, and B01, B02 for As, respectively. Grain sizes range from 6.2 to 7.6 u (u = log2D, where D is the diameter of a particle in mm). The grain sizes are homogenous in study area, indicating that the diversity of metal concentration was affected not by grain size, but by the source. Comparison of metals in the study area with those in other regions is listed in Table 2. It can be seen that the average concentration of Cu in the study area is relatively higher than those in the South Yellow Sea and East China Sea, but is lower than those in Coastal Bohai Bay and South China Sea. The Pb concentration is relatively higher than those in the South Yellow Sea and South China Sea, but is lower than those in the Coastal Bohai Bay and East China
Gao and Chen (2012)
Sea. The Zn concentration is relatively higher than those in the East China Sea, but is lower than those in the Coastal Bohai Bay. The concentration of Cd in this area is lower than those in other regions. Although our study area is located in the South Yellow Sea, the mean concentration of most metals is higher than that of the South Yellow Sea. Higher metal concentrations might be attributed to the sources of sediments as discussed above and the fact that mean grain size is fine in our study area. 3.2. Metal baseline values The elemental concentration in the earth’s crust (Taylor and Mclennan, 1995) or the abundance of the upper crust shale is usually used as the baseline value for elements. However, the assessment of contamination levels when compared with a global standard (average shale or crust composition) is not always satisfactory because of the presence of local lithological anomalies (Zhou et al., 2013). Sediment chronologies established by the 210Pb dating techniques, combining with the vertical distribution of elements, are
Fig. 2. Vertical distribution of the core.
210
Pbexcess and
137
Cs activity in Z01 sediment
Table 3 The baseline values and granularity of sediments in the near-shore area, north Jiangsu Province and concentration of metals of sediments in other materials. Elements
Cu
Pb
Zn
Cd
As
Al
Mz
Reference
Baseline The loess materials of the YRD Upper continental crust
26 21.1 25
18.9 21.6 20
70.5 64.5 71
0.11 0.10 0.10
11.8 10.7 1.5
6.31 6.27 8.06
6.9 No data No data
This study CNEMC (1990), Bai et al. (2012) Taylor and McLennan (1995)
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
4
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
Table 4 Geoaccumulation index (Igeo) and enrichment factor (EF) of surface sediment in the near-shore area, north Jiangsu Province. Parameters Igeo EF
Range Mean Range Mean
Cu
Pb
Zn
Cd
As
0.6 to 0.3 0.4 1.0–1.2 1.1
0.5 to 0.3 0.4 1.0–1.2 1.1
0.6 to 0.5 0.5 1.0–1.1 1.0
0.3 to 0.2 0.1 1.1–1.6 1.3
0.4 to 0.1 0.2 1.1–1.4 1.3
Fig. 3. The graphs–boxplot of the geoaccumulation index (Igeo) in near-shore area, north Jiangsu Province.
used to determine the element baseline value before modern industrialization (about 100 years ago). The 210Pb profile for Z01 core was established for this study together with 137Cs analysis, and these profiles are presented in Fig. 2. The type of 210Pb profile shows low values and no notable decay in excess 210Pb activity, which is interpreted as the reflect of no net sediment accumulation in the past 100 years but being caused by marine erosion as previously reported (Yuan and Chen, 1983). In this case, the accumulation rate is expressed as zero. The sediment accumulation rates determined by 210Pb activity was evaluated according to 137Cs activity in the same profile, assuming that the measured penetration of 137Cs corresponds to its introduction into the atmosphere in 1954 and its maximum atmospheric fallout in 1964–1965 (Cambray et al., 1982). The 137 Cs activity shows a constant prolongation with a value of zero, also indicating that there was no accumulation and material deposited in the station of Z01. The surface sediment of Z01 core was probably accumulated between 1128 and 1855, this is in agreement with results obtained later (Liu et al., 2013). It can be seen that the metal baseline values in the study area are close to
Fig. 4. The distribution of Igeo (As) and EF (As) in near-shore area, north Jiangsu Province.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
the environmental background concentrations of the loess materials of the Yellow River Delta, and also close to the upper continental crust, except for As and Al (Table 3). Z01 sediment core located in the old subaqueous Yellow River Delta has the same provenance with the surface sediments studied above. So the abundance of elements in the surface sediment of Z01 is able to represent the elemental baseline values in the study area. 3.3. Assessment of heavy metals pollution Geoaccumulation index (Igeo), originally defined by Müller’s (1979), is used to assess the extent of sediment pollution in our study area with the following equation:
Igeo ¼ log2 ½ðC n =AlÞ=ð1:5 Bn Þ=Al
ð1Þ
where Cn is the measured content of the examined metal ‘‘n’’ in the sediment, Bn is its geochemical baseline content, and factor 1.5 is the baseline matrix correction factor because of lithogenic effects. Al is the reference element. It was found that the relative proportion of a metal to Al in crustal material is fairly constant (Taylor, 1964; Turekian and Wedepohl, 1961). The ratio of heavy metal to Al can minimize the grain size effect between measured content and baseline value and reveal the actual geochemical imbalance (Din, 1992; Schropp et al., 1990). Müller has distinguished seven classes of geoaccumulaion index from class 0 (Igeo 6 0) to class 6 (Igeo P 5) (Müller, 1981). Results in Table 4 and Fig. 3 indicate that no station is polluted by Cu, Pb, Zn and As (Igeo 6 0), but the geoaccumulation index of As
5
is higher than Cu, Pb and Zn. At Stations of B01, B02, B03, the geoaccumulation index of As is close to zero (Igeo = 0.1) (Fig. 4). For Cd, slight pollution is observed at stations of B10, B15 (Igeo > 0), B03, B08 and B18 (Igeo = 0) (Fig. 5).
3.4. Sources of heavy metals in marine sediments 3.4.1. Relationships between heavy metals and Al Enhanced concentration of terrigenous element Al has been interpreted as an increasing supply of siliciclastic materials of fluvial or aeolian origin in marine sediments (Arz et al., 1998; Jansen et al., 1998; Chen et al., 2010, 2011). Al is considered to be one of well conserved elements since it is extremely resistant to weathering and erosion (Wei et al., 2003). The EF mean value of Al in our study area is 1.2, indicating that Al was mainly terrigenous. Similar to heavy metals, Al accumulates easily in the fine sediments. Therefore, Al is able to trace the terrigenous material in the marine surface sediment (Chen et al., 2013) and the relationship between heavy metals and Al can be used to identify the sources of the heavy metals effectively. To distinguish the sources of heavy metals in the surface sediments, a statistical analysis with Pearson’s correlation coefficients is conducted and the results are shown in Table 5. Significantly positive correlations are found between heavy metals (Cu, Pb and Zn) and Al, indicating that all these heavy metals were from the terrigenous material and not polluted by human activities. Such results are consistent with the Igeo. Moderate positive correlation is found between As and Al, indicating that As was probably
Fig. 5. The distribution of Igeo (Cd) and EF (Cd) in near-shore area, north Jiangsu Province.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
6
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
Table 5 Pearson’s correlation coefficients for the heavy metals and Al.
