Impacts of Lindane Usage in the Canadian Prairies on the Great Lakes Ecosystem. 2. Modeled Fluxes and Loadings to the Great Lakes
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- 作者：Jianmin Ma ; Sreerama Daggupaty ; Tom Harner ; Pierrette Blanchard ; and Don Waite
- 刊名：Environmental Science & Technology
- 出版年：2004
- 出版时间：February 15, 2004
- 年：2004
- 卷：38
- 期：4
- 页码：984 - 990
- 全文大小：233K
- 年卷期：v.38,no.4(February 15, 2004)
- ISSN：1520-5851
文摘
Atmospheric loadings of 
-hexachlorocyclohexane (-HCH) from May 1, 1998, to April 30, 1999, to the GreatLakes simulated by a coupled soil-air and water-airatmospheric transport model are presented. Modeling resultson an annual basis indicate that Lake Superior receivedthe highest dry deposition load of 2.17 kg yr-1. Dry depositionto the lower Great Lakes (Lakes Erie and Ontario) was2-6 times lower as compared to the upper Great Lakes.Greater deposition in the upper Great Lakes is due mainlyto their larger surface area and greater proximity tosources of -HCH. Dry deposition fluxes (pg m-2) to lakesurfaces were much lower than to land as a result of lowerdeposition velocities and lower air concentrations of-HCH over the lakes. The highest -HCH loading (kg yr-1,in 1998-99) due to wet deposition occurred for LakeOntario. This was mainly attributed to greater annual rainfallover Lake Ontario. An investigation of average seasonalfluxes predicted by the model shows that deposition fluxesto the Great Lakes are considerably higher in the summerthan that in the autumn and winter seasons. The netdirection of gas exchange also exhibits a seasonaldependence. Lakes Michigan, Huron, and Ontario shownet absorption in the summer 1998 whereas at all other timesnet outgassing occurred at all of the lakes. Overall, gasexchange was the dominant process affecting loadings tothe Great Lakes. Model-derived loadings and totaldeposition flows across the Great Lakes basin due to dryand wet depositions and net gas exchange agreereasonably well with the summer estimates compiled bythe Integrated Atmospheric Deposition Network whereasautumn values show greater discrepancies. Better agreementwas also observed for dry deposition as compared towet deposition. Specifically, to improve short-term loadingestimates (e.g., over days to months), the model resultsindicate the need for better spatially and temporally resolvedinformation on concentrations in air and surface waterand better estimates of precipitation and depositionvelocities over the lakes.
-hexachlorocyclohexane (-HCH) from May 1, 1998, to April 30, 1999, to the GreatLakes simulated by a coupled soil-air and water-airatmospheric transport model are presented. Modeling resultson an annual basis indicate that Lake Superior receivedthe highest dry deposition load of 2.17 kg yr-1. Dry depositionto the lower Great Lakes (Lakes Erie and Ontario) was2-6 times lower as compared to the upper Great Lakes.Greater deposition in the upper Great Lakes is due mainlyto their larger surface area and greater proximity tosources of -HCH. Dry deposition fluxes (pg m-2) to lakesurfaces were much lower than to land as a result of lowerdeposition velocities and lower air concentrations of-HCH over the lakes. The highest -HCH loading (kg yr-1,in 1998-99) due to wet deposition occurred for LakeOntario. This was mainly attributed to greater annual rainfallover Lake Ontario. An investigation of average seasonalfluxes predicted by the model shows that deposition fluxesto the Great Lakes are considerably higher in the summerthan that in the autumn and winter seasons. The netdirection of gas exchange also exhibits a seasonaldependence. Lakes Michigan, Huron, and Ontario shownet absorption in the summer 1998 whereas at all other timesnet outgassing occurred at all of the lakes. Overall, gasexchange was the dominant process affecting loadings tothe Great Lakes. Model-derived loadings and totaldeposition flows across the Great Lakes basin due to dryand wet depositions and net gas exchange agreereasonably well with the summer estimates compiled bythe Integrated Atmospheric Deposition Network whereasautumn values show greater discrepancies. Better agreementwas also observed for dry deposition as compared towet deposition. Specifically, to improve short-term loadingestimates (e.g., over days to months), the model resultsindicate the need for better spatially and temporally resolvedinformation on concentrations in air and surface waterand better estimates of precipitation and depositionvelocities over the lakes.