Environmental Evaluation of Potentially toxic Elements Pollution in Sediments of Waterways of Saadabad Region, South of Kashan

Abstract

Introduction Soil and sediments are considered to be the main places for absorption of heavy metals in contaminated environments (Priju and Narayana, 2007; Øygard and Gjengedal, 2009; Ahmed and Al-Hajri, 2009). Therefore, they are used in Heavy Metals Pollution Index in geochemical studies. Saadabad area that is a part of the Urumieh-Dokhtar magmatic belt is located at 30 km south of Kashan. The natural processes along with hydrothermal processes, altered areas and mineral activities on mineralization areas have potential for releasing toxic elements in the environment. Therefore, the presence of toxic elements in sediments of the Saadabad is expected. The purpose of this study is to evaluate the concentration of toxic elements and determine their source in the sediments of the Saadabad region. Material and Methods To investigate the status of environmental pollution of sediments, 174 samples were collected from the surface of sediments in the Saadabad area. The samples were analyzed by ICP-MS spectroscopy for determination of elements such as As, Cd, Pb, Zn, Cu, Co in the Zarazma Laboratory, Tehran, Iran. Discussion and Results Geochemical studies are carried out using various statistical techniques to map the various elemental abnormalities. These maps play an important role in determining high-­risk areas. The results of preliminary investigations showed that according to the correlations between the various elements studied the patterns of dispersion of various elements in the sediments of the Saadabad region are similar to each other. The anomalies observed of As and Cd in the southwest of the region can be attributed to the presence of travertine in this part of the region (Smedley and Kinniburgh, 2005). Maximum concentrations of Co and Fe in the central part of the Saadabad region are consistent with the location of igneous and sedimentary rocks, skarnification and hydrothermal alterations. The enrichment of elements Cu, Pb, and Zn in sediments of the Saadabad region, emphasizes the effective role of sulfide mineralization and hydrothermal alteration processes in the region. Several methods that are applied for the assessment of trace elements contamination as follows: 1- Contamination Factor (CF) is defined as follows (Reboredo, 1993): 1) CF=Cm Sample/Cm Background According to the calculated CF, Cd, As, Fe and Pb have moderate levels and Co, Cu and Zn have low levels of contamination. 2- Enrichment Factor (EF) The value of the EF of the toxic elements was computed for the sediments of the area. The highest value of 102 for an enrichment factor is associated with As. Next came those for Cd, and Pb, 36.47, and 11.89, respectively. 3- Cluster analysis Based on this method, target trace elements were divided into three groups. The first group comprises of the elements As, and Cd. The second group comprises of the element S, and the third group, has been subdivided into three subgroups. Subgroup 1 comprises of the elements Zn, and Cu; subgroup 2, comprises the elements Fe, and Co; and subgroup 3, comprises of the element Pb. 4- Factor analysis (FA) Factor analysis is a multivariate statistical method that ultimately produces a subset of independent variables (components) that explain variance in the dataset (Anazawa and Ohmori, 2005). According to the factor analysis, the trace elements originate from 1) natural and 2) anthropogenic sources. Acknowledgements The authors would like to thank the respectable reviewers of the Journal of Economic Geology for their valuable suggestions and comments. References Ahmed, T.‌A. and Al-Hajri, H.‌H., 2009. Effects of Treated Municipal Wastewater and Sea Water Irrigation on Soil and Plant Characteristics. 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Keywords

• alteration
• contamination factor
• enrichment factor
• potentially toxic elements
• kashan