Heavy-metal distribution and risk assessment of sediment and fish from El-Mex Bay, Alexandria, Egypt

Abstract

Heavy metals are increasingly being released into natural waters from geological and anthropogenic sources. The distribution of several heavy metals (Cr, Cu, Cd, Pb, Zn, and Hg) was investigated in muscle, gill, and liver in two different fish species seasonally collected in El-Mex Bay (autumn 2004–summer 2005). In order to evaluate the pollution status of the Bay, the concentrations of the selected metals in the labile and total fractions were analysed in sediment samples collected from eight sites in El-Mex Bay during autumn 2004. Also, the Index of Geoaccumulation (I geo) for the sediment was estimated. The total and labile fractions of the selected metals in sediment samples were 15.2 and 62.8 μg g−1 dw for Cu, 1.8 and 5.0 μg g−1 dw for Cd, 79.1 and 130.3 μg g−1 dw for Zn, 0.2 and 1.2 μg g−1 dw for Hg, 35.8 and 93.0 μg g−1 dw for Pb, and 13.9 and 31.0 μg g−1 dw for Cr. The concentrations of all metals were lower in flesh than those recorded in liver and gill due to their physiological roles. The metal pollution index for fish was calculated. Health hazard calculations for the contaminated sediments and fish consumption were calculated to evaluate the effect of pollution on health.