Influence of 850 mb trajectories on acid precipitation in southwestern British Columbia |
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| Authors: | M S Kotturi T S Murty M B Danard |
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| Institution: | (1) Waste Management Branch, British Columbia Ministry of Environment and Parks, V8V 1X5 Victoria, British Columbia, Canada;(2) Department of Fisheries and Oceans, Institute of Ocean Sciences, West Saanich Road, PO Box 6000, V8L 4B2 Sidney, British Columbia, Canada;(3) University of Victoria, PO Box 1700, V8W 2Y2 Victoria, British, Columbia, Canada |
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| Abstract: | Precipitation chemistry in southwestern British Columbia has been examined to determine if the shutdown of the ASARCO smelter in Tacoma, Washington in March of 1985 had a significant effect.The smelter emitted about 300 tonnes/day of sulphur dioxide and about one tonne/day of arsenic. The smelter had a supplementary control system (SCS) which was implemented during adverse meteorological conditions to meet ambient air standards. The SCS was in operation in October 1984.Five storms from October 1984, before the shutdown, that produced precipitation over the eight-station network in southwestern British Columbia, were considered. The 850 mb back trajectories and ionic loadings in the collected precipitation samples were compared. A similar comparison was made for three storms in October 1985, after the shutdown of the smelter. An examination of cases whose trajectories passed over the smelter before and after the shutdown indicated an over 50% decrease in volume weighted average sulphate concentration in precipitation over the Gulf Islands (islands in the southern Strait of Georgia). However, when the trajectory from the northwest passes over British Columbia coastal sources, higher excess SO4 concentrations were observed in the precipitation over the Gulf Islands, indicating a linkage between these concentrations and the British Columbia coastal sources. There was no apparent change in values at stations farthest from the Strait of Georgia with one exception. It was also noted that there was reduction in arsenic in precipitation, which could be considered as a tracer, after the shutdown of the ASARCO smelter. This paper enlarges on the above observation with comparisons of the major meteorological and chemical characteristics related to eight storms. |
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| Keywords: | Acid precipitation British Columbia 850 mb trajectories ASARCO smelter sulphate arsenic eight storms |
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