Continuous and filter-based measurements of PM2.5 nitrate and sulfate at the Fresno Supersite

Chow, Judith C.; Watson, John G.; Lowenthal, Douglas H.; Park, Kihong; Doraiswamy, Prakash; Bowers, Ken; Bode, Richard

doi:10.1007/s10661-007-9987-5

Cited by 25 publications

(22 citation statements)

References 33 publications

(35 reference statements)

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“…This effect has been attributed to incomplete volatilization and/or incomplete catalytic conversion of NO − 3 to NO. Two identical instruments at the Fresno supersite yielded data that were also well correlated but different by 10-55 % in the annual average (Chow et al, 2008). As a result, we treat these observations as uncalibrated but internally consistent over time.…”

Section: A1 Long-term Recordsmentioning

confidence: 99%

“…There data were collected in Fresno in -2001(Watson et al, 2000 as part of the EPA PM Supersites program (http://www.epa.gov/ttnamti1/ supersites.html). These measurements were made by flash volatilizing NH 4 NO 3 , reducing HNO 3 across a heated catalyst to nitric oxide (NO), and detecting NO by chemiluminescence (Stolzenburg et al, 2003;Chow et al, 2008). It was reported that 24 h averages of these high-time-resolution observations were well correlated with, but 20-40 % lower than, 24 h PM 2.5 filter samples (annual averages).…”

Section: A1 Long-term Recordsmentioning

confidence: 99%

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On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

et al. 2016

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Abstract. Nitrogen oxides (NO x ) have fallen steadily across the US over the last 15 years. At the same time, NO x concentrations decrease on weekends relative to weekdays, largely without co-occurring changes in other gas-phase emissions, due to patterns of diesel truck activities. These trends taken together provide two independent constraints on the role of NO x in the nonlinear chemistry of atmospheric oxidation. In this context, we interpret interannual trends in wintertime ammonium nitrate (NH 4 NO 3 ) in the San Joaquin Valley of California, a location with the worst aerosol pollution in the US and where a large portion of aerosol mass is NH 4 NO 3 . Here, we show that NO x reductions have simultaneously decreased nighttime and increased daytime NH 4 NO 3 production over the last decade. We find a substantial decrease in NH 4 NO 3 since 2000 and conclude that this decrease is due to reduced nitrate radical-initiated production at night in residual layers that are decoupled from fresh emissions at the surface. Further reductions in NO x are imminent in California, and nationwide, and we make a quantitative prediction of the response of NH 4 NO 3 . We show that the combination of rapid chemical production and efficient NH 4 NO 3 loss via deposition of gas-phase nitric acid implies that high aerosol days in cities in the San Joaquin Valley air basin are responsive to local changes in NO x within those individual cities. Our calculations indicate that large decreases in NO x in the future will not only lower wintertime NH 4 NO 3 concentrations but also cause a transition in the dominant NH 4 NO 3 source from nighttime to daytime chemistry.

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Section: A1 Long-term Recordsmentioning

confidence: 99%

Section: A1 Long-term Recordsmentioning

confidence: 99%

On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

et al. 2016

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“…The OC or OC mass (OCM) estimated from the material balance can be compared with those measured from quartz fiber filters using different multipliers to evaluate other artifact correction methods. This assumes that other semi-volatile species (e.g., ammonium nitrate [47][48][49][50] ) are accounted for in the material balance. This approach provides a basis to evaluate artifact correction methods and to estimate the OC artifact in PM 2.5 mass.…”

Section: Regression Intercept Approachmentioning

confidence: 99%

Methods to Assess Carbonaceous Aerosol Sampling Artifacts for IMPROVE and Other Long-Term Networks

