Contemporary Urban Affairs 2017, Volume 1, Number 3, pages 67– 72 Quality Evaluation and Study of Ecological Toxicity of Heavy Metals in Shadegan Wetland * Dr. Samar Mortazavi 1, Dr. Mohsen Tizhoosh 2, Dr. Zahra Cheraghi 3 1, 2, 3 Department of Environmental Science, Faculty of Natural Recourses and Environmental Science, Malayer University, Iran 1 E mail: [email protected] , 3 E mail: [email protected] A R T I C L E I N F O: A B S T R A C T Article history: Wetlands hold a principal position in storing food for primary producers, so they are not able to bear the pressure. The slightest disturbance, hence, may harm wetlands Received 2 August 2017 and cause detrimental effects. The present study aims at monitoring heavy metals and Accepted 10 August 2017 evaluation of the sediment quality index of Shadegan wetland in Iran. Thus, a sampling of surface sediments of the wetland was performed at ten stations with three Available online 12 October replications; after the preparation of samples with aqua regia, the concentrations of 2017 heavy metals were measured by atomic absorption spectroscopy. The quantification Keywords: of sediment pollution using the contamination factor, contamination degree, pollution load index, ecological risk assessment index, and ecological toxicity of heavy metals Sediment quality; in the region were all carried out. The results of Cf and Cd showed that the degree of zinc and copper contamination is low; however, the degree of lead contamination is Toxicity; heavy metals; moderate. Moreover, the obtained PLI was less than 1 indicating a lack of sediments contamination with heavy metals. The RI was less than 150 indicating a low risk of Shadegan wetland. contamination. In addition, comparing the concentrations of elements with National Oceanic and Atmospheric Administration and Sediment Quality Guidelines showed slightly toxic and non-toxic sediments, respectively. Finally, based on a mixture of This work is licensed under a effect range median, all sediment samples are placed in the first category with less Creative Commons Attribution - NonCommercial - NoDerivs 4.0. than 12% toxicity probability. CONTEMPORARY URBAN AFFAIRS (2017) 1(3), 66-72. "CC-BY-NC-ND" https://doi.org/10.25034/ijcua.2018.3683 www.ijcua.com Copyright © 2017 Contemporary Urban Affairs. All rights reserved. 1. Introduction environment and aquatic ecosystems. Among Aquatic ecosystems, as one of the main the existing pollutants in the sewage, heavy en vironmental features, are a key supplier of metals can be mentioned, especially the ones food and a roof over aquatic organism’s head; that play important roles in society as the main on the other hand, they are also large sources raw materials for many industries. (Zhuang and for a wide range of pollutants. Since these ecosystems withstand a high capacity for *Corresponding Author: development, they are subject to more serious Department of Environmental Science, Faculty of Natural risk due to the pollutants. Domestic and industrial Recourses and Environmental Science, Malayer University, sewage discharges, the growth in urbanization, Iran, and industrial activities in coastal areas are severe threats to the safety of the coastal E-mail address: [email protected] JOURNAL OF CONTEMPORARY URBAN AFFAIRS, 1(3), 67-72/ 2017 Gao, 2014; Caerio, et l, 2005) Some, such as Ramsar Settlement in 1972. (Nasirian et al., 2015) copper and zinc, play a vital role in the metabolism of the human body. However, in high concentrations, they turn into toxic substances. Being attributable to high persistence toxicity, solubility low absorption and accumulation in the bottom sediments, heavy metals cause contamination in aquatic environments. (Caerio, et al., 2005) The biological toxicity and bio-magnification in food chains have made the issue of heavy metals a significant global problem. (Förstner and Wittmann, 1983) the ways to clean up contaminated