降雨径流污染对深圳湾富营养化影响的模拟研究

A Simulation Study on Effects of Urban Rainfall Runoff Pollutions on Eutrophication in Deep Bay,Shenzhen,China

提出了城市降雨径流污染模型和海湾富营养化模型耦合模拟的方法,识别出了深圳湾受降雨径流污染影响显著的敏感区域和敏感时段,分析了城市降雨径流污染影响深圳湾富营养化的演变规律。结果表明,2014年5月—9月深圳湾流域降雨径流输出的氨氮、硝态氮和磷酸盐总负荷分别为1 268.6、1 598.0、169.7 t,占全年径流营养盐负荷的77%;进入深圳湾的降雨径流营养盐负荷主要来自深圳河,占全流域的51%~56%。深圳湾内湾2014年5月—9月的营养盐和叶绿素a浓度明显高于其他月份,且变化范围较大;内湾营养盐和叶绿素a浓度与全流域降雨量及流域径流污染负荷量呈正相关;外湾全年营养盐浓度和叶绿素a浓度变化较为平稳。降雨径流污染负荷对内湾营养盐浓度和叶绿素a浓度均有滞后效应;外湾基本上不受流域降雨径流污染影响。

Based on an urban rainfall runoff pollution model and a marine eutrophication model, a coupled model was developed to identify sensitive areas and periods in Deep Bay after receiving rainfall runoff pollutions from the Deep Bay basin. In addition, the effect of urban rainfall runoff pollutants on the coastal eutrophication evolution was assessed in Deep Bay. The results showed that： ① The total load of ammonia nitrogen, nitrate, and phosphate in a wet season was 1 268.6 t, 1 598.0 t, and 169.7 t, re- spectively, which approximately contributed to 77% of the yearly total nutrient loads; moreover, the nu- trients were mainly received from the Shenzhen River, accounted for 51% -56% of the load of the entire basin. ② The concentrations of nutrients and chlorophyll-a in the inner bay between May and September in 2014 were apparently higher than other months, and had a larger range of variation comparing with the outer bay. There was a positive correlation between the concentrations of nutrients and chlorophyll-a in the inner bay and the rainfall runoff pollution loads from the Deep Bay basin. ③ Urban rainfall runoff pollution had a hysteresis effect on the variation of the concentration of nutrients and chlorophyll-a in the inner bay, while the outer bay was essentially free from the rainfall runoff pollution.