| 15757332 |
Harner T, Shoeib M, Kozma M, Gobas FA, Li SM: Hexachlorocyclohexanes and endosulfans in urban, rural, and high altitude air samples in the Fraser Valley, British Columbia: evidence for trans-Pacific transport. Environ Sci Technol. 2005 Feb 1;39(3):724-31.
High-volume air samples collected over the period Aug. 14-30, 2001, in the Lower Fraser Valley, BC, Canada, were used to assess urban/rural differences of organochlorine pesticides (OCPs) for ground level samples and to attempt to directly measure events of trans-Pacific inputs through the mid-troposphere. Hexachlorocyclohexanes (alpha- and gamma-isomers; 2-25 pg m (-3)) and endosulfan1 and -2 (5-150 pg m (-3)) were detected in all ground level samples. Seven air samples were collected during mid-troposphere flights (approximately 4400 m altitude) over the Lower Fraser Valley. These flights occurred concurrently with ground level sampling. Trajectory analysis identified three events of substantial mid-troposphere, trans-Pacific flow where 10-day back trajectories stemmed from potential source regions in Asia. These events were also characterized by higher air concentrations of alpha-HCH at 4400 m as compared to the ground level stations. This represents the first event-based, aircraft measurement of advection inputs of OCPs in the mid-troposphere of the west coast of North America. |
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