** *
Elements
Cu
Pb
Zn
Cd
As
Al
Cu Pb Zn Cd As Al
1 .795** .882** .605** .548* .846**
1 .807** .503* .532* .852**
1 .485* .594** .898**
1 0.401 0.436
1 .629**
1
Correlation is significant at the 0.1 level (2-tailed). Correlation is significant at the 0.05 level (2-tailed).
affected by both the siliciclastic and anthropogenic inputs. No significant correlation is observed between Cd and Al, indicating that Cd was obviously affected by the human activities in some stations. 3.4.2. Enrichment factor (EF) of heavy metals In order to get a better understanding of the sources of the heavy metals in our study area, we also considered another approach–Enrichment factor (EF), which acts as a useful tool in distinguishing the sources of heavy metal pollution (Zhang and Liu, 2002; Han et al., 2006). To minimize the grain size affect between the measured values in the surface sediments and the regional baseline values, geochemical normalization of heavy metal concentration to Al was employed. Besides, the normalization of the surface sediment to a reference element, such as Al which is not associated with anthropogenic influences, can be used to determine the sources of heavy metals. The EF is defined by Eq. (2) using Al as a reference element:
EF ¼ ðM n =AlÞsample =ðMn =AlÞbackground
ð2Þ
where (Mn/Al)sample is the ratio of heavy metal ‘‘n’’ content to Al content in a sample, (Mn/Al)background is the ratio of the natural baseline value of metal ‘‘n’’ to that of Al. Zhang and Liu (2002) regarded EF = 1.5 as an assessment criterion. EF value ranging from 0.5 to 1.5 indicates that the heavy metal was entirely coming from crustal materials or natural weathering processes. In contrast, EF value greater than 1.5 indicates that a significant portion of heavy metal is derived from anthropogenic materials. As shown in Table 4 and Fig. 6, the results from our study area show that the EF of Cu ranges from 1.0 to 1.2 (average 1.1 with two outliers, 1.2 and 1.0), the EF of Pb ranges from 1.0 to 1.2 (average 1.1 with two abnormal values, 1.2 and 1.0), the EF of Zn ranges
from 1.0 to 1.1 (average 1.0), the EF of Cd ranges from 1.1 to 1.6 (average 1.3 with two outliers, 1.5 and 1.6), and the EF of As ranges from 1.1 to 1.4 (average 1.3). Overall, the average EF values of Cu, Pb and Zn are less than 1.5 in the study area, indicating that all these heavy metals are from the crustal materials. The average EF value of As is found to be close to 1.5. Especially, at stations B02 and B03 the Igeo value of As is 0.1, and the EF value of As is 1.4, suggesting that As at these stations might be affected by anthropogenic inputs. It is noticeable that the average EF value of Cd is close to 1.5. At stations B10 and B15, the EF values (>1.5) and Igeo values (>0) of Cd suggest that the contaminated Cd was obviously controlled by anthropogenic materials (Fig. 5). Previous studies have shown that the distributions of As and Cd were closely related to the intensive usage of phosphate fertilizers containing a significant amounts of metals, particularly Cd and As impurities (Zhang and Shan, 2008; Xia et al., 2011). These contaminated stations are located around 15 m isobaths, where rivers around the study area carried a vast amounts of suspended sediments and dissolved substances to the near-shore area, such as heavy metals derived from continental runoff, riverbank erosion and domestic agricultural and industrial runoff. And then the heavy metals in suspended sediments arrived at the 15 m isobaths, where fine sediments were easily deposited because of the weak hydrological conditions, and light pollution was caused in these stations. 4. Conclusions Analyses of heavy metals (Cu, Pb, Zn, As, Cd) from the nearshore area of north Jiangsu Province showed that the diversity of metal concentration was controlled not by the grain size of the mineral, but by the material provenience. The baseline values of elements in the study area are 26.0 mg kg1 for Cu, 18.9 mg kg1 for Pb, 70.5 mg kg1 for Zn, 0.11 mg kg1 for Cd, 11.8 mg kg1 for As and 6.31 % for Al. The Igeo indicates that no station is polluted by Cu, Pb, Zn and As (Igeo 6 0), but the average Igeo values of the As was higher than those of Cu, Pb, Zn. In stations of B01, B02, B03, the Igeo values of As are close to zero. Light pollution caused by Cd is observed in some stations. The correlation and enrichment factor suggests that Cu, Pb and Zn are of lithogenic origin while Cd and As are mixed origin. Especially, the Cd in some contaminated stations shows an obvious anthropogenic origin. Acknowledgements Financial support for this study mainly came from the National Natural Science Foundation of China (Grant Nos. 41330964, 41206073, 41206052), the China Geological Survey (Grant No. 1212010611401), and the Funding of Science and Technology Activities for Scholars from Abroad: Application of isotope tracer techniques to precisely determine the carbon sequestration capacity in wetland waters. We thank Prof. Qixiang He for his help in preparation of this manuscript. We express our appreciation to the anonymous reviewers for their thoughtful comments. References
Fig. 6. The graphs–boxplot of Enrichment factor (EF) in the near-shore area, north Jiangsu Province.
Arz, H.W., Pätzold, J., Wefer, G., 1998. Correlated millennial-scale changes in surface hydrography and terrigenous sediment yield inferred from last-glacial marine deposits off northeastern Brazil. Quatern. Res. 50, 157–166. Bai, J.H., Xiao, R., Zhang, K.J., Gao, H.F., 2012. Arsenic and heavy metal pollution in wetland soils from tidal freshwater and salt marshes before and after the flowsediment regulation regime in the Yellow River, China. J. Hydrol. 450–451, 244– 253. Bettinetti, R., Giarei, C., Provini, A., 2003. Chemical analysis and sediment toxicity bioassays to assess the contamination of the River Lambro (Northern Italy). Arch. Environ. Contam. Toxicol. 45, 72–78.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx Cambray, R.S., Playford, K., Lewis, G.N.J., 1982. Radioactive fallout in air and rain: results to the end of 1981. AERE-R10485, Atomic Energy Research Establishment Report, London, p. 43. Chen, H.F., Song, S.R., Lee, T.Q., Loˇwemark, L., Chi, Z.Q., Wang, Y., Hong, E., 2010. A multiproxy lake record from Inner Mongolia displays a late Holocene teleconnection between central Asian and North Atlantic climates. Quatern. Int. 227, 170–182. Chen, H.F., Chang, Y.P., Kao, S.J., Chen, M.T., Song, S.R., Kuo, L.W., Wen, S.Y., Yang, T.N., Lee, T.Q., 2011. Mineralogical and geochemical investigations of sedimentsource region changes in the Okinawa Trough during the past 100 ka (IMAGES core MD012404). J. Asian Earth Sci. 40, 1238–1249. Chen, H.F., Yeh, P.Y., Song, S.R., Hsu, S.C., Yang, T.N., Wang, Y., Chi, Z.Q., Lee, T.Q., Chen, M.T., Cheng, C.L., Zou, J.J., Chang, Y.P., 2013. The Ti/Al molar ratio as a new proxy for tracing sediment transportation process and its application in Aeolian events and sea level change in East Asia. J. Asian Earth Sci. 73, 31–38. China National Environmental Monitoring Center (CNEMC), 1990. Chinese Elemental Background Values for soils. Chinese Environmental Science Press, Beijing. Cuadrado, D.G., Perillo, G.M.E., 1997. Principal component analysis applied to geomorphologic evolution. Estuar. Coast. Shelf Sci. 44, 411–419. Dai, J.C., Song, J.M., Li, X.G., Yuan, H.M., Li, N., Zheng, G.X., 2007. Environmental changes reflected by sedimentary geochemistry in recent hundred years of Jiaozhou Bay, North China. Environ. Pollut. 