Assessment of Heavy Metals in Hooralazim Wetland Sediments by Calculation of Pollution Index

Heavy metals have received much attention in recent years due to their stability in the environment and pollution potential in the soil. In sediments, a significant proportion of toxic metals are absorbed by clays and remain for a long time, so they can increase the severity of air pollution due to dust which is rising by wind. The aim of this study was to investigate the contamination level of heavy metals in Hooralazim wetland sediments which known as dust zone. For this purpose, 65 samples were collected from 0-15 cm depth of Hooralazim Wetland sediments and the concentration of heavy metals were measured using atomic absorption spectrometry. In order to evalute the contamination level, Molar geochemical index, enrichment factor, contamination coefficient and contamination load index were calculated. Based on the molar geochemical index, the results showed Cd, Ni and Cr were in the non-contaminated range to moderate contamination and Pb, Cu, Zn, Fe and Mn were in the non-contaminated range. Also, based on the enrichment factor, Cd had the highest enrichement, Ni and Cr had moderately enrichement and Pb, Cu, Zn, Fe and Mn had low enrichment. Contamination coefficients were also found to be low for Pb, Cu, Zn, Fe and Mn, moderate for Ni and Cr and high for Cd. The contamination load index showed no pollution for the sediments. Therefore, based on the calculated indices, the amount of Cd, and then Ni and Cr were above the standard level. Since, the effluents of industerial, oil fasilitiess and chemical fertilizers are entering into Hoorolazim wetland.