The Xiamen Symposium on Marine Environmental Sciences (XMAS 2027)

This study investigated the distribution characteristics and multi-interface transport fluxes of organochlorine pesticides (OCPs) in Taiwan Strait (TWS). The results showed that the average concentrations of hexachlorocyclohexanes (HCHs), chlordanes (CHLs) and hexachlorobenzene (HCB) in surface seawater were 8.2 ± 2.6, 3.1 ± 1.6 and 2.0 ± 1.2 ng·L^-1, respectively. Although these concentrations were relatively high on a global scale, the ecological risk was low. The average atmospheric concentration of OCPs was 227.7 ± 58.7 ng·m^-3, with HCB and HCHs accounting for 65% and 23%, respectively. For phase distribution, CHLs exhibited the strongest affinity for particulate matter. Diagnostic ratios indicated that HCHs represented a mixture of recent industrial inputs and historical residues, while CHLs consisted primarily of historical residues with some local new sources. Air-sea exchange was dominated by atmospheric deposition (highest for γ-HCH at 55.0 ± 7.4 μg·m^-2·day^-1), with only γ-chlordane and methoxychlor exhibiting net volatilization. The fluxes of HCHs , CHLs  and HCB from dry and wet deposition were 64.9 ± 48.5 and 84.8 ± 63.4, 18.9 ± 12.3 and 24.7 ± 16.1, and 9.0 ± 1.1 and 11.7 ± 1.4 μg·m^-2·day^-1, respectively. River input (8.4 kg·day^-1) was far less than the net ocean current input (2.8 ton·day^-1), and particulate deposition removed only 1.9 μg·m^-2·day^-1. Overall, the strait was a net recipient (28.6 ton·day^-1), with a stock of approximately 52.2 tons in the 60-meter water column.