Methodology of analysis associating survey results by the filter-pack method with those of precipitation- Acid-base balance on acid-related and alkali-related chemical species in urban ambient air and its influence on the acidification of precipitation - |
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| Authors: | Masahide Aikawa Takatoshi Hiraki |
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| Institution: | (1) Hyogo Prefectural Institute of Public Health and Environmental Sciences, 3-1-27 Yukihira-cho, Suma-ku, Kobe Hyogo, 654-0037, Japan |
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| Abstract: | Continuous weekly monitoring on the concentration of gases and aerosols in urban ambient air by a four-stage filter-pack method
was carried out for 7 years in order to study not only the acid-base balance of acid-related (HNO3, NO3
−, and non-sea-salt-(nss-)SO4
2−) and alkali-related (NH3, NH4
+, and nss-Ca2+) chemical species but also its influence on the acidification of precipitation. The concentrations of the total nitrate (=
NO3− + HNO3) and nss-SO42− showed a similar seasonal variation: high in the summer and low in the winter. The total nitrate and nss-SO42− accounted for 0.43 and 0.57 of the acid-related species, respectively, on an equivalent basis. The total ammonium (= NH3 + NH4+) accounted for more than 0.9 of the alkali-related species, except for a springtime nss-Ca2+ episodic peak. The alkali-related species were generally overabundant compared with the acid-related species in the HNO3-NO3−-nss-SO42−-NH3-NH4+-nss-Ca2+ system. The alkali-rich distribution was especially pronounced in the winter, but the acid-related species was comparable
to the alkali-related species in the summer, which was attributed to the larger H+ deposition by precipitation in the summer. This study can provide a methodology to associate survey results obtained by a
filter-pack method with those of precipitation. |
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| Keywords: | Acid-base balance ∙ Ammonia Ammonium Calcium Filter pack Nitric acid Nitrate Precipitation Sulfate |
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