Worldwide heavy oil and bitumen deposits amount to 9 trillion barrels of oil distributed in over 280 basins around the world, with Canada home to oil sands deposits of 1.7 trillion barrels. The ...global development of this resource and the increase in oil production from oil sands has caused environmental concerns over the presence of toxic compounds in nearby ecosystems and acid deposition. The contribution of oil sands exploration to secondary organic aerosol formation, an important component of atmospheric particulate matter that affects air quality and climate, remains poorly understood. Here we use data from airborne measurements over the Canadian oil sands, laboratory experiments and a box-model study to provide a quantitative assessment of the magnitude of secondary organic aerosol production from oil sands emissions. We find that the evaporation and atmospheric oxidation of low-volatility organic vapours from the mined oil sands material is directly responsible for the majority of the observed secondary organic aerosol mass. The resultant production rates of 45-84 tonnes per day make the oil sands one of the largest sources of anthropogenic secondary organic aerosols in North America. Heavy oil and bitumen account for over ten per cent of global oil production today, and this figure continues to grow. Our findings suggest that the production of the more viscous crude oils could be a large source of secondary organic aerosols in many production and refining regions worldwide, and that such production should be considered when assessing the environmental impacts of current and planned bitumen and heavy oil extraction projects globally.
The nocturnal nitrogen oxides, which include the nitrate radical (NO.sub.3 ), dinitrogen pentoxide (N.sub.2 O.sub.5 ), and its uptake product on chloride containing aerosol, nitryl chloride ...(ClNO.sub.2 ), can have profound impacts on the lifetime of NO.sub.x ( = NO + NO.sub.2 ), radical budgets, and next-day photochemical ozone (O.sub.3) production, yet their abundances and chemistry are only sparsely constrained by ambient air measurements.
The oil sands industry in Alberta, Canada, represents a large anthropogenic
source of secondary organic aerosol (SOA). Atmospheric emissions from oil
sands operations are a complex mixture of gaseous ...and particulate
pollutants. Their interaction can affect the formation and characteristics
of SOA during plume dispersion, but their chemical evolution remains poorly
understood. Oxidative processing of organic vapours in the presence of
NOx can lead to particulate organo-nitrate (pON) formation, with
important impacts on the SOA budgets, the nitrogen cycle and human health.
We provide the first direct field evidence, from ground- and aircraft-based
real-time aerosol mass spectrometry, that anthropogenic pON contributed up
to half of SOA mass that was freshly produced within the emission plumes of
oil sands facilities. Using a top-down emission-rate retrieval algorithm
constrained by aircraft measurements, we estimate the production rate of pON
in the oil sands region to be ∼15.5 t d−1. We
demonstrate that pON formation occurs via photo-oxidation of
intermediate-volatility organic compounds (IVOCs) in high-NOx
environments, providing observational constraints to improve current SOA
modelling frameworks. Our ambient observations are supported by laboratory
photo-oxidation experiments of IVOCs from bitumen vapours under high-NOx
conditions, which demonstrate that pON can account for 30 %–55 % of the
observed SOA mass depending on the degree of photochemical ageing. The large
contribution of pON to freshly formed anthropogenic SOA illustrates the
central role of pON in SOA production from the oil and gas industry, with
relevance for other urban and industrial regions with significant
anthropogenic IVOC and NOx emissions.
