Distribution of organochlorine compounds in the sea-surface microlayer, water column and sediment of singapore’s coastal environment

Hexachlorocyclohexanes (HCHs), dichlorodiphenylethanes (DDTs) and 38 PCB congeners were determined in the water column (sea-surface microlayer, subsurface, mid-depth and bottom water) and sediments from Singapore’s coastal environment. The concentration ranges for ∑HCHs, ∑DDTs and ∑PCBs in the seawater dissolved phase (DP) were 101–6110 (mean 1833), <5–405 (mean 76) and 60–6979 (mean 1611) pg/l, respectively. The concentration ranges for ∑HCHs, ∑DDTs and ∑PCBs in the suspended particulate matter (SPM) were 26–2395 (mean 243), <5–124 (mean 19) and 38–3793 (mean 715) pg/l, respectively. Concentration levels in sediments ranged between 521 and 1758 (mean 1094), 50 and 290 (mean 88) and 339 and 1356 (mean 858) pg/g for ∑HCHs, ∑DDTs and ∑PCBs, respectively. It was shown that the interfaces of the sea-surface microlayer (SML) and near bottom water are important compartments for the distribution of organochlorine compounds (OCs) in the water column. In comparison with data from China, the concentration levels in the water column and sediments of Singapore can be considered as low, but the reported levels were higher compared to available data from Europe.