Critical loads of acidity for 90,000 lakes in northern Saskatchewan: A novel approach for mapping regional sensitivity to acidic deposition

Cathcart, Hazel; Aherne, Julian; Jeffries, D. S.; Scott, Kenneth A.

doi:10.1016/j.atmosenv.2016.08.048

Cited by 21 publications

(20 citation statements)

References 35 publications

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“…The impact of weak acidity downwind of the oil sands specifically is not clear. Critical load exceedances for highly sensitive aquatic systems in northern Alberta have mainly been assessed from the perspective of sulfur and nitrogen (Cathcart et al, 2016;Whitfield et al, 2016). While the impact of the large amount of weak organic acidity formed downwind of the oil sands has not been evaluated, it may have a relevant impact on ecosystem acidification in highly sensitive systems that are approaching their respective sulfur and/or nitrogen critical loads.…”

Section: J Liggio Et Al: Gaseous Organic Acids In the Oil Sands Regmentioning

confidence: 99%

Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

et al. 2017

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Abstract. Organic acids are known to be emitted from combustion processes and are key photochemical products of biogenic and anthropogenic precursors. Despite their multiple environmental impacts, such as on acid deposition and human-ecosystem health, little is known regarding their emission magnitudes or detailed chemical formation mechanisms. In the current work, airborne measurements of 18 gas-phase low-molecular-weight organic acids were made in the summer of 2013 over the oil sands region of Alberta, Canada, an area of intense unconventional oil extraction. The data from these measurements were used in conjunction with emission retrieval algorithms to derive the total and speciated primary organic acid emission rates, as well as secondary formation rates downwind of oil sands operations. The results of the analysis indicate that approximately 12 t day −1 of low-molecular-weight organic acids, dominated by C 1 -C 5 acids, were emitted directly from off-road diesel vehicles within open pit mines. Although there are no specific reporting requirements for primary organic acids, the measured emissions were similar in magnitude to primary oxygenated hydrocarbon emissions, for which there are reporting thresholds, measured previously (≈ 20 t day −1 ). Conversely, photochemical production of gaseous organic acids significantly exceeded the primary sources, with formation rates of up to ≈ 184 t day −1 downwind of the oil sands facilities. The formation and evolution of organic acids from a Lagrangian flight were modelled with a box model, incorporating a detailed hydrocarbon reaction mechanism extracted from the Master Chemical Mechanism (v3.3). Despite evidence of significant secondary organic acid formation, the explicit chemical box model largely underestimated their formation in the oil sands plumes, accounting for 39, 46, 26, and 23 % of the measured formic, acetic, acrylic, and propionic acids respectively and with little contributions from biogenic VOC precursors. The model results, together with an examination of the carbon mass balance between the organic acids formed and the primary VOCs emitted from oil sands operations, suggest the existence of significant missing secondary sources and precursor emissions related to oil sands and/or an incomplete mechanistic and quantitative understanding of how they are processed in the atmosphere.

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Section: J Liggio Et Al: Gaseous Organic Acids In the Oil Sands Regmentioning

confidence: 99%

Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

et al. 2017

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“…We define first the equations used for determining critical 5 loads, and follow with the description of the data used to estimate critical loads of acidifying sulphur (S) and nitrogen (N) for terrestrial and aquatic ecosystems in Alberta and Saskatchewan, based on a Canada-wide implementation (Carou et al., 2008), and two more recent studies focused on terrestrial ecosystems in the province of Alberta,and aquatic ecosystems in northern Alberta and Saskatchewan (Cathcart et al, 2016).…”

Section: Critical Loads and Critical Load Exceedances -Definitionsmentioning

confidence: 99%

“…A regression kriging approach was used to generate (predict) water chemistry for 137,587 lake catchments following Cathcart et al (2016). Regression kriging is a spatial interpolation method wherein a regression of the target variable on covariate variables (e.g., landscape characteristics such as soil, climates, 10 vegetation; a total of 185 covariates were included) is combined with kriging on the regression residuals (Hengl et al, 2007;Hengl, 2009).…”

Section: Northern Alberta and Saskatchewan: Critical Loads Of Aciditymentioning

confidence: 99%

“…We begin with Canada-wide critical loads of acidity, which employ modifications to the above UNECE methodology (CLRTAP, 2004), used in eastern North America (NEG-ECP, 2001, Ouimet, 2005, and then expanded across Canada (Carou et al, 2008;Jeffries et al, 2010;Aherne, 2013). We follow with more recent estimated determined using the UNECE protocols, for terrestrial ecosystems for the province of 5 Alberta (Aklilu,201x), and aquatic ecosystems in northern Alberta and Saskatchewan (Cathcart et al, 2016).…”

mentioning

confidence: 99%

“…(CLRTAP, 2016); further details regarding the sensitivity of the critical load estimates to these functions 15 are described in Cathcart et al (2016).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Estimates of Exceedances of Critical Loads for Acidifying Deposition in Alberta and Saskatchewan

