污水排放影响下平潭近岸海水COD和DIN浓度场的数值模拟

利用Delft3D数学模型建立了平潭综合实验区近岸海域物质输运数学模型，模拟了澳前、海坛海峡北、海坛海峡南、流水、竹屿5个排污口在不同污水排放量下COD、无机氮浓度的分布．结果表明：在污水排放规模为3．0×10^4t／d时，竹屿排污口邻近海域海水COD、无机氮质量浓度分别为3．80、0．51mg／dm3，流水排污口邻近海域海水COD、无机氮质量浓度分别为3．60、0．42mg／dm3，都超过二类海水水质标准值，表明这2个海域水动力条件较弱、污染物扩散缓慢，不是理想的排污口．在污水排放量为1．5×10^5t／d时，海坛海峡北排污口邻近海域海水COD、无机氮质量浓度分别为1．87、0．28mg／dm3，海坛海峡南排污口邻近海域海水COD、无机氮质量浓度分别为1．84、0．27mg／dm3；澳前排污口在污水排放量为5．0×10^5t／d时，其邻近海域海水COD、无机氮质量浓度分别为2．48、0．28mg／dm3，均符合二类海水水质要求，表明上述海域水动力条件良好、纳污能力强、环境容量大，是较好的污水排放口．该研究可为平潭综合实验区海域污水排放口选址优化提供科学依据，为该海域入海污染物总量控制和海洋环境管理提供参考．

Numerical simulation for COD and inorganic nitrogen concentrations field under the influence of sewage discharge in Pingtan coastal seawater

Delft3D mathematical model is used to set up the inshore species transport model of Pingtan comprehen- sive experimental zone. Distribution of COD and inorganic nitrogen pollutants is simulated under different incremental scale at sewage outfalls of Aoqian, the north and south of Haitan Strait, Liushui and Zhuyu. The results showed that at Zhuyu and Liushui sewage ouffalls when discharge is in the rate of 3.0 × 10^4 t/d, COD and inorganic nitrogen are 3.8 mg/dm3 and 0.51 mg/dm3 near Zhuyu, and 3.60 mg/dm3 and 0.42 mg/dm3 at Liushui, respectively. All COD and inorganic nitrogen exceeded the second-class of the water quality standard ,which indicates that these 2 outfalls are not ideal outfalls due to weak hydrodynamic condition and slow diffusion. At the sewage outfalls of north and south of Haitan Strait when discharge is in the rate of 1.5 × 10^5 t/d, COD and inorganic nitrogen concentrations are 1.87 mg/dm3 and 0.28 mg/dm3 in the north of Haitan Strait, and 1.84 mg/dm3 and 0.27 mg/dm3 in the south of Haitan Strait, respectively. At Aoqian sewage ouffall when discharge is in the rate of 5.0 × 10^5 t/d, COD and inorganic nitrogen in nearby waters are 2.48 mg/dm3 and 0.28 mg/dm3. In these areas the pollutant concentrations meet the second-class of the water quality standards, which shows that the hydrodynamic conditions and environmental capacity are good for the pollutant disposal and they are idea outfalls. The results provide scientific basis for ouffall site optimization and are valuable as reference for the control of total pollutant disposals in the marine environmental management of Pingtan comprehensive experimental zone.