Concentrations andδ34S values for SO2 and size-segregated sulfate aerosols were determined for air monitoring station 13 (AMS 13) at Fort MacKay in the Athabasca oil sands region, northeastern ...Alberta, Canada as part of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring (JOSM) campaign from 13 August to 5 September 2013. Sulfate aerosols and SO2 were collected on filters using a high-volume sampler, with 12 or 24 h time intervals.Sulfur dioxide (SO2) enriched in 34S was exhausted by a chemical ionization mass spectrometer (CIMS) operated at the measurement site and affected isotope samples for a portion of the sampling period. It was realized that this could be a useful tracer and samples collected were divided into two sets. The first set includes periods when the CIMS was not running (CIMS-OFF) and no 34SO2 was emitted. The second set is for periods when the CIMS was running (CIMS-ON) and 34SO2 was expected to affect SO2 and sulfate high-volume filter samples.δ34S values for sulfate aerosols with diameter D>0.49 µm during CIMS-OFF periods (no tracer 34SO2 present) indicate the sulfur isotope characteristics of secondary sulfate in the region. Such aerosols had δ34S values that were isotopically lighter (down to-5.3 ‰) than what was expected according to potential sulfur sources in the Athabasca oil sands region (+3.9 to +11.5 ‰). Lighter δ34S values for larger aerosol size fractions are contrary to expectations for primary unrefined sulfur from untreated oil sands (+6.4 ‰) mixed with secondary sulfate from SO2 oxidation and accompanied by isotope fractionation in gas phase reactions with OH or the aqueous phase by H2O2 or O3. Furthermore, analysis of34S enhancements of sulfate and SO2 during CIMS-ON periods indicated rapid oxidation of SO2 from this local source at ground level on the surface of aerosols before reaching the high-volume sampler or on the collected aerosols on the filters in the high-volume sampler. Anti-correlations between δ34S values of dominantly secondary sulfate aerosols with D<0.49 µm and the concentrations of Fe and Mn (r = -0.80 and r = -0.76, respectively) were observed, suggesting that SO2 was oxidized by a transition metal ion (TMI) catalyzed pathway involving O2 and Fe3+ and/orMn2+, an oxidation pathway known to favor lighter sulfur isotopes.Correlations between SO2 to sulfate conversion ratio (F(s)) and the concentrations of α-pinene (r = 0.85), β-pinene (r = 0.87), and limonene (r = 0.82) during daytime suggests thatSO2 oxidation by Criegee biradicals may be a potential oxidation pathway in the study region.
Volatile organic compounds were quantified during two aircraft-based field campaigns using highly automated, whole air samplers with expedited post-flight analysis via a new custom-built, ...field-deployable gas chromatography–mass spectrometry instrument. During flight, air samples were pressurized with a stainless steel bellows compressor into electropolished stainless steel canisters. The air samples were analyzed using a novel gas chromatograph system designed specifically for field use which eliminates the need for liquid nitrogen. Instead, a Stirling cooler is used for cryogenic sample pre-concentration at temperatures as low as −165 °C. The analysis system was fully automated on a 20 min cycle to allow for unattended processing of an entire flight of 72 sample canisters within 30 h, thereby reducing typical sample residence times in the canisters to less than 3 days. The new analytical system is capable of quantifying a wide suite of C2 to C10 organic compounds at part-per-trillion sensitivity. This paper describes the sampling and analysis systems, along with the data analysis procedures which include a new peak-fitting software package for rapid chromatographic data reduction. Instrument sensitivities, uncertainties and system artifacts are presented for 35 trace gas species in canister samples. Comparisons of reported mixing ratios from each field campaign with measurements from other instruments are also presented.
Mixing ratios of the criteria air contaminant nitrogen dioxide (NO
2
) are commonly quantified by reduction to nitric oxide (NO) using a photolytic converter followed by NO-O
3
chemiluminescence ...(CL). In this work, the performance of a photolytic NO
2
converter prototype originally designed for continuous emission monitoring and emitting light at 395 nm was evaluated. Mixing ratios of NO
2
and NO
x
(= NO + NO
2
) entering and exiting the converter were monitored by blue diode laser cavity ring-down spectroscopy (CRDS). The NO
2
photolysis frequency was determined by measuring the rate of conversion to NO as a function of converter residence time and found to be 4.2 s
−1
. A maximum 96% conversion of NO
2
to NO over a large dynamic range was achieved at a residence time of (1.5 ± 0.3) s, independent of relative humidity. Interferences from odd nitrogen (NO
y
) species such as peroxyacyl nitrates (PAN; RC(O)O
2
NO
2
), alkyl nitrates (AN; RONO
2
), nitrous acid (HONO), and nitric acid (HNO
3
) were evaluated by operating the prototype converter outside its optimum operating range (i.e., at higher pressure and longer residence time) for easier quantification of interferences. Four mechanisms that generate artifacts and interferences were identified as follows: direct photolysis, foremost of HONO at a rate constant of 6% that of NO
2
; thermal decomposition, primarily of PAN; surface promoted photochemistry; and secondary chemistry in the connecting tubing. These interferences are likely present to a certain degree in all photolytic converters currently in use but are rarely evaluated or reported. Recommendations for improved performance of photolytic converters include operating at lower cell pressure and higher flow rates, thermal management that ideally results in a match of photolysis cell temperature with ambient conditions, and minimization of connecting tubing length. When properly implemented, these interferences can be made negligibly small when measuring NO
2
in ambient air.
