Investigation of Heavy Metals Pollution Based on Environmental Indicators in the Surface Sediments of Hourolazim Wetland- Southwestern Iran

Abstract

Abstract This study aims to investigate the pollution by heavy metals in the surface sediments of Hourolazim Wetland (HW) using pollution indices and statistical analysis of 16 samples from 8 stations at a distance of 50m from oil drilling sites. Based on the results, the average concentrations of Pb, Zn, V, and Cr are 40.7, 103.1, 135.5, and 115.8, respectively, which are higher than the average shale values. The results of heavy metal concentrations based on the geo-accumulation Index (Igeo) show that As, Zn, Ni, V, and Cr have low enrichment while Pb has medium enrichment, with the latter showing an alarming condition. Also, based on the contamination factor (CF), Pb with an average value of 2.03 and moderate level of pollution has the highest level of pollution warning compared with other elements. Modified contamination degree (mCd) for St3 and St4 is 1.61 and 1.56, respectively indicating low level of pollution. The enrichment factor (EF) for lead represents the average level of enrichment. Cluster analysis for the metals shows that V and Ni lie in one cluster while the rest of the metals (As, Pb, Zn, and Cr) lie in the other. Further, cluster analysis for the studied stations shows that stations St3, St4, and St7 are located in one cluster whereas, stations St1, St2, St5, St6, and St8 in another cluster that has the high compliance with the average of the combined pollution index. High correlation between some metals and sampling stations with cluster analysis provide insights into the same level of contamination and an approximate contamination source for these metals.