145, 656–667. Dassenakis, M., Scoullos, M., Gaitis, A., 1997. Trace metals transport and behaviour in the Mediterranean estuary of Acheloos river. Mar. Pollut. Bull. 34, 103–111. Din, Z.B., 1992. Use of aluminum to normalize heavy-metal data from estuarine and coastal sediments of Straits of Melaka. Mar. Pollut. Bull. 24, 484–491. Dou, Y.G., Li, J., Zhao, J.T., Hu, B.Q., Yang, S.Y., 2013. Distribution, enrichment and source of heavy metals in surface sediments of the eastern Beibu Bay, South China Sea. Mar. Pollut. Bull. 67, 137–145. Fang, T.H., Li, J.Y., Feng, H.M., Chen, H.Y., 2009. Distribution and contamination of trace metals in surface sediments of the East China Sea. Mar. Environ. Res. 68, 178–187. Feng, H., Han, X.F., Zhang, W.G., Yu, L.Z., 2004. A preliminary study of heavy metal contamination in Yangtze River intertidal zone due to urbanization. Mar. Pollut. Bull. 49, 910–915. Folk, R.L., Ward, W.C., 1957. Brazos river bar: a study in the significance of grain size parameters. J. Sediment. Petrol. 31, 514–519. Gao, X.L., Chen, C.T.A., 2012. Heavy metal pollution status in surface sediments of the coastal Bohai Bay. Water Res. 46, 1901–1911. Han, Y.M., Du, P.X., Cao, J.J., Posmentier, E.S., 2006. Multivariate analysis of heavy metal contamination in urban dusts of Xi’an, Central China. Sci. Total Environ. 355, 176–186. Irabien, M.J., Velasco, F., 1999. Heavy metals in Oka River sediments (Urdaihai National Biosphere Reserve, northern Spain): lithogenic and anthropogenic effects. Environ. Geol. 37, 54–63. Jansen, J.H.F., Van der Gaast, S.J., Koster, B., Vaars, A.J., 1998. CORTEX, a shipboard XRF-scanner for element analyses in split sediment cores. Mar. Geol. 151, 143– 153. Jones, B., Turki, A., 1997. Distribution and speciation of heavy metals in surficial sediments from the Tees Estuary, north-east England. Mar. Pollut. Bull. 34, 768– 779. Kaushik, A., Kansal, A., Meena, S., Kumari, S., Kaushik, C.P., 2009. Heavy metal contamination of river Yamuna, Haryana, India: assessment by metal enrichment factor of sediments. J. Hazard. Mater. 164, 265–270. Liu, J., Yoshiki, S., Kong, X.H., Wang, H., Xiang, L.H., Wen, C., Rei, N., 2010. Sedimentary record of environmental evolution off the Yangtze River estuary, East China Sea, during the last 13,000 years, with special reference to the influence of the Yellow River on the Yangtze River delta during the last 600 years. Quatern. Sci. Rev. 29, 2424–2438. Liu, J., Kong, X.H., Saito, Y., Liu, J.P., Yang, Z.S., Wen, C., 2013. Subaqueous deltaic formation of the Old Yellow River (AD 1128–1855) on the western South Yellow Sea. Mar. Geol. 344, 19–33. Loska, K., Wiechula, D., 2003. Application of principal component analysis for the estimation of source of heavy metal contamination in surface sediments from Rybnik Reservoir. Chemosphere 51, 723–733. Marchand, C., Lallier-Vergs, E., Baltzer, F., Albric, P., Cossa, D., Baillif, P., 2006. Heavy metals distribution in mangrove sediments along the mobile coastline of French Guiana. Mar. Chem. 98, 1–17. Müller, G., 1979. Heavy metals in the surfaces sediment of the Rhine-Changes seitt. 1971. Umschan. 79, 778–783.
7
Müller, G., 1981. Die Schwermetallbelastung der sediments des Neckars und seiner Nebenflusse: eine Bestandsaufnahme. Chem. Ztg. 05, 157–164. Nobi, E.P., Dilipan, E., Thangaradjou, T., Sivakumar, K., Kannan, L., 2010. Geochemical and geo-statistical assessment of heavy metal concentration in the sediments of different coastal ecosystems of Andaman Islands, India. Estuar. Coast. Shelf Sci. 87, 253–264. Oldfield, F., Appleby, P.G., Battarbee, R.W., 1978. Alternative 210Pb dating: results from the New Guinea Highlands and Lough Erne. Nature 271, 339–342. San Miguel, E.G., Bolívar, J.P., García-Tenorio, R., 2004. Vertical distribution of the isotope ratios, 210Pb, 226Ra and 137Cs in sediment cores from an estuary affected by anthropogenic releases. Sci. Total Environ. 318, 143–157. Schropp, S.J., Lewis, F.G., Windom, H.L., Ryan, J.D., Calder, F.D., Burney, L.C., 1990. Interpretation of metal concentrations in estuarine sediments of Florida using aluminum as a reference element. Estuaries 13, 227–235. Singh, K.P., Mohan, D., Singh, V.K., Malik, A., 2005. Studies on distribution and fractionation of heavy metals in Gomti river sediments—a tributary of the Ganges, India. J. Hydrol. 312, 14–27. Tam, N.F.Y., Wong, Y.S., 2000. Spatial variation of heavy metals in surface sediments of Hong Kong mangrove swamps. Environ. Pollut. 110, 195–205. Taylor, S.R., 1964. Abundance of chemical elements in the continental crust: a new table. Geochim. Cosmochim. Acta 28, 1273–1285. Taylor, S.R., Mclennan, S.M., 1995. The geochemical evolution of the continental crust. Rev. Geophys. 33, 241–265. Turekian, K.K., Wedepohl, K.H., 1961. Distribution of the elements in some major units of the Earth’s crust. Geol. Soc. Am. 72, 175–192. Wei, G.J., Liu, Y., Li, X.H., Shao, L., Liang, X.R., 2003. Climatic impact on Al, K, Sc and Ti in marine sediments: Evidence from ODP Site 1144, South China Sea. Geochem. J. 37, 593–602. Xia, N., Zhang, Q., Yao, D., Li, G.H., 2008. Geochemistry analysis of marine sediments using fused glass disc by X-ray fluorescence spectrometry. Chin. J. Oceanol. Limnol. 26 (4), 475–479. Xia, P., Meng, X.W., Yin, P., Cao, Z.M., Wang, X.Q., 2011. Eighty-year sedimentary record of heavy metal inputs in the intertidal sediments from the Nanliu River estuary. Beibu Gulf of South China Sea. Environ. Pollut. 159, 92–99. Xu, G., Liu, J., Wen, C., Kong, X.H., 2010. Sedimentary characteristics and provenance of surficial sediments in the west South Yellow Sea. Mar. Geol. Quaternary Geol. 30, 49–56 (in Chinese with English abstract). Xue, C.T., Zhou, Y.Q., Zhu, X.H., 2004. The river course and delta from end of Late Pleistocene to the 7th century BC. Acta Oceanologica Sinica 26, 48–61 (in Chinese with English abstract). Yang, S.Y., Youn, J.S., 2007. Geochemical compositions and provenance discrimination of the central south Yellow Sea sediments. Mar. Geol. 243, 229–241. Yu, Z.Y., Chen, D., 1986. The formaiton and erosion of the old Yellow River dela northern Jiangsu Province. ACTA Oceanologica Sinica 8, 197–207 (in Chinese with English abstract). Yu, R.L., Yuan, X., Zhao, Y.H., Hu, G.R., Tu, X.L., 2008. Heavy metal pollution in intertidal sediments from Quanzhou Bay, China. J. Environ. Sci. 20, 664–669. Yuan, Y.R., Chen, Q., 1983. Development and erosion of the ancient Yellow River delta. Chin. Sci. Bull. 21, 1322–1324 (in Chinese). Yuan, H., Song, J., Li, X., Li, N., Duan, L., 2012. Distribution and contamination of heavy metals in surface sediments of the South Yellow Sea. Mar. Pollut. Bull. 64, 2151–2159. Zhang, J., Liu, C.L., 2002. Riverine composition and estuarine geochemistry of particulate metals in China-weathering features, anthropogenic impact and chemical fluxes. Estuar. Coast. Shelf Sci. 54, 1051–1070. Zhang, H., Shan, B.O., 2008. Historical records of heavy metal accumulation in sediments and the relationship with agricultural intensification in the Yangtze– Huaihe region, China. Sci. Total Environ. 399, 113–120. Zhang, W.G., Feng, H., Chang, J.N., Qu, J.G., Xie, H.X., Yu, L.Z., 2009. Heavy metal contamination in surface sediments of Yangtze River intertidal zone: An assessment from different indexes. Environ. Pollut. 157, 1533–1543. Zhou, G.H., Sun, B.B., Zeng, D.M., Wei, H.L., Liu, Z.Y., Zhang, B.M., 2013. Vertical distribution of trace elements in the sediment cores from major rivers in east China and its implication on geochemical background and anthropogenic effects. J. Geochem. Explor. http://dx.doi.org/10.1016/j.gexplo.2013.03.007. Zhu, L.M., Xu, J., Wang, F., Lee, B., 2011. An assessment of selected heavy metal contamination in. Geoche. Explor. 108,1–14.fore 1998. ontamination in the surface sediemnts s of northeren efore and after the flow-the surface sediments from the South China Sea before 1998. J. Geochem. Explor. 108, 1–14.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
