Document Type : علمی - پژوهشی
Environmental Group, Natural Resources Department, Khorramshahr University of Marine Sciences and Technology, Khuzestan, Iran
Introduction: Parishan wetland is one of the most valuable and ecologically important ecosystems in the world which has completely dried up in recent years due to successive droughts (Dehghani, 2007). Considering that heavy metals are among the most important pollutants of the environment, their survival time is high in sediments (Ullah et al., 2017). Also, these metals have harmful effects on aquatic ecosystems, and sediments are both a source of and a place to store these elements. Acquiring information about these metals is important (Bhuiyana et al., 2010). Materials and methods: The purpose of this study was to estimate the level of contamination of Perishan wetland sediments with the heavy metals copper, iron, manganese and zinc using the enrichment index, geochemical accumulation index, degree of contamination and the comprehensive pollution factor index. In this study, 40 sediment samples with a weight of 200 g were systematically harvested. After acid digestion and filtering to read the concentration of toxic metals liberated in each sample, an AAS atomic absorption device by the Thermo Company (UK) was used. In this study, because of the lack of any specific standard for soil contamination in our country, standards from other countries were used. The average concentration of the metals studied in the region is lower than the maximum acceptable concentration (mg / kg) for the countries of Poland, Canada and Australia.Results and discussion: The changes in pH and electrical conductivity (Ec) were calculated in the range of 2.7-9.2 and 4.2-34, respectively, and the concentration of heavy metals based on mg/kg was found in most samples including manganese (2.18-3.71), iron (3.6-4.26), zinc (2.15-8.3) and copper (5.3-8.13), respectively. The background concentration for manganese, copper, iron and zinc was 950, 50, 41000 and 75 mg/kg, respectively. The geochemical accumulation index, the pollution factor and the comprehensive pollution factorindex were all used to determine contamination levels in the area. The geochemical accumulation index was less than zero for all metals, which shows the non-contamination class of the area. In addition, the factor of contamination index for most of the samples was in the class unpolluted, and the contamination factor for all metals was less than one, so that all data were placed in the non-contaminated class. The results also showed that the elements of manganese, copper, iron and zinc have a geological and agricultural origin, while the concentration of metals in the soil was related to their natural origin.Conclusion: Finally, it can be stated that the studied area has the lowest risk of contamination with heavy metals. In fact, it can be said that the copper, iron, manganese and zinc found in this region have a geological origin and they change through the natural processes of geology and through springs in the wetland.
- Abrahim, G. M. S. and Parker, R. J. Assessment of heavy metal enrichment factors and the degree of contamination in marine sediments from Tamaki Estuary, Auckland, New Zealand. Journal of Environ Monit Assess; 2008; 136; 227â238.
- Alloway, B.J. Heavy Metals in Soils. Chapman & Hall, London; 1995.
- Bhuiyana, M. A. H.; Parvez, L.; Islam, M. A.; Dampare, S. B. and Suzukia, S. Heavy metal pollution of coal mine-affected agricultural soils in the northern part of Bangladesh. Journal of Hazardous Materials; 2010; 173: 384â392.
- Bi nam. Statistical Yearbook of of Hamedan province. Planning Office of Statistics and Information, Hamedan; 2006. [In Persian]
- Cao, H. F.; Chang, A. C. and Page, A. L. Heavy Metal Contents of Sludge-treated Soils as Determined by Three Extraction Procedures. Journal of Environ Qual; 1984; 13(4):632-634.
- Carman, C. M., X. D. Li., G. Zhang., O. W. H. Wai., and Y. S. Li. Trace metal distribution in sediments of the Pearl river stuary and the surrounding coastal area: South China. Journal of Environmental Pollution; 2007; 147, 311-323.
- Dehghani, A. Ecosystems of Parishan wetland. Role of October, Tehran; 2005. [In Persian]
- Dickinson,W.W., G.B.,Dunbar and H.,McLeod. Heavy metal history from cores in Wellington Harbour, New Zealand. Journal of Environmental Geology; 1996; 27, 59â69.
- Farkas, A., C. Erratico., and L. Vigano. Assessment of the environmental significance of heavy metal pollution in surficial sediments of river Po. Journal of Chemosphere; 2007; 68(4), 761-768.
- Gay, D., and W. Maher. Natural variation of Copper, Zinc, Cadmium and Selenium concentrations in Bembicium nanum and their potential use as a bioremediator of trace metals. Journal of Water Research; 2003; 37, 2173-2185.
- Gong, M.; Bi, X. Y.; Ren, L. M.; Wang, L.; Ma, Z. D.; Bao, Z. Y. and Li, Z. G. Assessing heavy-metal contamination and sources by GIS-based approach and multivariate analysis of urbanârural topsoils in Wuhan, central China. Journal of Environ Geochem Health; 2009; 32(1):59-72.
- Hakanson, L. Ecological risk index for aquatic pollution control, a sedimentological approach. Journal of Water Research; 1980; 14, 975â1001
- Khodakarami, L. Evaluation of non-point sources of pollution in agriculture using RS and GIS. Thesis Master of Environment, Department of Natural Resources, Esfahan University of Technology. 2009. [In Persian]
- Lee, C. S.; Li, X. and Shi, W. Metal contamination in urban, suburban, and country park soils of Hong Kong: A study based on GIS and multivariate statistics. Journal of Science of the Total Environment; 2006; 356(1â3):45â61.
- Li, L. G.; Xue, L. D. and Ming, L. Q. Heavy metals contamination characteristics in soil of different mining activity zones, Trans. Nonferrous Met. Soc; 2008; 18: 207-211.
- Liu, W.; Zhao, J.; Ouyang, Z.; SÃ¶derlund, L. and Liu, G. Impacts of sewage irrigation on heavy metal distribution and contamination in Beijing, China. Journal of Environment International; 2005; 31(6):805â812.
- McGrath, S. P.; Chaudri, A. M. and Giller, K. E. Long term effects of metals in sewage sludge on soils, micro-organisms and plants. Journal of Ind. Microbiol; 1995; 14(2):94-104.
- Mousavi, M, H., Purnia, M. And Amiri, F. Distribution of heavy metals in agricultural soils around factory of Karoon Cement, South-East Masjed Soleiman, Journal of geochemistry; 2013; 3, 215-226. [In Persian]
- Muller, G. Index of geoaccumulation in sediments of the Rhine River. Geo journals; 1969; 2: 108-118.
- Ravichandran, M. and et al. History of trace metal pollution in Sabine-Neches; 1995.
- Salomons, W., and U. Forstner. Metals in the hydrocycle: New York, Springer-Verlag; 1984. P. 333.
- Shahbazi, A. Evaluation of the impact of agricultural activities on the accumulation of heavy metals in agricultural soils in Hamadan province, environmental masters thesis, Department of Natural Resources, Esfahan University of Technology; 2011. [In Persian]
- Singh, B. R. and Steinnes, E. Advances in soil science. Soil processes and water quality, Soil and water Contamination by heavy metals, CRC Press, INC; 1994.
- Vahabzadeh, A. Environmental bases, First Printing, publishing Jahad of Mashhad University; 1993. [In Persian]
- Yalcin, M. G.; Battaloglu, R. and Ilhan, S. Heavy metal sources in Sultan Marsh and its neighborhood, Kayseri, Turkey. Journal of Environ Geol; 2007; 53: 399-415.
- Zhong, A. P., S. H. Guo., F. M. Li., G. Li., and K. X. Jiang. Impact of anions on the heavy metals release from marine sediments: Journal of Environmental Sciences; 2006; 18(6), 1216-1220.