Internal waves (IWs) are ubiquitous features and have pronounced impacts on carbon biogeochemistry in marginal seas and deep oceans. In the northern South China Sea (NSCS), the IWs generated frequently in the Luzon Strait and propagated westward to reach or break down on the Dongsha continental shelf. To understand the biogeochemical response of IWs impacts in the Dongsha margin, the study was conducted in several cruises to measure hydrological (T, S, D) and biogeochemical (nutrients, Chl-a, organic carbon) conditions from two transects covering the slope, shelf break and shelf zones of Dongsha Atoll. We found that the surface water off Dongsha Atoll was generally depleted with nutrients and its DIN/DIP ratio was quite low and similar to the typical ratio of surface water in the South China Sea. However, the concentrations of nutrients, Chl-a and particulate organic carbon (POC) were enhanced after IWs lifted cold and nutrient rich water to the surface. Meanwhile, the DIN/DIP ratio in the euphotic zone was elevated to close to aphotic zone after lifting subsurface water to the surface layer. Such features can be seen in both eastern transect (M1-M6) and northeastern transect (NM1-NM4) particularly in the shallow zones near the Atoll. The effects of a down-welling occurrence (W2 moored station) on biogeochemical distributions can be evaluated through a short-term observation of T, DO and nutrients at 50 m during the passage of IWs. The down-welling IWs can transport DOC and POC into subsurface layer and affect carbon budget significantly. In addition, the moored station (the rmistor and trap array) show simultaneous changes of T and Chl-a at 40, 100 and 150 m, indicating a significant effect of IWs on T and phytoplankton abundance. The enhanced POC did not accumulate on shelf sediments (<100 m), which may imply a transport of Chl-a and POC toward north-western regions. Biological pump (active and passive carbon transport) was also elevated under the impacts of IWs in the Dongsha continental shelf.

EDUCATION

     Ph.D., 1984. University of Wisconsin-Madison (Soil and Water Chemistry)

     M.S., 1978.NationalTaiwanUniversity(Agricultural Chemistry)

     B.S., 1974.NationalChung-HsingUniversity(Soil and Environmental Science)