Contents lists available at ScienceDirect
Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul
Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China Gang Xu a,b,⇑, Jian Liu a,b, Shaofeng Pei a,b,c, Xianghuai Kong a,b, Gang Hu a,b a
Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Ministry of Land and Resources, Qingdao 266071, China Qingdao Institute of Marine Geology, Qingdao 266071, China c Key Laboratory of Coastal Wetland Biogeosciences, China Geologic Survey, Qingdao Institute of Marine Geology, Qingdao 266071, China b
a r t i c l e
i n f o
Keywords: Heavy metals Distribution Source Surface sediments Near-shore area North Jiangsu Province
a b s t r a c t Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, 210Pbexcess and 137Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the Igeo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Sediments in the surface water are the most vulnerable to heavy metal pollution due to their open access to the disposal of terrestrial agricultural and industrial wastewater. Heavy metal contamination of the marine environmental media has received a great deal of world-wide attention because of their toxicity, persistence and non-biodegradable nature (Irabien and Velasco, 1999; Yu et al., 2008). Sediment quality has been recognized as an important environment indicator of water pollution (Jones and Turki, 1997; Feng et al., 2004; Marchand et al., 2006; Yu et al., 2008; Zhang et al., 2009) because marine sediment are the main sink for various pollutants, including heavy metals discharged into the environment (Dassenakis et al., 1997; Tam and Wong, 2000; Bettinetti et al., 2003; Singh et al., 2005), The natural source of heavy metals in marine sediments is mainly from the weathering and erosion of the lithosphere. Comparatively, anthropogenic sources are mainly from industrial processing, urban sewage and agricultural run-off (Kaushik et al., 2009). In order to make a more accurate assessment of heavy metal accumulation from anthropogenic source and the resultant environmental impact on sediments (Cuadrado and Perillo, 1997; ⇑ Corresponding author at: Key Laboratory of Marine Hydrocarbon Resources and Environment Geology, Ministry of Land and Resources, Qingdao 266071, China. Tel.: +86 532 857 55864; fax: +86 532 857 20553. E-mail address: [email protected] (G. Xu).
Loska and Wiechula, 2003; Zhang et al., 2009; Nobi et al., 2010), a complementary approach, which brings grain size effect, geoaccumulation index, correlation, enrichment factor together, is required. From 1128 to 1855, the Yellow River discharged into the South Yellow Sea, and contributed to the formation of the subaqueous old Yellow River Delta (Xu et al., 2010). After 1855, the river changed its channel and discharged into the Bohai Sea. The coast of north Jiangsu Province was eroded for the lack of sediment supply, and the eroded materials were redeposited partially in the near-shore area (Yu and Chen, 1986; Xue et al., 2004), partially in the subaqueous Yangtze River Delta (Liu et al., 2010) and partially in the mud area of South Yellow Sea (Yang and Youn, 2007). Many rivers surrounding the study area, such as the Guanhe River, the New Huaihe River, the Sheyang River, the Fanshen River, and the Beiba Tanqu and Subei Irrigation Channels, have provided a large amount of agricultural, residential and industrial wastewater. Heavy metals discharged into near-shore area by these rivers probably have exerted an effect on the marine environment. Therefore, the present study was carried out to meet the following objectives: (1) to study the characteristics of metal deposition in the surface sediments; (2) to determine the background values of heavy metals and Al by combination of 210Pb and 137Cs; (3) to assess the contamination status of heavy metals by geoaccumulation index; and (4) to distinguish the possible sources of heavy metals by correlation and enrichment factor.
http://dx.doi.org/10.1016/j.marpolbul.2014.03.041 0025-326X/Ó 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
2
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
2. Sampling and methods 2.1. Sampling In this study, 18 (B01-B18) surface sediment samples and one sediment core (Z01) were collected in the summer of 2008 in the near-shore area, north Jiangsu Province (Fig. 1). The surface sediment samples here conform to the top 5 cm of the center of the sampling box. Core sample was taken with a gravity corer with automatic clutch and reverse catcher. The bulk surface sediment samples were divided into two sub-samples for determination of heavy metals and grain size analysis. About 28 samples (at 2-cm intervals between 0 and 9.5 cm and at 4-cm intervals between 9.5 and 110 cm) were taken from Z01 core for further grain size, elements analysis and radionuclide measurement. 2.2. Analytical method 2.2.1. Grain size analysis The sediment samples were pretreated with 10% H2O2 to digest the organic matter. The excessive H2O2 solution was removed by
heating and evaporation. After that, 0.5% of sodium hexametaphosphate was added to the samples, making the sediments completely dispersed, and then the mixture was analyzed with a Mastersize-2000 laser particle size analyzer at the Qingdao Institute of Marine Geology, China. Grain-size parameter was calculated following the method of Folk and Ward (1957).
2.2.2. Element analysis Element geochemistry of the samples was analyzed at the Center of Testing, Qingdao Institute of Marine Geology, China Geological Survey. Major elements and some trace elements (Al, Cu, Pb, Zn) were determined by X-ray fluorescence spectrometer (model Philips PW4400), following the method described by Xia et al. (2008). The trace element As was analyzed by atomic fluorescence spectrometry (AFS) and the element Cd measured by inductively coupled plasma mass spectrometry (ICP–MS), using the method described by Dai et al. (2007). All the sediment samples were analyzed in duplicates and the quality was controlled by stand reference materials (see Dou et al., 2013 for detail). The differences of the concentrations between the determined and
Fig. 1. Bathymetry and location of surface sediment and sediment core sampling stations in the near-shore area, north Jiangsu Province.
