Tracing industrial emissions in the Athabasca oil sands region using stable isotope techniques

Bibliography: p. 228-264Some pages are in colour.The Athabasca oil sands region (A0SR) in northeastern Alberta, Canada, is one of the world's largest oil reservoirs. Its heavy oil will become increasingly important as conventional energy resources decline. Due to the rapid industrial development in the A0SR, there have been increasing concerns about the impact of the emissions from the oil sands operations on the surrounding terrestrial and aquatic ecosystems. Stable isotope techniques may help to assess such impact provided that industrial emissions are isotopically distinct from background components. In order to trace nitrogen (N), sulfur (S) and molybdenum (Mo) emissions released by the oil sands industry, chemical and isotopic compositions of various N, S and Mo compounds in emissions and several environmental receptors were determined. Industrial N and S04 emissions were found to be isotopically distinct. 8 180 and ?? 170 of atmospheric nitrate deposition and 8180 values of atmospheric sulfate deposition showed trends towards lower values with increasing nitrate and sulfate deposition rates allowing for the quantification of industrial contributions to atmospheric nitrate and sulfate deposition in the A0SR (quantitative tracers). Lichens responded to elevated N and S deposition in close proximity to the oil sands operations, whereas chemical and isotopic compositions of N and S in pine needles showed no significant industrial impact. 15 8 N values of industrial emissions provide a qualitative tracer of industrial N emissions 34 in atmospheric ammonium deposition, lichen samples and soil water. 8 S values in atmospheric sulfate deposition and total S in lichen samples were indicative of emissions of reduced sulfur compounds, likely from tailing ponds. Different sample preparation techniques were tested for the analyses of 898195Mo. Results of Mo concentration and isotope ratio analyses on snow, air filter samples and fly ash samples from a coal-fired power plant suggest that industrial activities are associated with an increase in Mo concentrations and with Mo isotope fractionation, providing a potential new tracer for industrial activities in the AOSR. In summary, quantitative and qualitative tracers revealed that impact of industrial emissions on the surrounding environment in the AOSR were limited to 30 km distance to one of the major emission stacks

Tracing Industrial Nitrogen and Sulfur Emissions in the Athabasca Oil Sands Region using Stable Isotopes

The rapid development in the Athabasca Oil Sands Region (AOSR) in northeastern Alberta, Canada, has raised concerns about the impact of the industrial emissions on the surrounding terrestrial and aquatic ecosystems. Stable isotope techniques may help to trace the transport and fate of industrial emissions provided that they are isotopically distinct from background isotope ratios in environmental receptors. In order to trace nitrogen (N) and sulfur (S) emissions released by the oil sands industry, chemical and isotopic compositions of various N and S compounds in emissions, in atmospheric deposition, and in several environmental receptors were determined. It was found that d18O values of nitrate and sulfate and ?17O values of nitrate are indicators that constitute excellent new monitoring tools for tracing industrial N and S emissions in the surrounding environment. Application of quantitative and qualitative stable isotope tracers revealed that industrial N and S emissions were observable in the surrounding environment within ca. 30 km distance to the major emission source

Deep groundwater circulation through the High Arctic cryosphere forms Mars-like gullies

We report here the discovery of the northernmost known perennial spring, located in the polar desert of the Canadian High Arctic (average precipitation 75.5 mm/yr; average annual air temperature –19.7 °C). The high-discharge spring (~520 L/s) has also anomalously high temperatures (9.0 °C), despite occurring in a region of low geothermal gradient and thick (>400 m) permafrost. Active erosion at the spring outlet forms gullies with alcove-channel-apron morphology, remarkably similar to archetypal gullies observed on mid-latitude regions of Mars. Geochemical and isotopic data show a meteoric origin for the waters, demonstrating that deep circulating groundwater systems can form active connections through the cryosphere to the subsurface, even in the absence of thermal anomalies. This discovery challenges current understanding of high-latitude permafrost hydrology

Tracing industrial sulfur contributions to atmospheric sulfate deposition in the Athabasca oil sands region, Alberta, Canada

