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Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea
MPB-07976; No of Pages 7 Marine Pollution Bulletin xxx (2016) xxx–xxx
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Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea Siamak Jamshidi ⁎, Kazem Darvish Bastami Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), No. 3, Etemadzadeh St., Fatemi Ave., 1411813389 Tehran, Islamic Republic of Iran
a r t i c l e
i n f o
Article history: Received 13 June 2016 Received in revised form 23 July 2016 Accepted 22 August 2016 Available online xxxx Keywords: Metals Surface sediment ERM quotient Anzali wetland Caspian Sea
a b s t r a c t In this study, the accumulation of metals, including Al, Fe, Zn, V, Ni, Cu, Cr, Cd, Co, As, and Pb, in sediments of Anzali wetland in the southwest region of the Caspian Sea was investigated. For this purpose, the sediments were collected from 17 sampling sites in Anzali wetland, Caspian Sea. The samples were then analyzed using inductively coupled plasma–optical emission spectrometry (ICP-OES). Pearson correlation coefficient showed significant and positive correlation between concentration of all metals (except As and Cd). Furthermore, the results implied that Al and Fe are probably responsible for the transportation of heavy metals into the sediments of Anzali wetland. According to mean effects range-median quotient (mean ERM quotient), the sediments from Anzali wetland had a 21% probability of toxicity. © 2016 Elsevier Ltd. All rights reserved.
Marine pollutants are part of several environmental pollution crises. With two-thirds of the Earth's surface covered by water, the effects of pollution on marine habitats are very high. Aqueous ecosystems have become more susceptible and vulnerable to pollution because of the rather higher rate of accumulation of chemical compounds, and in fact, these ecosystems act as reservoirs of various anthropogenic toxicants and contaminants that are stressful through vast inputs of pollution. The issue of marine pollution has recently attracted worldwide attention (Callender, 2005; Bastami et al., 2015). Bottom sediment, specifically as a tool for monitoring metals in the sea, represents advantageous results of pollutant distribution. Sediments are accumulated over the years and can be regarded as fixators of contamination level. After being discharged into bodies of water, pollutants are gradually deposited at the bottom in various forms. When the pollution level of sediments exceeds a specific limit, it would disturb and eventually destroy the ecosystem equilibrium. Monitoring the deposition of metals in sediments provides a continuous surveillance of pollution in the studied area, and sediment analysis could make the specification of pollution type easier in order to adopt any management decisions for advisable controlling (ElNemr et al., 2007; Bastami et al., 2015). Metals discharging into the aquatic system during their transport are distributed between the aqueous phase and sediments. Because of adsorption, hydrolysis, and coprecipitation of metal ions, a large quantity of them are deposited in the sediment while only a small portion of ⁎ Corresponding author. E-mail addresses: [email protected] (S. Jamshidi), [email protected] (K.D. Bastami).
free metal ions remain dissolved in the water column. Therefore, sediments in aquatic environments can either retain metals or release them to the water column by various remobilization processes. Sediment parameters (mineralogy, texture), metal characteristics, pH, organic matter, and oxidation–reduction potential are important parameters for controlling the accumulation and availability of metals in the sediment (Hakanson, 1980; Wright and Mason, 1999; Tam and Wong, 2000; Buccolieri et al., 2006; ElNemr et al., 2007; Bastami et al., 2012; Bastami et al., 2015). Hence, sediments are enumerated as sources of metals in marine environments, and they play a key role in transmission and deposition of metals. Generally, normal metal concentrations found in sediments are not detrimental to inhabiting organisms. For normal metabolism, live organisms essentially require some metals like zinc, which have toxic effects above a critical threshold. Anzali wetland is located in the southwest region of the Caspian Sea with an area of about 193 km2. Anzali has been registered as an international wetland in the 1975 Ramsar Convention. Catchment of the wetland covers an area of about 3610 km2 and is bounded by the Caspian Sea in the north, the Alborz mountain range in the south, the Talysh Mountains in the west, and the Sefidrud Delta in the east. Approximately 93,525 and 196,020 ha of the catchment are covered by farmlands (particularly rice farms) and forestlands, respectively. The wetland, with mean annual precipitation and evaporation rates of about 1280 and 980 mm, respectively, has no dry season. It is covered with reed bed, and it plays a key role in spawning and development of the fish. Furthermore, it provides breeding place for many water birds and serves as a staging and wintering site. Anzali wetland's environment
http://dx.doi.org/10.1016/j.marpolbul.2016.08.049 0025-326X/© 2016 Elsevier Ltd. All rights reserved.
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Fig. 1. Locations of the sampling sites at Anzali wetland, Caspian Sea.
has been jeopardized by the contaminants produced from urbanization; population growth; and agricultural, industrial, and tourism activities (Hargalani et al., 2014: Esmaeilzadeh et al., 2016). The aim of this study is to investigate metal distributions in the sediments obtained from different parts of Anzali wetland and, therefore, to discover the relationship between the sediment characteristics and distribution of metals in Anzali wetland. Sediment samples from 17 different sites were collected using Van Veen Grab sampler for analyzing metals during winter (February 2016, Fig. 1). The samples were then packed and carried to the laboratory in ice boxes and stored at 4 °C until analysis. After drying in an oven, sediment samples were ground by using a hand mortar followed by screening with a 0.5-mm sieve to remove large particles. Thereafter, the samples (0.5 g) were digested using a mixed solution of HF\\HCl\\HNO 3\\HClO 4 according to the ASTM standard D5258-92 (ASTM, 2013). The samples were analyzed for Al, Fe, As, Cd, Cu, Ni, Pb, Co, Cr, V, and Zn by inductively coupled plasma–optical emission spectrometry (ICP-OES; Varian VISTAMPX). In addition, major element contents (SiO 2 , CaO, Fe 2 O 3 , Al 2 O 3 , MgO, K 2 O, Na 2 O, TiO 2 , P 2 O 5 , and MnO 2 ) were measured using an X-ray fluorescence spectrometer (Bruker Model). The precision and accuracy of the methods were systematically and routinely verified using standard reference materials. Accepted recoveries range from 93% to 108%. For the determination of total organic matter, sediment samples were dried at 70 °C for 24 h and then combusted in the oven at 550 °C for 4 h. Total organic matter, as described by Abrantes et al. (1999), was measured by the following equation: Total organic matter ðTOM%Þ ¼ ½ðB−CÞ=B 100