Table 1 Granularity and metal contents in the surface sediments in the near-shore area, north Jiangsu Province. Station
Mz (u)
Cu (mg/kg)
Pb (mg/kg)
Zn (mg/kg)
Cd (mg/kg)
As (mg/kg)
Al (%)
B01 B02 B03 B04 B05 B06 B07 B08 B09 B10 B11 B12 B13 B14 B15 B16 B17 B18 Min Max Mean SD
7.26 6.80 7.04 7.38 7.34 7.26 7.28 7.61 6.91 7.45 6.64 6.21 6.85 6.85 6.54 6.69 6.83 6.90 6.2 7.6 7.0 ±0.4
35.1 36.1 32.8 35.1 34 32.7 37 40.2 33.2 37.8 38 31.2 40 29 37.2 31.5 34.5 34.7 29.0 40.2 35.0 ±3.0
25.9 25.8 24.8 26 25.1 23.3 26.6 27.9 23.9 26.2 28 22.7 26.6 22.9 28.3 26.5 25.7 26.6 22.7 28.3 25.7 ±1.7
87.2 90.6 88.6 88.8 87.2 81.4 89.7 93.6 86.7 91.8 97.2 81.3 95.7 79.8 89.3 84.4 90.3 91.9 79.8 97.2 88.6 4.7
0.19 0.18 0.2 0.19 0.18 0.18 0.18 0.21 0.17 0.23 0.19 0.18 0.19 0.17 0.22 0.16 0.17 0.2 0.16 0.23 0.19 ±0.02
20.1 20.5 19.7 18.6 17.8 16.2 19.6 19.4 17.2 18.9 19.7 17.7 17.4 16.2 19 16.5 19.6 17.9 16.2 20.5 18.4 ±1.4
7.94 7.71 7.62 7.82 7.64 7.24 7.83 7.97 7.52 7.75 7.95 7.22 8.07 7.29 7.81 7.53 7.83 7.85 7.22 8.07 7.70 ±0.26
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
3
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx Table 2 Comparison of metals of surface sediments in the near-shore area, north Jiangsu Province and representative seas. Location Study area South Yellow Sea Coastal Bohai Bay East China Sea South China Sea
Range Mean Range Mean Range Mean Range Mean Range Mean
Cu
Pb
Zn
Cd
As
Al
Reference
29–40.2 35.0 6.0–32.9 16.9 20.1–62.9 38.5 4.3–42 15 5.29–122 38.1
22.7–28.3 25.7 6.2–39.3 17.8 20.9–66.4 34.7 10–49 27 4.18–58.7 23.6
79.8–97.2 88.6 24.6–244 93.7 55.3–457 131 18–114 60 10.7–346 87.4
0.16–0.23 0.19 0.06–1.54 0.3 0.12–0.66 0.22 No data
16.2–20.5 18.4 No data
This study Yuan et al. (2012)
No data
7.22–8.07 7.7 3.99–7.79 6.34 No data
No data
No data
Fang et al. (2009)
0.08–2.14 0.4
No data
No data
Zhu et al. (2011)
certified values were less than 5%, and the analytical precision for replicate samples was within ± 10%. 2.2.3. Radionuclide measurement 210 Pb, 226Ra and 137Cs were analyzed using the BE3830 gammaray spectrometer (made in Canberra Company of USA) at the Testing Center of Qingdao Institute of Marine Geology, China Geological Survey, following a procedure similar to that of Xia et al. (2011). And counting uncertainties associated with sample measurements were typically less than 10%. Supported 210Pb activities were assumed to be equal to the measured 226Ra activities, and 210Pb activities were calculated by subtracting supported 210 Pb activities from total 210Pb activities (San Miguel et al., 2004). The sediment accumulation rates were calculated by the constant initial concentration (CIC) model (Oldfield et al., 1978). 3. Results and discussion 3.1. 3.1 Metal Contents in the surface sediments Results of grain size and total metal concentrations of the surface sediment samples from the near-shore area, north Jiangsu Province are listed in Table 1. The total concentrations (mg kg1) vary from 29.0 to 40.2 (average 35.0 ± 3.0) for Cu, 22.7–28.3 (average 25.7 ± 1.7) for Pb, 79.8–97.2 (average 88.6 ± 4.7) for Zn, 0.16– 0.23 (average 0.19 ± 0.02) for Cd, 16.2–20.5 (average 18.4 ± 1.4) for As and 7.22–8.07 (average 7.70 ± 0.26) for Al. The spatial distributions of Cu, Pb, Zn and Al were similar to each other with high concentrations at stations B08, B11 and B13. However, Cd and As showed a different spatial distribution pattern from other metals with high concentrations at stations B10, B15, B08 for Cd, and B01, B02 for As, respectively. Grain sizes range from 6.2 to 7.6 u (u = log2D, where D is the diameter of a particle in mm). The grain sizes are homogenous in study area, indicating that the diversity of metal concentration was affected not by grain size, but by the source. Comparison of metals in the study area with those in other regions is listed in Table 2. It can be seen that the average concentration of Cu in the study area is relatively higher than those in the South Yellow Sea and East China Sea, but is lower than those in Coastal Bohai Bay and South China Sea. The Pb concentration is relatively higher than those in the South Yellow Sea and South China Sea, but is lower than those in the Coastal Bohai Bay and East China
Gao and Chen (2012)
Sea. The Zn concentration is relatively higher than those in the East China Sea, but is lower than those in the Coastal Bohai Bay. The concentration of Cd in this area is lower than those in other regions. Although our study area is located in the South Yellow Sea, the mean concentration of most metals is higher than that of the South Yellow Sea. Higher metal concentrations might be attributed to the sources of sediments as discussed above and the fact that mean grain size is fine in our study area. 3.2. Metal baseline values The elemental concentration in the earth’s crust (Taylor and Mclennan, 1995) or the abundance of the upper crust shale is usually used as the baseline value for elements. However, the assessment of contamination levels when compared with a global standard (average shale or crust composition) is not always satisfactory because of the presence of local lithological anomalies (Zhou et al., 2013). Sediment chronologies established by the 210Pb dating techniques, combining with the vertical distribution of elements, are
Fig. 2. Vertical distribution of the core.