Watson

Chow

Chen

et al. 2009

Journal of the Air & Waste Management Association

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120

100

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Volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) adsorb to quartz fiber filters during fine and coarse particulate matter (PM 2.5 and PM 10 , respectively) sampling for thermal/optical carbon analysis that measures organic carbon (OC) and elemental carbon (EC). Particulate SVOCs can evaporate after collection, with a small portion adsorbed within the filter. Adsorbed organic gases are measured as particulate OC, so passive field blanks, backup filters, prefilter organic denuders, and regression methods have been applied to compensate for positive OC artifacts in several long-term chemical speciation networks. Average backup filter OC levels from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network were approximately 19% higher than field blank values. This difference is within the standard deviation of the average and likely results from low SVOC concentrations in the rural to remote environments of most IMPROVE sites. Backup filters from an urban (Fort Meade, MD) site showed twice the OC levels of field blanks. Sectioning backup filters from top to bottom showed nonuniform OC densities within the filter, contrary to the assumption that VOCs and SVOCs on a backup filter equal those on the front filter. This nonuniformity may be partially explained by evaporation and readsorption of vapors in different parts of the front and backup quartz fiber filter owing to temperature, relative humidity, and ambient concentration changes throughout a 24-hr sample duration. OC-PM 2.5 regression analysis and organic denuder approaches demonstrate negative sampling artifact from both Teflon membrane and quartz fiber filters.

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“…The PM 2.5 fraction is dominated by ammonium nitrate and carbonaceous aerosol during fall and winter. Sulfur dioxide emissions in the SJV are low (CARB, 2012), but oxides of nitrogen and ammonia emissions are high (Mansell and Roe, 2002), so lower temperatures and higher relative humidities during late fall and winter favor ammonium nitrate formation (Stockwell et al, 2000;Chow et al, 2005b;Lurmann et al, 2006;Chow et al, 2008). PM 2.5 carbonaceous aerosol in the SJV derives from engine exhaust, biomass burning, cooking, and conversion of organic gases to particles (Chow et al, 1992;Strader et al, 1999;Schauer and Cass, 2000;Chow et al, 2007b).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Ambient PM10 Bioaerosols in a California Agricultural Town

Chow

Yang

Wang

et al. 2015

Aerosol Air Qual. Res.

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Ambient bioaerosols in PM 10 samples were measured at three sites in Corcoran, an agricultural town in the southern San Joaquin Valley (SJV) of California, during fall of 2000 corresponding to the cotton harvest season. Elevated bioaerosol concentrations were measured near grain elevators (GRA site) and a cotton handling facility (BAI site) as compared to levels in a residential community (COP site), ~2 km northeast of these sources. Average endotoxin levels (13 ± 17 EU/m 3 ) at the grain elevator site were three to eight times higher than averages at the nearby cotton-handling and residential sites. The highest level (47.6 EU/m 3 ) at the grain elevator site was about half of the exposure limit of 90 EU/m 3 set by the Dutch Expert Committee on Occupational Safety. Particle counts of fungal spore (66,333 particles/m 3 ) and pollen grain (2,600 particles/m 3 ) concentrations were more than double those reported in the literature. Average fungal biomarker concentrations of 170 and 131 ng/m 3 for arabitol and mannitol, respectively, were 1-2 orders of magnitude higher than those from nonagricultural areas. The low correlation (r < 0.11) of three fungal markers (i.e., (1→3)-β-D-glucan, arabitol, and mannitol) with fungi counts is consistent with findings by others and indicates that these are insufficient as surrogates to represent fungal exposure. Agricultural activities contributed measureable amounts to PM 10 mass and organic carbon (OC), dominated by fungal spores (i.e., 5.4-5.8% PM 10 mass and 11.5-14.7% OC). The sum of fungal spores, pollen grains, and plant detritus accounted for an average of 11-15% PM 10 and 24-33% OC mass. Bioaerosols can be important contributors to PM 10 mass in farming communities similar to Corcoran, especially during intense agricultural activities.

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Continuous and filter-based measurements of PM2.5 nitrate and sulfate at the Fresno Supersite

Cited by 25 publications

References 33 publications

On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

Methods to Assess Carbonaceous Aerosol Sampling Artifacts for IMPROVE and Other Long-Term Networks

Characterization of Ambient PM10 Bioaerosols in a California Agricultural Town

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