ð1Þ
where B and C are the weights of dried sediment before and after combustion in the oven, respectively.Grain size was analyzed using laser
particle size analyzer (HORIBA-LA950, France & Japan). Before analysis, about 4 g of samples was combusted in the oven at 550 °C for 4 h and 950 °C for 2 h to remove organic matter and biogenic carbonate, respectively.Enrichment factor (EF), which is an appropriate tool to determine sedimentary metal source produced by anthropogenic events or natural origin, normalizes metal concentrations according to the sediment texture properties (Selvaraj et al., 2004; Vald'es et al., 2005; Bastami et al., 2014). In this index, aluminum is widely used, indicating aluminum silicate in coastal areas where this element is predominant. Enrichment factor was also applied as a degree of sedimentation (Lee Table 1 General characteristics of the sediments (average ± SD) sampled in Anzali wetland. Sampling sites
Mud (%)
Sand (%)
TOM (%)
Carbonate Inorganic (%) carbon (IC %)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ±
41.93 88.44 66.78 87.03 2.20 96.77 82.75 86.84 82.05 81.85 88.41 82.39 71.95 50.82 34.98 45.17 19.94 65.31 ±
58.07 11.56 33.22 12.97 97.80 3.23 17.25 13.16 17.95 18.15 11.59 17.61 28.05 49.18 65.02 54.83 80.06 34.69 ±
4.56 6.57 7.06 7.77 1.34 7.97 6.83 12.40 13.03 14.80 13.30 14.38 4.29 2.39 3.11 2.71 2.52 7.35 ±
3.63 6.00 2.48 6.21 1.39 4.03 3.76 13.30 8.67 11.39 11.37 11.62 2.66 2.50 1.26 1.97 2.58 5.58 ±
27.97
27.97
4.70
4.20
SD
0.72 1.20 0.49 1.24 0.28 0.81 0.75 2.65 1.73 2.25 2.27 2.32 0.52 0.50 0.25 0.39 0.51 1.11 ± 0.84
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
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Table 2 Major elements of the sediments (average ± SD) sampled in Anzali wetland. Sampling sites
SiO2 (%)
Al2O3 (%)
CaO (%)
Fe2O3 (%)
K2O (%)
MgO (%)
MnO2 (%)
Na2O (%)
P2O5 (%)
TiO2 (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ± SD
60.43 55.06 61.11 50.35 71.80 55.68 61.98 44.53 48.15 45.66 44.61 42.87 65.48 64.30 69.56 70.29 73.87 57.98 ± 10.50
12.94 13.93 15.09 15.23 11.06 13.80 12.96 11.45 11.78 11.79 11.02 11.33 14.11 12.89 13.57 12.99 12.23 12.83 ± 1.33
4.87 5.52 1.90 4.41 2.83 2.86 2.30 11.69 7.02 9.21 9.88 8.92 1.87 1.99 1.11 1.13 1.02 4.62 ± 3.49
6.88 7.23 6.78 7.73 4.75 8.42 7.00 5.72 6.67 6.06 5.95 6.15 5.88 5.63 5.04 4.84 4.11 6.17 ± 1.13
0.71 0.56 0.74 1.12 0.70 0.65 0.85 0.67 0.68 0.84 0.60 0.96 0.62 1.07 0.91 0.93 0.66 0.78 ± 0.17
1.95 2.47 1.99 2.69 0.85 2.61 1.93 1.80 2.02 1.95 1.90 1.91 1.61 1.61 1.40 1.34 1.11 1.83 ± 0.49
0.140 0.146 0.150 0.121 0.119 0.140 0.158 0.221 0.233 0.264 0.274 0.252 0.142 0.110 0.113 0.112 0.110 0.17 ± 0.06
2.00 1.90 2.12 1.52 2.98 1.10 1.89 1.07 1.03 1.49 1.33 1.42 2.85 2.88 3.13 2.89 3.09 2.04 ± 0.78
0.115 0.091 0.121 0.182 0.114 0.106 0.138 0.109 0.111 0.136 0.097 0.155 0.101 0.174 0.148 0.151 0.107 0.127 ± 0.027
0.735 0.640 0.613 0.716 0.359 0.740 0.703 0.437 0.539 0.514 0.430 0.499 0.506 0.608 0.489 0.508 0.343 0.552 ± 0.126
et al., 1998; Woitke et al., 2003; Bastami et al., 2015), and can be determined as follows: Enrichmentfactor ¼ ðHs =Als Þ=ðHc =Alc Þ
ð2Þ
where Hs and Hc are metal concentrations in sample and background reference, respectively, and Als and Alc are the aluminum contents in sample and background reference, respectively. In this study, we used background concentrations of metals in sediment from Anzali wetland, which are 3.9, 2.1, 34.6, 140.2, 35.1, 135.5, 33.3, 86.1, 104.4 ppm, and 3.1% for As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, and Al, respectively (Hargalani et al., 2014). To assess the sediment environmental quality, an integrated pollution load index (PLI) of eight metals was calculated as suggested by Suresh et al. (2011): PLI ¼ ðCF1 CF2 CF3 …CFn Þ1=n
ð3Þ
where CF is the ratio of the content of each metal to the background values, and. CFmetals ¼ CHmetal =CHback
ð4Þ
where CHmetal is the concentration of the examined metal and CHback is the background value of the metal, respectively.
Potential ecological risk (PER) index was also introduced to assess the contamination degree of metals in the collected sediments. The equations for calculating the PER, proposed by Hakanson (1980), are as follows: E ¼ TC
ð5Þ
C ¼ Ca =Cb
ð6Þ
PER ¼ ∑E ¼ ∑TC
ð7Þ
where C is the single-element pollution factor, Ca is the content of the element in samples, and Cb is the reference value of the element. The sum of C for all the metals examined represents the integrated pollution degree (C) of the environment. E is the PER factor of an individual element. T is the biological toxic factor of individual elements, whose values are Cu = Pb = 5, Zn = 1, As =10, Cd = 30, Cr = 2, and Ni = 6 (Hakanson, 1980). PER is a comprehensive potential ecological index, which equals to the sum of E. It represents the sensitivity of biological community to toxic substances and illustrates the PER caused by the overall contamination. A Pearson correlation analysis was conducted to test the relationship between various metals and environmental parameters. Difference in metal content between sites was indicated by a cluster analysis, which
Table 3 Heavy metal content (average ± SD) of the sediments sampled in Anzali wetland. Sampling sites
Al (%)
Fe (%)
As (ppm)
Cd (ppm)
Co (ppm)
Cr (ppm)
Cu (ppm)
Ni (ppm)
Pb (ppm)
V (ppm)
Zn (ppm)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ±
6.85 7.37 7.99 8.06 5.85 7.30 6.86 6.06 6.24 6.24 5.83 5.99 7.47 6.82 7.18 6.87 6.47 6.79 ±
4.82 5.06 4.74 5.41 3.33 5.89 4.90 4.00 4.67 4.24 4.16 4.31 4.12 3.94 3.53 3.39 2.87 4.32 ±
6.00 5.00 8.12 16.66 13.92 16.11 19.04 20.34 9.11 8.22 11.09 10.08 9.25 6.95 7.36 10.26 9.65 11.01 ±
0.32 0.30 0.27 0.40 0.44 0.65 0.66 0.85 1.02 0.98 0.59 0.73 0.30 0.46 0.65 0.38 0.40 0.55 ±
19.43 18.32 19.39 19.79 7.51 23.00 20.93 14.02 16.26 15.34 13.36 15.09 15.37 16.68 14.90 14.20 11.27 16.17 ±
121.03 103.79 114.96 112.13 74.40 130.48 114.54 86.67 102.50 103.24 93.80 96.68 97.63 89.22 107.43 89.41 96.49 102.02 ±
63.34 61.34 42.55 61.00 20.41 53.00 36.31 38.09 50.47 41.72 37.79 42.59 32.17 24.16 24.50 19.64 19.47 39.33 ±
60.81 47.18 50.88 54.05 18.49 63.31 49.98 38.30 46.87 42.28 42.38 42.89 39.21 37.46 37.69 35.54 28.28 43.27 ±
19.21 14.56 25.96 16.21 8.56 12.20 19.80 13.15 14.38 9.67 10.18 12.63 7.16 6.27 7.28 2.67 2.37 11.90 ±
141.79 134.53 134.58 149.81 79.02 168.50 138.95 102.51 117.36 107.01 95.87 105.24 113.37 116.62 107.62 102.94 87.51 117.84 ±
113.00 104.44 110.77 103.95 66.88 110.46 99.01 92.65 97.04 87.54 86.11 88.60 79.73 72.90 67.26 62.69 54.19 88.07 ±
0.71
0.79
4.58
0.24
3.77
13.92
14.84
11.08
6.22
23.63
18.30
SD
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Fig. 2. Dendrogram of cluster analysis between the sampling sites at Anzali wetland, Caspian Sea.