210
Pbexcess and
137
Cs activity in Z01 sediment
Table 3 The baseline values and granularity of sediments in the near-shore area, north Jiangsu Province and concentration of metals of sediments in other materials. Elements
Cu
Pb
Zn
Cd
As
Al
Mz
Reference
Baseline The loess materials of the YRD Upper continental crust
26 21.1 25
18.9 21.6 20
70.5 64.5 71
0.11 0.10 0.10
11.8 10.7 1.5
6.31 6.27 8.06
6.9 No data No data
This study CNEMC (1990), Bai et al. (2012) Taylor and McLennan (1995)
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
4
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
Table 4 Geoaccumulation index (Igeo) and enrichment factor (EF) of surface sediment in the near-shore area, north Jiangsu Province. Parameters Igeo EF
Range Mean Range Mean
Cu
Pb
Zn
Cd
As
0.6 to 0.3 0.4 1.0–1.2 1.1
0.5 to 0.3 0.4 1.0–1.2 1.1
0.6 to 0.5 0.5 1.0–1.1 1.0
0.3 to 0.2 0.1 1.1–1.6 1.3
0.4 to 0.1 0.2 1.1–1.4 1.3
Fig. 3. The graphs–boxplot of the geoaccumulation index (Igeo) in near-shore area, north Jiangsu Province.
used to determine the element baseline value before modern industrialization (about 100 years ago). The 210Pb profile for Z01 core was established for this study together with 137Cs analysis, and these profiles are presented in Fig. 2. The type of 210Pb profile shows low values and no notable decay in excess 210Pb activity, which is interpreted as the reflect of no net sediment accumulation in the past 100 years but being caused by marine erosion as previously reported (Yuan and Chen, 1983). In this case, the accumulation rate is expressed as zero. The sediment accumulation rates determined by 210Pb activity was evaluated according to 137Cs activity in the same profile, assuming that the measured penetration of 137Cs corresponds to its introduction into the atmosphere in 1954 and its maximum atmospheric fallout in 1964–1965 (Cambray et al., 1982). The 137 Cs activity shows a constant prolongation with a value of zero, also indicating that there was no accumulation and material deposited in the station of Z01. The surface sediment of Z01 core was probably accumulated between 1128 and 1855, this is in agreement with results obtained later (Liu et al., 2013). It can be seen that the metal baseline values in the study area are close to
Fig. 4. The distribution of Igeo (As) and EF (As) in near-shore area, north Jiangsu Province.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
the environmental background concentrations of the loess materials of the Yellow River Delta, and also close to the upper continental crust, except for As and Al (Table 3). Z01 sediment core located in the old subaqueous Yellow River Delta has the same provenance with the surface sediments studied above. So the abundance of elements in the surface sediment of Z01 is able to represent the elemental baseline values in the study area. 3.3. Assessment of heavy metals pollution Geoaccumulation index (Igeo), originally defined by Müller’s (1979), is used to assess the extent of sediment pollution in our study area with the following equation:
Igeo ¼ log2 ½ðC n =AlÞ=ð1:5 Bn Þ=Al
ð1Þ
where Cn is the measured content of the examined metal ‘‘n’’ in the sediment, Bn is its geochemical baseline content, and factor 1.5 is the baseline matrix correction factor because of lithogenic effects. Al is the reference element. It was found that the relative proportion of a metal to Al in crustal material is fairly constant (Taylor, 1964; Turekian and Wedepohl, 1961). The ratio of heavy metal to Al can minimize the grain size effect between measured content and baseline value and reveal the actual geochemical imbalance (Din, 1992; Schropp et al., 1990). Müller has distinguished seven classes of geoaccumulaion index from class 0 (Igeo 6 0) to class 6 (Igeo P 5) (Müller, 1981). Results in Table 4 and Fig. 3 indicate that no station is polluted by Cu, Pb, Zn and As (Igeo 6 0), but the geoaccumulation index of As
5
is higher than Cu, Pb and Zn. At Stations of B01, B02, B03, the geoaccumulation index of As is close to zero (Igeo = 0.1) (Fig. 4). For Cd, slight pollution is observed at stations of B10, B15 (Igeo > 0), B03, B08 and B18 (Igeo = 0) (Fig. 5).
3.4. Sources of heavy metals in marine sediments 3.4.1. Relationships between heavy metals and Al Enhanced concentration of terrigenous element Al has been interpreted as an increasing supply of siliciclastic materials of fluvial or aeolian origin in marine sediments (Arz et al., 1998; Jansen et al., 1998; Chen et al., 2010, 2011). Al is considered to be one of well conserved elements since it is extremely resistant to weathering and erosion (Wei et al., 2003). The EF mean value of Al in our study area is 1.2, indicating that Al was mainly terrigenous. Similar to heavy metals, Al accumulates easily in the fine sediments. Therefore, Al is able to trace the terrigenous material in the marine surface sediment (Chen et al., 2013) and the relationship between heavy metals and Al can be used to identify the sources of the heavy metals effectively. To distinguish the sources of heavy metals in the surface sediments, a statistical analysis with Pearson’s correlation coefficients is conducted and the results are shown in Table 5. Significantly positive correlations are found between heavy metals (Cu, Pb and Zn) and Al, indicating that all these heavy metals were from the terrigenous material and not polluted by human activities. Such results are consistent with the Igeo. Moderate positive correlation is found between As and Al, indicating that As was probably
Fig. 5. The distribution of Igeo (Cd) and EF (Cd) in near-shore area, north Jiangsu Province.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
6
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx
Table 5 Pearson’s correlation coefficients for the heavy metals and Al.
** *
Elements
Cu
Pb
Zn
Cd
As
Al
Cu Pb Zn Cd As Al
1 .795** .882** .605** .548* .846**
1 .807** .503* .532* .852**
1 .485* .594** .898**
1 0.401 0.436
1 .629**
1
Correlation is significant at the 0.1 level (2-tailed). Correlation is significant at the 0.05 level (2-tailed).
affected by both the siliciclastic and anthropogenic inputs. No significant correlation is observed between Cd and Al, indicating that Cd was obviously affected by the human activities in some stations. 3.4.2. Enrichment factor (EF) of heavy metals In order to get a better understanding of the sources of the heavy metals in our study area, we also considered another approach–Enrichment factor (EF), which acts as a useful tool in distinguishing the sources of heavy metal pollution (Zhang and Liu, 2002; Han et al., 2006). To minimize the grain size affect between the measured values in the surface sediments and the regional baseline values, geochemical normalization of heavy metal concentration to Al was employed. Besides, the normalization of the surface sediment to a reference element, such as Al which is not associated with anthropogenic influences, can be used to determine the sources of heavy metals. The EF is defined by Eq. (2) using Al as a reference element:
EF ¼ ðM n =AlÞsample =ðMn =AlÞbackground
ð2Þ
where (Mn/Al)sample is the ratio of heavy metal ‘‘n’’ content to Al content in a sample, (Mn/Al)background is the ratio of the natural baseline value of metal ‘‘n’’ to that of Al. Zhang and Liu (2002) regarded EF = 1.5 as an assessment criterion. EF value ranging from 0.5 to 1.5 indicates that the heavy metal was entirely coming from crustal materials or natural weathering processes. In contrast, EF value greater than 1.5 indicates that a significant portion of heavy metal is derived from anthropogenic materials. As shown in Table 4 and Fig. 6, the results from our study area show that the EF of Cu ranges from 1.0 to 1.2 (average 1.1 with two outliers, 1.2 and 1.0), the EF of Pb ranges from 1.0 to 1.2 (average 1.1 with two abnormal values, 1.2 and 1.0), the EF of Zn ranges
