Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Significant impactor sampling artifacts of ammonium, nitrate, and organic acids
https://orcid.org/0000-0002-1106-6561
Abstract The evaporation losses of semi-volatile compounds such as ammonium nitrate and organic acids on denuded and undenuded impactors can significant underestimate their mass loadings. In this study, sampling artifacts of formate, oxalate, and other semi-volatile inorganic components were measured using a combination of an upstream-denuded and a downstream-denuded MOUDI system in Shanghai. Compared to regular sampling, the concentrations of semi-volatile ammonium, nitrate, formate, and oxalate collected on the upstream-denuded MOUDI sampler decreased by 11%–43%, suggesting removing acidic and alkaline gaseous compounds from the sampled air had significant negative sampling artifacts for semi-volatile inorganic salts and low-molecular-weight organic acids. Evaporation losses from regular MOUDI sampling were confirmed by the higher concentrations of acidic and alkaline gaseous compounds in the downstream denuder. The concentration of aerosol formate was seriously underestimated, with average sampling efficiencies of 36.7 ± 10% and 55.2 ± 8.5% on denuded and undenuded MOUDIs, respectively. The mass ratio of total organic acids to sulfate increased to approximately 0.5 for the particle population smaller than 0.1 μm, indicating that organic acids might influence particle acidity and chemical behaviors in this size range.
Highlights Upstream stripping reduces filter sampling efficiency for semi-volatile compounds. Formate losses may exceed 50% on a MOUDI sampler. A considerable fraction of formic acid partitions into the particle phase.
Significant impactor sampling artifacts of ammonium, nitrate, and organic acids
https://orcid.org/0000-0002-1106-6561
Abstract The evaporation losses of semi-volatile compounds such as ammonium nitrate and organic acids on denuded and undenuded impactors can significant underestimate their mass loadings. In this study, sampling artifacts of formate, oxalate, and other semi-volatile inorganic components were measured using a combination of an upstream-denuded and a downstream-denuded MOUDI system in Shanghai. Compared to regular sampling, the concentrations of semi-volatile ammonium, nitrate, formate, and oxalate collected on the upstream-denuded MOUDI sampler decreased by 11%–43%, suggesting removing acidic and alkaline gaseous compounds from the sampled air had significant negative sampling artifacts for semi-volatile inorganic salts and low-molecular-weight organic acids. Evaporation losses from regular MOUDI sampling were confirmed by the higher concentrations of acidic and alkaline gaseous compounds in the downstream denuder. The concentration of aerosol formate was seriously underestimated, with average sampling efficiencies of 36.7 ± 10% and 55.2 ± 8.5% on denuded and undenuded MOUDIs, respectively. The mass ratio of total organic acids to sulfate increased to approximately 0.5 for the particle population smaller than 0.1 μm, indicating that organic acids might influence particle acidity and chemical behaviors in this size range.
Highlights Upstream stripping reduces filter sampling efficiency for semi-volatile compounds. Formate losses may exceed 50% on a MOUDI sampler. A considerable fraction of formic acid partitions into the particle phase.
Significant impactor sampling artifacts of ammonium, nitrate, and organic acids
https://orcid.org/0000-0002-1106-6561
Abstract The evaporation losses of semi-volatile compounds such as ammonium nitrate and organic acids on denuded and undenuded impactors can significant underestimate their mass loadings. In this study, sampling artifacts of formate, oxalate, and other semi-volatile inorganic components were measured using a combination of an upstream-denuded and a downstream-denuded MOUDI system in Shanghai. Compared to regular sampling, the concentrations of semi-volatile ammonium, nitrate, formate, and oxalate collected on the upstream-denuded MOUDI sampler decreased by 11%–43%, suggesting removing acidic and alkaline gaseous compounds from the sampled air had significant negative sampling artifacts for semi-volatile inorganic salts and low-molecular-weight organic acids. Evaporation losses from regular MOUDI sampling were confirmed by the higher concentrations of acidic and alkaline gaseous compounds in the downstream denuder. The concentration of aerosol formate was seriously underestimated, with average sampling efficiencies of 36.7 ± 10% and 55.2 ± 8.5% on denuded and undenuded MOUDIs, respectively. The mass ratio of total organic acids to sulfate increased to approximately 0.5 for the particle population smaller than 0.1 μm, indicating that organic acids might influence particle acidity and chemical behaviors in this size range.
Highlights Upstream stripping reduces filter sampling efficiency for semi-volatile compounds. Formate losses may exceed 50% on a MOUDI sampler. A considerable fraction of formic acid partitions into the particle phase.
Significant impactor sampling artifacts of ammonium, nitrate, and organic acids
Yao, Yinghui (Autor:in) / Ye, Xingnan (Autor:in) / Gao, Tianxiang (Autor:in) / Feng, Hao (Autor:in) / Chen, Yanan (Autor:in) / Chen, Jianmin (Autor:in)
Atmospheric Environment ; 274
02.02.2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Nitrate Artifacts during PM25 Sampling in the South Coast Air Basin of California
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| Elsevier | 1983
| British Library Online Contents | 2002