| Summary: | Mercury (Hg) in rivers and streams of the Mackenzie River Basin (MRB) presents a risk to fish, aquatic mammals, and humans. This thesis makes use of newly-released water quality data, including total mercury (THg) and dissolved mercury (DHg), gathered through the NWT-Wide Community-based Water Quality Monitoring (CBM) program. Landscape metrics extracted from geospatial datasets (e.g. vegetation type cover and ground ice presence), along with the water quality parameters were transformed, as needed, and then assessed for relationships with Hg concentration in rivers using principle component analysis, correlation and linear regression. Transformed turbidity, total phosphate, total sulfate, and the 1st principle component representing total metals were positively correlated with log10 THg and log10 particulate Hg (PHg) (p < 0.05) in major tributaries on the MRB. Major tributaries had a greater proportion of THg as PHg. Dissolved organic carbon and total organic carbon were positivity correlated to log10 DHg in minor tributaries (p < 0.05) of the MRB. Logit-transformed ground ice presence was positively correlated with median log10 PHg and log10 THg (PHg; p < 0.05, THg; p < 0.05). Median log10 DHg was positively correlated with logit-transformed landcover metric mixed forest (R2 = 0.67), and negativity correlated with logit-transformed landcover metric sub-polar taiga needleleaf forest (R2 = 0.64) (p < 0.05). This suggests suspended particles, derived potentially from suspended mineral matter, kerogens, and/ or weathering of sulfides could be a control on PHg in major tributaries of the MRB, while thicker, organic soils, potentially in forested areas, releasing TOC and DOC, could control export of DHg to minor tributaries in the MRB.
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