from 1.0 to 1.1 (average 1.0), the EF of Cd ranges from 1.1 to 1.6 (average 1.3 with two outliers, 1.5 and 1.6), and the EF of As ranges from 1.1 to 1.4 (average 1.3). Overall, the average EF values of Cu, Pb and Zn are less than 1.5 in the study area, indicating that all these heavy metals are from the crustal materials. The average EF value of As is found to be close to 1.5. Especially, at stations B02 and B03 the Igeo value of As is 0.1, and the EF value of As is 1.4, suggesting that As at these stations might be affected by anthropogenic inputs. It is noticeable that the average EF value of Cd is close to 1.5. At stations B10 and B15, the EF values (>1.5) and Igeo values (>0) of Cd suggest that the contaminated Cd was obviously controlled by anthropogenic materials (Fig. 5). Previous studies have shown that the distributions of As and Cd were closely related to the intensive usage of phosphate fertilizers containing a significant amounts of metals, particularly Cd and As impurities (Zhang and Shan, 2008; Xia et al., 2011). These contaminated stations are located around 15 m isobaths, where rivers around the study area carried a vast amounts of suspended sediments and dissolved substances to the near-shore area, such as heavy metals derived from continental runoff, riverbank erosion and domestic agricultural and industrial runoff. And then the heavy metals in suspended sediments arrived at the 15 m isobaths, where fine sediments were easily deposited because of the weak hydrological conditions, and light pollution was caused in these stations. 4. Conclusions Analyses of heavy metals (Cu, Pb, Zn, As, Cd) from the nearshore area of north Jiangsu Province showed that the diversity of metal concentration was controlled not by the grain size of the mineral, but by the material provenience. The baseline values of elements in the study area are 26.0 mg kg1 for Cu, 18.9 mg kg1 for Pb, 70.5 mg kg1 for Zn, 0.11 mg kg1 for Cd, 11.8 mg kg1 for As and 6.31 % for Al. The Igeo indicates that no station is polluted by Cu, Pb, Zn and As (Igeo 6 0), but the average Igeo values of the As was higher than those of Cu, Pb, Zn. In stations of B01, B02, B03, the Igeo values of As are close to zero. Light pollution caused by Cd is observed in some stations. The correlation and enrichment factor suggests that Cu, Pb and Zn are of lithogenic origin while Cd and As are mixed origin. Especially, the Cd in some contaminated stations shows an obvious anthropogenic origin. Acknowledgements Financial support for this study mainly came from the National Natural Science Foundation of China (Grant Nos. 41330964, 41206073, 41206052), the China Geological Survey (Grant No. 1212010611401), and the Funding of Science and Technology Activities for Scholars from Abroad: Application of isotope tracer techniques to precisely determine the carbon sequestration capacity in wetland waters. We thank Prof. Qixiang He for his help in preparation of this manuscript. We express our appreciation to the anonymous reviewers for their thoughtful comments. References
Fig. 6. The graphs–boxplot of Enrichment factor (EF) in the near-shore area, north Jiangsu Province.
Arz, H.W., Pätzold, J., Wefer, G., 1998. Correlated millennial-scale changes in surface hydrography and terrigenous sediment yield inferred from last-glacial marine deposits off northeastern Brazil. Quatern. Res. 50, 157–166. Bai, J.H., Xiao, R., Zhang, K.J., Gao, H.F., 2012. Arsenic and heavy metal pollution in wetland soils from tidal freshwater and salt marshes before and after the flowsediment regulation regime in the Yellow River, China. J. Hydrol. 450–451, 244– 253. Bettinetti, R., Giarei, C., Provini, A., 2003. Chemical analysis and sediment toxicity bioassays to assess the contamination of the River Lambro (Northern Italy). Arch. Environ. Contam. Toxicol. 45, 72–78.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041
G. Xu et al. / Marine Pollution Bulletin xxx (2014) xxx–xxx Cambray, R.S., Playford, K., Lewis, G.N.J., 1982. Radioactive fallout in air and rain: results to the end of 1981. AERE-R10485, Atomic Energy Research Establishment Report, London, p. 43. Chen, H.F., Song, S.R., Lee, T.Q., Loˇwemark, L., Chi, Z.Q., Wang, Y., Hong, E., 2010. A multiproxy lake record from Inner Mongolia displays a late Holocene teleconnection between central Asian and North Atlantic climates. Quatern. Int. 227, 170–182. Chen, H.F., Chang, Y.P., Kao, S.J., Chen, M.T., Song, S.R., Kuo, L.W., Wen, S.Y., Yang, T.N., Lee, T.Q., 2011. Mineralogical and geochemical investigations of sedimentsource region changes in the Okinawa Trough during the past 100 ka (IMAGES core MD012404). J. Asian Earth Sci. 40, 1238–1249. Chen, H.F., Yeh, P.Y., Song, S.R., Hsu, S.C., Yang, T.N., Wang, Y., Chi, Z.Q., Lee, T.Q., Chen, M.T., Cheng, C.L., Zou, J.J., Chang, Y.P., 2013. The Ti/Al molar ratio as a new proxy for tracing sediment transportation process and its application in Aeolian events and sea level change in East Asia. J. Asian Earth Sci. 73, 31–38. China National Environmental Monitoring Center (CNEMC), 1990. Chinese Elemental Background Values for soils. Chinese Environmental Science Press, Beijing. Cuadrado, D.G., Perillo, G.M.E., 1997. Principal component analysis applied to geomorphologic evolution. Estuar. Coast. Shelf Sci. 44, 411–419. Dai, J.C., Song, J.M., Li, X.G., Yuan, H.M., Li, N., Zheng, G.X., 2007. Environmental changes reflected by sedimentary geochemistry in recent hundred years of Jiaozhou Bay, North China. Environ. Pollut. 145, 656–667. Dassenakis, M., Scoullos, M., Gaitis, A., 1997. Trace metals transport and behaviour in the Mediterranean estuary of Acheloos river. Mar. Pollut. Bull. 34, 103–111. Din, Z.B., 1992. Use of aluminum to normalize heavy-metal data from estuarine and coastal sediments of Straits of Melaka. Mar. Pollut. Bull. 24, 484–491. Dou, Y.G., Li, J., Zhao, J.T., Hu, B.Q., Yang, S.Y., 2013. Distribution, enrichment and source of heavy metals in surface sediments of the eastern Beibu Bay, South China Sea. Mar. Pollut. Bull. 67, 137–145. Fang, T.H., Li, J.Y., Feng, H.M., Chen, H.Y., 2009. Distribution and contamination of trace metals in surface sediments of the East China Sea. Mar. Environ. Res. 68, 178–187. Feng, H., Han, X.F., Zhang, W.G., Yu, L.Z., 2004. A preliminary study of heavy metal contamination in Yangtze River intertidal zone due to urbanization. Mar. Pollut. Bull. 49, 910–915. Folk, R.L., Ward, W.C., 1957. Brazos river bar: a study in the significance of grain size parameters. J. Sediment. Petrol. 31, 514–519. Gao, X.L., Chen, C.T.A., 2012. Heavy metal pollution status in surface sediments of the coastal Bohai Bay. Water Res. 46, 1901–1911. Han, Y.M., Du, P.X., Cao, J.J., Posmentier, E.S., 2006. Multivariate analysis of heavy metal contamination in urban dusts of Xi’an, Central China. Sci. Total Environ. 355, 176–186. Irabien, M.J., Velasco, F., 1999. Heavy metals in Oka River sediments (Urdaihai National Biosphere Reserve, northern Spain): lithogenic and anthropogenic effects. Environ. Geol. 37, 54–63. Jansen, J.H.F., Van der Gaast, S.J., Koster, B., Vaars, A.J., 1998. CORTEX, a shipboard XRF-scanner for element analyses in split sediment cores. Mar. Geol. 151, 143– 153. Jones, B., Turki, A., 1997. Distribution and speciation of heavy metals in surficial sediments from the Tees Estuary, north-east England. Mar. Pollut. Bull. 34, 768– 779. Kaushik, A., Kansal, A., Meena, S., Kumari, S., Kaushik, C.P., 2009. Heavy metal contamination of river Yamuna, Haryana, India: assessment by metal enrichment factor of sediments. J. Hazard. Mater. 164, 265–270. Liu, J., Yoshiki, S., Kong, X.H., Wang, H., Xiang, L.H., Wen, C., Rei, N., 2010. Sedimentary record of environmental evolution off the Yangtze River estuary, East China Sea, during the last 13,000 years, with special reference to the influence of the Yellow River on the Yangtze River delta during the last 600 years. Quatern. Sci. Rev. 29, 2424–2438. Liu, J., Kong, X.H., Saito, Y., Liu, J.P., Yang, Z.S., Wen, C., 2013. Subaqueous deltaic formation of the Old Yellow River (AD 1128–1855) on the western South Yellow Sea. Mar. Geol. 344, 19–33. Loska, K., Wiechula, D., 2003. Application of principal component analysis for the estimation of source of heavy metal contamination in surface sediments from Rybnik Reservoir. Chemosphere 51, 723–733. Marchand, C., Lallier-Vergs, E., Baltzer, F., Albric, P., Cossa, D., Baillif, P., 2006. Heavy metals distribution in mangrove sediments along the mobile coastline of French Guiana. Mar. Chem. 98, 1–17. Müller, G., 1979. Heavy metals in the surfaces sediment of the Rhine-Changes seitt. 1971. Umschan. 79, 778–783.