sediment are mostly costly, and in some cases impossible. Hence, the evaluation of sediment contamination in the aquatic environment, identifying sources of pollution, applying management policies, and processes to reduce a number of pollutants into the aquatic environment is more important than focusing on clearing techniques. Many studies have been done in this regard, among which the one carried out by Zarezadeh and Rezai, (2014) can be mentioned through which they have investigated the heavy metals in the sediments bed of mangroves Khurgabrik in Jack Port involving Molar coefficient, the degree of reformed contamination, and ecological risk assessment index. Vaezi et all, (2014) have investigated Mollar environmental index, pollution load, ecological toxicity in sediments in Mosa Firth, Persian Gulf. Chai et al., (2016) explored heavy metal pollution in river sediments in Serbia by calculating the pollution load index and ecological risk assessment. Chai and et al. Sakan and Dordevic, (2015) examined the index of enrichment, molar and ecological risk assessment in Xiangjiang River sediments. In the present study, the types of sediment Figure 1. The location of the Shadegan wetland (left) geochemical index have been determined. [Source: Google map], and the locations of the sampling Moreover, the ecological risks have been stations within the wetland (right). assessed, and ecological toxicity of sediments with heavy metals, namely lead, zinc and 2.2 Sampling and Preparing Samples copper have been analyzed. The results have As per available access points, a sampling of been compared with the standards of NOAA surface sediments was carried in 10 stations with and SQG, respectively. three replications and recording the geographic coordinates (table 1). 2. Materials and Methods For the purpose of preparation, the sediment 2.1Area of study samples were dried in an oven at a temperature The Shadegan Wetland with an area of of 105° C. Then, they were crushed in a stone approximately 400,000 hectares in the range of mortar and screened by a 63-micron sieve. For coordinates 48 degrees 17 minutes and degrees the acid ingestion of sediments, Direct Aqua 50 minutes east, 30 degrees 17 minutes 30 Regia was employed, following the ingestion; degrees and 58 minutes north is located in with the contribution of double distilled water in Khuzestan province, Iran, and has been a 25 mL volumetric flask, the volume was recognized as an international wetland in the delivered. (Yap et al., 2012) To ensure the accuracy of ingestion and elimination of errors Samar Mortazavi, Mohsen Tizhoosh, Zahra Cheraghi 68 JOURNAL OF CONTEMPORARY URBAN AFFAIRS, 1(3), 67-72/ 2017 due to sample preparation and to undo the pollution,Cd5 Pollution Degree Index. (Davaulter, effect of consumed materials on the and Rognerud, 2001). concentration of metals in each of ingestion operations, a control sample was considered; at Table 2. Different contamination factor (Cf) and factor (Cd), the end of atomic absorption (Hakanson,1980) ContrAA700analyticjena, the concentration of metals in the samples was read. Detection limit for Cu, Pb and Zn in flame method was 0.23, 0.88 and 0.25 microgram per gram, respectively. Table 1. Geographical coordinates of the sampling stations within Shadegan wetland. Land use Geographical Coordinates Road& Entrance N 66.55  49 30 74.1 E 4833 of the village Rural residential N 32.3  3048 34.25E 4832 area Rural residential N 23.58  3045 18.57 E 4831 Total coefficients of pollutant contamination area which are being studied show the overall Recreation area N 85.48  3043 87.58E 4830 Recreation area N 99.38  3045 83.11E 4835 degree of sediment contamination called Recreation area N 12.5  3042 96.47 E 4839 Hakson pollution degree and is obtained from Place& Pleasure N 87.0  3041 44.15E 4827 𝐶 =∑𝑛 𝐶𝑓 (Table 2). Pier refueling 𝑑 𝑖=1 𝑖 Agricultural area N 16.26 3048 70.36E 4838 Agricultural area