was derived from group average. This analysis was also performed using PRIMER 5 (Clarke and Warwick, 2001). Carbonate levels at the sampling sites ranges from 1.26% to 13.30%, with an average value of 5.58 ± 4.20%. The highest and lowest carbonate levels were observed at sites 8 and 15, respectively (Table 1). Organic materials constitute a considerable part of sediments in fresh and salt waters. These materials in marine sediments originate from either the land (allochthonous) or the sea (autochthonous), which have different chemical compounds according to their sources. Most organic materials are finally deposited in seabed sediments through a series of physical, chemical, and biological processes (Bastami et al., 2015). In the present study, the organic matter ranged from 1.34% to 14.80%, with the lowest and highest levels at sites 5 and 10, respectively (Table 1). Particle size analysis indicated that muddy sediment is dominant in the majority of sampling sites. The mud and sand contents averaged 65.31 ± 27.97% and 34.69 ± 27.97%, respectively (Table 1). In general, higher values of mud are observed in the western parts of Anzali wetland. It may be due to the lower turbulence of water that allows sedimentation of fine-grained particles. The frequencies of major elements within the sediments are presented in Table 2. SiO2 had the highest frequency with a mean value of 57.98% compared to other oxides. Al2O3 had the second highest frequency, with a mean value of 12.83%, while Fe 2 O 3, CaO, and Na2O had frequencies of 6.17%, 4.62%, and 2.04%, respectively. The contents of K2O, MgO, TiO2, P2O5, and MnO2 were very low. It is noteworthy that the distribution of major elements in this study reflects the mineralogy of sediments. It was also found that K2O, CaO, MgO, and Na2O were mobile, but Al2O3 and TiO2 were immobile (Bauluz et al., 2000). The ratio of K2O to Al2O3 can be used to determine the combination of sediment sources as the range of this ratio varies between clay and feldespato minerals (0–0.3 and 0.3–0.9, respectively)
(Cox et al., 1995). Therefore, the studied samples contain clay mineral. Contents of Al, Fe, As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn were 6.79 ± 0.71%, 4.32 ± 0.79%, 11.01 ± 4.58, 0.55 ± 0.24, 16.17 ± 3.77, 102.02 ± 13.92, 39.33 ± 14.84, 43.27 ± 11.08, 11.90 ± 6.22, 117.84 ± 23.63, and 88.07 ± 18.30 ppm, respectively (Table 3). The total metal contents in sediments in this study followed the order: Al N Fe N V N Cr N Zn N Ni N Cu N Co N Pb N As N Cd. According to cluster analysis using metal levels, the sampling sites formed three distinctive groups, in which stations 5 and 17 were included in the first group; stations 1, 2, 3, 4, 6, and 7 in the second group; and stations 8, 9, 10, 11, 12, 13, 14, 15, and 16 in the third group (Fig. 2). Hargalani et al. (2014) measured the contents of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn in sediment of Anzali wetland in November 2011. Cd, Co, Cr, Ni, Pb, and Zn concentrations in sediments were higher than our results in Anzali wetland, while As, Cu, and V levels were lower than our results. Furthermore, comparison of the present and previous results in this area suggested that levels of all metals except Cd are lower than those reported by Esmaeilzadeh et al. (2016). Although a quantitative comparison across reported metal data is difficult because of variances in the number of samples collected in each study, the sediment fractions were analyzed using analytical methods. Sediment quality guidelines (SQGs) are important tools for the assessment of contamination in marine and estuarine sediments (Long et al., 1995). Two sets of SQGs developed for marine and estuarine ecosystems (MacDonald et al., 1996; Long and MacDonald, 1998) were applied in this study to assess the ecotoxicological risk of metals in sediments: (a) the effect range low (ERL)/effect range median (ERM) and (b) the threshold effect level (TEL)/probable effect level (PEL) values. Low-range values (i.e., ERLs or TELs) are concentrations below
Table 4 Sediment quality guidelines from NOAA (Long et al., 1995) and Environment Canada (ISQG, 1995). SQGs
ERLa ERMb ISQGc PELd This study a b c d
Heavy metals As (ppm)
Cd (ppm)
Cr (ppm)
Cu (ppm)
Ni (ppm)
Pb (ppm)
Zn (ppm)
8.2 70 7.24 41.6 11.01 ± 4.58 (5.00–20.34)
1.2 9.6 0.68 4.21 0.55 ± 0.24 (0.27–1.02)
81 370 52.3 160 102.02 ± 13.92 (74.40–121.03)
34 270 18.7 108 39.33 ± 14.84 (19.47–63.34)
20.9 51.6 15.9 42.8 43.27 ± 11.08 (18.49–63.31)
46.7 218 30.2 112 11.90 ± 6.22 (2.37–25.96)
150 410 124 271 88.07 ± 18.30 (54.19–113.00)
ERL = Effect range low (NOAA). ERM = Effect range medium (NOAA). ISQG = Interim sediment quality guideline (Environment Canada). PEL = Probable effects level (Environment Canada).
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
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Fig. 3. Mean ERM quotient in the sediment samples of Anzali wetland, Caspian Sea.
ratio, organic carbon, and ionic absorption power, are more capable of absorbing metals (McCave, 1984; Horowitz and Elrick, 1987). Pearson's correlation test (Table 5) showed that the mud had a significant and positive correlation with Fe, Cu, Co, Ni, V, and Zn (p b 0.05). Furthermore, there was a positive correlation between Cd, Pb, Cr, As, and Al with mud (p N 0.05). Positive relationship of Al and Fe with other metals might infer the transportation of these metals together with Al and Fe. TOM, carbonate, and inorganic carbon (IC) were positively correlated with Cd (p b 0.05). Pearson correlation coefficient showed a significant and positive correlation between the concentration of all metals (except As and Cd). This positive correlation indicates that metals found in the sediments have common sources, mutual dependence, and identical behavior during transportation. Many researchers have applied EF index in the contamination assessment of metals (Feng et al., 2004; Reddy et al., 2004; Cevik et al., 2009; Bastami et al., 2012). EF values were interpreted as follows: EF ≤ 2 – Deficiency to minimal enrichment; 2 b EF ≤ 5 – Moderate enrichment; 5 b EF ≤ 20 – Significant enrichment; 20 b EF ≤ 40 – Very high enrichment; and EF N 40 – Extremely high enrichment (Grant and Middleton, 1990; Loska et al., 1997; Abrahim and Parker, 2008). EF value ranged from 1.12 to 3.63 in the sampling sites. Co and Cu showed the highest and lowest factored, respectively, in the sampling sites (Table 8). At all the sampling sites, the EF values of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn ranged between 0.54 and 2.68, 0.05 and 0.24, 0.12 and 0.28, 0.28 and 0.39, 0.25 and 0.82, 0.10 and 0.21, 0.03 and 0.27, 0.49 and 0.75, and 0.25 and 0.49, respectively, indicating minimal to moderate enrichment (Table 6). In general, EF b 2 indicated that the sediments are unaffected by human activities, and thus are in the range of natural variability. EF N 2.0 represents enrichment and contamination of metals in the sediment, resulting from significant anthropogenic inputs (Sutherland, 2000; Liaghati et al., 2003). In the sediments, the mean EF values of all metals were b 2, thus implying natural inputs.
which adverse effects upon sediment dwelling fauna would be expected infrequently. In contrast, the ERMs and PELs represent chemical concentrations above which adverse effects are likely to occur (Long and MacDonald, 1998). Concentrations of As, Cr, and Cu in some sampling sites were higher than the corresponding values of ERL (Table 4), suggesting that these metals in sediments from Anzali wetland would be occasionally expected to cause adverse biological effects on the biota. Furthermore, nickel levels at some sites were higher than ERM. These results implicate that negative eco-risk effects frequently occur in the sampling sites. All the SQGs used above were achieved through assessing individual chemicals by comparing the chemical concentrations with their corresponding limit concentrations. On the basis of the fact that metals always occur in sediments as complex mixtures, the mean ERM quotient method was used to determine the possible biological effect of combined toxicant groups by calculating mean quotients for a large range of contaminants using the following formula (Carr et al., 1996; Gao and Chen, 2012): mean ERM quotient ¼ ∑ðCX =ERMX Þ=n
ð8Þ
where Cx is the sediment concentration of component x, ERMx is the ERM of x, and n is the number of components. The toxicity probabilities of mean ERM quotients of b0.1, 0.11–0.5, 0.51–1.5, and N1.50 are 9%, 21%, 49%, and 76%, respectively (Long et al. (2000)). As shown in Fig. 3, in surface sediments of Anzali wetland, the mean ERM quotients varied within the range of 0.15–0.34, indicating that the combination of the seven studied metals might have a toxicity probability of 21%. Effects of TOM and grain size on the spatial variation of metals in the sediment are shown in several studies (Stephenson and Mackie, 1988; Coquery and Welbourn, 1995; Bastami et al., 2012; Bastami et al., 2015). The fine sediments, with higher values of surface to volume
Table 5 Correlation between heavy metals and major elements in the sediments of Anzali wetland. Parameters Mud Sand TOM Carbonate IC Al Fe As Cd Co Cr Cu Ni Pb V Zn
Mud −1.000⁎⁎ 0.744⁎⁎ 0.640⁎⁎ 0.641⁎⁎ 0.170 0.737⁎⁎ 0.274 0.379 0.625⁎⁎ 0.422 0.628⁎⁎ 0.653⁎⁎ 0.426 0.543⁎ 0.672⁎⁎
Sand
−0.744⁎⁎ −0.640⁎⁎ −0.641⁎⁎ −0.170 −0.737⁎⁎ −0.274 −0.379 −0.625⁎⁎ −0.422 −0.628⁎⁎ −0.653⁎⁎ −0.426 −0.543⁎ −0.672⁎⁎
TOM
Carbonate
IC
0.932⁎⁎ 0.932⁎⁎ −0.374 0.359 0.189 0.722⁎⁎
1.000⁎⁎ −0.514⁎ 0.182 0.233 0.667⁎⁎
−0.514⁎ 0.184 0.236 0.666⁎⁎
0.147 0.107 0.442 0.320 0.307 0.046 0.434
−0.048 −0.131 0.351 0.134 0.140 −0.133 0.282
−0.047 −0.131 0.352 0.135 0.141 −0.131 0.283
Al
0.482⁎⁎ −0.108 −0.564⁎⁎ 0.652⁎⁎ 0.597⁎ 0.335 0.500⁎ 0.361 0.696⁎⁎ 0.380
Fe
As
Cd
Co
Cr
Cu
Ni
Pb
V
0.204 0.052 0.875⁎⁎ 0.763⁎⁎ 0.864⁎⁎ 0.900⁎⁎ 0.696⁎⁎ 0.914⁎⁎ 0.919⁎⁎
0.286 0.089 −0.007 −0.020 0.048 0.146 0.131 0.138
−0.051 −0.039 0.042 0.022 −0.033 −0.142 0.048
0.881⁎⁎ 0.684⁎⁎ 0.932⁎⁎ 0.624⁎⁎ 0.965⁎⁎ 0.790⁎⁎
0.653⁎⁎ 0.898⁎⁎ 0.575⁎ 0.876⁎⁎ 0.709⁎⁎
0.830⁎⁎ 0.678⁎⁎ 0.736⁎⁎ 0.902⁎⁎
0.664⁎⁎ 0.916⁎⁎ 0.878⁎⁎
0.612⁎⁎ 0.873⁎⁎
0.808⁎⁎
⁎ Correlation is significant at the 0.05 level. ⁎⁎ Correlation is significant at the 0.01 level.
