Hexachlorocyclohexanes and endosulfans in urban, rural, and high altitude air samples in the Fraser Valley, British Columbia: evidence for trans-Pacific transport.
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.
Harner
Tom
T
Meteorological Service of Canada, Environment Canada, Toronto, Ontario, Canada M3H 5T4. tom.harner@ec.gc.ca
Shoeib
Mahiba
M
Kozma
Melissa
M
Gobas
Frank A P C
FA
Li
Shao Meng
SM
D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D000401:Aircraft; D000531:Altitude; D001272:Atmosphere; D001955:British Columbia; D002947:Cities; D004726:Endosulfan / Q000032:analysis*; D004784:Environmental Monitoring; D001556:Hexachlorocyclohexane / Q000032:analysis*; D007306:Insecticides / Q000032:analysis*
D000393:Air Pollutants; D007306:Insecticides; D001556:Hexachlorocyclohexane; D004726:Endosulfan