Anthropogenic S emissions in the Athabasca oil sands region (AOSR) in Alberta, Canada, affect SO4 deposition in close vicinity of industrial emitters. Between May 2008 and May 2009, SO4-S deposition was monitored using open field bulk collectors at 15 sites and throughfall collectors at 14 sites at distances between 3 and 113 km from one of the major emission stacks in the AOSR. At forested plots >90 km from the operations, SO4 deposition was 1.4 kg SO4-S ha1 yr1 for bulk deposition and 3.3 kg SO4-S ha1 yr1 for throughfall deposition. Throughfall SO4 deposition rates in the AOSR exceeded bulk deposition rates atall sites by a factor of 2–3, indicating significant inputs of dry deposition especially under forest canopies. Both bulk and throughfall SO4 deposition rates were elevated within 29 km distance of the industrial operations with deposition rates as high as 11.7 kg SO4-S ha1 yr1 for bulk deposition and 39.2 kg SO4-S ha1 yr1 for throughfall at industrial sites. Sulfur isotope ratio measurements of atmospheric SO4 deposited in the AOSR revealed that at a few selected locations 34S-depleted SO4, likely derived from H2S emissions from tailing ponds contributes to local atmospheric SO4 deposition. In general, however, d34S values of SO4 deposition at distant forested plots (>74 km) with low deposition rates were not isotopically different from d34S values at sites with high deposition rates in the AOSR and are, therefore, not suitable to determine industrial S contributions. However, O isotope ratios of atmospheric SO4 in bulkand throughfall deposition in the AOSR showed a distinct trend of decreasing d18O-SO4 values with increasing SO4 deposition rates allowing quantification of industrial contributions to atmospheric SO4 deposition. Two-end-member mixing calculations revealed that open field bulk SO4 deposition especially at industrial sites in close proximity (<29 km) to the operations is significantly (17–59%) affected by industrial S emissions and that throughfall generally contained 49–100% SO4 of industrial origin. Hence, it is suggested that d18O values of SO4 may constitute a suitable tracer for quantifying industrial contributions to atmospheric SO4 deposition in the AOSR

A multi-isotope approach for estimating industrial contributions to atmospheric nitrogen deposition in the Athabasca oil sands region in Alberta, Canada

Industrial nitrogen (N) emissions in the Athabasca oil sands region (AOSR), Alberta, Canada, affect nitrate (NO3) and ammonium (NH4) deposition rates in close vicinity of industrial emitters. NO3eN and NH4eN open field and throughfall deposition rates were determined at various sites between 3 km and 113 km distance to the main oil sand operations between May 2008 and May 2009. NO3 and NH4 were analyzed for d15NeNO3, d18OeNO3, D17OeNO3 and d15NeNH4. Marked differences in the d18O and D17O values between industrial emissions and background deposition allowed for the estimation of minimum industrial contributions to atmospheric NO3 deposition. d15NeNH4 values also allowed for estimates of industrial contributions to atmospheric NH4 deposition. Results revealed that particularly sites withinw30 km radius from the main oil sands developments are significantly affected by industrial contributions to atmospheric NO3 and NH4 deposition

Concentration measurements and isotopic composition of airborne molybdenum collected in an urban environment

Here, we report the first measurements of the molybdenum (Mo) isotopic composition of aerosols collected on Teflon air filters. Mo concentrations and isotopic compositions were measured at selected locations in the city of Calgary, Canada, including a residence, theisotope laboratory at the University of Calgary, the University of Calgary weather station, and the City of Calgary Transit bus garage. Concentrations ranged from 0.07 ng/m3 in the laboratory to 19.0 ng/m3 in the bus garage. The concentrations of Mo in the air samplescollected in the bus garage were the highest measured in this study. To date, there are no reported data for the Mo isotopic composition of airborne Mo. In this study, the d98/95Mo values measured for the different urban sampling sites and reported relative to SRM 3134, ranged from -0.18 to +0.94 ‰. The results of this investigation suggest that measurements of Mo concentrations and isotopic compositions have the potential to trace anthropogenic emissions in an urban environment

Isotopic characterization of nitrate, ammonium and sulfate in stack PM2.5 emissions in the Athabasca Oil Sands Region, Alberta, Canada