Implications: A new near-UV photolytic converter for measurement of the criteria pollutant nitrogen dioxide (NO
2
) in ambient air by CL was characterized. Four mechanisms that generate interferences were identified and investigated experimentally: direct photolysis of HONO which occurred at a rate constant 6% that of NO
2
, thermal decomposition of PAN and N
2
O
5
, surface promoted chemistry involving HNO
3
, and secondary chemistry involving NO in the tubing connecting the converter and CL analyzer. These interferences are predicted to occur in all NO
2
P-CL systems but can be avoided by appropriate thermal management and operating at high flow rates.
Concentrations and
δ34S values for SO2 and size-segregated sulfate aerosols were determined for air monitoring station
13 (AMS 13) at Fort MacKay in the Athabasca oil sands region, northeastern
...Alberta, Canada as part of the Joint Canada-Alberta Implementation Plan for
Oil Sands Monitoring (JOSM) campaign from 13 August to 5 September 2013.
Sulfate aerosols and SO2 were collected on filters using a
high-volume sampler, with 12 or 24 h time intervals. Sulfur dioxide (SO2) enriched in 34S was exhausted by a chemical
ionization mass spectrometer (CIMS) operated at the measurement site and
affected isotope samples for a portion of the sampling period. It was
realized that this could be a useful tracer and samples collected were
divided into two sets. The first set includes periods when the CIMS was not
running (CIMS-OFF) and no 34SO2 was emitted. The second set is for
periods when the CIMS was running (CIMS-ON) and 34SO2 was expected
to affect SO2 and sulfate high-volume filter samples. δ34S values for sulfate aerosols with diameter D>0.49 µm
during CIMS-OFF periods (no tracer 34SO2 present) indicate the
sulfur isotope characteristics of secondary sulfate in the region. Such
aerosols had δ34S values that were isotopically lighter (down to
−5.3 ‰) than what was expected according to potential sulfur
sources in the Athabasca oil sands region (+3.9 to +11.5 ‰).
Lighter δ34S values for larger aerosol size fractions are contrary
to expectations for primary unrefined sulfur from untreated oil sands
(+6.4 ‰) mixed with secondary sulfate from SO2 oxidation
and accompanied by isotope fractionation in gas phase reactions with OH or
the aqueous phase by H2O2 or O3. Furthermore, analysis of
34S enhancements of sulfate and SO2 during CIMS-ON periods
indicated rapid oxidation of SO2 from this local source at ground
level on the surface of aerosols before reaching the high-volume sampler or
on the collected aerosols on the filters in the high-volume sampler.
Anti-correlations between δ34S values of dominantly secondary
sulfate aerosols with D< 0.49 µm and the concentrations of Fe
and Mn (r = −0.80 and r = −0.76, respectively) were observed,
suggesting that SO2 was oxidized by a transition metal ion (TMI)
catalyzed pathway involving O2 and Fe3+ and/or
Mn2+, an oxidation pathway known to favor lighter sulfur isotopes. Correlations between SO2 to sulfate conversion ratio (F(s)) and the
concentrations of α-pinene (r = 0.85), β-pinene
(r = 0.87), and limonene (r = 0.82) during daytime suggests that
SO2 oxidation by Criegee biradicals may be a potential oxidation
pathway in the study region.
