Spatial variation of heavy metals in surface sediments of Hong Kong mangrove swamps

The degree of heavy metal contamination in the fine-grained (-1 Cu, 240 μg g^-1 Zn, 40 μg g^-1 Cr, 30 μg g^-1 Ni, 3 μg g^-1 Cd and 80 μg g^-1 Pb. The second cluster, made up of another four swamps distributed in different geographical locations (two in Sai Kung district and two in Tolo region), also had elevated levels of Cu, Pb, Ni and Cr in the sediments. Field observation reveals that these seven stands received industrial, livestock and domestic sewage as well as pollution from mariculture activities, suggesting that anthropogenic input is the main source of heavy metal contamination in Hong Kong mangroves. The sediments from other mangrove swamps were relatively uncontaminated. Copyright (C) 2000 Elsevier Science Ltd.