Stable isotope techniques may be a suitable tool for tracing industrial emissions in the atmosphere and the environment provided that the isotopic compositions of industrial emissions are distinct. We determined the isotopic compositions of nitrate, ammonium and sulfate in PM2.5 emitted from two industrial stacks at a large upgrader site in the Athabasca oil sands region (AOSR), northeastern Alberta, Canada, and compared them to the nitrogen and sulfur isotopic compositions of source materials and upgrading by-products. We found distinct isotopic compositions of nitrate and ammonium in PM2.5 compared to those reported for atmospheric nitrate and ammonium in the literature. Nitrate in PM2.5 had d15N values of 9.4& (Stack A) and 16.1 1.2& (Stack B) that were significantly enriched in 15N compared to the feedstock materials (w2.5&), by-products of upgrading (0.3e1.3&), and atmospheric N2 (0&). d15N of ammonium in PM2.5 showed a large range with values between 4.5 to þ20.1& (StackB). We report the first measurements of the triple oxygen isotopic composition of industrial emitted nitrate. Nitrate emitted as PM2.5 is not mass-independently enriched in 17O resulting inD17O ¼ 0.5 0.9& (Stack B) and is therefore distinct from atmospheric nitrate, constituting an excellent indicator of industrial derived nitrate. d18O values of nitrate in PM2.5 (36.0 and 17.6 1.8& for Stack A and B, respectively) were also significantly lower than d18O values of atmospheric nitrates and hence isotopically distinct. d34S values of sulfate in PM2.5 were with 7.3 0.3& (Stack A) and 9.4 2.0& (Stack B) slightly enriched in 34S compared to d34S in bitumen (4.3 0.3&) and coke (3.9 0.2&). d18O values of sulfate in PM2.5 were 18.9 2.9& and 14.2 2.8& for Stack A and Stack B, respectively. The isotopic composition of sulfate in PM2.5 was not sufficiently different from d34S and d18O values of sulfate in longrange atmospheric deposition in industrial countries to serve as a quantitative indicator for industrial emitted PM2.5.We conclude that d18O and D17O values of nitrate in stack-emitted PM2.5 are excellent, and d15N values of nitrate and ammonium are suitable indicators for identifying and tracing of PM2.5 nitrate and ammonium emitted from two stacks in the AOSR in the surrounding terrestrial and aquatic ecosystems

Foliage Chemistry of Pinus baksiana in the Athabasca Oil Sands Region, Alberta, Canada

Industrial emissions in the Athabasca Oil Sands Region (AOSR), Alberta, Canada, have caused concerns about the effect of oil sands operations on the surrounding terrestrial environments, including jack pine (Pinus banksiana Lamb.) stands. We collected jack pine needles from 19 sites in the AOSR (13–128 km from main operations) for foliar chemical analyses to investigate the environmental impact on jack pine. Pine needles from three age classes, the current annual growth (CAG, 2011), one year and two year old pine needles, were collected. Samples were analyzed for total carbon (TC), nitrogen (TN), and sulfur (TS), inorganic S (SO4-S), base cations (Ca, Mg, Na), and other elements (B, Cu, Fe, Mn, P, Zn); CAG needles were also analyzed for their nitrogen and carbon isotopic compositions. Only TN, TS, Ca, B, Zn, and Fe contents showed weak but significant increases with proximity to the major oil sands operations. C and N isotopic compositions showed no trend with distance or TC and TN contents. Total S contents in CAG of pine foliage increased significantly with proximity to the main industrial operation while foliar inorganic S to organic S ratios (SO4-S/Sorg) ranged consistently between 0.13 and 0.32, indicating low to moderately high S loading. Hence, this study suggests some evidence of uptake of S emissions in close proximity to anthropogenic sources, although the reported values have not reached a level of environmental concern

Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction

The latest Permian extinction (LPE), ca. 252 Ma, represents the most severe extinctionevent in Earth’s history. The cause is still debated, but widespread marine anoxicto euxinic (H2S rich) conditions, from deep to shallow water environments, are commonlysuggested. As a proxy for marine oxygen levels, we analyzed d98/95Mo of two LPEsections that represent a gradient in water depth on the northwest margin of Pangea.Results from deep-water slope environments show a large shift in d98/95Mo values from–2.02‰ to +2.23‰ at the extinction horizon, consistent with onset of euxinic conditions. Incontrast, sub-storm wave base shelf environments show little change in the molybdenum isotopic composition (–1.34‰ to +0.05‰), indicating ongoing oxic conditions across the LPE.These results indicate that areas of the continental shelf of northwest Pangea underwent massextinction under oxic conditions throughout the LPE event, and that shallow-water anoxiawas therefore not a global phenomenon