Long-term air concentrations, wet deposition, and scavenging ratios of inorganic ions, HNO3 and SO2 and assessment of aerosol and precipitation acidity at Canadian rural locations (original) (raw)

Long-term air concentrations, wet deposition, and scavenging ratios of inorganic ions, HNO3 and SO2 and assessment of aerosol and precipitation acidity at Canadian rural locations

Atmospheric Chemistry and Physics Discussions

This study analyzed long-term air concentrations and annual wet deposition of inorganic ions and aerosol and precipitation acidity at 30 Canadian sites from 1983–2011. Scavenging ratios of inorganic ions and relative contributions of particulate- and gas-phase species to NH4+, NO3−, and SO42− wet deposition were determined. Long-term median atmospheric NH4+, NO3−, and SO42− between sites ranged from 0.1–1.7, 0.03–2.0, and 0.6–3.5 μg m−3, respectively. Their median annual wet deposition varied from 0.2–5.8, 0.8–23.3, and 0.8–26.6 kg ha−1 a−...

Supplementary material to "Long-term Atmospheric Deposition of Nitrogen and Sulfur and Assessment of Critical Loads Exceedances at Canadian Rural Locations

S1 Daily average dry deposition velocities (Vd) of N and S species S1.1 Spatial patterns Daily average Vd for gas-phase compounds (SO2, HNO3) and particulate-phase compounds (pSO4 2-, pNH4 + and pNO3-) for the 2000-2018 period are summarized in Table S2. For gaseous compounds, the mean daily Vd (cm/s) among 15 CAPMoN sites were 1.2 for HNO3 and 0.46 for SO2. For particulate sulfate (pSO4 2-), ammonium (pNH4 +) and nitrate (pNO3-), the mean daily Vd were 0.16, 0.15 and 0.21 cm/s, respectively. Vd of N and S compounds exhibited strong variability between sites. The regions with higher Vd for N and S compounds include the west coast, southeast and Atlantic (Table S2). According to the land use data surrounding a CAPMoN site (Table S1), the west coast and Atlantic sites have higher Vd likely because of nearby land use coverage that is associated with higher Vd. For example, water surfaces and forests. In particular, evergreen needleleaf or broadleaf trees are typically associated with larger leaf area index (LAI) and hence larger Vd. Meteorological conditions also differ substantially across Canadian sites, which can drive the spatial variability in Vd. S1.2 Cold vs. warm seasonal patterns Vd of gaseous N and S compounds were slightly greater in the warm season than cold season at most of the sites based on the monthly variations in Fig. S1. This was also the case for particulate nitrate due to the higher fraction of nitrate in coarse PM during the warm season, which is based on size-fractionated measurements previously conducted at CAPMoN sites (Zhang et al., 2008). Given that Vd of coarse PM (PM2.5-10) is larger than that of fine PM (PM2.5), a higher fraction in coarse PM results in higher Vd. During the cold season, nitrate is predominantly associated with fine PM at CAPMoN sites (Zhang et al., 2008). Vd of sulfate and ammonium were slightly higher in the cold season than warm season. This pattern is likely attributed to meteorology perhaps higher wind speeds in the cold season. S1.3 Long-term annual trends Long-term annual trends in Vd were estimated using Theil-Sen slopes of the seasonal average Vd, which have been seasonally adjusted using LOESS (locally estimated scatterplot smoothing). Statistically significant trends in Vd (p<0.05) are shown in Fig. S2. Among the sites, annual trends in Vd (cm/s of change per year) ranged from 2.

TB118: Composition of Precipitation at the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) Site in Greenville, Maine

1986

There has been a great deal of attention focused on the issue of "acid rain" 1n the last 10 to 15 years with regard to the possible effects that atmospherically derived chemicals may have on lakes, streams, crops, forests, and materials. The term "acid rain" 1s derived from the occurrence of sulfuric (H2SO4) and nitric (HNO3) acids 1n all forms of precipitation as a result of emissions of sulfur (S) and nitrogen (N), largely from man's activities. Add precipitation 1s only one component of our modern chemical climate which results 1n the deposition of adds 1n precipitation as well as base cations (e.g. calcium, magnesium, potassium, sodium), anions (e.g. phosphate, chloride, fluoride), trace metals (e.g. lead, copper, nickel, zinc, cadmium), photochemical oxidants (e.g. ozone) and organic compounds (e.g. hydrocarbons). Relatively poor Information exists for the levels of most of these materials 1n deposition for rural areas across the nation with the exception of the monitoring of major cations and anions 1n precipitation carried out by the National Atmospheric Deposition Program (NADP). Currently the NADP has the most extensive network for monitoring atmospheric deposition 1n the United States. This Federal/State program 1s carried out through the Cooperative State Research Service (U.S. Department of Agriculture) and involves a large number of Federal, State, University, and industry participants. The monitoring activity 1s highly organized with respect to siting and operational criteria for sampling sites, analytical methodology, and data handling and storage. The NADP was created 1n 1978 as Regional Project NC-141

