不同河岸带修复策略对氮磷非点源污染的净化作用

选择北江的重要支流流溪河流域为研究对象,基于现有河岸带对非点源污染削减作用的模拟结果,采用情景分析法,预测不同河岸带修复策略对非点源污染的削减作用,使用效益-成本指数表征TN和TP削减率提高幅度与增加河岸带面积的关系,比较不同河岸带修复策略的效率.结果表明:河岸带对TN和TP的削减能力具有较大的空间差异性.各修复情景都在不同程度上提高了河岸带对TN和TP的削减率(TN:23.36%~30.72%;TP:27.19%~39.86%),河岸带增加总面积与削减率呈现对数增长关系(P<0.05).选择综合考虑了流域非点源负荷量以及河岸带状况的优先修复子流域进行河岸带修复时,效益-成本指数达最高为1.19%.

Reduction rate of nitrogen and phosphorus non-point source pollution under different riparian buffer restoring strategies

This study was conducted along Liuxi River watershed, a main branch of Beijiang River, in Guangdong Province. Based on the non-point source (NPS) pollution and riparian buffer’s reduction in current situations of the Liuxi River Basin, the differences of NPS pollution reduction improvement of different restoration strategies were investigated by scenario simulations. In order to compare the efficiency of different restoration strategies, the relationships between the improvement of NPS reduction rate and the increase of buffer area were interpreted by benefit-cost index. The results showed the NPS reduction rate performed remarkable spatial variation. Each scenario had improved the NPS reduction rates to varying degrees (TN: 23.36%~30.72%; TP: 27.19%~39.86%). The relationships between buffer areas and NPS reduction rate of each scenario were fitted well by the logarithmic function (P<0.05). The strategy with restoring the sub-basins of prior riparian buffer restoration, which integrated NPS loading and riparian buffers conditions, could reach the best benefit-cost index (1.19%).