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Many measurements, tools, and approaches are used to identify and track the influence of human activities on the physicochemical status of streams. Commonly, chemical concentrations are utilized, but in some areas, such as downstream of coal mines, capacity indices such as specific conductivity have also been used to estimate exposure and risk. However, straightforward tools such as conductivity may not identify human influences in areas with saline groundwater inputs, diffuse exposure pathways, and few discharges of industrial wastewater. Researchers have further suggested in conductivity relative to alkalinity may also reveal human influences, but little has been done to evaluate the utility and necessity of this approach. Using data from 16 example sites in the Peace, Athabasca, and Slave Rivers in northern Alberta (but focusing on tributaries in Canada's oil sands region) available from multiple regional, provincial, and national monitoring programs, we calculated residual conductivity and determined if it could identify the potential influence of human activity on streams in northern Alberta. To account for unequal sampling intervals within the compiled datasets, but also to include multiple covariates, we calculated residual conductivity using the Generalized Estimating Equation (GEE). The Pearson residuals of the GEEs were then plotted over time along with three smoothers (two locally weighted regressions and one General Additive Model) and a linear model to estimate temporal patterns remaining relative to known changes in human activity in the region or adjacent to the study locations. Although there are some inconsistencies in the results and large gaps in the data at some sites, many increases in residual conductivity correspond with known events in northern Alberta, including the potential influence of site preparation at oil sands mines, reductions in particulate emissions, mining, spills, petroleum coke combustion at one oil sands plant, and hydroelectric development in the Peace basin. Some differences in raw conductivity measurements over time were also indicated. Overall, these analyses suggest residual conductivity may identify broad influences of human activity and be a suitable tool for augmenting broad surveillance monitoring of water bodies alongside current approaches. However, some anomalous increases without apparent explanations were also observed suggesting changes in residual conductivity may also be well-suited for prompting additional and more detailed studies or analyses of existing data. [ABSTRACT FROM AUTHOR]

• Sphagnum moss was collected from 22 bogs near bitumen mines and upgraders. • Hg was determined using sector-field ICP-MS and a direct Hg analyzer. • ICP-MS: average Hg was slightly but significantly greater near industry. • Hg analyzer: average Hg was slightly but significantly lower near industry. • Hg accumulation rates were within the range for natural background rates. Sphagnum moss was collected from 22 ombrotrophic (rain-fed) bogs near open pit mines and upgraders within the Athabasca Bituminous Sands (ABS) region of Alberta (AB). Mercury was quantified using two approaches: sector-field ICP-MS of acid digests, and a Direct Mercury Analyser (DMA) for solid samples. Using ICP-MS, the mean Hg concentration in moss from the ABS region (34.7 ± 1.5 µg/kg, n = 75) was significantly greater than the control site, Utikuma (26.7 ± 4.0 µg/kg, n = 3). Using DMA, the mean Hg concentration in moss from the ABS region (26.2 ± 0.9 µg/kg, n = 71) was significantly lower than the control site (28.5 ± 1.3 µg/kg, n = 6). These contradictory findings illustrate the challenges associated with comparing the results of two analytical methods, especially given the similarity in Hg concentrations between industrial and background sites, Similar Hg concentrations were also found in Sphagnum moss from two other bogs in AB which are far removed from the ABS region. The Hg concentrations in Sphagnum from the ABS bogs are well below the range found in bog vegetation collected earlier in eastern Canada, and comparable to the lowest values (5th percentile) reported for forest moss collected in 2015 from Norway and Sphagnum moss sampled in 2008 from northern Sweden. Given the rates of Sphagnum accumulation in the ABS region (ca. 215 g/m2/yr), Hg accumulation rates there were 5.8–7.5 µg/m2/yr versus 5.7–6.1 µg/m2/yr at the control site (UTK); these are at the upper limit of the range in pre-anthropogenic rates of Hg accumulation for peat from European bogs. Sphagnum moss is abundant in Canada and found in bogs from coast to coast, offering an opportunity to obtain quantitative information on atmospheric Hg deposition to terrestrial ecosystems from natural as well as anthropogenic sources. [ABSTRACT FROM AUTHOR]