Metal contamination in Sunairi Point sediment core along Karachi coast, Pakistan

This paper describes the pollution level in sediment core collected from Sunairi Point of Karachi coastal area Pakistan. The sediment was characterized in terms of particle size, pH, total organic carbon, calcium carbonate, metals and mineralogical composition of sediments. The metals were determined using proton induced X-ray emission. It appeared from the results of grain size that sediment of core was mainly sandy in nature and neutral pH was observed throughout the core. The calcium carbonate in the core sediment seemed to be dependent on the pH outline of the sediment. The results of heavy metals in the sediment core indicated a significant upward enrichment in heavy metals with the highest concentrations found in the upper most layer sediments, may be due to anthropogenic activities, which could be the cause of upward enrichment in heavy metals. The pollution load index values, although showed no pollution, but showing an increasing trend from bottom to top in core, may be due to the influence of anthropogenic sources. The average geo-accumulation index values for sediment core showed that sediments were moderately polluted with Co and Pb. The results of sediment quality guidelines of United States Environmental Protection Agency, indicated, sediment of core was moderately polluted with Ni and Zn. It was concluded from the guidelines that heavy metals in sediment may cause danger to aquatic life. It was also inferred from the study that Sunairi Point area of Karachi coast is facing moderately metals pollution which increased with time.