程海流域非点源污染负荷估算及其控制对策

计算流域非点源氮磷污染负荷并以此开展源解析对于寻求水体污染控制最佳管理措施具有重要意义.通过对经典的Johnes输出系数模型进行改进,考虑了降水、坡度以及污染源与水体之间距离等因素,建立了一套在资料缺乏情况下,适用于受地形、降水影响较大的高原湖泊地区的非点源污染负荷评估方法.选取云南省九大高原湖泊之一的程海作为研究对象,验证了改进输出系数模型的合理性,并对流域溶解态氮磷入湖污染负荷进行了全面的分析.结果表明:(1)2014年,程海流域溶解态氮磷入湖负荷分别是158.48 t·a~(-1)和24.70 t·a~(-1),且二者空间分布相似;(2)在土地利用方面,农业用地对溶解态氮磷入湖污染负荷贡献最大,分别是46.19%和48.16%;(3)畜禽养殖和农村生活是溶解态氮磷入湖污染负荷治理的优先控制污染源,南岸是溶解态氮磷入湖污染负荷重点治理区域;(4)若实行农村生活和畜禽养殖、化肥流失及土地利用治理,可使溶解态氮磷入湖污染负荷分别减少38.47%和40.76%.研究成果可为缺乏资料的高原湖泊地区非点源污染治理提供科学的理论依据.

Estimation of and Control Strategies for Pollution Loads from Non-point Sources in the Chenghai Watershed

The calculation of non-point source (NPS) pollutant loads of nitrogen and phosphorus is the key step in preparing a pollution control plan. This study modified the export coefficient model by taking into account the precipitation, slope, distance between pollution sources and water bodies, and other relevant factors. The NPS pollution load assessment method established in this study can be applied to data-scarce basins and is suitable for plateau lake regions affected by terrain and precipitation. In this study, Chenghai Lake, which belongs to one of the nine major plateau lakes in Yunnan Province, is selected for the case study. This study first verifies the rationality of the improved export coefficient model based on actual observed values, and then utilizes the improved export coefficient model to assess the loads of dissolved nitrogen (DN) and dissolved phosphorus (DP) pollution. As indicated by the results, in 2014, the loads of DN and DP into Chenghai Lake are 158.48 t·a^-1 and 24.70 t·a^-1, respectively. The maximum contributions of DN and DP pollution load into Chenghai Lake are from agricultural cultivated land are 46.19% and 48.16%, respectively, in terms of land use. The results present a relatively consistent spatial distribution of DN and DP that indicates that the south bank is a key area for governance. Livestock and rural living are the main pollution sources influencing the load of DN and DP into Chenghai Lake and should be prioritized for control. If the pollution from rural living, livestock, fertilizer loss, and land use can be effectively controlled, the load of DN and DP into Chenghai Lake will be decreased by a maximum of 38.47% and 40.76%, respectively. The results of this study suggest that the improved export coefficient model can be applied for study of the NPS pollution assessment of plateau lake regions and can provide a theoretical basis for the NPS pollution control of the Chenghai Lake basin.