| Summary: | This research examined the potential cumulative impacts of air pollution in northeast British Columbia (BC). It was part of a larger project to develop tools for assessing the cumulative impacts of development in BC’s Treaty 8 traditional territory. Although this study was framed from a First Nations perspective, it has relevance to all residents of the region. The focus is on Criteria Air Contaminants (CAC); whose reporting in Canada is required based on contributions to acid rain, ozone and poor regional air quality. Air pollution in northeast BC is dominated by the upstream oil and gas (UOG) sector. An analysis of official emissions data and reporting policies showed that inventories severely underestimate UOG emission sources. Industry-based emission estimates were combined with a conventional government-based emissions inventory to give a more comprehensive dataset for the region. When CAC sources were considered inclusively and cumulatively across the region’s landscape, emissions of the CAC sulphur dioxide (SO₂), nitrogen oxides (NOx) and volatile organic compounds approximately doubled, reaching intensities comparable to urban areas. Due to the magnitude of SO₂ and NOx emissions, and their known contribution to the acidification of ecosystems in parts of Canada, the Critical Loads of Acidity (CL(A)) were estimated for freshwater lakes in the region. A scarcity of detailed lake chemistry data pre-empted the development of empirical methods for estimating CL(A). Alkalinity and calcium measurements were available for a significant number of lakes and were consequently used as indicators of acidification sensitivity using relationships between these parameters and existing CL(A) estimation procedures. The resulting CL(A) were used alongside Ambient Air Quality Objectives (AAQO) and critical limits for various ecosystem elements, as thresholds for measuring potential air pollution effects. The AERMOD model, traditionally used for simulating the dispersion of UOG emissions from individual sources in BC, was used here to predict ambient concentrations and surface deposition of both SO₂ and NOx from numerous emission sources in an area of both cultural significance and high source density. Results predicted potential threshold exceedances that may have implications for ecosystems, human health and First Nations Treaty rights. === Forestry, Faculty of === Graduate
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