Japan Geoscience Union Meeting 2015

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS21] Atmospheric Chemistry

Wed. May 27, 2015 4:15 PM - 6:00 PM 201B (2F)

Convener:*Yousuke Sawa(Oceanography and Geochemistry Research Department, Meteorological Research Institute), Nobuyuki Takegawa(Graduate School of Science and Engineering, Tokyo Metropolitan University), Yugo Kanaya(Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology), Kenshi Takahashi(Research Institute for Sustainable Humanosphere, Kyoto University), Hiroshi Tanimoto(National Institute for Environmental Studies), Chair:Tomoki Nakayama(Solar-Terrestrial Environment Laboratory, Nagoya University)

5:09 PM - 5:12 PM

[AAS21-P11] Enhancement of dimethylsulfide production by anoxic stress in natural seawater

3-min talk in an oral session

*Yuko OMORI1, Hiroshi TANIMOTO1, Satoshi INOMATA1, Shigeki WADA2, Kathleen Thume3, Pohnert Georg3 (1.National Institute for Environmental Studies, 2.University of Tsukuba, 3.Friedrich Schiller University Jena)

Keywords:dimethylsulfide, dimethylsulfoniopropionate, dissolved oxygen

Dimethylsulfide (DMS) is the dominant reduced sulfur species in the ocean and an important source of aerosols particles and clouds in the marine atmosphere. Marine DMS plays a key role in the climate system of the Earth. A better knowledge of the distribution of marine DMS and its controlling factors is required. Previous field studies have reported the formation of DMS peak upper anoxic layer though the governing processes have not been clearly understood yet. Here we show the first direct evidence for the enhancement of DMS production caused by anoxic stress.
Isotope tracer experiments were made using the oxic and anoxic coastal seawater to quantitatively evaluate DMS production rates in three processes; cleavage of dimethylsulfoniopropionate (DMSP), dimethylsulfoxide reduction and phytoplankton release.
Under the anoxic condition, DMS production was considerably enhanced and DMS consumption was inhibited, resulting in an 8-fold higher rate of gross DMS production than that under the oxic condition. While almost all DMS was derived from DMSP cleavage (99%) under the oxic condition, the DMS production under the anoxic condition was mainly due to direct release of DMS from phytoplankton (63%). These results demonstrate that phytoplankton suffered from anoxic stress emits DMS into the seawater, resulting in a rise in DMS levels. Anoxic stress is indicated to be one of important environmental factors in the dynamics of marine DMS, suggesting the possible global importance due to a ubiquity of anoxic conditions in the coastal oceans.