Atmospheric DDTs over the North Pacific Ocean and the adjacent Arctic region: Spatial distribution, congener patterns and source implication

During the 2003 Chinese Arctic Research Expedition (CHINARE 2003) from Bohai Sea to the high Arctic (37°N–80°N), air samples were collected and analyzed for DDTs. ∑DDTs (sum of six congeners) ranged from 0.52 to 265 pg m−3 with an average of 13.1 pg m−3. Higher DDT concentrations were observed in Bohai Sea and near eastern Russia. The congener patterns were obviously different between the Far East Asia and the higher latitudinal regions that p,pʹ-DDT and o,pʹ-DDT were dominated in the former; while o,pʹ-DDT and o,pʹ-DDE were dominated in the latter. The source contributions of technical DDT and dicofol type DDT were estimated. Results showed that technical DDT was the dominant source (>94%) which was fresher in the Far East Asia compared to the North Pacific Ocean and the Arctic. For dicofol type DDT, the estimated contribution was minor. The “new” o,pʹ-DDT observed should have relatively more contribution from dicofol type DDT in the North Pacific Ocean and the Arctic.