Organic acids contribute to rainwater acidity at a rural site in eastern China

Niu, Y.; Li, Xinling; Pu, Jingjiao; Huang, Zhen

doi:10.1007/s11869-018-0553-9

Cited by 21 publications

(14 citation statements)

References 60 publications

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“…We find that rainwater pH increases by 0.4-1 unit in the Amazon, tropical Africa, and southeast Asia, consistent with observations (Andreae et al, 1990;Sanhueza et al, 1992;Sigha-Nkamdjou et al, 2003;Yoboué et al, 2005). Over the US, Europe, and eastern China the increase in pH is 0.1-0.4 units, which is similar to the observed contribution of carboxylic acids to rainwater H + (10-60%) in these areas (Keene and Galloway, 1984;Kawamura et al, 1996;Peña et al, 2002;Xu et al, 2010;Niu et al, 2018). Over the oceans, the change in pH from HCOOH and CH3COOH is small (~0.15 units) and in agreement with marine observations (Keene et al, 2015).…”

Section: Global Distribution Of Rainwater Ph and Compositionsupporting

confidence: 88%

Global modeling of cloudwater acidity, rainwater acidity, and acid inputs to ecosystems

Shah

Jacob

Moch

et al. 2020

Preprint

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Abstract. Cloudwater acidity affects the atmospheric chemistry of sulfate and organic aerosol formation, halogen radical cycling, and trace metal speciation. Rainwater acidity including post-depositional inputs adversely affects soil and freshwater ecosystems. Here we use the GEOS-Chem model of atmospheric chemistry to simulate the global distributions of cloud- and rainwater acidity, and the total acid inputs to ecosystems from wet deposition. The model accounts for strong acids (H2SO4, HNO3, HCl), weak acids (HCOOH, CH3COOH, CO2, SO2), and weak bases (NH3, dust and sea salt aerosol alkalinity). We compile a global dataset of cloudwater pH measurements for comparison with the model. The global mean observed cloudwater pH is 5.2 ± 0.9, compared to 5.0 ± 0.8 in the model, with a range of 3 to 8 depending on region. The lowest values are over East Asia and the highest values are over deserts. Cloudwater pH over East Asia is low because of large acid inputs (H2SO4, HNO3), despite NH3 and dust neutralizing 70 % of these inputs. Cloudwater pH is typically 4–5 over the US and Europe. Carboxylic acids account for less than 25 % of cloudwater H+ in the northern hemisphere on an annual basis, but 25–50 % in the southern hemisphere and over 50 % in the southern tropical continents where they push the cloudwater pH below 4.5. Anthropogenic emissions of SO2 and NOx (precursors of H2SO4 and HNO3) are decreasing at northern mid-latitudes, but the effect on cloudwater pH is strongly buffered by NH4+ and carboxylic acids. The global mean rainwater pH is 5.5 in GEOS-Chem, higher than the cloudwater pH because of dilution and below-cloud scavenging of NH3 and dust. GEOS-Chem successfully reproduces the rainwater pH observations in North America, Europe, and eastern Asia. Carboxylic acids, which are undetected in routine observations due to biodegradation, lower the annual mean rainwater pH in these areas by 0.2 units. The acid wet deposition flux to terrestrial ecosystems taking into account the acidifying potential of NO3− and NH4+ in N-saturated ecosystems exceeds 50 meq m−2 a−1 in East Asia and the Americas, which would affect sensitive ecosystems. NH4+ is the dominant acidifying species in wet deposition, contributing 41 % of the global acid flux to continents under N-saturated conditions.

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Section: Global Distribution Of Rainwater Ph and Compositionsupporting

confidence: 88%

Global modeling of cloudwater acidity, rainwater acidity, and acid inputs to ecosystems

Shah

Jacob

Moch

et al. 2020

Preprint

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“…Comparison of pH and Volume-Weighted Mean (VWM) concentration of ionic and organic components of rainwater from different places in the world . This study; b(Pelicho et al, 2006); c(Hu et al, 2003); d(Masood et al, 2018); e(Niu et al, 2018); f(Chon et al, 2015); g(Zhang et al, 2011); …”

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confidence: 84%

Changes on wet deposition of major organic and inorganic ions in subtropical region of Brazil

Batista

Martins

Beal

et al. 2022

Rev. Bras. Geog. Fis.

