Estimating submarine groundwater discharge and associated nutrient inputs into Daya Bay during spring using radium isotopes  

作　　者：Jing-yan Gao Xue-jing Wang Yan Zhang Hai-long Li 

机构地区：[1]School of Environment, Harbin Institute of Technology [2]School of Environmental Science and Engineering, Southern University of Science and Technology [3]School of Water Resources and Hydropower Engineering, Wuhan University [4]State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences

出　　处：《Water Science and Engineering》2018年第2期120-130,共11页水科学与水工程（英文版）

基　　金：supported by the National Key Basic Research Program of China(973 Program,Grants No.2015CB452901 and 2015CB452902);the National Natural Science Foundation of China(Grant No.41430641)

摘　　要：Daya Bay, a semi-enclosed bay in the South China Sea, is well known for its aquaculture, agriculture, and tourism. In recent years, many environmental problems have emerged, such as the frequent(almost yearly) occurrence of harmful algal blooms and red tides. Therefore,investigations of submarine groundwater discharge(SGD) and associated nutrient inputs to this bay have important theoretical and practical significance to the protection of the ecological system. Such a study was conducted using short-lived radium isotopes ^(223)Ra and ^(224)Ra. The estimated SGD fluxes were 2.89 × 10~7 m^3/d and 3.05 × 10~7 m^3/d based on ^(223)Ra and ^(224)Ra, respectively. The average SGD flux was about 35 times greater than that of all the local rivers. The SGD-associated dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphorus(DIP)fluxes ranged from 1.95 × 10~6 to 2.06 × 10~6 mol/d and from 5.72 × 10~4 to 6.04 × 10~4 mol/d, respectively. The average ratio of DIN to DIP fluxes in SGD was 34, much higher than that in local rivers(about 6.46), and about twice as large as the Redfield ratio(16). Our results indicate that SGD is a significant source of nutrients to the bay and may cause frequent occurrence of harmful algal blooms. This study provides baseline data for evaluating potential environmental effects due to urbanization and economic growth in this region.Daya Bay, a semi-enclosed bay in the South China Sea, is well known for its aquaculture, agriculture, and tourism. In recent years, many environmental problems have emerged, such as the frequent(almost yearly) occurrence of harmful algal blooms and red tides. Therefore,investigations of submarine groundwater discharge(SGD) and associated nutrient inputs to this bay have important theoretical and practical significance to the protection of the ecological system. Such a study was conducted using short-lived radium isotopes ^(223)Ra and ^(224)Ra. The estimated SGD fluxes were 2.89 × 10~7 m^3/d and 3.05 × 10~7 m^3/d based on ^(223)Ra and ^(224)Ra, respectively. The average SGD flux was about 35 times greater than that of all the local rivers. The SGD-associated dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphorus(DIP)fluxes ranged from 1.95 × 10~6 to 2.06 × 10~6 mol/d and from 5.72 × 10~4 to 6.04 × 10~4 mol/d, respectively. The average ratio of DIN to DIP fluxes in SGD was 34, much higher than that in local rivers(about 6.46), and about twice as large as the Redfield ratio(16). Our results indicate that SGD is a significant source of nutrients to the bay and may cause frequent occurrence of harmful algal blooms. This study provides baseline data for evaluating potential environmental effects due to urbanization and economic growth in this region.

关 键 词：Submarine groundwater discharge(SGD) RADIUM ISOTOPES RADIUM mass balance model SGD-associated nutrient FLUXES DAYA Bay 

分 类 号：TV[水利工程]