NWT Air Quality Report (2011) - Environment and Natural ...
NWT Air Quality Report (2011) - Environment and Natural ...
NWT Air Quality Report (2011) - Environment and Natural ...
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Snare RapidsSince 1989, ENR has operated a Canadian <strong>Air</strong> <strong>and</strong> Precipitation Monitoring (CAPMoN)station at the Northwest Territories Power Corporation’s Snare Rapids hydro site. This site islocated 150 kilometres northwest of Yellowknife. Rain <strong>and</strong> snow samples are collected on adaily basis <strong>and</strong> sent to <strong>Environment</strong> Canada’s CAPMoN laboratory in Toronto for analysis ofprecipitation chemistry. Select results are presented below.Figure 24: Snare Rapids Acid Deposition (1993 - <strong>2011</strong>)(kg/ha/year)1.61.41.210.80.60.40.2093 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11Sulphate Nitrate Calcium MagnesiumFigure 24 shows the deposition rates for sulphate, calcium, nitrate <strong>and</strong> magnesium from1993 to <strong>2011</strong>.The geology of the <strong>NWT</strong> is mostly characterized by non-carbonate bedrock resistant toweathering <strong>and</strong>/or shallow, coarse-textured soils with low cation exchange capacity, lowsulphate adsorption capacity <strong>and</strong> low pH. The sulphate level of deposition that is consideredto be protective of sensitive ecosystems in the <strong>NWT</strong> is 7 kg/ha/yr. In areas of easternCanada where acid rain is a more serious environmental problem, sulphate deposition hasbeen measured by CAPMoN in excess of 20 kg/ha/yr. Nitrate deposition at Snare Rapids isalso low relative to eastern Canada.Sulphate <strong>and</strong> nitrate deposition rates measured at Snare Rapids remain below levels thatwould be expected to cause a significant environmental effect in sensitive ecosystems.30 <strong>NWT</strong> <strong>Air</strong> <strong>Quality</strong> <strong>Report</strong> <strong>2011</strong>