scholarly journals Spatiotemporal Variability in the Oxidative Potential of Ambient Fine Particulate Matter in Midwestern United States

2021 ◽  
Author(s):  
Haoran Yu ◽  
Joseph Varghese Puthussery ◽  
Yixiang Wang ◽  
Vishal Verma
Keyword(s):  
United States ◽  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Water Soluble ◽  
Spatiotemporal Variability ◽  
Large Set ◽  
Oxidative Potential ◽  
Midwestern United States ◽  
Spatiotemporal Trends ◽  
Fine Particulate

Abstract. We assessed the oxidative potential (OP) of both water-soluble and methanol-soluble fractions of ambient fine particulate matter (PM2.5) in the midwestern United States. A large set of PM2.5 samples (N = 241) were collected from five sites, setup in different environments, i.e. urban, rural and roadside, in Illinois, Indiana and Missouri during May 2018–May 2019. Five acellular OP endpoints, including the consumption rate of ascorbic acid and glutathione in a surrogate lung fluid (SLF) (OPAA and OPGSH, respectively), dithiothreitol (DTT) depletion rate (OPDTT), and ·OH generation rate in SLF and DTT (OPOH-SLF and OPOH-DTT, respectively), were measured for all PM2.5 samples. PM2.5 mass concentrations in the Midwest US as obtained from these samples were spatially homogeneously distributed, while most OP endpoints showed significant spatiotemporal heterogeneity. Seasonally, higher activities occurred in summer for most OP endpoints for both water- and methanol-soluble extracts. Spatially, roadside site showed highest activities for most OP endpoints in the water-soluble extracts, while only occasional peaks were observed at urban sites in the methanol-soluble OP. Most OP endpoints showed similar spatiotemporal trends between mass- and volume-normalized activities across different sites and seasons. Comparisons between two solvents (i.e. water and methanol) showed that methanol-soluble OP generally had higher activity levels than corresponding water-soluble OP. Site-to-site comparisons of OP showed stronger correlations for methanol-soluble OP compared to water-soluble OP, indicating a better extraction of water-insoluble redox-active compounds from various emission sources into methanol. We found a weak correlation and inconsistent slope values between PM2.5 mass and most OP endpoints. Moreover, the poor-to-moderate intercorrelations among different OP endpoints infer different mechanisms of OP represented by these endpoints, and thus demonstrate the rationale for analyzing multiple acellular endpoints for a better and comprehensive assessment of OP.

scholarly journals Spatiotemporal variability in the oxidative potential of ambient fine particulate matter in the Midwestern United States

2021 ◽  
Vol 21 (21) ◽  
pp. 16363-16386
Author(s):  
Haoran Yu ◽  
Joseph Varghese Puthussery ◽  
Yixiang Wang ◽  
Vishal Verma
Keyword(s):  
United States ◽  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Water Soluble ◽  
Spatiotemporal Variability ◽  
Large Set ◽  
Oxidative Potential ◽  
Midwestern United States ◽  
Spatiotemporal Trends ◽  
Fine Particulate

Abstract. We assessed the oxidative potential (OP) of both water-soluble and methanol-soluble fractions of ambient fine particulate matter (PM2.5) in the Midwestern United States. A large set of PM2.5 samples (N=241) was collected from five sites set up in different environments, i.e., urban, rural, and roadside, in Illinois, Indiana, and Missouri during May 2018–May 2019. Five acellular OP endpoints, including the consumption rate of ascorbic acid and glutathione in a surrogate lung fluid (SLF) (OPAA and OPGSH, respectively), dithiothreitol (DTT) depletion rate (OPDTT), and ⚫OH generation rate in SLF and DTT (OPOH−SLF and OPOH−DTT, respectively), were measured for all PM2.5 samples. PM2.5 mass concentrations in the Midwestern US as obtained from these samples were spatially homogeneously distributed, while most OP endpoints showed significant spatiotemporal heterogeneity. Seasonally, higher activities occurred in summer for most OP endpoints for both water- and methanol-soluble extracts. Spatially, the roadside site showed the highest activities for most OP endpoints in the water-soluble extracts, while only occasional peaks were observed at urban sites in the methanol-soluble OP. Most OP endpoints showed similar spatiotemporal trends between mass- and volume-normalized activities across different sites and seasons. Comparisons between two solvents (i.e., water and methanol) showed that methanol-soluble OP generally had higher activity levels than corresponding water-soluble OP. Site-to-site comparisons of OP showed stronger correlations for methanol-soluble OP compared to water-soluble OP, indicating a better extraction of water-insoluble redox-active compounds from various emission sources into methanol. We found a weak correlation and inconsistent slope values between PM2.5 mass and most OP endpoints. Moreover, the poor to moderate intercorrelations among different OP endpoints indicate different mechanisms of OP represented by these endpoints and thus demonstrate the rationale for analyzing multiple acellular endpoints for a better and more comprehensive assessment of OP.

