浙江省水体富营养化特征及防治对策

为研究浙江省水体富营养化特征,对全省历年省控断面地表水水质、污染源和重点藻华高发河流营养盐通量等数据进行了统计分析。结果表明:全省水体营养盐水平总体仍处于高位,重点流域富营养化问题突出,省控断面富营养、重富营养占比分别为78.7%和43.0%,营养盐已持续成为地表水首要污染超标因子。通过近年来的集中整治,浙江省水体营养盐浓度下降明显。但治理过程中也出现了总氮减排滞后,部分水域总磷浓度反弹等不利现象。特别是相应的藻类生长势能尚未进入下降敏感区间,对藻华防控贡献有限。同时,全省入河营养盐城镇生活源和农业面源占比突出,总氮合计占89.27%,总磷占95.45%。重点流域地表径流对营养盐入河通量贡献明显,汛期其对河流总磷浓度的贡献明显高于固定源排放。建议在营养盐总量控制、跨部门协调机制、水资源配置、农业面源管理、城镇雨污管网建设、雨污处理以及河流生态修复等方面加强应对。

Characteristics of Water Eutrophication and Its Countermeasures in Zhejiang Province

In order to study the characteristics of eutrophication in Zhejiang province, the data including surface water quality, pollutant source at province-scale and nutrient fluxes in a major high-incidence river of algae blooms was statistically analyzed. The results showed that:the concentration of nutrient salts was still at a high level in Zhejiang waterbodies, especially in some key river basins. The proportion of eutrophication and hyper-eutrophication in provincial control sections was 78.7% and 43.0%, respectively. Nutrient salts had continued to be primary pollutants. In recent years, the concentration of nutrient salts had decreased significantly though centralized rehabilitation. But some unfavorable phenomena still existed such as less reducing effectiveness in total nitrogen and concentration rebound of total phosphorus in some waterbodies. The corresponding growth potential of algae had not yet entered the downward sensitive range, which revealed the effectiveness of alone through the nutrient reduction to prevent and control algal blooms should be limited. In Zhejiang province, urban life and agricultural non-point source contributed outstandingly in nutrient emission with total nitrogen amounting to 89.27% and total phosphorus amounting to 95.45%. The surface runoff also contributed significantly to the flux of nutrients in the river. During the flood season, the contribution from surface runoff to total phosphorus concentration was significantly higher than that from fixed source discharge. At the end, countermeasures and suggestions were put forward in the aspects of total nutrient control, trans departmental coordination, water resource allocation, agricultural non-point source management, rainwater/sewage collection and treatment, and river ecological restoration.