Geochemical assessment of metal pollution and ecotoxicology in sediment cores along Karachi Coast, Pakistan Azhar Mashiatullah & Muhammad Zaman Chaudhary & Nasir Ahmad & Nisar Ahmad & Tariq Javed & Abdul Ghaffar Received: 5 November 2014 /Accepted: 18 March 2015 # Springer International Publishing Switzerland 2015 Abstract This paper is an attempt to compare the pol- lution status in two sediment cores, one from a polluted site (Ghizri Creek) and another from a relatively unpol- luted site (Sandspit). Sediment cores (45 cm in length) from coastal locations were characterized in terms of grain size, sediment composition, pH, organic matter, calcium carbonate, and metal element contents. Metal elements, including Al, Ca, Cr, Co Cu, Fe, K, Mg, Mn, Ni, Pb, V, Ti, and Zn, were determined using PIXE. Grain size analysis and sediment composition demon- strated a sandy nature of both cores. Acidic trend in sediment core I was predominant from bottom to top, whereas neutral pH was observed throughout core II. TOC values varied in the range of 1.23–2.68 and 1.14– 2.60 % in core I and core II, respectively; however, there was an increasing trend in TOC level from bottom to top. The values of enrichment factor for Zn, Cu, Co, Ni, Pb, and Cr were slightly higher in core I than core II. The average geo-accumulation index values for core I and core II showed that sediments were moderately Co- and Pb-polluted but not polluted with Mg, Al, Ca, K, Cr, Cu, Fe, Mn, Ni, Ti, V, and Zn. The degree of contami- nation was however considerably higher in core I rela- tive to core II. The pollution load index values, although showing an increasing trend from bottom to top in both cores, overall rendered the marine sediment pollution free. The metal toxicology results demonstrated that heavy metal pollution, except Cr, may pose low to moderate risk to marine biota. The sum of toxic unit values however indicated that sediment core I was rel- atively more polluted than that of core II. Keywords Metal element contents . Marine sediments . Sediment quality guidelines . Pollution load index . Degree of contamination . Enrichment factor . Toxic units . Geo-accumulation index Introduction Metal pollution of the marine environment has received considerable attention because of its transfer to man through the food chains in quantities that can be harmful (GESAMP 2001; Goldberg 1992). Metals are introduced to the marine environment by domestic and industrial activities as anthropogenic pollutants. Much of this input ultimately accumulates in the estuarine zone and conti- nental shelf, which are important sinks for suspended matter and associated land-derived contaminants. Among the components of the marine environment, Environ Monit Assess (2015) 187:249 DOI 10.1007/s10661-015-4467-9 A. Mashiatullah (*) : M. Z. Chaudhary : T. Javed : A. Ghaffar Isotope Applications Division, Pakistan Institute of Nuclear Science & Technology (PINSTECH), Islamabad, Pakistan e-mail: azhar@pinstech.org.pk A. Mashiatullah e-mail: mashiatullah@gmail.com N. Ahmad Institute of Geology, University of the Punjab, Lahore, Pakistan N. Ahmad Accelerator Laboratory, CASP, Government College University, Lahore, Pakistan