N 16.22 3049 33.24 E 4840 with an area of 3.2 Pollution Load Index (PLI) low Tomlinson, pollution load index, has been the n- Agricultural& N 75.20 3050 87.52E 4841 th root pollution load factor at one station from Wastewater all the elements and is determined as 𝐼 = discharge 𝑛√𝐶𝑓 ×……×𝐶𝑓 . If 1> PLI, it indicates a low 1 𝑛 3. The Investigated Indices concentration of heavy metals and the lack of Data geochemical description and choosing pollution; PLI = 0 indicates the proximity of metal the sample ground play an important role in concentration to the background investigations. Many researchers have used the concentration, and PLI> 1 indicates mean of cortical or frequency of data as a base. contaminated sediment. (Varol, 2001) In the present study, to determine the extent of sediment contamination by heavy metals Shil 3.3 Ecological Risk Assessment Index (RI) Mean of Cu, Zn and Pb were 45, 95 and 20, For assessment of ecological risk index deposits respectively, which are presented by Turkian, in the aquatic environment, Hakansvn,(1980) and Wedephol, (1964) This index is a benchmark presented 𝑅𝐼 =∑𝑚𝑖=1𝐸𝑟 with 𝐸𝑟 =𝑇𝑟∗𝐶𝑓 where Er is to measure pollution which is achieved by potential ecological risk for each element and RI dividing the concentration of the elements to is potential ecological risk of the total metals the same concentration of elements in the (cumulative). Hakanson's theory, (1980), T, is r reference material (Shil average). it shows the defined as the ratio of toxicity in this equation, for amount of sediment contamination by heavy Pb, Zn and Cu is 5, 1, and 5, respectively (Table metals. The classification of Hakanson pollution 3). index.(Hakanson,1980) 𝐶 =𝑀 ⁄𝑀 (Table 2). 𝑓 𝑥 𝑏 Table 3. Risk index levels and their effects. 3.1Cp Potential Pollution Index Risk index Ecological risk criteria of Potential pollution index is obtained by dividing environment the maximum amount of each metal in the RI<150 Low sediment on the average value of the same 150≤R< 300 Moderate metal in the earth’s surface and is calculated as 300≤R<600 Considerable follows: 600≤R Very high 𝐶𝑝= (𝑚𝑒𝑡𝑎𝑙)𝑠𝑎𝑚𝑝𝑙𝑒 𝑀𝑎𝑥 , (𝑚𝑒𝑡𝑎𝑙)𝐵𝑎𝑐𝑘𝑔𝑟𝑜𝑢𝑛𝑑 where Cp <1 indicates a low pollution, 1≤CP <3 3.4 Estimation of Ecotoxicology moderate pollution, and 3≤Cp severe Diverse amounts of pollutants affect the exposed organisms in different ways. In this Samar Mortazavi, Mohsen Tizhoosh, Zahra Cheraghi 69 JOURNAL OF CONTEMPORARY URBAN AFFAIRS, 1(3), 67-72/ 2017 regard, in some countries standards for 𝑛 Ci ⁄ pollutants have been proposed, among which m−ERM−Q=∑ ERMi America Standard Quality Sediment NOAA and n Canada Guidelines quality sediments SQGS are 𝑖=1 Table 5. The relationship between sediment toxicity value of the best-knowns, and the most widely used ones. ERMQ and PELQ and chance of sediment toxicity classification The primary purpose of these standards is based on ERM. (Hwang et al ,2008) protecting the fish from the negative impact of Sediment ERMQ PELQ m-ERM- Possibility organic and inorganic pollutants in sediments, toxicity Q of grading and prioritizing contaminated areas for toxicity further investigation, and estimating the location non toxic <0.1 <1.0 <0.1 12% of sediment pollution. Two sets of instructions that slightly toxic 0.1-0.5 0.1-1.5 0.5-0.11 30% are commonly used include: Effect Range Low (ERL), Effect Range-Median (ERM), Probable moderately 0.5-1.5 1.5-2.3 1/5-0.51 40% Effect Level (PEl), and Threshold Effect Level toxic (TEL). While the effect range low (ERL or TEL) heavily toxic >1.5 >2.3 >1/5 74% shows the concentration below which there is no possibility of harmful effects, the major impact 4. Results range (ERM or PEL) refers to the higher The results of the concentration of zinc, copper concentrations above which harmful effects and lead in surface sediment samples of and side effects of pollutants are likely to be Shadegan wetland (in micrograms per gram dry observed. (MacDonald