典型生态拦截措施水质净化效果研究

Study on water purification effect of typical ecological interception measures

为探讨生态拦截系统对洱海流域农田尾水氮(N)、磷(P)和化学需氧量(COD)的去除效应,提高生态拦截系统对农业面源污染物的净化效果,研究了生态沟渠、表流库塘、潜流库塘、生态沟渠+表流库塘4种改建的生态拦截系统对水质净化效果的影响。结果表明,与进水口污染物浓度相比,经生态拦截系统净化后,各系统出水口污染物浓度均有所下降。4种生态拦截系统中生态沟渠+表流库塘系统对污染物总氮(TN)、总磷(TP)和COD的削减效果最好,平均削减率为59.66%、55.99%和38.33%,出流全年各月可用于各类型农田灌溉,且TN、TP和COD浓度全年分别有3个月、10个月和10个月可满足地表水环境质量标准中Ⅴ类水质要求;潜流库塘系统削减效果次之,对TN、TP和COD的平均削减率为42.13%、31.31%和34.29%,出流全年各月可用于旱作回灌,全年有9个月可用于水作灌溉,TN、TP和COD浓度全年分别有10个月、6个月和2个月可达到地表Ⅳ类水质要求;生态沟渠系统和表流库塘系统削减能力相对较弱,对TN、TP、COD的平均削减率分别为40.59%、21.03%、25.25%和37.60%、27.69%、26.07%,但这2个系统出水全年可用于水作和旱作灌溉,其中生态沟渠系统出流TN浓度全年有4个月可达地表水Ⅴ类标准,TP浓度全年有11个月可达到地表水Ⅳ类水质要求,表流库塘系统出流TN浓度全年有3个月可达地表水Ⅴ类标准,TP浓度全年有11个月可达地表水Ⅳ类标准,COD浓度全年有3个月可达到地表Ⅴ类水质要求。综合而言,改建的4个生态拦截系统对污染物的净化效果表现为生态沟渠+表流库塘>潜流库塘>表流库塘>生态沟渠。

To improve the purification effect of an ecological interception system on agricultural non-point source pollutants,The ecological interception system′s effect on the removal of nitrogen,phosphorus,and chemical oxygen demand(COD)in the farming tail water of the Erhai Lake basin was investigated.Here four reconstructed ecological interception systems′purification capabilities were studied,including an ecological ditch,a surface-flow pond,a subsurface flow constructed pond,and an ecological ditch+surface-flow pond.Results indicated that compared with the pollutant concentration in the inlet,the pollutant concentration in the outlet of the four systems decreased after purification by the ecological interception system.The ecological ditch+surface-flow pond system achieved better results in reducing the total nitrogen(TN),total phosphorus(TP),and COD of pollutants,with average reduction rates of 59.66%,55.99%,38.33%,respectively.The outflow of this system could meet the irrigation needs for annual,monthly arming.The TN,TP,and COD concentrations increased to the classⅤof environmental quality standards.Additionally,the subsurface-flow pond system had the second-highest removal rate,with average reduction rates of 42.13%,31.31%,34.29%,respectively.The outflow could be used for dry farming irrigation every month of the year and water farming for nine months.The TN,TP,and COD concentrations in 10,6,and 2 months of the year met the environmental quality standards′requirements on surface water,exceeding the classⅣ.The ecological ditch and the surface-flow pond systems′removal ability were relatively weak,with an average reduction rate of 40.59%,21.03%,25.25%,and 37.60%,27.69%,26.07%,respectively.Furthermore,the two systems could be used for dry and water farming irrigation all year round.For the ecological ditch system,the TN and TP outflow concentrations in 4 and 11 months of the whole year reached the classⅤandⅣin the environmental quality standards′requirements of surface water.For the surface-flow pond system,the TN,TP,and COD concentrations in 3,11,and 3 months of the year were more than the classⅤ,Ⅳ,andⅤin the environmental quality standards′requirements of surface water,respectively.In summary,the average effectiveness of the four ecological interception systems modified in terms of pollutant purification was as follows:ecological ditch+surface-flow pond>subsurface flow constructed pond>surface-flow pond>ecological ditch.