Makar¹,

Akingunola²,

Aherne³

et al. 2018

Preprint

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Abstract.Estimates of potential harmful effects to ecosystems in the Canadian provinces of Alberta and Saskatchewan due to acidifying deposition were calculated, using a one year simulation of a high resolution implementation of the Global Environmental Multiscale -Modelling Air-quality and Chemistry (GEM-MACH) model, and estimates of aquatic and terrestrial ecosystem critical loads. The model simulation was evaluated against two different sources of deposition data; 20 total deposition in precipitation and total deposition to snowpack in the vicinity of the Athabasca oil sands. The model captured much of the variability of observed ions in wet deposition in precipitation (observed versus model sulphur, nitrogen and base cation R 2 values of 0.90, 0.76 and 0.72, respectively), while being biased high for sulphur deposition, and low for nitrogen and base cations (slopes 2.2, 0.89 and 0.40, respectively). Aircraft-observation-based estimates of fugitive dust emissions, shown to be a factor of ten higher than reported values (Zhang et al.., 2017), were used to estimate the impact of 25 increased levels of fugitive dust on model results. Model comparisons to open snowpack observations were shown to be biased high, but in reasonable agreement for sulphur deposition when observations were corrected to account for throughfall in needleleaf forests. The model-observation relationships for precipitation deposition data, along with the expected effects of increased (unreported) base cation emissions, were used to provide a simple observation-based correction to model deposition fields. Base cation deposition was estimated using published observations of base cation fractions in surface 30 collected particles .Both original and observation-corrected model estimates of sulphur, nitrogen and base cation deposition were used in conjunction with critical load data created using the NEG-ECP (2001) and CLRTAP (2004, 2016, 2017) Base cation deposition was shown to have a neutralizing effect on acidifying deposition, and the use of the aircraft and precipitation observation-based corrections to base cation deposition resulted in reasonable agreement with snowpack data collected in the oil sands area. However, critical load exceedances calculated using both observations and observationcorrected deposition suggest that the neutralization effect is limited in spatial extent, decreasing rapidly with distance from 10 emissions sources, due to the rapid deposition of emitted primary particles dust particles as a function of their size.

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A critical review of the ecological status of lakes and rivers from Canada's oil sands region

Arciszewski

Hazewinkel

Dubé

2021

Integr Envir Assess & Manag

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We synthesize the information available from the peer‐reviewed literature on the ecological status of lakes and rivers in the oil sands region (OSR) of Canada. The majority of the research from the OSR has been performed in or near the minable region and examines the concentrations, flux, or enrichment of contaminants of concern (CoCs). Proximity to oil sands facilities and the beginning of commercial activities tend to be associated with greater estimates of CoCs across studies. Research suggests the higher measurements of CoCs are typically associated with wind‐blown dust, but other sources also contribute. Exploratory analyses further suggest relationships with facility production and fuel use data. Exceedances of environmental quality guidelines for CoCs are also reported in lake sediments, but there are no indications of toxicity including those within the areas of the greatest atmospheric deposition. Instead, primary production has increased in most lakes over time. Spatial differences are observed in streams, but causal relationships with industrial activity are often confounded by substantial natural influences. Despite this, there may be signals associated with site preparation for new mines, potential persistent differences, and a potential effect of petroleum coke used as fuel on some indices of health in fish captured in the Steepbank River. There is also evidence of improvements in the ecological condition of some rivers. Despite the volume of material available, much of the work remains temporally, spatially, or technically isolated. Overcoming the isolation of studies would enhance the utility of information available for the region, but additional recommendations for improving monitoring can be made, such as a shift to site‐specific analyses in streams and further use of industry‐reported data. Integr Environ Assess Manag 2022;18:361–387. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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Critical loads of acidity for 90,000 lakes in northern Saskatchewan: A novel approach for mapping regional sensitivity to acidic deposition

Cited by 21 publications

References 35 publications

Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

Understanding the primary emissions and secondary formation of gaseous organic acids in the oil sands region of Alberta, Canada

Estimates of Exceedances of Critical Loads for Acidifying Deposition in Alberta and Saskatchewan

A critical review of the ecological status of lakes and rivers from Canada's oil sands region

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