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Table 6 Enrichment factor (EF) of different metals from the sampling sites in the surface sediments of Anzali wetland. Sampling sites
As
Cd
Co
Cr
Cu
Ni
Pb
V
Zn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average
0.70 0.54 0.81 1.65 1.90 1.76 2.21 2.68 1.16 1.05 1.52 1.34 0.99 0.81 0.82 1.19 1.19 1.31
0.07 0.06 0.05 0.07 0.11 0.13 0.14 0.21 0.24 0.23 0.15 0.18 0.06 0.10 0.13 0.08 0.09 0.12
0.25 0.22 0.22 0.22 0.12 0.28 0.27 0.21 0.23 0.22 0.21 0.23 0.18 0.22 0.19 0.19 0.16 0.21
0.39 0.31 0.32 0.31 0.28 0.40 0.37 0.32 0.36 0.37 0.36 0.36 0.29 0.29 0.33 0.29 0.33 0.33
0.82 0.74 0.47 0.67 0.31 0.64 0.47 0.56 0.72 0.59 0.57 0.63 0.38 0.31 0.30 0.25 0.27 0.51
0.19 0.14 0.14 0.21 0.06 0.21 0.19 0.14 0.17 0.17 0.16 0.13 0.13 0.12 0.13 0.13 0.10 0.15
0.26 0.18 0.30 0.19 0.14 0.16 0.27 0.20 0.22 0.14 0.16 0.20 0.09 0.09 0.09 0.04 0.03 0.16
0.75 0.66 0.61 0.67 0.49 0.83 0.73 0.61 0.68 0.62 0.59 0.63 0.55 0.62 0.54 0.54 0.49 0.62
0.49 0.42 0.41 0.38 0.34 0.45 0.43 0.46 0.46 0.42 0.44 0.44 0.32 0.32 0.28 0.27 0.25 0.39
±
±
±
±
±
±
±
±
±
0.58
0.06
0.04
0.04
0.18
0.04
0.08
0.09
0.08
± SD
According to Hakanson (1980), the PER of coastal sediments posed by metals can be classified into the following categories: Low risk: E b 40; PER b 150. Moderate risk: 40 ≤ E b 80; 150 ≤ PER b 300. Considerable risk: 80 ≤ E b 160; 300 ≤ PER b 600. High risk: 160 ≤ E b 320; PER ≥ 600. Very high risk: E ≥ 320. The calculated E values are shown in Table 7. Single risk factors (E) were 28.09 ± 11.67, 7.90 ± 3.41, 1.46 ± 0.20, 5.60 ± 2.11, 1.92 ± 0.49, 1.79 ± 0.93, and 0.84 ± 0.18 for As, Cd, Cr, Cu, Ni, Pb, and Zn, respectively (Table 7). As and Zn had the highest and lowest single risk factors, respectively. The average ecological risk of E value for all metals in most surface sediments was b40, indicating a low risk to the local ecosystem. PLI provides a simple, comparative tool to assess the level of metal pollution, and the pollution load was then classified as no (PLI b 1), moderate (1 b PLI b 2), heavy (2 b PLI b 3), or extremely heavy (3 b PLI) pollution (Chakravarty and Patgiri, 2009; Seshan et al., 2010).
Table 7 Classification of sediment samples based on the potential ecological risk factor (E) in the surface sediments from Anzali wetland. Sampling sites
As
Cd
Cr
Cu
Ni
Pb
Zn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average
15.31 12.76 20.71 42.50 35.51 41.10 48.57 51.89 23.24 20.97 28.29 25.71 23.60 17.73 18.78 26.17 24.62 28.09 ±
4.57 4.29 3.86 5.71 6.29 9.29 9.43 12.14 14.57 14.00 8.43 10.43 4.29 6.57 9.29 5.43 5.71 7.90 ±
1.73 1.48 1.64 1.60 1.06 1.86 1.63 1.24 1.46 1.47 1.34 1.38 1.39 1.27 1.53 1.28 1.38 1.46 ±
9.02 8.74 6.06 8.69 2.91 7.55 5.17 5.43 7.19 5.94 5.38 6.07 4.58 3.44 3.49 2.80 2.77 5.60 ±
2.69 2.09 2.25 2.39 0.82 2.80 2.21 1.70 2.08 1.87 1.88 1.90 1.74 1.66 1.67 1.57 1.25 1.92 ±
2.88 2.19 3.90 2.43 1.29 1.83 2.97 1.97 2.16 1.45 1.53 1.90 1.08 0.94 1.09 0.40 0.36 1.79 ±
1.08 1.00 1.06 1.00 0.64 1.06 0.95 0.89 0.93 0.84 0.82 0.85 0.76 0.70 0.64 0.60 0.52 0.84 ±
11.67
3.41
0.20
2.11
0.49
0.93
0.18
± SD
Table 8 PLI of the sampling sites in the surface sediments of Anzali wetland. Sampling sites
As
Cd
Co
Cr
Cu
Ni
Pb
V
Zn
PLI
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
1.53 1.28 2.07 4.25 3.55 4.11 4.86 5.19 2.32 2.10 2.83 2.57 2.36 1.77 1.88 2.62 2.46
0.15 0.14 0.13 0.19 0.21 0.31 0.31 0.40 0.49 0.47 0.28 0.35 0.14 0.22 0.31 0.18 0.15
0.56 0.53 0.56 0.57 0.22 0.66 0.60 0.41 0.47 0.44 0.39 0.44 0.44 0.48 0.43 0.41 0.33
0.86 0.74 0.82 0.80 0.53 0.93 0.82 0.62 0.73 0.74 0.67 0.69 0.70 0.64 0.77 0.64 0.69
1.80 1.75 1.21 1.74 0.58 1.51 1.03 1.09 1.44 1.19 1.08 1.21 0.92 0.69 0.70 0.56 0.55
0.45 0.35 0.38 0.40 0.14 0.47 0.37 0.28 0.35 0.31 0.31 0.32 0.29 0.28 0.28 0.26 0.21
0.58 0.44 0.78 0.49 0.26 0.37 0.59 0.39 0.43 0.29 0.31 0.38 0.22 0.19 0.22 0.08 0.07
1.65 1.56 1.56 1.74 0.92 1.96 1.61 1.19 1.36 1.24 1.11 1.22 1.32 1.35 1.25 1.20 1.02
1.08 1.00 1.06 1.00 0.64 1.06 0.95 0.89 0.93 0.84 0.82 0.85 0.76 0.70 0.64 0.60 0.52
0.76 0.67 0.75 0.84 0.47 0.91 0.86 0.74 0.78 0.69 0.64 0.7 0.56 0.54 0.57 0.46 0.54
The calculated PLI values of metals in sediment are summarized in Table 8, which were b 1 at all sampling sites. Therefore, all sampling sites had no pollution. In this study, we investigated the concentrations of metals, including As, Cd, Cu, Cr, Co, V, Ni, Pb, and Zn from sediments of Anzali wetland in relation to sediment properties. Statistical analysis revealed that Al and Fe are effective factors in the distribution of the metals on the sediments. This study also showed higher concentration of As, V, and Cu in the sampling sites than those reported in previous studies. In addition, the contents of Ni, As, Cr, and Cu were higher than those in the SQGs. This may cause toxicity to certain exposed organisms. The above results confirmed that Anzali wetland is facing a serious environmental degradation problem, especially due to metal contamination.
