678 / 2024-09-18 22:37:28

The response of biogenic dimethylated sulfur compounds to ocean acidification

dimethylsulfide,Ocean acidification

Session 9 - Global Ocean Changes: Regional Processes and Ecological Impacts

The ocean functions as the Earth's primary carbon reservoir, absorbing approximately one-third of anthropogenic CO₂ emissions. This process has contributed to a partial mitigation of global warming. However, the substantial uptake of CO₂ has reduced seawater pH, leading to the increasingly severe phenomenon of ocean acidification. The decline in seawater pH is expected to impede the growth of calcifying organisms, impact primary productivity in the ocean, and consequently influence oceanic carbon, nitrogen, and sulfur cycles. Dimethylsulfide (DMS) is a biogenically significant gas released by the ocean, serving as the interface between the sea and the atmospheric sulfur cycle and playing a pivotal role in the global sulfur cycle. A reduction in pH may directly or indirectly affect the release of DMS by influencing phytoplankton abundance, community composition, and related enzyme activities. This study investigated the impacts of ocean acidification on DMS and its associated sulfur compounds through a combination of field research and incubation experiments. The findings indicated a positive correlation between seawater acidification and the concentrations of DMS, dimethylsulfoniopropionate (DMSP), and dimethyl sulfoxide (DMSO) in the East China Sea and Yellow Sea. This correlation suggests that acidification may somewhat impede the production of dimethylated sulfur compounds. Furthermore, photochemical experiments displayed that reduced pH levels can hinder the photochemical oxidation rate of DMS and diminish the concentration of DMSO. Ship-based culture experiments further revealed that acidification inhibited phytoplankton growth, subsequently reducing the release of DMS and DMSP.