Distribution, residence time, autotrophic production, and heterotrophic removal of DOP in the Mirs Bay, northern South China Sea

作     者：Huaming Shi Yu Ma Xulu Li Xiaoyong Shi Junxiao Zhang 

作者机构：College of Environmental Science and Engineering Ocean University of China Qingdao 266100 China South China Sea Marine Survey and Technology Center Ministry of Natural Resources Guangzhou 510300 China National Marine Hazard Mitigation Service Ministry of Natural Resources Beijing 100194 China 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2019年第38卷第8期

页      面：17-26页

核心收录：

学科分类：07[理学] 

基　　金：The National Key Basic Research Special Foundation of China under contract No.2013CB965101 the Marine Science and Technology Foundation of the South China Sea Sub-administration,SOA,China under contract No.1624 

主　　题：dissolved organic phosphorus temporal and spatial distributions residence time autotrophic production heterotrophic removal Mirs Bay northern South China Sea 

摘      要：The importance of dissolved organic phosphorus(DOP) as a potential nutrient source for primary producers in marine systems has been recognized for up to eight decades, but currently, the understanding of the biogeochemistry of DOP is in its infancy. In the present study, monthly data between 2000 and 2014 were used to analyze the temporal and spatial distributions of DOP in the Mir Bay, the northern South China Sea. The DOP residence time(TDOP) was also investigated using a simple regression analysis in combination with chlorophyll a(Chl a) measurements while excess DOP(ΔDOP), produced by the biogeochemical processes of autotrophic production and heterotrophic removal, was determined using a two-component mixing mass-balance model in combination with salinity measurements. The results showed that the DOP concentration was(0.017±0.010) mg/L higher in the surface-water compared with the bottom-water and higher in the inner Tolo Harbour and waters adjacent to Shatoujiao compared with the main zone of the bay. Although seasonal changes and annual variability in the DOP were small, the surface DOP concentration was higher in the wet season(April–September)than in the dry season(October–March) due to the impacts of seaward discharges and atmospheric deposition into the bay. Measurement and regression results showed that the DOP release rate from phytoplankton production was about 1.83(gP)/(gChl a) and the TDOP was about 7 d, which implied that the DOP cycle in the bay was rapid. The ΔDOP was calculated from the model to be about 0.000 mg/L in the main zone of the bay and about 0.002 mg/L in the inner Tolo Harbour and waters adjacent to Shaotoujiao, suggesting that the autotrophic production of DOP was almost balanced by the heterotrophic removal in the main zone of the bay and dominated in the inner Tolo Harbour and waters adjacent to Shaotoujiao. In conclusion, the Mirs Bay is very productive and fairly heterotrophic.