Evolution of the sink and source of dissolved inorganic nitrogen with salinity as a tracer during summer in the Pearl River Estuary.
In this study, we evaluated the sink and source of the surface water along the PRE using a mixing model method with salinity as tracer. The observational data showed that the decreasing of dissolved inorganic nitrogen (DIN) did not closely follow the physical mixing lines of freshwater and modified seawater. In the western part, DIN consumption by phytoplankton and bacteria uptake (ΔDIN)varied from 15.81 μmol L-1to 88.53 μmol L-1. On the contrary, in the eastern part, ΔDIN varied from -63.66 μmol L-1to -10.45 μmol L-1. DIN source in the eastern part may be mainly caused by organic matter decomposition, while DIN remove is strongly associated with phytoplankton growth and bacteria consumption. These differential behaviors of the estuary with respect to DIN are largely due to varying degrees of hydrodynamics due to different topography in the two areas. Sensitivity analysis indicated reduction strategies of DIN inputs to coastal waters may improve environment quality in the PRE, due to DIN changes in the freshwater end-member having a determined influence on biological activities (R). Our results indicate that the model may be a valuable way to address the sources and sink of DIN in the river-dominated estuaries.
State Key Laboratory of Tropical Oceanography and Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.|Marine Biology Research Station at Daya Bay, Chinese Academy of Sciences, Shenzhen 518121, China.
Mei-Lin
ML
Wu
State Key Laboratory of Tropical Oceanography and Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Yi-Guo
YG
Hong
State Key Laboratory of Tropical Oceanography and Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.|Marine Biology Research Station at Daya Bay, Chinese Academy of Sciences, Shenzhen 518121, China.
Jian-Ping
JP
Yin
State Key Laboratory of Tropical Oceanography and Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Jun-De
JD
Dong
State Key Laboratory of Tropical Oceanography and Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.|Marine Biology Research Station at Daya Bay, Chinese Academy of Sciences, Shenzhen 518121, China.
You-Shao
YS
Wang