et al,2000; NOAA,2009) weight) are shown in the Figure 2. The potential (Table 4). contamination index (Cp) values of Pb, Zn and Cu are 1.209, 0.483 and 0.316, respectively. Table 4. Sediment Quality Guidelines (US and Canada) based on standard values. Reference Cu Zn Pb Index Standard NOAA,2009 34 150 47 ERL NOAA 40 270 410 218 ERM zn 30 Smith et 70.35 123 35 TEL SQGS al,1996 cu 20 197 315 30.91 PEL pb 10 0 To obtain more realistic amounts of sediment 10 9 8 7 6 5 4 3 2 1 toxicity effects in living organisms, the probable effective limit coefficient (PELQ) and the Figure 2. Average concentration of Zn, Cu and Pb in surface average effective limit coefficient (ERMQ) are sediment Shadegan wetland (µg/g). calculated according to the following In order to determine the extent of equations: contamination in the area Cf, Cd, mCd, PLI, RI and m-ERM- Q indices were calculated. The n Mi n Mi results are presented in Table 6. Ecological   toxicity calculation results PELQ and ERMQ were PELi ERMi PELQ  i1 and ERMQ  i1 . 0.86 and 0.70, respectively, which are indicative n n of low toxicity and non-toxic sediments of the Here Mi is concentrations in sediment I, PELi and area in comparison to the studied elements. The ERMi: The possible effective concentration and results of the calculation of sediment average effective concentrations in sediment i, contamination based on the of the ERM and the respectively. The variable n is the number of ERL indices are indicating that, in all the samples, investigated metals in each instance. concentrations of Pb, Cu and Zn are less than Correspondingly, the factors associated with the effective limit (<ERL). The calculated results of all quantity of sediments are reported in Table 5. To the stations show that m-ERM-Q for the sediment calculate the amount of toxicity resulting from samples exhibit 12% probability to contain the mixture of a group of toxic elements, SQGS is toxicity probability. calculated as follows (ERM: mid- effective range, Ci: concentration, N: the number of elements): Samar Mortazavi, Mohsen Tizhoosh, Zahra Cheraghi 70 Table 6. The results of heavy metal pollution in sediments of the Shadegan wetland. Cd MCd 10 9 8 7 6 5 4 3 2 1 St.No 11.08 1.11 1.04 0.96 1.04 1.20 1.15 1.14 1.20 1.15 1.20 1.00 Pb 4.28 0.43 0.48 0.47 0.43 0.39 0.45 0.43 0.402 0.38 0.43 0.42 Cu Cf 2.90 0.29 0.29 0.35 0.29 0.28 0.30 0.30 0.29 0.25 0.28 0.31 Zn - - 0.52 0.55 0.51 0.51 0.54 0.53 0.52 0.47 0.52 0.51 PLI - - 7.89 7.46 7.64 8.23 8.30 8.15 8.44 7.90 8.43 7.41 RI - - 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.07 0.08 0.08 m-ERM-Q 5. Discussion and Conclusion Compared with the existing standards of the U.S. Investigating the mean concentrations of heavy and Canada, the results of the present study are metals in wetland sediments indicates that Zn> representative of low- or non-toxic nature of the Pb> Cu. The mean concentration of Zn and Cu sediments for the living organisms in all the compared to the permissible concentration of stations with low-toxic ratios. Lastly, according to these metals in a global average is lower, and the results of the sediments assessment indices, the mean of lead is higher than the average the prominent role of the destructions of heavy global of the Earth’s crust. The cause of this can metals in threatening wildlife and the be the contamination of the sediments to these involvement of both human and natural factors metals resulting from the discharge of industrial on the distribution and concentration of heavy sewage at the sampling stations which is in line metals, as well as maintaining the balance of with the findings of Hatefi et al, (2016) and ecosystems, reviewing and monitoring the Mohammad Saleh et al, (2012) The Cp index quality of the sediments are among the most results for 1<Pb<3 indicate that the average important environmental considerations. 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