Distribution and accumulation of heavy metals in surface sediments from a subtropical bay affected by the Special Economic Zone, China

Abstract

The concentrations of nine metals (Cd, Cr, Cu, Ni, Mn, Pb, Zn, Fe, and Al) in surface sediments from 14 sampling sites in Shantou Bay were determined in order to understand current metal levels and spatial distribution due to the rapid development of the Shantou Special Economic Zone. Results showed that metal concentrations in surface sediments varied from 0.31 to 1.74 mg kg–1 for Cd, 35.98 to 74.19 mg kg–1 for Cr, 24.43 to 79.24 mg kg–1 for Cu, 428.45 to 809.87 mg kg−1 for Mn, 16.91 to 31.51 mg kg−1 for Ni, 35.59 to 64.84 mg kg−1 for Pb, 84.91 to 246.51 mg kg−1 for Zn, 2.93 to 3.93% for Fe, and 5.25 to 9.28% for Al. Although all metal concentrations in sediments meet Chinese National Standard Criteria for Marine Sediment Quality, both enrichment factor (EF) and geo-accumulation index (Igeo) show Pb and Cd pollution existed in the upper and middle bay, and pollution of other metals is also recorded in some sites depending on the sources; river input, sewage discharge, and port activities are the main sources of pollutant to the bay.