基于BMPs的鄱阳湖区小流域农村面源污染控制

RURAL NON-POINT POLLUTION CONTROLLED BASED ON BMPS IN SMALL POYANG LAKE BASIN

鄱阳湖小流域农村面源污染严重,环境问题不断加剧。通过背景值调查与污染源解析,显示农村生活和种植业是鄱阳湖小流域农村面源污染的主要来源。采取集成式BMPs模式,将源头控制与末端治理相结合,充分利用当地优势,合理搭配植物缓冲带、沟渠湿地、人工湿地,兼性塘等,实现氮、磷流失的有效拦截,达到有效控制示范区小流域农村面源污染目的,从而为鄱阳湖农村面源污染控制提供借鉴。结果表明:BMPs系统污染物去除能力高,运行成本低。系统单位面积削减总量分别为CODcr710.17kg、SS 114.91kg、TP 4.08kg、TN 35.93kg、NO-3-N 4.74kg、NH+4-N 19.18kg,而运行成本不到0.1元/t。整个系统中尤以表面流人工湿地减污效果最好,耐负荷冲击能力最强。沟渠湿地整体去污能力不低,但耐冲击负荷能力弱,易受外界因素的影响。为加强减污效果,可通过完善生态系统尤其是挺水性植物加以改进。

Rural non-point source pollution is serious and environmental problems intensified in Poyang Lake small watershed. It is of great urgency to control agricultural pollution, because the pollution from agriculture is more wide and serious compared with others. Agricultural pollution is principally transported from agricultural land. The harm is more serious than point source pollutions and hard to be monitored and controlled, because the indefinite quantity of agricultural pollutants are discharged during uncertain period through uncertain process. The rural life and farming are the main source of rural non-point source pollution through the background investigation and analysis of pollution sources in Poyang Lake small watershed. Farming in the demonstration area is one of the main sources of rural non-point source pollution, the proportion of total, nitrogen and phosphorus load more than 50%, 48% and 49 %, respectively. Country life is also an important source of rural non-point source pollution. Nitrogen and phosphorus loss can be intercepted effectively by integrated BMPs, in which source control and end treatments are combined, buffer, ditch wetland, artificial wetland, facultative pond are added into a group rationally. Pollutant cutting quantity per area of the whole system is 710.17 kg of CODes, 114.91 kg of SS, 4.08 kg of TP, 19. 18 kg of NH＋-N, 4. 74 kg of NOj-N and 35.93 kg of TN respectively, while the total investment is less than 27 thousand yuan, i.e. investment cost of less than 2 700 yuan/ma , and the operation cost less than 0. 1 yuan/ma. The cutting quantity of SS through buffer zones is 63.07 kg, accounted for 50% of all. The surface flow constructed wetland has the highest removal capacity and impact resistance, through which total nitrogen can be cut down more than 3.0 g per unit area. Adsorption capacity of phosphorus by wetland soil is also high. Equilibrium Phosphorus Concentration （EPC0） of Wetland substrate is lower than 0. 05 mg/L. If inflow concentration of SPR of wetland is higher than EPC0, wetland is for phosphorus ＂source＂ by contrast if inflow concentration of SPR of wetland is less than EPC0, wetlands is for phosphorus ＂collect＂. But the reduction of nitrate nitrogen ability is not strong; the followed faeultative pond just make up for the defect, reductions of nitrate nitrogen stay above 0. 13 g/m2. Overall, decontamination ability of ditch wetland is not low, but the capacity of resisting impact load is weak, easily affected by external factor. Decontamination ability can be enhanced by improving the eco-system, the emergent maerophytes especially.