Distribution of organochlorines in the dissolved and suspended phase of the sea-surface microlayer and seawater in Hong Kong, China

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in the dissolved and suspended particulate phase in the sea-surface microlayer (SML) and subsurface water (SSW) collected from Hong Kong’s coastal environment. The concentration ranges (pg/L) for ∑HCHs, ∑DDTs and ∑PCBs in the SSW dissolved phase (DP i.e. sum of truly dissolved and colloidal phase) were 409–940 (mean 602), 774–5583 (mean 1908) and 266–433 (mean 278), respectively. The concentration ranges (pg/L) for ∑HCHs, ∑DDTs and ∑PCBs in SSW suspended particulate matter (SPM) were <5–85 (mean 59), 358–1369 (mean 787) and 85.6–273 (mean 172), respectively. The enrichment factor of PCBs and OCPs in the SML varied between 1.1 and 4.5 for the DP, and 0.4–8.2 for the SPM. The distribution of contaminants between DP and SPM in both the SML and SSW indicates that particulate matter plays an important role in the distribution and fate of DDTs and PCBs, but not for HCH isomers. The Pearl River Estuary is likely to be a major source of contaminants transported to Hong Kong.