Network comparability and the reconstruction of a precipitation chemistry record at a monitoring site in the eastern United States

Atmospheric Environment, 2003

Prior comparability studies of precipitation chemistry networks in eastern North America have reported that data derived from daily sampling are preferred over those obtained from weekly integrated sampling. However, the record of daily wet-only precipitation chemistry in the United States was interrupted for more than 3 years (from 5 January 1990 to 26 December 1993), precluding the generation of a single, continuous record since the start of operations in September 1976. A first attempt was made to reconstruct the record during the intervening (“gap”) years at a site in central Pennsylvania, where the Canadian Air and Precipitation Monitoring Network (CAPMoN) collocated daily sampling operations beginning in 1987. First, data from the original daily wet deposition monitoring program (the Multistate Atmospheric Power Production Pollution Study (MAP3S)) and from the most recent program (the Atmospheric Integrated Research Monitoring Network (AIRMoN)) were separately compared with the CAPMoN data. The internetwork biases so obtained were then merged and used to adjust the uninterrupted, overlapping CAPMoN data, thus enabling us to combine the different data sets and reconstruct the whole record for the major ions (SO42−, NO3−, NH4+, and H3O+). The between-network differences derived from the paired daily data (US datum–CAPMoN datum) show statistically significant negative biases (MAP3S, AIRMoN<CAPMoN) of about 0.5 mm for rain gage depth and 4–5 μeq l−1 for the concentrations of SO42− and NO3−. The relative precision obtained for [SO42−] and [NO3−] ranged from 9% to 13%, which is similar to the findings of previous weekly based intercomparison studies. The reconstructed record (1988–2000) reveals the highest daily concentrations for all major ions for 1991, followed by a consistent decrease over the following 6 years.

Meteorological influences on the spatial and temporal variability of NO₂in Toronto and Hamilton

Canadian Geographer, 2009

canadienne des géographes 166 M. Altaf Arain et al. emissions mean that the degree of spatial variability in NO 2 concentrations changes from season to season. This study will help to improve existing land-use regression-based NO 2 prediction models by incorporating meteorological controls on NO 2 distributions for health effect studies. Key words: nitrogen dioxide, urban air quality, air pollution, health effects, meteorology, lake breeze autoroutes, des agglomérations et des zones industrielles sont exposésà des concentrations pluś elevées de polluants. Les tendances saisonnières en matière de concentrations en NO 2 témoignent d'une hétérogénéité spatiale significative, particulièrement dans le cas de Toronto. Les vents du large protègent les habitants de la côte qui autrement seraient exposésà des niveauxélevés de NO 2. Les variations saisonnières des paramètres météorologiques et deś emissions ont pour conséquence que la variabilité spatiale des concentrations en NO 2 varie d'une saisoǹ a l'autre. Cetteétude est une contributionà l'amélioration de la capacité de prédire les niveaux de NO 2 sur la base de modèles de régression de l'occupation du sol, avec l'introduction dans leś etudes d'impact sur la santé de variables contrôles qui prennent en compte les effets météorologiques sur la distribution du NO 2. Mots clés: dioxyde d'azote, qualité de l'air urbain, pollution de l'air, impacts sur la santé, météorologie, brise de lac

Measurements of reactive oxidized nitrogen at eight Canadian rural sites

Atmospheric Environment, 2008

The partitioning of reactive oxidized nitrogen (NO y ) across eastern Canada was studied through the measurements of total NO y and the major individual species comprising NO y (NO, NO 2 , PAN, PPN, HNO 3 , and particle-NO 3 À ) during 14 short-term (18-50 days) field campaigns at eight selected rural sites from 2001 to 2005. Significant differences were found between populated and remote regions in the budget and partitioning of NO y and in their seasonal and diurnal variations. Median NO y mixing ratios were higher than 5 ppbv at rural sites located in populated regions and lower than 1 ppbv at remote locations. NO y mixing ratios were 30-40% higher during the cold seasons compared to the warm and hot seasons at all locations. Seasonal variations of NO x were much larger than NO y in populated regions, although their seasonal variations were of a similar magnitude at remote locations. On average, NO x contributed 50-80% to total NO y during the cold seasons and 30-60% during the warm and hot seasons; PAN, HNO 3 and NO 3 À also contributed an appreciable amount (each up to 19%) to total NO y . PPN mixing ratios were 10-15% of PAN during the warm and hot seasons and were 15-25% during the cold seasons. The NO y deficit was found to be 15-42%, depending on location, during the warm and hot season. The NO y deficit was generally smaller than 10% during the cold season, although a 25% deficit was also observed during one cold-season campaign. The maximum NO y deficit seemed to appear in early spring instead of mid-summer at locations where nearby sources had little impact. Crown

