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Surface Ocean and Lower Atmosphere Study—Air-Sea interactions and their climatic and environmental impacts
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Spatio-temporal variability and transformation of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the East China Sea (Invited)
Wednesday 9th @ 1330-1350, Conference Room 7
Gui-Peng Yang* , Ocean University of China
Hong-Hai Zhang, Ocean University of China
Qian-Yao Ma, Ocean University of China
Presenter Email: gpyang@ouc.edu.cn |
| Spatio-temporal variations of dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP), including dissolved (DMSPd) and particulate fractions (DMSPp) were determined in the East China Sea from 1993 to 2017. DMS and DMSP concentrations exhibited pronounced seasonal variations with the maxima in spring/summer and the minima in winter. The spatial distributions of DMS and DMSP in the East China Sea were obviously influenced by the Yangtze River effluent and the Kuroshio water. Both DMS and DMSPp concentrations were significantly correlated with chlorophyll a concentrations in the most cruises, suggesting that phytoplankton biomass might play an important role in controlling DMS production in the East China Sea. Over the past several decades, the N/P ratio in the study area increased dramatically due to the enhanced dissolved inorganic nitrogen discharges, while the Si/N ratio decreased. The long-term changes in nutrients could be responsible for the shift in the phytoplankton community structure in the East China Sea. The percentage of diatoms decreased while dinoflagellates increased over the past several decades. This shift in phytoplankton community has caused a significant increase in DMS concentrations from 2.9 nmol/l in 1993 to 4.8 nmol/l in 2017. In addition, transformation of DMS and DMSP on three major marine interfaces and their control factors were studied in the East China Sea during spring and summer. Regarding loss processes, bacterial consumption contributed nearly 50% of total DMSP loss, approximately 38% of which was converted into DMS in spring. Microbial consumption, photolysis and ventilation accounted for 56%, 34%, 10% in spring and 49%, 44%, 7% in summer of DMS removal processes, respectively. Moreover, the low positive sediment-to-water column flux of DMS suggests that sediment is a potential source for DMS. Finally, the East China Sea was identified as a hotspot for atmospheric DMS because the sea-to-air flux of DMS was approximately five times as many as the global average. |
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