Geochemical assessment of metal contamination in Manora picnic point sediment core from Karachi coast, Pakistan

摘要

This study is focused on the metals' pollution level in sediment core collected from Manora Picnic Point of Karachi coastal area Pakistan. The sediment was categorized in terms of pH, particle size, total organic carbon (TOC), calcium carbonate, and heavy metals, besides the determining the mineralogy composition of sediment. Metals were determined using proton-induced X-ray emission spectroscopy (PIXE) technique. The results of abundant and heavy metals in the sediment core indicated a significant upward enrichment, which could be the cause of discharge of industrial effluents and domestic wastewaters of Metropolitan Karachi into sea. The average geo-accumulation index values showed that sediments were moderately polluted with Co and Pb, and unpolluted for metals (Al, Ca Mg, Cr, Cu, Fe, K, Mn, Ni, Ti, V, and Zn). The pollution load index values indicate an increasing trend from bottom to top, which may be due to the influence of anthropogenic sources. According to the sediment quality guidelines of United States Environmental Protection Agency (USEPA), core sediment was heavily polluted with Ni and moderately polluted with Pb, Cu and Zn.