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Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea Siamak Jamshidi ⁎, Kazem Darvish Bastami Iranian National Institute for Oceanography and Atmospheric Science (INIOAS), No. 3, Etemadzadeh St., Fatemi Ave., 1411813389 Tehran, Islamic Republic of Iran
a r t i c l e
i n f o
Article history: Received 13 June 2016 Received in revised form 23 July 2016 Accepted 22 August 2016 Available online xxxx Keywords: Metals Surface sediment ERM quotient Anzali wetland Caspian Sea
a b s t r a c t In this study, the accumulation of metals, including Al, Fe, Zn, V, Ni, Cu, Cr, Cd, Co, As, and Pb, in sediments of Anzali wetland in the southwest region of the Caspian Sea was investigated. For this purpose, the sediments were collected from 17 sampling sites in Anzali wetland, Caspian Sea. The samples were then analyzed using inductively coupled plasma–optical emission spectrometry (ICP-OES). Pearson correlation coefficient showed significant and positive correlation between concentration of all metals (except As and Cd). Furthermore, the results implied that Al and Fe are probably responsible for the transportation of heavy metals into the sediments of Anzali wetland. According to mean effects range-median quotient (mean ERM quotient), the sediments from Anzali wetland had a 21% probability of toxicity. © 2016 Elsevier Ltd. All rights reserved.
Marine pollutants are part of several environmental pollution crises. With two-thirds of the Earth's surface covered by water, the effects of pollution on marine habitats are very high. Aqueous ecosystems have become more susceptible and vulnerable to pollution because of the rather higher rate of accumulation of chemical compounds, and in fact, these ecosystems act as reservoirs of various anthropogenic toxicants and contaminants that are stressful through vast inputs of pollution. The issue of marine pollution has recently attracted worldwide attention (Callender, 2005; Bastami et al., 2015). Bottom sediment, specifically as a tool for monitoring metals in the sea, represents advantageous results of pollutant distribution. Sediments are accumulated over the years and can be regarded as fixators of contamination level. After being discharged into bodies of water, pollutants are gradually deposited at the bottom in various forms. When the pollution level of sediments exceeds a specific limit, it would disturb and eventually destroy the ecosystem equilibrium. Monitoring the deposition of metals in sediments provides a continuous surveillance of pollution in the studied area, and sediment analysis could make the specification of pollution type easier in order to adopt any management decisions for advisable controlling (ElNemr et al., 2007; Bastami et al., 2015). Metals discharging into the aquatic system during their transport are distributed between the aqueous phase and sediments. Because of adsorption, hydrolysis, and coprecipitation of metal ions, a large quantity of them are deposited in the sediment while only a small portion of ⁎ Corresponding author. E-mail addresses: [email protected] (S. Jamshidi), [email protected] (K.D. Bastami).
free metal ions remain dissolved in the water column. Therefore, sediments in aquatic environments can either retain metals or release them to the water column by various remobilization processes. Sediment parameters (mineralogy, texture), metal characteristics, pH, organic matter, and oxidation–reduction potential are important parameters for controlling the accumulation and availability of metals in the sediment (Hakanson, 1980; Wright and Mason, 1999; Tam and Wong, 2000; Buccolieri et al., 2006; ElNemr et al., 2007; Bastami et al., 2012; Bastami et al., 2015). Hence, sediments are enumerated as sources of metals in marine environments, and they play a key role in transmission and deposition of metals. Generally, normal metal concentrations found in sediments are not detrimental to inhabiting organisms. For normal metabolism, live organisms essentially require some metals like zinc, which have toxic effects above a critical threshold. Anzali wetland is located in the southwest region of the Caspian Sea with an area of about 193 km2. Anzali has been registered as an international wetland in the 1975 Ramsar Convention. Catchment of the wetland covers an area of about 3610 km2 and is bounded by the Caspian Sea in the north, the Alborz mountain range in the south, the Talysh Mountains in the west, and the Sefidrud Delta in the east. Approximately 93,525 and 196,020 ha of the catchment are covered by farmlands (particularly rice farms) and forestlands, respectively. The wetland, with mean annual precipitation and evaporation rates of about 1280 and 980 mm, respectively, has no dry season. It is covered with reed bed, and it plays a key role in spawning and development of the fish. Furthermore, it provides breeding place for many water birds and serves as a staging and wintering site. Anzali wetland's environment
http://dx.doi.org/10.1016/j.marpolbul.2016.08.049 0025-326X/© 2016 Elsevier Ltd. All rights reserved.
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Fig. 1. Locations of the sampling sites at Anzali wetland, Caspian Sea.
has been jeopardized by the contaminants produced from urbanization; population growth; and agricultural, industrial, and tourism activities (Hargalani et al., 2014: Esmaeilzadeh et al., 2016). The aim of this study is to investigate metal distributions in the sediments obtained from different parts of Anzali wetland and, therefore, to discover the relationship between the sediment characteristics and distribution of metals in Anzali wetland. Sediment samples from 17 different sites were collected using Van Veen Grab sampler for analyzing metals during winter (February 2016, Fig. 1). The samples were then packed and carried to the laboratory in ice boxes and stored at 4 °C until analysis. After drying in an oven, sediment samples were ground by using a hand mortar followed by screening with a 0.5-mm sieve to remove large particles. Thereafter, the samples (0.5 g) were digested using a mixed solution of HF\\HCl\\HNO 3\\HClO 4 according to the ASTM standard D5258-92 (ASTM, 2013). The samples were analyzed for Al, Fe, As, Cd, Cu, Ni, Pb, Co, Cr, V, and Zn by inductively coupled plasma–optical emission spectrometry (ICP-OES; Varian VISTAMPX). In addition, major element contents (SiO 2 , CaO, Fe 2 O 3 , Al 2 O 3 , MgO, K 2 O, Na 2 O, TiO 2 , P 2 O 5 , and MnO 2 ) were measured using an X-ray fluorescence spectrometer (Bruker Model). The precision and accuracy of the methods were systematically and routinely verified using standard reference materials. Accepted recoveries range from 93% to 108%. For the determination of total organic matter, sediment samples were dried at 70 °C for 24 h and then combusted in the oven at 550 °C for 4 h. Total organic matter, as described by Abrantes et al. (1999), was measured by the following equation: Total organic matter ðTOM%Þ ¼ ½ðB−CÞ=B 100
