Potentially Toxic Elements Risk Assessment and Source Identification of an At-Risk International Wetland in SW Iran

Abstract

Choghakhor is a freshwater permanent International Wetland in SW Iran where rapid agricultural and ecotourism development has changed the face of the landscape. In this study, the possible effect of these activities was assessed on the accumulation of potentially toxic elements (PTEs) in the wetland surface sediment. The concentration of PTEs varied considerably by sampling station in the order of Fe > Mn > As > Ni > Cr > Pb > Zn > Cd and exceeded the ISQG limits for Cd (11.46 mg/kg) and As (59.30 mg/kg). The results of pollution indices -Geoaccumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI) and Potential Ecological Risk Index (RI)- were spatially investigated using an interpolation technique, showing that the wetland is not contaminated nor severely enriched with Cr, Mn and Zn but is exposed to significantly high Cd and As contamination and enrichment levels across its entire area. Based on PLI, the entire wetland area is heavily polluted. The potential ecological risk of the PTEs was found to be considerably high which is a severe threat to the wetland species and its food web. The primary factors contributing to HM contamination in the wetland were recognized as agricultural land development, inappropriate application of phosphate pesticides and fertilizers, and the overuse of gasoline-powered boats for fishing and tourism activities.