1992 Fiscal Year Final Research Report Summary
Chemical composition of fog water classified according to their sizes and their formation process.
| Project/Area Number |
03804024
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | Nagoya University |
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Principal Investigator |
ISHIZAKA Yutaka Water Research Institute Associate Professor., 水圏科学研究所, 助教授 (50022710)
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| Co-Investigator(Kenkyū-buntansha) |
TSURUTA Haruo National Institute of Agro-Environmental Sciences Head of Environmental Survey L, 環境管理部, 室長
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| Project Period (FY) |
1991 – 1992
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| Keywords | acidic fog / pH of fog water / chemical composition of fog water / SO_2 / HNO_3 / sulfate ion / nitrate ion |
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| Research Abstract |
In order to study the formation process of acidic fog, chemical composition of fog water was examined simultaneously with chemical analysis of gaseous and particulate materials near the top of Mt. Norikura (Height of observation site:2770m). In this experiment, fog water was classified into four size classes and sampled with a newly made string-type cloud collector, in addition to bulk fog water sampling.
Acidity measurement showed that acidic fogs are often formed in the summer seasons and minimum pH of fog water reached 3.30. It was also found that change in pH is a function of the droplet size and minimum pH of the smallest droplets(mean diameter(] SY.simeq.[)3.6um) was 3.03. Main anions in fog water were sulfate and nitrate and concentration of many constituents increased generally with decreasing fog droplet size. On the other hand, chemical composition of particulate materials suggested that aerosol particles consisted mainly of ammonium sulfate. Therefore, we assumed that ammonium in fog water was originated from aerosols captured into fog droplets. It was estimated from the assumption that sulfate produced within fog droplets by absorption of sulfur dioxide exceed 50 % of sulfate in the smallest fog droplets. Based on our observations, three processes were suggested for the formation of acidic fogs: nucleation of acidic particles such as ammonium sulfate, sulfate produced in fog droplets and absorption of nitric acid vapor.
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