7
Müller, G., 1981. Die Schwermetallbelastung der sediments des Neckars und seiner Nebenflusse: eine Bestandsaufnahme. Chem. Ztg. 05, 157–164. Nobi, E.P., Dilipan, E., Thangaradjou, T., Sivakumar, K., Kannan, L., 2010. Geochemical and geo-statistical assessment of heavy metal concentration in the sediments of different coastal ecosystems of Andaman Islands, India. Estuar. Coast. Shelf Sci. 87, 253–264. Oldfield, F., Appleby, P.G., Battarbee, R.W., 1978. Alternative 210Pb dating: results from the New Guinea Highlands and Lough Erne. Nature 271, 339–342. San Miguel, E.G., Bolívar, J.P., García-Tenorio, R., 2004. Vertical distribution of the isotope ratios, 210Pb, 226Ra and 137Cs in sediment cores from an estuary affected by anthropogenic releases. Sci. Total Environ. 318, 143–157. Schropp, S.J., Lewis, F.G., Windom, H.L., Ryan, J.D., Calder, F.D., Burney, L.C., 1990. Interpretation of metal concentrations in estuarine sediments of Florida using aluminum as a reference element. Estuaries 13, 227–235. Singh, K.P., Mohan, D., Singh, V.K., Malik, A., 2005. Studies on distribution and fractionation of heavy metals in Gomti river sediments—a tributary of the Ganges, India. J. Hydrol. 312, 14–27. Tam, N.F.Y., Wong, Y.S., 2000. Spatial variation of heavy metals in surface sediments of Hong Kong mangrove swamps. Environ. Pollut. 110, 195–205. Taylor, S.R., 1964. Abundance of chemical elements in the continental crust: a new table. Geochim. Cosmochim. Acta 28, 1273–1285. Taylor, S.R., Mclennan, S.M., 1995. The geochemical evolution of the continental crust. Rev. Geophys. 33, 241–265. Turekian, K.K., Wedepohl, K.H., 1961. Distribution of the elements in some major units of the Earth’s crust. Geol. Soc. Am. 72, 175–192. Wei, G.J., Liu, Y., Li, X.H., Shao, L., Liang, X.R., 2003. Climatic impact on Al, K, Sc and Ti in marine sediments: Evidence from ODP Site 1144, South China Sea. Geochem. J. 37, 593–602. Xia, N., Zhang, Q., Yao, D., Li, G.H., 2008. Geochemistry analysis of marine sediments using fused glass disc by X-ray fluorescence spectrometry. Chin. J. Oceanol. Limnol. 26 (4), 475–479. Xia, P., Meng, X.W., Yin, P., Cao, Z.M., Wang, X.Q., 2011. Eighty-year sedimentary record of heavy metal inputs in the intertidal sediments from the Nanliu River estuary. Beibu Gulf of South China Sea. Environ. Pollut. 159, 92–99. Xu, G., Liu, J., Wen, C., Kong, X.H., 2010. Sedimentary characteristics and provenance of surficial sediments in the west South Yellow Sea. Mar. Geol. Quaternary Geol. 30, 49–56 (in Chinese with English abstract). Xue, C.T., Zhou, Y.Q., Zhu, X.H., 2004. The river course and delta from end of Late Pleistocene to the 7th century BC. Acta Oceanologica Sinica 26, 48–61 (in Chinese with English abstract). Yang, S.Y., Youn, J.S., 2007. Geochemical compositions and provenance discrimination of the central south Yellow Sea sediments. Mar. Geol. 243, 229–241. Yu, Z.Y., Chen, D., 1986. The formaiton and erosion of the old Yellow River dela northern Jiangsu Province. ACTA Oceanologica Sinica 8, 197–207 (in Chinese with English abstract). Yu, R.L., Yuan, X., Zhao, Y.H., Hu, G.R., Tu, X.L., 2008. Heavy metal pollution in intertidal sediments from Quanzhou Bay, China. J. Environ. Sci. 20, 664–669. Yuan, Y.R., Chen, Q., 1983. Development and erosion of the ancient Yellow River delta. Chin. Sci. Bull. 21, 1322–1324 (in Chinese). Yuan, H., Song, J., Li, X., Li, N., Duan, L., 2012. Distribution and contamination of heavy metals in surface sediments of the South Yellow Sea. Mar. Pollut. Bull. 64, 2151–2159. Zhang, J., Liu, C.L., 2002. Riverine composition and estuarine geochemistry of particulate metals in China-weathering features, anthropogenic impact and chemical fluxes. Estuar. Coast. Shelf Sci. 54, 1051–1070. Zhang, H., Shan, B.O., 2008. Historical records of heavy metal accumulation in sediments and the relationship with agricultural intensification in the Yangtze– Huaihe region, China. Sci. Total Environ. 399, 113–120. Zhang, W.G., Feng, H., Chang, J.N., Qu, J.G., Xie, H.X., Yu, L.Z., 2009. Heavy metal contamination in surface sediments of Yangtze River intertidal zone: An assessment from different indexes. Environ. Pollut. 157, 1533–1543. Zhou, G.H., Sun, B.B., Zeng, D.M., Wei, H.L., Liu, Z.Y., Zhang, B.M., 2013. Vertical distribution of trace elements in the sediment cores from major rivers in east China and its implication on geochemical background and anthropogenic effects. J. Geochem. Explor. http://dx.doi.org/10.1016/j.gexplo.2013.03.007. Zhu, L.M., Xu, J., Wang, F., Lee, B., 2011. An assessment of selected heavy metal contamination in. Geoche. Explor. 108,1–14.fore 1998. ontamination in the surface sediemnts s of northeren efore and after the flow-the surface sediments from the South China Sea before 1998. J. Geochem. Explor. 108, 1–14.
Please cite this article in press as: Xu, G., et al. Distribution and source of heavy metals in the surface sediments from the near-shore area, north Jiangsu Province, China. Mar. Pollut. Bull. (2014), http://dx.doi.org/10.1016/j.marpolbul.2014.03.041