Levels of persistant organic pollutants in air in China and over the Yellow Sea

The occurrence of persistent toxic substances (PTS) in China and possibly their regional transport in the Yellow and East China Seas region was studied. Organochlorines in atmospheric gas-phase and particulate matter were collected by high-volume sampling (filters and polyurethane foams) during 2 weeks in June 2003 (dry season) simultaneously at a Yellow Sea coastal site in an urban area, Qingdao, China, and a rural island site, Gosan, Jeju Island, Korea. Using GC methods, the samples were analysed for 9 persistent organic pollutants (POPs) regulated under the global POP convention, namely aldrin, chlordane (cis- and trans-isomers CC and TC), DDT and metabolites (o,p’-DDT, p,p’-DDD, and p,p’-DDE), dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex and PCB (congeners number 28, 52, 101, 153 and 180), and for hexachlorocyclohexane (α-, β- and γ-isomers), a PTS and now considered for regulation under the convention, too. At the coastal site additionally o,p’-DDE and -DDD, β-endosulfan, isodrin, heptachlorepoxide and d-HCH, and at the island site additionally p,p’-DDT and the PCB congeners number 77, 81, 114, 118, 123, 126, 138, 156, 167, 169, 170 and 189 were analysed. 9 samples were collected at the coastal and 15 (for PCBs 5) at the island site. Long-range advection pathways were determined based on analysed back-trajectory calculations. The mean concentrations of DDT and its metabolites, HCB, HCH, and PCB at the coast were in the 100-1000 pg m-3 range. Higher concentrations prevailed during night-time. The levels were in general lower at the island site, but not for DDT. Local sources are likely. PCBs were even 2 orders og magnitude lower, suggesting that PCBs are not subject to regional transport but elevated concentrations in air are limited to the source areas. Organochlorine pesticide levels on the other hand were seemingly determined by regional transport over mainland China rather than by emissions in the coastal area. The currently used pesticides mirex and chlordane were found at elevated levels, i.e. 79 (6.6-255) and 36 (<6-71) pg m-3, respectively, at the coast but not over the island. The POPs pesticides aldrin, dieldrin and eldrin, never registered in China, were mostly found at