Geochemical and stable isotope characteristics of urban heavy rain in the downtown of Tokyo, Japan

Ryunosuke Uchiyama, Hiroshi Okochi, Hiroko Ogata, Naoya Katsumi, Daisuke Asai, Takanori Nakano

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    In order to make clear the impact of air pollution on the formation of sudden and locally-distributed heavy rain in urban area (hereafter Urban Heavy Rain: UHR), we analyzed inorganic ion concentration and stable isotope ratio of water (δD and δ18O) in rainwater. Rainwater samples were collected in Shinjuku, which is a representative downtown of Tokyo, Japan, during four years from October 2012 to December 2015. The concentration and wet deposition fluxes of acidic components (H+, NH4 +, NO3 , and nss-SO4 2 −) in UHR were especially higher than those in other types of rain events, i.e. normal rain, typhoon heavy rain, and frontal heavy rain. UHR had distinctly lower stable isotope ratios than those in other urban rains with same rainfall amount and summer precipitation systems. There was a high negative correlation between δ18O and the distances from the sampling point to the formation area of UHR within 10 km, while there were high positive correlations between δ18O and the concentration of acidic components in UHR. These findings indicate that UHR could effectively scavenge acidic substances within cloud and suggest the use of stable isotope ratios as tracers of an urban heavy rain's water and in-cloud scavenging process.

    Original languageEnglish
    Pages (from-to)109-118
    Number of pages10
    JournalAtmospheric Research
    Volume194
    DOIs
    Publication statusPublished - 2017 Sep 15

    Keywords

    • Acidic substances, anthropogenic
    • Air pollutants
    • Heavy rain
    • Stable isotopes
    • Urban heat island

    ASJC Scopus subject areas

    • Atmospheric Science

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