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Latebreaking Poster

Session: Forests (Latebreaking)

LB 23-197 - Canopy leaching rather than desorption of PM2.5 from leaves is the dominant source of throughfall dissolved organic carbon in forest

Thursday, August 10, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall

    Presenting Author(s)

  • JC

    Ji-Yeon Cha

    Seoul National University, Republic of Korea

    • Coauthor(s)

  • SL

    Seung-Cheol Lee

    Seoul National University, Republic of Korea

  • EL

    Eun-Ju Lee

    Seoul National University, Republic of Korea

  • KL

    Kyuyeon Lee

    Seoul National University, Republic of Korea

  • HL

    Hojin Lee

    Seoul National University, Seoul-t'ukpyolsi, Republic of Korea

  • HK

    Hyun Seok Kim

    Professor
    Seoul National University, Republic of Korea

  • JA

    Jinho Ahn

    Seoul National University, Republic of Korea

  • NO

    Neung-Hwan Oh

    Seoul National University, Republic of Korea

Dissolved organic carbon (DOC) of throughfall provides carbon and energy to many organisms in forest ecosystems, and thus, identifying the sources of throughfall DOC is critical to understand how the forest ecosystem works. Throughfall DOC has been known to be mainly derived from canopy leaching. However, desorption of dry-deposited atmospheric fine particulate matter (PM2.5) from plant foliage also has a potential to be a source of throughfall DOC, considering that PM2.5 includes organic carbon which shows humic-like fluorescence spectra. Here, we have investigated and apportioned three different sources of throughfall DOC, including DOC being leached from plant tissues, DOC in PM deposited on plant foliage, and DOC in precipitation, using carbon isotope analysis. Rainwater, atmospheric PM2.5, and throughfall were collected from pine and oak forests in South Korea from March 2021 to November 2021. The mean concentration of throughfall DOC was 7.9 mg L-1, which was about six times larger than that of rainfall. The mean Δ14C of throughfall DOC was -38.2‰, which was higher by ~200‰ than those of rainwater or PM2.5, indicating that a large amount of recently photosynthesized organic carbon has been leached from the tree canopy. Mass balance estimates showed that the contribution of canopy leaching to throughfall DOC was about 83%, while the desorption of PM2.5 from the tree canopy and rainwater accounted for only ~3% and ~14% of throughfall DOC, respectively. The results clearly demonstrate that leaching from plant tissues is still the most important source of carbon input to the forest floor, with relatively little contribution from desorption of PM2.5.