茅洲河清淤后底泥氮磷含量分析及其生态风险评价

Nitrogen and Phosphorus Content Analysis and Ecological Risk Assessment of Sediment after Dredging in Maozhou River

为了解茅洲河清淤后底泥沉积物中总氮和总磷的含量、分布和环境污染风险,从清淤前相关研究中优选20个典型断面和36个取样点位,测试分析了底泥中的总氮、总磷含量,并对其环境污染风险进行了讨论与评价。结果表明,茅洲河底泥中总氮含量由高到低为:沙井河支流段>沙井河口—珠江口段>洋涌河水闸—沙井河口段,清淤后整个研究区底泥总氮含量较清淤前降低74.70%、总氮的内梅罗综合污染指数降为2.07,为中污染级,生态风险明显降低;清淤后底泥总磷的生态风险虽有所降低,但仍为重污染级,推测主要是由于清淤厚度不足及水体内磷的循环、迁移转换所致。

In order to understand the content,distribution and environmental pollution risk of total nitrogen and total phosphorus in the sediment of Maozhou River after dredging,20 typical sections and 36 sampling sites are selected from relevant studies before dredging to test and analyze the content of total nitrogen and total phosphorus in the sediment,and the environmental pollution risk is discussed and evaluated.The results show that the total nitrogen content in the sediment of Maozhou River arranged from high to low is in the order of Shajing River tributary section,Shajing Estuary to Zhujiang River Estuary section,Yangyong River Sluice to Shajing Estuary section.After dredging,the total nitrogen content in the sediment of the whole study area is reduced by 74.70%compared with that before dredging,and the Nemero comprehensive pollution index of total nitrogen is 2.07,indicating a moderate pollution level,and the ecological risk is significantly reduced.Although the ecological risk of total phosphorus in sediment is reduced somewhat after dredging,it is still at heavy pollution level,which is speculated to be mainly caused by the insufficient thickness of dredging and the circulation,migration and transformation of phosphorus in water.