An ambient air particulate matter sampling study was conducted at the Wood Buffalo Environmental Association (WBEA) AMS-1 Fort McKay monitoring station in the Athabasca Oil Sand Region (AOSR) in ...Alberta, Canada from February 2010 to July 2011. Daily 24h integrated fine (PM2.5) and coarse (PM10–2.5) particulate matter was collected using a sequential dichotomous sampler. Over the duration of the study, 392 valid daily dichotomous PM2.5 and PM10–2.5 sample pairs were collected with concentrations of 6.8±12.9μgm−3 (mean±standard deviation) and 6.9±5.9μgm−3, respectively. A subset of 100 filter pairs was selected for element analysis by energy dispersive X-ray fluorescence and dynamic reaction cell inductively coupled plasma mass spectrometry. Application of the U.S. EPA positive matrix factorization (PMF) receptor model to the study data matrix resolved five PM2.5 sources explaining 96% of the mass including oil sands upgrading (32%), fugitive dust (26%), biomass combustion (25%), long-range Asian transport lead source (9%), and winter road salt (4%). An analysis of historical PM2.5 data at this site shows that the impact of smoke from wildland fires was particularly high during the summer of 2011. PMF resolved six PM10–2.5 sources explaining 99% of the mass including fugitive haul road dust (40%), fugitive oil sand (27%), a mixed source fugitive dust (16%), biomass combustion (12%), mobile source (3%), and a local copper factor (1%). Results support the conclusion of a previous epiphytic lichen biomonitor study that near-field atmospheric deposition in the AOSR is dominated by coarse fraction fugitive dust from bitumen mining and upgrading operations, and suggest that fugitive dust abatement strategies targeting the three major sources of PM10–2.5 (e.g., oil sand mining, haul roads, bulk material stockpiles) would significantly reduce near-field atmospheric deposition gradients in the AOSR and reduce ambient PM concentrations in the Fort McKay community.
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•Fine and coarse particulate matter was quantified in Fort McKay, Alberta.•Receptor modeling elucidated and quantified significant contributing sources.•58% of PM2.5 and 83% of PM10–2.5 was attributable to oil sands production operations.•25% of the observed PM2.5 was attributed to biomass combustion.
Due to the potential ecological effects on terrestrial and aquatic ecosystems from atmospheric deposition in the Athabasca Oil Sands Region (AOSR), Alberta, Canada, this study was implemented to ...estimate atmospheric nitrogen (N) and sulfur (S) inputs. Passive samplers were used to measure ambient concentrations of ammonia (NH3), nitrogen dioxide (NO2), nitric acid/nitrous acid (HNO3/HONO), and sulfur dioxide (SO2) in the AOSR. Concentrations of NO2 and SO2 in winter were higher than those in summer, while seasonal differences of NH3 and HNO3/HONO showed an opposite trend, with higher values in summer. Concentrations of NH3, NO2 and SO2 were high close to the emission sources (oil sands operations and urban areas). NH3 concentrations were also elevated in the southern portion of the domain indicating possible agricultural and urban emission sources to the southwest. HNO3, an oxidation endpoint, showed wider ranges of concentrations and a larger spatial extent. Concentrations of NH3, NO2, HNO3/HONO and SO2 from passive measurements and their monthly deposition velocities calculated by a multi-layer inference model (MLM) were used to calculate dry deposition of N and S. NH3 contributed the largest fraction of deposited N across the network, ranging between 0.70–1.25kgNha−1yr−1, HNO3/HONO deposition ranged between 0.30–0.90kgNha−1yr−1, and NO2 deposition between 0.03–0.70kgNha−1yr−1. During the modeled period, average dry deposition of the inorganic gaseous N species ranged between 1.03 and 2.85kgNha−1yr−1 and SO4-S deposition ranged between 0.26 and 2.04kgha−1yr−1. Comparisons with co-measured ion exchange resin throughfall data (8.51kgSha−1yr−1) indicate that modeled dry deposition combined with measured wet deposition (1.37kgSha−1yr−1) underestimated S deposition. Gas phase NH3 (71%) and HNO3 plus NO2 (79%) dry deposition fluxes dominated the total deposition of NH4-N and NO3-N, respectively.