scholarly journals Composition and sources of fine particulate matter across urban and rural sites in the Midwestern United States

2014 ◽  
Vol 16 (6) ◽  
pp. 1360-1370 ◽  
Author(s):  
Shuvashish Kundu ◽  
Elizabeth A. Stone
Keyword(s):  
United States ◽  
Particulate Matter ◽  
Fine Particulate Matter ◽  
Midwestern United States ◽  
Fine Particulate ◽  
Rural And Urban ◽  
Rural Sites

The composition and sources of fine particulate matter (PM2.5) were investigated in rural and urban locations in Iowa, located in the agricultural and industrial Midwestern United States, from April 2009 to December 2012.

Organosulfates in the Midwestern United States: abundance, composition and stability

2019 ◽  
Vol 16 (5) ◽  
pp. 312 ◽  
Author(s):  
Dagen D. Hughes ◽  
Elizabeth A. Stone
Keyword(s):  
United States ◽  
Particulate Matter ◽  
Organic Carbon ◽  
Fine Particulate Matter ◽  
Unknown Origin ◽  
Anthropogenic Pollution ◽  
Acid Sulfate ◽  
Midwestern United States ◽  
Atmospheric Particle ◽  
Fine Particulate

Environmental contextOrganosulfates in the atmosphere are an indicator that particulate matter has formed from gases in the presence of anthropogenic pollution. By characterising organosulfates in atmospheric fine particulate matter from the Midwestern USA, we found that organosulfates account for a significant fraction of organic carbon and that they are associated with both plant-derived and anthropogenic gases. Our results demonstrate that anthropogenic pollution significantly influences atmospheric particle concentrations and composition. AbstractOrganosulfates are components of secondary organic aerosol resulting from the oxidation of volatile organic compounds in the presence of acidic sulfate. This study characterises organosulfates in the Midwestern United States for the first time. In fine particulate matter (PM2.5) collected in Iowa City, IA, in September 2017, organosulfates were analysed using liquid chromatography coupled to high-resolution and tandem mass spectrometry (MS) to identify and quantify (or semi-quantify) major species. Among the 22 identified species, methyltetrol sulfate (m/z 215; C5H11SO7−) had the largest contribution to the bisulfate (m/z 97) product ion, as determined by precursor-ion MS/MS (59.5% of signal), followed by ten other isoprene-derived organosulfates (15.2%), seven monoterpene-derived organosulfates (5.6%), three anthropogenic organosulfates (4.3%) and one species of unknown origin (0.6%). Among the quantified species were hydroxyacetone sulfate (4.8±1.1ngm−3), glycolic acid sulfate (21.0±1.5ngm−3), 2-methylgyceric acid sulfate (15.1±0.8ngm−3), C5H7SO7− (m/z 211; 17.9±0.9ngm−3), C5H9SO7− (m/z 213; 16.0±1.0ngm−3), and methyltetrol sulfate (214±8ngm−3); together, these species accounted for 4.4% of organic carbon. To further validate the measurement of organic species in PM using filter samples, the stability of organosulfates on filters frozen at −20°C was evaluated over the course of 1 year. The stored samples revealed no degradation of organosulfates, indicating their stability on filters stored frozen for extended periods of time. This study provides new insight into the abundance and identity of organosulfates in the Midwestern US and demonstrates that isoprene-derived organosulfates, in particular, are a significant contributor to PM2.5 organic carbon.

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