HEAVY METAL INVESTIGATION OF COASTAL SAND (CLIFTON BEACH, KARACHI, PAKISTAN): ENVIRONMENTAL IMPLICATIONS

Preliminary trace element investigations were carried out on representative samples collected from the Sea View, Karachi, Pakistan. The focus of this study was to determine the chemical composition of collected sands and interpret their depositional and environmental aspects. Routine XRF and heavy mineral separation techniques were utilized and compared with USGS standard sample for precision. Geographically, the area of investigation lies at the coordinates 24° 80'62''53 North, 67°02'21''38 East. Current study area is also known as the part of Clifton Beach located adjacent to the Arabian Sea. It is noted by geologists that structurally, the Karachi region, is a part of the folded belt of the Karachi Embayment and lies on a vast elongated syncline, which was refolded and faulted due to subsequent tectonism. Beach sands are tan to brown, micaceous and contain abundant silt. Among the identified trace elements, four elements appear to be dominant in samples and include Zr, Ni, Cr, and Ti. Abundance of Zr was noticeable in fine-grained sand and coarse silt. The presence of Zr indicates that it has been reworked and subjected to long distance transport. Concentration of Ni was very low amount in all the samples; however, Ni was more abundant in the coarser sand than in the finer sand. Enrichment of Ti in all the samples was uniform and could be attributed to possible leaching effect and this trend is apparently displayed by soil samples capping beach sediments. The findings of these heavy metals perhaps are indicative of non-treated water being dispersed in the Arabian Sea, Clifton Beach and Sea View. Trace metal assemblages in beach sand fluctuates from one region to another depending on a number of factors including type of exposed rocks, climatic conditions, mechanism of transport and hydraulic sorting during deposition.