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Wet precipitation composition could be an indicator of air quality since it carries components such as strong and weak inorganic and organic acids. These originate from oxidation of compounds containing sulphur, nitrogen, and hydrocarbons, coming from biomass burning, fuel combustion and industrial processes, as well as agricultural and biogenic activities. Wet precipitation samples were obtained from May 2014 to May 2015 in the city of Londrina -Paraná, Brazil, with an automatic rain collector. Volume, pH, conductivity, acetate, format, chloride, nitrate, sulphate, and ammonium concentrations were determined. The pH results revealed slightly acidic rainfall in 41% of the samples. The Volume Weighted Mean (VWM) showed an average annual concentration of inorganic ions of 0.71, 0.55, 0.24 and 0.20 mg L -1 for nitrate, sulphate, chloride, and ammonium, respectively and for organic ions of 1.00 and 0.29 mg L -1 for acetate and format, respectively. In the spring, the highest concentrations of nitrate and chloride were observed, which were possibly influenced by long-distance transport from fires in the north and west regions. The VWM of inorganic ions decreased compared with previous work (1998)(1999)(2000)(2001)(2002) carried out for the same place, with reductions of approximately 35% for nitrate and sulphate. Finally, the extensive use of fuel ethanol in Brazil contributes to the higher concentrations of acetate and format compared to other places in the world. Keywords: rainfall, air pollution, majority ions, the trajectories of air masses Mudanças na deposição úmida em relação aos principais íons orgânicos e inorgânicos em região subtropical do Brasil R E S U M OA composição da precipitação úmida pode ser um indicador da qualidade do ar, uma vez que transporta componentes como ácidos inorgânicos e orgânicos fortes e fracos. Estes se originam da oxidação de compostos contendo enxofre, nitrogênio e hidrocarbonetos, provenientes da queima de biomassa, combustão de combustível e processos industriais, assim como atividades agrícolas e biogênicas. As amostras de precipitação úmida foram obtidas no período de maio de 2014 a maio de 2015 na cidade de Londrina-Paraná, Brasil, com um coletor de chuva automático. Foram determinados volume, pH, condutividade e as concentrações dos íons acetato, formato, cloreto, nitrato, sulfato e amônio. Os resultados de pH revelaram chuvas ligeiramente ácidas em 41% das amostras. A média ponderada pelo volume (MPV) mostrou a concentração média anual de íons inorgânicos de 0,71, 0,55, 0,24 e 0,20 mg L -1 para nitrato,sulfato, cloreto e amônio, respectivamente e para os íons orgânicos de 1,00 e 0,29 mg L -1 para acetato e fomato, respectivamente. Na primavera, foram observadas as maiores concentrações de nitrato e cloreto, que foram possivelmente influenciadas pelo transporte de longa distância dos incêndios nas regiões norte e oeste do país. O MPV de íons inorgânicos diminuiu em comparação com trabalhos anteriores (1998)(1999)(2000)(2001)(2002) realizados no mesmo local, com reduções de a...

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“…High abundances of formic (5–18 µeq L −1 ) and acetic acids (3–9 µeq L −1 ) were reported in rainwater samples from China, 37 ) India, 38 ) South Africa, 39 ) and Brazil. 40 ) In a rural site (Lin’an) of China, concentrations of organic acids, including oxalate, were 2.6–114 µeq L −1 , and the average contribution of those organic acids to precipitation total acidity was reported as 13.7%.…”

Section: Atmospheric Abundances Forms and Sources Of Lmw Monoacidsmentioning

confidence: 98%

Geochemical studies of low molecular weight organic acids in the atmosphere: sources, formation pathways, and gas/particle partitioning

Kawamura

2023

Proc. Jpn. Acad., Ser. B

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Low molecular weight monocarboxylic acids (LMW monoacids, C 1 –C 10 ) are the most abundant gaseous organic compound class in the atmosphere. Formic or acetic acid is the dominant volatile organic compound (VOC) in Earth’s atmosphere. They can largely contribute to rainwater acidity, especially in the tropical forest, and react with alkaline metals, ammonia, and amines, contributing to new particle formation and secondary organic aerosol production. Gaseous and particulate LMW monoacids were abundantly reported in China. They can be directly emitted from fossil fuel combustion and biomass burring; however, the secondary formation is more important than primary emissions via the photochemical oxidation of anthropogenic and biogenic VOCs. In this paper, we review the distributions of LMW monoacids from urban, mountain, and marine sites as well as from rainwater and alpine snow samples and discuss their sources and formation mechanisms in the atmosphere. We also discuss their importance as cloud condensation nuclei (CCN) and provide future perspectives of LMW monoacids study in the warming world.

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Organic acids contribute to rainwater acidity at a rural site in eastern China

Cited by 21 publications

References 60 publications

Global modeling of cloudwater acidity, rainwater acidity, and acid inputs to ecosystems

Global modeling of cloudwater acidity, rainwater acidity, and acid inputs to ecosystems

Changes on wet deposition of major organic and inorganic ions in subtropical region of Brazil

Geochemical studies of low molecular weight organic acids in the atmosphere: sources, formation pathways, and gas/particle partitioning

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