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•NH3, HNO3, NO2, and SO2 concentrations were characterized by passive measurements.•Dry deposition fluxes of N and S were estimated by a multi-layer model.•Spatial distributions of N and S dry deposition in the AOSR were determined.
Tree cores and bark were sampled from jack pine trees at 18 sites in the Athabasca Oil Sands Region (AOSR) of Alberta, Canada, to investigate spatial and temporal trends of polycyclic aromatic ...compounds (PACs). Spatial trends were investigated in the bark samples, where ΣPAC concentrations ranged from 75 to 3615 ng/g. Highest concentrations were observed from trees within 40 km of the nearest mining or upgrading facility perimeter fence, in line with previous deposition studies in the AOSR. The sampled tree cores were separated into segments representing 5 years of growth/atmospheric collection by counting tree rings. A significant increase in PAC concentrations over the lifetime of the tree was observed at sites with the highest PAC concentrations, and the average % increase in concentration from 1970 to 2015 was in line with average % growth in bitumen extraction in the AOSR. Finally, the concentrations in the tree core segments representing collection from 2010 to 2015 were converted into an atmospheric PAC concentration using previously published wood-air partition coefficients. The calculated atmospheric concentrations were within the same range as concentrations reported from the passive atmospheric sampling network in this region. The importance of site location is highlighted, with forest edge sites providing an improved comparison for atmospheric exposure and deposition. This is the first study to use tree cores to calculate an atmospheric concentration of PACs, demonstrating the applicability of this methodology for providing historic atmospheric data.
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•Spatial, temporal trends of PACs assessed in tree cores and bark from the Oil Sands•Trends matched previous atmospheric and deposition studies•Atmospheric concentrations were calculated from the tree cores•Calculated and measured atmospheric concentrations were in line•Tree cores can be used as complimentary method for deposition studies
•A method for determining PAHs and PACs in lichens by GC-TOF-MS is described.•GC-TOF mass spectra show possibility for misclassifying C3 and C4 PACs.•Data are compared with other lichen-PAH and ...passive sampling-PAC studies.•Standardization of methodological reporting among investigators is needed.
Development of the Athabasca Oil Sands Region in northeastern Alberta, Canada has contributed polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic compounds (PACs), which include alkyl PAHs and dibenzothiophenes, to the regional environment. A new analytical method was developed for quantification of PAHs and PACs in the epiphytic lichen bioindicator species Hypogymnia physodes for use in the development of receptor models for attribution of PAH and PAC concentrations to anthropogenic and natural emission sources. Milled lichens were extracted with cyclohexane, and extracts were cleaned on silica gel using automated solid phase extraction techniques. Quantitative analysis was performed by gas chromatography with selected ion monitoring (GC-SIM-MS) for PAHs, and by GC with time-of-flight mass spectrometry (GC-TOF-MS) for PACs. PACs were quantitated in groups using representative reference compounds as calibration standards. Analytical detection limits were ≤2.5ngg−1 for all individual compounds. Precision as measured by laboratory duplicates was variable; for individual analytes above 5ngg−1 the mean absolute difference between duplicates was typically <20%. Selection of single-analyte markers for source attribution should include consideration of data quality indicators. Use of TOF-MS to spectrally characterize PAC group constituents identified significant challenges for the accurate quantitation of PACs with more than two carbons in their side chain(s). Total PAH concentrations in lichen samples ranged from 12 to 482ngg−1. Total PACs in each sample varied from a fraction of total PAHs to more than four times total PAHs. Results of our analyses of H. physodes are compared with other studies using other species of lichens as PAH receptors and with passive monitoring data using polyurethane foam (PUF) samplers in the Athabasca Oil Sands Region (AOSR). This study presents the first analytical methodology developed for the determination of PACs in an epiphytic lichen bioindicator species.
