The role of humic-like substances as atmospheric surfactants in the formation of summer-heavy rainfall in downtown Tokyo

Toshiki Sugo; Hiroshi Okochi; Ryunosuke Uchiyama; Eri Yamanokoshi; Hiroko Ogata; Naoya Katsumi; Takanori Nakano

City and Environment Interactions (Nov 2019)

The role of humic-like substances as atmospheric surfactants in the formation of summer-heavy rainfall in downtown Tokyo

Toshiki Sugo,
Hiroshi Okochi,
Ryunosuke Uchiyama,
Eri Yamanokoshi,
Hiroko Ogata,
Naoya Katsumi,
Takanori Nakano

Affiliations

Toshiki Sugo: Corresponding author at: Department of Resources and Environmental Engineering, School of Creative and 14 Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan.; Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Hiroshi Okochi: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Ryunosuke Uchiyama: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Eri Yamanokoshi: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Hiroko Ogata: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Naoya Katsumi: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
Takanori Nakano: Department of Resources and Environmental Engineering, Graduate School of Creative Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan

Journal volume & issue: Vol. 3

Abstract

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In order to study the impact of organic aerosols in the formation of UHR (hereafter UHR = urban-induced heavy rain), we analyzed humic-like substances (hereafter HULIS) that serve as major atmospheric surfactants as well as the major inorganic ions in rainwater collected on an event basis at the Nishi-Waseda Campus of Waseda University in Shinjuku, Tokyo. Fulvic and humic acid fractions in HULIS was determined by the DEAE (Diethylaminoethyl cellulose) -UV method. The total wet deposition flux of HULIS in UHR was 33.5 times higher than that found in a normal rainfall and 57.3 times higher than that found in THR (hereafter THR = typhoon heavy rain). The accumulation of HULIS to acidic anions such as NO3− and SO42− in UHR compared to other types of rain indicates that HULIS in UHR accelerated the growth of cloud droplets via reduction of surface tension, which likely led to the rapid development of cumulonimbus clouds.

Published in City and Environment Interactions

ISSN: 2590-2520 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Geography. Anthropology. Recreation: Environmental sciences; Social Sciences: Communities. Classes. Races: Urban groups. The city. Urban sociology
Website: https://www.journals.elsevier.com/city-and-environment-interactions

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