象山港溶解无机氮环境容量研究

综合考虑凫溪、颜公河、郭巨大碶等10个陆源污染物入海口的影响,建立了象山港三维水质模型并对该海域溶解无机氮(Dissolved Inorganic Nitrogen,DIN)时空分布进行了数值模拟。结合象山港海域功能区划要求,通过调整各入海口DIN最低排海浓度(Rmin)的取值范围设置了四类情境,基于排海通量最优化法计算了对应情境下象山港DIN的环境容量。结果表明,象山港DIN环境容量随Rmin的增大而减小,其范围介于127.16~274.17 t/a;同时Rmin的增大也导致各入海口DIN排海通量需要削减,按削减优先程度,可将各入海口划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ四级,入海口所处海域水体半交换时间越长、DIN年排海通量越大,相应的削减优先程度越高。

Environmental capacity assessment of dissolved inorganic nitrogen in the Xiangshan Bay

A three-dimensional water quality model was established to simulate the distribution of dissolved inorganic nitrogen (DIN) in the Xiangshan Bay, considering 10 land-based discharge sources (including Fuxi, Yangonghe, and Guojudaqi). Under the condition of water functional regionalization, the discharge optimization method was applied to calculate the environmental capacity (EC) of DIN with the minimum DIN discharge concentration (R_min) getting larger. The results show that the EC of DIN in the Xiangshan Bay is 127.16~274.17 t/a. The capacity will decrease when the R_min gets larger, which means the discharge flux of DIN needs to be reduced. Moreover, according to the reduction priority, which mainly depends on the water half-exchange time and the annual DIN discharge flux, the 10 discharge sources can be divided into four levels.