Tropospheric ozone (O
3) was first determined to be phytotoxic to grapes in southern California in the 1950s. Investigations followed that showed O
3 to be the cause of foliar symptoms on tobacco and ...eastern white pine. In the 1960s, “X” disease of ponderosa pines within the San Bernardino Mountains was likewise determined to be due to O
3. Nearly 50
years of research have followed. Foliar O
3 symptoms have been verified under controlled chamber conditions. Studies have demonstrated negative growth effects on forest tree seedlings due to season-long O
3 exposures, but due to complex interactions within forest stands, evidence of similar losses within mature tree canopies remains elusive. Investigations on tree growth, O
3 flux, and stand productivity are being conducted along natural O
3 gradients and in open-air exposure systems to better understand O
3 effects on forest ecosystems. Given projected trends in demographics, economic output and climate, O
3 impacts on US forests will continue and are likely to increase.
Elevated tropospheric ozone remains an important phytotoxic air pollutant over large areas of US forests.
Geological samples were collected from 27 representative locations in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada. These samples were resuspended onto filter substrates for PM
2.5
and PM
...10
size fractions. Samples were analyzed for 229 chemical species, consisting of elements, ions, carbon, and organic compounds. These chemical species are normalized to gravimetric mass to derive individual source profiles. Individual profiles were grouped into six categories typical of those used in emission inventories: paved road dust, unpaved road dust close to and distant from oil sand operations, overburden soil, tailings sands, and forest soils. Consistent with their geological origin, the major components are minerals, organic and elemental carbon, and ions. The sum of five major elements (i.e., Al, Si, K, Ca, and Fe) and their oxidized forms account for 25-40% and 45-82% of particulate matter (PM) mass, respectively. Si is the most abundant element, averaging 17-18% in the Facility (oil sand operations) and 23-27% in the Forest profiles. Organic carbon is the second most abundant species, averaging 9-11% in the Facility and 5-6% in the Forest profiles. Elemental carbon abundance is 2-3 times higher in Facility than Forest profiles. Sulfate abundance is ~7 times higher in the Facility than in the Forest profiles. The ratios of cation/anion and base cation (sum of Na
+
, Mg
2+
, K
+
, and Ca
2+
)/nitrogen- and sulfur-containing ions (sum of NH
4
+
, NO
2
-
, NO
3
-
, and SO
4
2-
) exceed unity, indicating that the soils are basic. Lead (Pb) isotope ratios of facility soils are similar to the AOSR stack and diesel emissions, while those of forest soils have much lower
206
Pb/
207
Pb and
208
Pb/
207
Pb ratios. High-molecular-weight n-alkanes (C
25
-C
40
), hopanes, and steranes are more than an order of magnitude more abundant in Facility than Forest profiles. These differences may be useful for separating anthropogenic from natural sources of fugitive dust at receptors.
Implications: Several organic compounds typical of combustion emissions and bitumen are enriched relative to forest soils for fugitive dust sources near oil sands operations, consistent with deposition uptake by biomonitors. AOSR dust samples are alkaline, not acidic, indicating that potential acid deposition is neutralized. Chemical abundances are highly variable within emission inventory categories, implying that more specific subcategories can be defined for inventory speciation.
