城市湿地景观水体富营养化评价、机理及治理

针对再生水回用的景观水体容易发生富营养化的问题，分别以再生水和径流雨水为主要补水水源的某城市湿地不同区域景观水体为研究对象，通过水体TN、TP、COD、SS、Chla、DO等水质指标检测分析，研究了污染物的空间变化和季节变化规律，评价了湿地水体富营养化程度并探讨其机理。结果表明，以再生水为主要补水水源的湿地水体全部呈现中度富营养，而以径流雨水为主要补水水源的湿地水体则整体呈现中营养。湿地生态系统对再生水输入的高浓度氮磷污染物有一定的净化效果，但净化效率有限且受季节因素影响明显，藻类的季节性增殖引起水体中TN、TP浓度降低、SS降低、透明度下降和COD浓度升高，高浓度氮磷营养盐输入是湿地水体藻类增殖并呈现富营养化的主要原因。提出了再生水补水的水质和水量控制、景观水体健康生态系统的构建和水体长期的维护管理是综合治理水体富营养化的有效对策。

Evaluation,mechanism and treatment of landscape water eutrophication in city wetland

The eutrophication is prone to occur when reclaimed water is reused as water source of landscape water. To address this issue, the landscape water bodies in different zones of a city wetland with their own water source from the reclaimed water or runoff rainwater were taken as the research object. Through analyzing the water quality indicators of TN, TP, COD, SS, Chla and DO, the spatial and the seasonal change rules of pollutants were investigated, then the eutrophication degree of wetland water was assessed, and the corresponding mechanism was also studied. The results indicate that the moderate eutrophication level occurred in the wetland water with the main water source from reclaimed water, while the middle nutrient level occurred in wetland water with the main water source from runoff rainwater. The wetland ecosystem had a certain purification performance on the nitrogenous and phosphorus pollutants in high concentration derived from the reclaimed water, but the purification efficiency was limited, which was significantly affected by seasonal factors. The seasonal algae bloom led to the decrease of TN and TP concentrations, SS and SD in the water, while the increase of COD. The excess input of nitrogenous and phosphorus salts was the main reason for the algae proliferation and eutrophication of wetland water. To conclude, the effective strategy for the eutrophication treatment is proposed, which includes the regulation of water quality and volume of reclaimed water source, the construction of healthy ecosystem of landscape water and the long-term maintenance and management of water body.