ð1Þ
where B and C are the weights of dried sediment before and after combustion in the oven, respectively.Grain size was analyzed using laser
particle size analyzer (HORIBA-LA950, France & Japan). Before analysis, about 4 g of samples was combusted in the oven at 550 °C for 4 h and 950 °C for 2 h to remove organic matter and biogenic carbonate, respectively.Enrichment factor (EF), which is an appropriate tool to determine sedimentary metal source produced by anthropogenic events or natural origin, normalizes metal concentrations according to the sediment texture properties (Selvaraj et al., 2004; Vald'es et al., 2005; Bastami et al., 2014). In this index, aluminum is widely used, indicating aluminum silicate in coastal areas where this element is predominant. Enrichment factor was also applied as a degree of sedimentation (Lee Table 1 General characteristics of the sediments (average ± SD) sampled in Anzali wetland. Sampling sites
Mud (%)
Sand (%)
TOM (%)
Carbonate Inorganic (%) carbon (IC %)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ±
41.93 88.44 66.78 87.03 2.20 96.77 82.75 86.84 82.05 81.85 88.41 82.39 71.95 50.82 34.98 45.17 19.94 65.31 ±
58.07 11.56 33.22 12.97 97.80 3.23 17.25 13.16 17.95 18.15 11.59 17.61 28.05 49.18 65.02 54.83 80.06 34.69 ±
4.56 6.57 7.06 7.77 1.34 7.97 6.83 12.40 13.03 14.80 13.30 14.38 4.29 2.39 3.11 2.71 2.52 7.35 ±
3.63 6.00 2.48 6.21 1.39 4.03 3.76 13.30 8.67 11.39 11.37 11.62 2.66 2.50 1.26 1.97 2.58 5.58 ±
27.97
27.97
4.70
4.20
SD
0.72 1.20 0.49 1.24 0.28 0.81 0.75 2.65 1.73 2.25 2.27 2.32 0.52 0.50 0.25 0.39 0.51 1.11 ± 0.84
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
3
Table 2 Major elements of the sediments (average ± SD) sampled in Anzali wetland. Sampling sites
SiO2 (%)
Al2O3 (%)
CaO (%)
Fe2O3 (%)
K2O (%)
MgO (%)
MnO2 (%)
Na2O (%)
P2O5 (%)
TiO2 (%)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ± SD
60.43 55.06 61.11 50.35 71.80 55.68 61.98 44.53 48.15 45.66 44.61 42.87 65.48 64.30 69.56 70.29 73.87 57.98 ± 10.50
12.94 13.93 15.09 15.23 11.06 13.80 12.96 11.45 11.78 11.79 11.02 11.33 14.11 12.89 13.57 12.99 12.23 12.83 ± 1.33
4.87 5.52 1.90 4.41 2.83 2.86 2.30 11.69 7.02 9.21 9.88 8.92 1.87 1.99 1.11 1.13 1.02 4.62 ± 3.49
6.88 7.23 6.78 7.73 4.75 8.42 7.00 5.72 6.67 6.06 5.95 6.15 5.88 5.63 5.04 4.84 4.11 6.17 ± 1.13
0.71 0.56 0.74 1.12 0.70 0.65 0.85 0.67 0.68 0.84 0.60 0.96 0.62 1.07 0.91 0.93 0.66 0.78 ± 0.17
1.95 2.47 1.99 2.69 0.85 2.61 1.93 1.80 2.02 1.95 1.90 1.91 1.61 1.61 1.40 1.34 1.11 1.83 ± 0.49
0.140 0.146 0.150 0.121 0.119 0.140 0.158 0.221 0.233 0.264 0.274 0.252 0.142 0.110 0.113 0.112 0.110 0.17 ± 0.06
2.00 1.90 2.12 1.52 2.98 1.10 1.89 1.07 1.03 1.49 1.33 1.42 2.85 2.88 3.13 2.89 3.09 2.04 ± 0.78
0.115 0.091 0.121 0.182 0.114 0.106 0.138 0.109 0.111 0.136 0.097 0.155 0.101 0.174 0.148 0.151 0.107 0.127 ± 0.027
0.735 0.640 0.613 0.716 0.359 0.740 0.703 0.437 0.539 0.514 0.430 0.499 0.506 0.608 0.489 0.508 0.343 0.552 ± 0.126
et al., 1998; Woitke et al., 2003; Bastami et al., 2015), and can be determined as follows: Enrichmentfactor ¼ ðHs =Als Þ=ðHc =Alc Þ
ð2Þ
where Hs and Hc are metal concentrations in sample and background reference, respectively, and Als and Alc are the aluminum contents in sample and background reference, respectively. In this study, we used background concentrations of metals in sediment from Anzali wetland, which are 3.9, 2.1, 34.6, 140.2, 35.1, 135.5, 33.3, 86.1, 104.4 ppm, and 3.1% for As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, and Al, respectively (Hargalani et al., 2014). To assess the sediment environmental quality, an integrated pollution load index (PLI) of eight metals was calculated as suggested by Suresh et al. (2011): PLI ¼ ðCF1 CF2 CF3 …CFn Þ1=n
ð3Þ
where CF is the ratio of the content of each metal to the background values, and. CFmetals ¼ CHmetal =CHback
ð4Þ
where CHmetal is the concentration of the examined metal and CHback is the background value of the metal, respectively.
Potential ecological risk (PER) index was also introduced to assess the contamination degree of metals in the collected sediments. The equations for calculating the PER, proposed by Hakanson (1980), are as follows: E ¼ TC
ð5Þ
C ¼ Ca =Cb
ð6Þ
PER ¼ ∑E ¼ ∑TC
ð7Þ
where C is the single-element pollution factor, Ca is the content of the element in samples, and Cb is the reference value of the element. The sum of C for all the metals examined represents the integrated pollution degree (C) of the environment. E is the PER factor of an individual element. T is the biological toxic factor of individual elements, whose values are Cu = Pb = 5, Zn = 1, As =10, Cd = 30, Cr = 2, and Ni = 6 (Hakanson, 1980). PER is a comprehensive potential ecological index, which equals to the sum of E. It represents the sensitivity of biological community to toxic substances and illustrates the PER caused by the overall contamination. A Pearson correlation analysis was conducted to test the relationship between various metals and environmental parameters. Difference in metal content between sites was indicated by a cluster analysis, which
Table 3 Heavy metal content (average ± SD) of the sediments sampled in Anzali wetland. Sampling sites
Al (%)
Fe (%)
As (ppm)
Cd (ppm)
Co (ppm)
Cr (ppm)
Cu (ppm)
Ni (ppm)
Pb (ppm)
V (ppm)
Zn (ppm)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average ±
6.85 7.37 7.99 8.06 5.85 7.30 6.86 6.06 6.24 6.24 5.83 5.99 7.47 6.82 7.18 6.87 6.47 6.79 ±
4.82 5.06 4.74 5.41 3.33 5.89 4.90 4.00 4.67 4.24 4.16 4.31 4.12 3.94 3.53 3.39 2.87 4.32 ±
6.00 5.00 8.12 16.66 13.92 16.11 19.04 20.34 9.11 8.22 11.09 10.08 9.25 6.95 7.36 10.26 9.65 11.01 ±
0.32 0.30 0.27 0.40 0.44 0.65 0.66 0.85 1.02 0.98 0.59 0.73 0.30 0.46 0.65 0.38 0.40 0.55 ±
19.43 18.32 19.39 19.79 7.51 23.00 20.93 14.02 16.26 15.34 13.36 15.09 15.37 16.68 14.90 14.20 11.27 16.17 ±
121.03 103.79 114.96 112.13 74.40 130.48 114.54 86.67 102.50 103.24 93.80 96.68 97.63 89.22 107.43 89.41 96.49 102.02 ±
63.34 61.34 42.55 61.00 20.41 53.00 36.31 38.09 50.47 41.72 37.79 42.59 32.17 24.16 24.50 19.64 19.47 39.33 ±
60.81 47.18 50.88 54.05 18.49 63.31 49.98 38.30 46.87 42.28 42.38 42.89 39.21 37.46 37.69 35.54 28.28 43.27 ±
19.21 14.56 25.96 16.21 8.56 12.20 19.80 13.15 14.38 9.67 10.18 12.63 7.16 6.27 7.28 2.67 2.37 11.90 ±
141.79 134.53 134.58 149.81 79.02 168.50 138.95 102.51 117.36 107.01 95.87 105.24 113.37 116.62 107.62 102.94 87.51 117.84 ±
113.00 104.44 110.77 103.95 66.88 110.46 99.01 92.65 97.04 87.54 86.11 88.60 79.73 72.90 67.26 62.69 54.19 88.07 ±
0.71
0.79
4.58
0.24
3.77
13.92
14.84
11.08
6.22
23.63
18.30
SD
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Fig. 2. Dendrogram of cluster analysis between the sampling sites at Anzali wetland, Caspian Sea.