Long-term declines in atmospheric nitrogen and sulfur deposition reduce critical loads exceedances at multiple Canadian rural sites, 2000–2018

Atmospheric Chemistry and Physics, 2022

Daily air concentrations of inorganic nitrogen (N) species, including gaseous HNO 3 and particulatebound (p)NH + 4 and pNO − 3 , and sulfur (S) species, including SO 2 and pSO 2− 4 , and precipitation concentrations of NO − 3 , NH + 4 , and SO 2− 4 , have been routinely monitored by the Canadian Air and Precipitation Monitoring Network (CAPMoN) since 1983. Data at 15 rural sites from 2000-2018 were used to estimate dry and wet N and S deposition fluxes, which were then used to explore their spatiotemporal trends and assess ecosystem damage through a retrospective analysis of critical loads (CLs) exceedances. Total (dry + wet) N deposition ranged from 1.7-9.5 kg N ha −1 yr −1 among the 15 sites, though dry deposition of NH 3 and some oxidized N species were not included due to lack of monitoring data. Based on additional N measurements in 2010 at one of the sites, annual total N deposition may be underestimated by up to 32 %. Total N deposition was dominated by wet NO − 3 and wet NH + 4 deposition, which together comprised 71 %-95 %. Contributions to dry N deposition were 40 %-74 % by HNO 3 , 11 %-40 % by pNH + 4 , and 5 %-25 % by pNO − 3. Total S deposition ranged from 1.3-8.5 kg S ha −1 yr −1 and was dominated by wet deposition of SO 2− 4 and dry deposition of SO 2. Relative percentages of wet and dry S deposition were 45 %-89 % and 11 %-55 %, respectively. Acidic ion fluxes were greatest in southeastern Canada and were comparable among the west coast, prairie, remote, and eastern Canadian sites. Oxidized N (dry HNO 3 , dry pNO − 3 , wet NO − 3) deposition was greater than that of reduced N (dry pNH + 4 , wet NH + 4) in the early 2000s. In 2014-2018, reduced N deposition surpassed that of oxidized N in southeastern Canada. Total N and S deposition decreased significantly at a rate of −0.03 to −0.25 kg N ha −1 yr −1 (−1.1 % yr −1 to −3.3 % yr −1) and −0.08 to −0.66 kg S ha −1 yr −1 (−3.5 % yr −1 to −6.6 % yr −1), respectively, among the sites. The weak declining trend in total N deposition at the west coast site was consistent with the slower decline in NO x emissions in western Canada. Reductions in total N deposition were driven by its oxidized form as trends in reduced N were non-significant. As a result, reduced N contributions to total N deposition increased on average from 42 % in 2000-2004 to 53 % in 2014-2018. Anthropogenic NO x and SO 2 emissions reductions in both eastern Canada and eastern US were highly effective in reducing total oxidized N and total S deposition, respectively, in eastern Canada. Acidic deposition exceeded terrestrial CL at 5 of the 14 sites and aquatic CL at 2 of the 5 sites in the early 2000s. However, exceedances have been trending downwards and acidic deposition fluxes were mostly near or below CL after 2012 for the subset of sites assessed, which support recovery from historical acidification.

The spatial distributions of precipitation acidity and major ion wet deposition in North America during 1980

Tellus B, 1984

Observations are presented of the mean annual concentration and deposition of H +, SO,, NO; and NH: ions in precipitation in North America during 1980, the first year that a reasonably compatible merger of U S and Canadian federal network data was possible. The maximum concentration and wet deposition of Ht, SO; and NO, occurred in-and south of-the great lakes region near maximum anthropogenic emissions of sulphur and nitrogen oxides. The NH: maximum, however, was located in the north central US where American livestock feedlots are concentrated. Peak H* concentrations were 6&80 pmole I-'. In the region of maximum emissions, 1980 observations of H i , SO; and NO; wet deposition are within 25% of the 5-year mean for 1977-198 I. The respective fraction of anthropogenic sulphur and nitrogen oxides released in eastern North America that are wet deposited in the same area is 24 6 and 25 k 6%. On a smaller scale, in the high sulphur and nitrogen oxide emissions area of the northeastern US. the deposition was 13 and 18% of emissions, respectively. Trends in emissions as well as in SO; and NO; concentrations in precipitation support the conclusion that a real increase in acidity of precipitation of 30-37 pmol I-' has occurred in the southeastern US since 1955156

Meteorological influences on the spatial and temporal variability of NO2 in Toronto and Hamilton

Canadian …, 2009

Long-term air concentrations, wet deposition, and scavenging ratios of inorganic ions, HNO3 and SO2 and assessment of aerosol and precipitation acidity at Canadian rural locations (original) (raw)

Related papers