In this paper, measurements of C9 – C16 biogenic volatile organic compounds (BVOCs) in the headspaces above near-shore marine vegetation samples of Fucus gardneri (rock weed), Ulva spp. (sea ...lettuce), Callophyllis spp. (red sea fans), Alaria marginata (winged kelp), and Nereocystis luetkeana (bull kelp) collected on the west coast of Vancouver Island, British Columbia, Canada, are presented. Numerous BVOCs were observed in the headspace samples, including n-alkanes (e.g., n-dodecane, n-tridecane, n-tetradecane and n-pentadecane) and oxygenated hydrocarbons (e.g., octanal, nonanal, geranyl acetone, and 6-methyl-hepten-2-one), though the majority of VOCs emitted was not identified. The emissions from Ulva spp., Callophyllis spp. and F. gardneri samples contained a similar assortment of n-alkanes and oxygenated BVOCs (e.g., n-aldehydes) as observed at Mace Head, Ireland, whereas the headspaces above N. luetkeana and A. marginata contained monoterpenes, foremost limonene, and toluene. Further studies are needed to constrain emissions of BVOCs from near-coastal vegetation as they have the potential to substantially impact coastal O3 budgets and the organic content of marine derived aerosol. Keywords: BVOC emissions, Kelp, Seaweed, Monoterpenes, Limonene, Hydrocarbons
Concentrations and delta.sup.34 S values for SO.sub.2 and size-segregated sulfate aerosols were determined for air monitoring station 13 (AMS 13) at Fort MacKay in the Athabasca oil sands region, ...northeastern Alberta, Canada as part of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring (JOSM) campaign from 13 August to 5 September 2013. Sulfate aerosols and SO.sub.2 were collected on filters using a high-volume sampler, with 12 or 24 h time intervals. Sulfur dioxide (SO.sub.2) enriched in .sup.34 S was exhausted by a chemical ionization mass spectrometer (CIMS) operated at the measurement site and affected isotope samples for a portion of the sampling period. It was realized that this could be a useful tracer and samples collected were divided into two sets. The first set includes periods when the CIMS was not running (CIMS-OFF) and no .sup.34 SO.sub.2 was emitted. The second set is for periods when the CIMS was running (CIMS-ON) and .sup.34 SO.sub.2 was expected to affect SO.sub.2 and sulfate high-volume filter samples. delta.sup.34 S values for sulfate aerosols with diameter D > 0.49 µm during CIMS-OFF periods (no tracer .sup.34 SO.sub.2 present) indicate the sulfur isotope characteristics of secondary sulfate in the region. Such aerosols had delta.sup.34 S values that were isotopically lighter (down to -5.3 0/00) than what was expected according to potential sulfur sources in the Athabasca oil sands region (+3.9 to +11.5 0/00). Lighter delta.sup.34 S values for larger aerosol size fractions are contrary to expectations for primary unrefined sulfur from untreated oil sands (+6.4 0/00) mixed with secondary sulfate from SO.sub.2 oxidation and accompanied by isotope fractionation in gas phase reactions with OH or the aqueous phase by H.sub.2 O.sub.2 or O.sub.3 . Furthermore, analysis of .sup.34 S enhancements of sulfate and SO.sub.2 during CIMS-ON periods indicated rapid oxidation of SO.sub.2 from this local source at ground level on the surface of aerosols before reaching the high-volume sampler or on the collected aerosols on the filters in the high-volume sampler. Anti-correlations between delta.sup.34 S values of dominantly secondary sulfate aerosols with D < 0.49 µm and the concentrations of Fe and Mn (r = -0.80 and r = -0.76, respectively) were observed, suggesting that SO.sub.2 was oxidized by a transition metal ion (TMI) catalyzed pathway involving O.sub.2 and Fe.sup.3+ and/or Mn.sup.2+, an oxidation pathway known to favor lighter sulfur isotopes. Correlations between SO.sub.2 to sulfate conversion ratio (F(s)) and the concentrations of α-pinene (r = 0.85), β-pinene (r = 0.87), and limonene (r = 0.82) during daytime suggests that SO.sub.2 oxidation by Criegee biradicals may be a potential oxidation pathway in the study region.
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