was derived from group average. This analysis was also performed using PRIMER 5 (Clarke and Warwick, 2001). Carbonate levels at the sampling sites ranges from 1.26% to 13.30%, with an average value of 5.58 ± 4.20%. The highest and lowest carbonate levels were observed at sites 8 and 15, respectively (Table 1). Organic materials constitute a considerable part of sediments in fresh and salt waters. These materials in marine sediments originate from either the land (allochthonous) or the sea (autochthonous), which have different chemical compounds according to their sources. Most organic materials are finally deposited in seabed sediments through a series of physical, chemical, and biological processes (Bastami et al., 2015). In the present study, the organic matter ranged from 1.34% to 14.80%, with the lowest and highest levels at sites 5 and 10, respectively (Table 1). Particle size analysis indicated that muddy sediment is dominant in the majority of sampling sites. The mud and sand contents averaged 65.31 ± 27.97% and 34.69 ± 27.97%, respectively (Table 1). In general, higher values of mud are observed in the western parts of Anzali wetland. It may be due to the lower turbulence of water that allows sedimentation of fine-grained particles. The frequencies of major elements within the sediments are presented in Table 2. SiO2 had the highest frequency with a mean value of 57.98% compared to other oxides. Al2O3 had the second highest frequency, with a mean value of 12.83%, while Fe 2 O 3, CaO, and Na2O had frequencies of 6.17%, 4.62%, and 2.04%, respectively. The contents of K2O, MgO, TiO2, P2O5, and MnO2 were very low. It is noteworthy that the distribution of major elements in this study reflects the mineralogy of sediments. It was also found that K2O, CaO, MgO, and Na2O were mobile, but Al2O3 and TiO2 were immobile (Bauluz et al., 2000). The ratio of K2O to Al2O3 can be used to determine the combination of sediment sources as the range of this ratio varies between clay and feldespato minerals (0–0.3 and 0.3–0.9, respectively)
(Cox et al., 1995). Therefore, the studied samples contain clay mineral. Contents of Al, Fe, As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn were 6.79 ± 0.71%, 4.32 ± 0.79%, 11.01 ± 4.58, 0.55 ± 0.24, 16.17 ± 3.77, 102.02 ± 13.92, 39.33 ± 14.84, 43.27 ± 11.08, 11.90 ± 6.22, 117.84 ± 23.63, and 88.07 ± 18.30 ppm, respectively (Table 3). The total metal contents in sediments in this study followed the order: Al N Fe N V N Cr N Zn N Ni N Cu N Co N Pb N As N Cd. According to cluster analysis using metal levels, the sampling sites formed three distinctive groups, in which stations 5 and 17 were included in the first group; stations 1, 2, 3, 4, 6, and 7 in the second group; and stations 8, 9, 10, 11, 12, 13, 14, 15, and 16 in the third group (Fig. 2). Hargalani et al. (2014) measured the contents of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn in sediment of Anzali wetland in November 2011. Cd, Co, Cr, Ni, Pb, and Zn concentrations in sediments were higher than our results in Anzali wetland, while As, Cu, and V levels were lower than our results. Furthermore, comparison of the present and previous results in this area suggested that levels of all metals except Cd are lower than those reported by Esmaeilzadeh et al. (2016). Although a quantitative comparison across reported metal data is difficult because of variances in the number of samples collected in each study, the sediment fractions were analyzed using analytical methods. Sediment quality guidelines (SQGs) are important tools for the assessment of contamination in marine and estuarine sediments (Long et al., 1995). Two sets of SQGs developed for marine and estuarine ecosystems (MacDonald et al., 1996; Long and MacDonald, 1998) were applied in this study to assess the ecotoxicological risk of metals in sediments: (a) the effect range low (ERL)/effect range median (ERM) and (b) the threshold effect level (TEL)/probable effect level (PEL) values. Low-range values (i.e., ERLs or TELs) are concentrations below
Table 4 Sediment quality guidelines from NOAA (Long et al., 1995) and Environment Canada (ISQG, 1995). SQGs
ERLa ERMb ISQGc PELd This study a b c d
Heavy metals As (ppm)
Cd (ppm)
Cr (ppm)
Cu (ppm)
Ni (ppm)
Pb (ppm)
Zn (ppm)
8.2 70 7.24 41.6 11.01 ± 4.58 (5.00–20.34)
1.2 9.6 0.68 4.21 0.55 ± 0.24 (0.27–1.02)
81 370 52.3 160 102.02 ± 13.92 (74.40–121.03)
34 270 18.7 108 39.33 ± 14.84 (19.47–63.34)
20.9 51.6 15.9 42.8 43.27 ± 11.08 (18.49–63.31)
46.7 218 30.2 112 11.90 ± 6.22 (2.37–25.96)
150 410 124 271 88.07 ± 18.30 (54.19–113.00)
ERL = Effect range low (NOAA). ERM = Effect range medium (NOAA). ISQG = Interim sediment quality guideline (Environment Canada). PEL = Probable effects level (Environment Canada).
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
5
Fig. 3. Mean ERM quotient in the sediment samples of Anzali wetland, Caspian Sea.
ratio, organic carbon, and ionic absorption power, are more capable of absorbing metals (McCave, 1984; Horowitz and Elrick, 1987). Pearson's correlation test (Table 5) showed that the mud had a significant and positive correlation with Fe, Cu, Co, Ni, V, and Zn (p b 0.05). Furthermore, there was a positive correlation between Cd, Pb, Cr, As, and Al with mud (p N 0.05). Positive relationship of Al and Fe with other metals might infer the transportation of these metals together with Al and Fe. TOM, carbonate, and inorganic carbon (IC) were positively correlated with Cd (p b 0.05). Pearson correlation coefficient showed a significant and positive correlation between the concentration of all metals (except As and Cd). This positive correlation indicates that metals found in the sediments have common sources, mutual dependence, and identical behavior during transportation. Many researchers have applied EF index in the contamination assessment of metals (Feng et al., 2004; Reddy et al., 2004; Cevik et al., 2009; Bastami et al., 2012). EF values were interpreted as follows: EF ≤ 2 – Deficiency to minimal enrichment; 2 b EF ≤ 5 – Moderate enrichment; 5 b EF ≤ 20 – Significant enrichment; 20 b EF ≤ 40 – Very high enrichment; and EF N 40 – Extremely high enrichment (Grant and Middleton, 1990; Loska et al., 1997; Abrahim and Parker, 2008). EF value ranged from 1.12 to 3.63 in the sampling sites. Co and Cu showed the highest and lowest factored, respectively, in the sampling sites (Table 8). At all the sampling sites, the EF values of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn ranged between 0.54 and 2.68, 0.05 and 0.24, 0.12 and 0.28, 0.28 and 0.39, 0.25 and 0.82, 0.10 and 0.21, 0.03 and 0.27, 0.49 and 0.75, and 0.25 and 0.49, respectively, indicating minimal to moderate enrichment (Table 6). In general, EF b 2 indicated that the sediments are unaffected by human activities, and thus are in the range of natural variability. EF N 2.0 represents enrichment and contamination of metals in the sediment, resulting from significant anthropogenic inputs (Sutherland, 2000; Liaghati et al., 2003). In the sediments, the mean EF values of all metals were b 2, thus implying natural inputs.
which adverse effects upon sediment dwelling fauna would be expected infrequently. In contrast, the ERMs and PELs represent chemical concentrations above which adverse effects are likely to occur (Long and MacDonald, 1998). Concentrations of As, Cr, and Cu in some sampling sites were higher than the corresponding values of ERL (Table 4), suggesting that these metals in sediments from Anzali wetland would be occasionally expected to cause adverse biological effects on the biota. Furthermore, nickel levels at some sites were higher than ERM. These results implicate that negative eco-risk effects frequently occur in the sampling sites. All the SQGs used above were achieved through assessing individual chemicals by comparing the chemical concentrations with their corresponding limit concentrations. On the basis of the fact that metals always occur in sediments as complex mixtures, the mean ERM quotient method was used to determine the possible biological effect of combined toxicant groups by calculating mean quotients for a large range of contaminants using the following formula (Carr et al., 1996; Gao and Chen, 2012): mean ERM quotient ¼ ∑ðCX =ERMX Þ=n
ð8Þ
where Cx is the sediment concentration of component x, ERMx is the ERM of x, and n is the number of components. The toxicity probabilities of mean ERM quotients of b0.1, 0.11–0.5, 0.51–1.5, and N1.50 are 9%, 21%, 49%, and 76%, respectively (Long et al. (2000)). As shown in Fig. 3, in surface sediments of Anzali wetland, the mean ERM quotients varied within the range of 0.15–0.34, indicating that the combination of the seven studied metals might have a toxicity probability of 21%. Effects of TOM and grain size on the spatial variation of metals in the sediment are shown in several studies (Stephenson and Mackie, 1988; Coquery and Welbourn, 1995; Bastami et al., 2012; Bastami et al., 2015). The fine sediments, with higher values of surface to volume
Table 5 Correlation between heavy metals and major elements in the sediments of Anzali wetland. Parameters Mud Sand TOM Carbonate IC Al Fe As Cd Co Cr Cu Ni Pb V Zn
Mud −1.000⁎⁎ 0.744⁎⁎ 0.640⁎⁎ 0.641⁎⁎ 0.170 0.737⁎⁎ 0.274 0.379 0.625⁎⁎ 0.422 0.628⁎⁎ 0.653⁎⁎ 0.426 0.543⁎ 0.672⁎⁎
Sand
−0.744⁎⁎ −0.640⁎⁎ −0.641⁎⁎ −0.170 −0.737⁎⁎ −0.274 −0.379 −0.625⁎⁎ −0.422 −0.628⁎⁎ −0.653⁎⁎ −0.426 −0.543⁎ −0.672⁎⁎
TOM
Carbonate
IC
0.932⁎⁎ 0.932⁎⁎ −0.374 0.359 0.189 0.722⁎⁎
1.000⁎⁎ −0.514⁎ 0.182 0.233 0.667⁎⁎
−0.514⁎ 0.184 0.236 0.666⁎⁎
0.147 0.107 0.442 0.320 0.307 0.046 0.434
−0.048 −0.131 0.351 0.134 0.140 −0.133 0.282
−0.047 −0.131 0.352 0.135 0.141 −0.131 0.283
Al
0.482⁎⁎ −0.108 −0.564⁎⁎ 0.652⁎⁎ 0.597⁎ 0.335 0.500⁎ 0.361 0.696⁎⁎ 0.380
Fe
As
Cd
Co
Cr
Cu
Ni
Pb
V
0.204 0.052 0.875⁎⁎ 0.763⁎⁎ 0.864⁎⁎ 0.900⁎⁎ 0.696⁎⁎ 0.914⁎⁎ 0.919⁎⁎
0.286 0.089 −0.007 −0.020 0.048 0.146 0.131 0.138
−0.051 −0.039 0.042 0.022 −0.033 −0.142 0.048
0.881⁎⁎ 0.684⁎⁎ 0.932⁎⁎ 0.624⁎⁎ 0.965⁎⁎ 0.790⁎⁎
0.653⁎⁎ 0.898⁎⁎ 0.575⁎ 0.876⁎⁎ 0.709⁎⁎
0.830⁎⁎ 0.678⁎⁎ 0.736⁎⁎ 0.902⁎⁎
0.664⁎⁎ 0.916⁎⁎ 0.878⁎⁎
0.612⁎⁎ 0.873⁎⁎
0.808⁎⁎
⁎ Correlation is significant at the 0.05 level. ⁎⁎ Correlation is significant at the 0.01 level.
Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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S. Jamshidi, K.D. Bastami / Marine Pollution Bulletin xxx (2016) xxx–xxx
Table 6 Enrichment factor (EF) of different metals from the sampling sites in the surface sediments of Anzali wetland. Sampling sites
As
Cd
Co
Cr
Cu
Ni
Pb
V
Zn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average
0.70 0.54 0.81 1.65 1.90 1.76 2.21 2.68 1.16 1.05 1.52 1.34 0.99 0.81 0.82 1.19 1.19 1.31
0.07 0.06 0.05 0.07 0.11 0.13 0.14 0.21 0.24 0.23 0.15 0.18 0.06 0.10 0.13 0.08 0.09 0.12
0.25 0.22 0.22 0.22 0.12 0.28 0.27 0.21 0.23 0.22 0.21 0.23 0.18 0.22 0.19 0.19 0.16 0.21
0.39 0.31 0.32 0.31 0.28 0.40 0.37 0.32 0.36 0.37 0.36 0.36 0.29 0.29 0.33 0.29 0.33 0.33
0.82 0.74 0.47 0.67 0.31 0.64 0.47 0.56 0.72 0.59 0.57 0.63 0.38 0.31 0.30 0.25 0.27 0.51
0.19 0.14 0.14 0.21 0.06 0.21 0.19 0.14 0.17 0.17 0.16 0.13 0.13 0.12 0.13 0.13 0.10 0.15
0.26 0.18 0.30 0.19 0.14 0.16 0.27 0.20 0.22 0.14 0.16 0.20 0.09 0.09 0.09 0.04 0.03 0.16
0.75 0.66 0.61 0.67 0.49 0.83 0.73 0.61 0.68 0.62 0.59 0.63 0.55 0.62 0.54 0.54 0.49 0.62
0.49 0.42 0.41 0.38 0.34 0.45 0.43 0.46 0.46 0.42 0.44 0.44 0.32 0.32 0.28 0.27 0.25 0.39
±
±
±
±
±
±
±
±
±
0.58
0.06
0.04
0.04
0.18
0.04
0.08
0.09
0.08
± SD
According to Hakanson (1980), the PER of coastal sediments posed by metals can be classified into the following categories: Low risk: E b 40; PER b 150. Moderate risk: 40 ≤ E b 80; 150 ≤ PER b 300. Considerable risk: 80 ≤ E b 160; 300 ≤ PER b 600. High risk: 160 ≤ E b 320; PER ≥ 600. Very high risk: E ≥ 320. The calculated E values are shown in Table 7. Single risk factors (E) were 28.09 ± 11.67, 7.90 ± 3.41, 1.46 ± 0.20, 5.60 ± 2.11, 1.92 ± 0.49, 1.79 ± 0.93, and 0.84 ± 0.18 for As, Cd, Cr, Cu, Ni, Pb, and Zn, respectively (Table 7). As and Zn had the highest and lowest single risk factors, respectively. The average ecological risk of E value for all metals in most surface sediments was b40, indicating a low risk to the local ecosystem. PLI provides a simple, comparative tool to assess the level of metal pollution, and the pollution load was then classified as no (PLI b 1), moderate (1 b PLI b 2), heavy (2 b PLI b 3), or extremely heavy (3 b PLI) pollution (Chakravarty and Patgiri, 2009; Seshan et al., 2010).
Table 7 Classification of sediment samples based on the potential ecological risk factor (E) in the surface sediments from Anzali wetland. Sampling sites
As
Cd
Cr
Cu
Ni
Pb
Zn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Average
15.31 12.76 20.71 42.50 35.51 41.10 48.57 51.89 23.24 20.97 28.29 25.71 23.60 17.73 18.78 26.17 24.62 28.09 ±
4.57 4.29 3.86 5.71 6.29 9.29 9.43 12.14 14.57 14.00 8.43 10.43 4.29 6.57 9.29 5.43 5.71 7.90 ±
1.73 1.48 1.64 1.60 1.06 1.86 1.63 1.24 1.46 1.47 1.34 1.38 1.39 1.27 1.53 1.28 1.38 1.46 ±
9.02 8.74 6.06 8.69 2.91 7.55 5.17 5.43 7.19 5.94 5.38 6.07 4.58 3.44 3.49 2.80 2.77 5.60 ±
2.69 2.09 2.25 2.39 0.82 2.80 2.21 1.70 2.08 1.87 1.88 1.90 1.74 1.66 1.67 1.57 1.25 1.92 ±
2.88 2.19 3.90 2.43 1.29 1.83 2.97 1.97 2.16 1.45 1.53 1.90 1.08 0.94 1.09 0.40 0.36 1.79 ±
1.08 1.00 1.06 1.00 0.64 1.06 0.95 0.89 0.93 0.84 0.82 0.85 0.76 0.70 0.64 0.60 0.52 0.84 ±
11.67
3.41
0.20
2.11
0.49
0.93
0.18
± SD
Table 8 PLI of the sampling sites in the surface sediments of Anzali wetland. Sampling sites
As
Cd
Co
Cr
Cu
Ni
Pb
V
Zn
PLI
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
1.53 1.28 2.07 4.25 3.55 4.11 4.86 5.19 2.32 2.10 2.83 2.57 2.36 1.77 1.88 2.62 2.46
0.15 0.14 0.13 0.19 0.21 0.31 0.31 0.40 0.49 0.47 0.28 0.35 0.14 0.22 0.31 0.18 0.15
0.56 0.53 0.56 0.57 0.22 0.66 0.60 0.41 0.47 0.44 0.39 0.44 0.44 0.48 0.43 0.41 0.33
0.86 0.74 0.82 0.80 0.53 0.93 0.82 0.62 0.73 0.74 0.67 0.69 0.70 0.64 0.77 0.64 0.69
1.80 1.75 1.21 1.74 0.58 1.51 1.03 1.09 1.44 1.19 1.08 1.21 0.92 0.69 0.70 0.56 0.55
0.45 0.35 0.38 0.40 0.14 0.47 0.37 0.28 0.35 0.31 0.31 0.32 0.29 0.28 0.28 0.26 0.21
0.58 0.44 0.78 0.49 0.26 0.37 0.59 0.39 0.43 0.29 0.31 0.38 0.22 0.19 0.22 0.08 0.07
1.65 1.56 1.56 1.74 0.92 1.96 1.61 1.19 1.36 1.24 1.11 1.22 1.32 1.35 1.25 1.20 1.02
1.08 1.00 1.06 1.00 0.64 1.06 0.95 0.89 0.93 0.84 0.82 0.85 0.76 0.70 0.64 0.60 0.52
0.76 0.67 0.75 0.84 0.47 0.91 0.86 0.74 0.78 0.69 0.64 0.7 0.56 0.54 0.57 0.46 0.54
The calculated PLI values of metals in sediment are summarized in Table 8, which were b 1 at all sampling sites. Therefore, all sampling sites had no pollution. In this study, we investigated the concentrations of metals, including As, Cd, Cu, Cr, Co, V, Ni, Pb, and Zn from sediments of Anzali wetland in relation to sediment properties. Statistical analysis revealed that Al and Fe are effective factors in the distribution of the metals on the sediments. This study also showed higher concentration of As, V, and Cu in the sampling sites than those reported in previous studies. In addition, the contents of Ni, As, Cr, and Cu were higher than those in the SQGs. This may cause toxicity to certain exposed organisms. The above results confirmed that Anzali wetland is facing a serious environmental degradation problem, especially due to metal contamination.
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Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049
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Please cite this article as: Jamshidi, S., Bastami, K.D., Metal contamination and its ecological risk assessment in the surface sediments of Anzali wetland, Caspian Sea, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.08.049