A 2014 case study investigated the relative accumulation efficiency of polycyclic aromatic hydrocarbons (PAHs), total sulfur (S), total nitrogen (N), major and minor elements and Pb isotopes in five ...common lichen species at three boreal forest sites in the Athabasca Oil Sands Region (AOSR) in northeastern Alberta, Canada to identify the optimum lichen species for future biomonitoring. Differences in concentrations of PAHs, multiple elements, and Pb isotopes in fruticose (Bryoria furcellata, Cladina mitis, Evernia mesomorpha) and foliose (Hypogymnia physodes and Tuckermannopsis americana) lichens were found along a 100 km distance gradient from the primary oil sands operations. Integration of insights from emission source samples and oil sands mineralogy in consort with aerosol collection indicates incorporation of more fine particulate matter (PM) into foliose than fruticose lichen biomass. Contrasting PAH with element concentrations allowed lichen species specific accumulation patterns to be identified. The ability of lichen species to incorporate different amounts of gas phase (S and N), petrogenic (V, Ni, Mo), clay (low Si/Al and more rare earth elements), and sand (higher Si/Al and Ti) components from the oil sand operations reflects aerosol particle size and lichen physiology differences that translate into differences in PM transport distances and lichen accumulation efficiencies. Based on these findings Hypogymnia physodes is recommended for future PAH biomonitoring and source attribution studies.
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•Five lichen species collected from three site transect in Athabasca Oil Sands Region.•Lichen specific concentration gradients in PAHs, S, N, and 32 elements were found.•Different coarse and fine particulate matter multi-element fingerprints identified.•Oil sands mineralogy and Pb isotopes provided particulate matter source insights.•Size dependent incorporation of aerosols in foliose and fruticose lichens documented.
Collocated comparisons for three PM
2.5
monitors were conducted from June 2011 to May 2013 at an air monitoring station in the residential area of Fort McMurray, Alberta, Canada, a city located in ...the Athabasca Oil Sands Region. Extremely cold winters (down to approximately −40°C) coupled with low PM
2.5
concentrations present a challenge for continuous measurements. Both the tapered element oscillating microbalance (TEOM), operated at 40°C (i.e., TEOM
40
), and Synchronized Hybrid Ambient Real-time Particulate (SHARP, a Federal Equivalent Method FEM), were compared with a Partisol PM
2.5
U.S. Federal Reference Method (FRM) sampler. While hourly TEOM
40
PM
2.5
were consistently ~20-50% lower than that of SHARP, no statistically significant differences were found between the 24-hr averages for FRM and SHARP. Orthogonal regression (OR) equations derived from FRM and TEOM
40
were used to adjust the TEOM
40
(i.e., TEOM
adj
) and improve its agreement with FRM, particularly for the cold season. The 12-year-long hourly TEOM
adj
measurements from 1999 to 2011 based on the OR equations between SHARP and TEOM
40
were derived from the 2-year (2011-2013) collocated measurements. The trend analysis combining both TEOM
adj
and SHARP measurements showed a statistically significant decrease in PM
2.5
concentrations with a seasonal slope of −0.15 μg m
−3
yr
−1
from 1999 to 2014.Implications: Consistency in PM
2.5
measurements are needed for trend analysis. Collocated comparison among the three PM
2.5
monitors demonstrated the difference between FRM and TEOM, as well as between SHARP and TEOM. The orthogonal regressions equations can be applied to correct historical TEOM data to examine long-term trends within the network.
Real-world fuel-based emission factors （EFs） from Caterpillar 797B diesel heavy haulers when used for oil sands mining operations were measured using an on-hoard portable emissions monitoring system. ...Average EFs （in g/kg fuel） for 16 separate tests on four trucks were 3150 ± 4 for CO2, 2.51 ± 1.30 for CH4, 10.28 ± 3.21 for CO, 0.61 ± 0.32 for non-methane hydrocarbons, 55.49 ± 9,75 for NOx （reported as NO2）, 0.70 ± 0.17 for PM2.s （mass of particles with aerodynamic diameter 〈2.5 μm）, and 0.34 ± 0.05 for black carbon （BC）. Ultrafine particle numbers averaged （4.7 ± 4.1 ） × 10^15 particleslkg fuel. Fuel-based EFs of NO, NO2, and particle numbers were higher during idling, whereas PM2.5 and BC EFs were higher during traveling without a load. A comparison of emissions with those reported by oil sands facilities showed large variations, both among the facilities and between the reported emissions and the real-world measurements.
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