Chemical mechanisms of acid generation in the troposphere

Calvert, Jack G.; Lazrus, A. L.; Kok, Gregory L.; Heikes, Brian G.; Walega, J.; Lind, John A.; Cantrell, C. A.

doi:10.1038/317027a0

Cited by 558 publications

(359 citation statements)

References 39 publications

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“…Therefore, H202 (or HOx) production appears to be still active in the autumn. The condition of {H202]<[S02} prior to the occurrence of fog is called Oxidant Limitation, in which a nonlinear relationship exists between the S02 concentration in air and the H2S04 produced in the aqueous phase (Calvert et al, 1985;Kleinman,1986;Meagher et al, 1990). Near the summit of Mt.…”

Section: Hydrogen Peroxidementioning

confidence: 99%

Chemical Composition of Fog Water near the Summit of Mt. Norikura in Japan

Watanabe

Ishizaka

Takenaka

1999

Journal of the Meteorological Society of Japan

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Chemical measurements of fog water have been made near the summit of Mt. Norikura (altitude 2770m) in central Japan, during the summer and autumn from 1994 to 1996. Highly acidic fogs (pH<4) were observed both in the summer and autumn. The SO42-was the most dominant anion in fog water. The [SO42-]/{NO-3] equivalent ratio was much less than that measured in the 1960s. The results may reflect the difference between the characteristics of air pollution in Japan during the 1960s, and that of the 1990s.The ratio of [SO42-}/[NO] in the fog water was significantly higher during the summer than in autumn. In addition, the [Cl-]/[Na+] ratio was much higher than that of seawater in the summer. The non-sea-salt Cl-also seems to contribute to the fog water acidification. The ratio of the summertime [NH4+]/[SO42-] was also higher than that in the autumn. A relatively high pH (pH>6) of fog water was observed, despite the high concentration of SO42-during July 1994. The hydrogen peroxide (H2O2) concentration during the summer varied over a range of 3-180uM, with an average concentration of 60uM. Relatively high concentrations of H2O2 (60-70uM) were observed, even in the autumn.

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Section: Hydrogen Peroxidementioning

confidence: 99%

Chemical Composition of Fog Water near the Summit of Mt. Norikura in Japan

Watanabe

Ishizaka

Takenaka

1999

Journal of the Meteorological Society of Japan

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“…Ambient particulate sulfate levels, however, are not linearly related to SO 2 emissions, with less than a 1:1 reduction in sulfate concentration per reduction in SO 2 emissions (on a molar basis). 15,16 Also, since SO 2 sources are not uniformly distributed in space and time, nor have they undergone uniform emission reductions, not all areas would be expected to experience a uniform reduction in sulfate-related fine mass.…”

Section: Seasonal Trendsmentioning

confidence: 99%

Historic PM_2.5/PM₁₀ Concentrations in the Southeastern United States—Potential Implications of the Revised Particulate Matter Standard

Parkhurst

Tanner

Weatherford

et al. 1999

Journal of the Air & Waste Management Association

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This report summarizes a PM 2.5 /PM 10 particulate matter data set consisting of 861 PM 2.5 /PM 10 sample pairs collected with dichotomous samplers by the Tennessee Valley Authority (TVA) from 1982 to 1991. Eight monitoring stations, ranging from urban-industrial to rural-background, were operated across three east-central U.S. states. Annual average PM 2.5 concentrations ranged from 12.6 to 21.3 micrograms per cubic meter (µg/m 3 ), with an overall mean of 15.7 µg/m 3 . Likewise, annual average PM 10 concentrations ranged from 17.8 to 33.7 µg/m 3 , with an overall mean of 23.7 µg/m 3 . High summer-low winter seasonality was evident, particularly for PM 2.5 , with the highest monthly PM 2.5 and PM 10 concentrations in August (26.4 and 37.5 µg/m 3 , respectively) and the lowest in February (9.9 and 15.3 µg/m 3 , respectively). A strong association (r 2 = 0.84) was found between PM 2.5 and PM 10 mass with PM 2.5 mass contributing, on average, 67% of PM 10 mass. Applying TVA's PM 2.5 /PM 10 ratio to recent (1993)(1994)(1995) . A decline in average PM 2.5 mass on the order of 3-5 µg/m 3 from 1982 through 1991 is also suggested. Daily PM 2.5 mass appears to be reasonably well associated (r = 0.47) with maximum hourly ozone during the warmer months (spring through fall). Sulfate compounds comprise a major portion of the measured PM 2.5 mass, with that fraction being highest in the summer months. Viewed collectively, these data suggest that although compliance with the annual and 24-hr PM 10 and 24-hr PM 2.5 metrics should prove readily attainable, the annual PM 2.5 metric will present a major regulatory management challenge for much of the east-central United States.

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“…Peroxides in atmospheric aqueous phases are of interest because of their role in dissolved SO 2 oxidation. Hydrogen peroxide is believed to be the dominant oxidant for SO 2 in atmospheric aqueous phases with pH b 5 (Calvert et al, 1985). Although the presence of organic peroxides is often considered, there have been only a few observations of aqueous phase organic peroxide levels in natural waters.…”

Section: Introductionmentioning

confidence: 99%