不同植物配置模式坡耕地面源污染生态阻控特征

Ecological Control Characteristics of Non-point Source Pollution in Slope Farmland Under Different Plant Allocation Modes

利用8个差异化植被配置野外规模化径流小区的构建,探索自然降水环境下差异化植被配置给面源污染所形成的制约作用,其中主要参考5个指标,一是总氮(TN),二是总磷(TP),三是化学需氧量(COD),四是生物需氧量(BOD5),五是总有机碳(TOC),从而可为库区水土流失的治理防控供给一定借鉴作用。结果表明:(1)植物对于面源污染有着显著的控制效果,天然降雨条件下,减流作用最好的是板栗(Castanea mollissima)+苦参(Sophora flavescens)小区,平均减流作用为70.58%,板栗+雀麦(Bromus japonicus)最差,但相比板栗单种仍减流56%。(2)苦参、紫花苜蓿(Medicago sativa)、薄荷(Mentha haplocalyx)、野牛草(Buchloe dactyloides)和板栗的间作模式能有效地降低坡耕地的磷素流失,丹参(Salvia miltiorrhiza)和板栗间作模型可在一定程度上降低坡耕地的氮素流失。除雀麦和板栗间作小区外,其他间作模式小区,分别比对照小区径流水中的COD,BOD5,TOC消减率为29.10%~95.04%,31.49%~93.60%和16.76%~62.17%。(3)间作板栗+苦参对TN,TP等相关参数具有最优改善效果,可实现最佳配置效果,经过整体性评估从而得出,其具备最大推广价值。研究结果可为坡耕地生态阻控植物配置技术提供一定数据参考。

Miyun reservoir is not only the main surface drinking water source,but also the ecological conservation area in Beijing.With the rise of water level and the construction of soil and water conservation project in Miyun reservoir,a series of changes have taken place in its ecological environment.In order to provide a certain reference for the control and prevention of soil erosion in this area,differential vegetation coverage can restrict non-point source pollution.Five indicators such as total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD),biological oxygen demand(BOD5),and total organic carbon(TOC)under natural rainfall conditions were studied by constructing 8 field standard runoff plots with different vegetation configurations.The results show that:(1)under natural rainfall conditions,the best runoff reduction effect was exerted by Castanea mollissima+Sophora flavescens plot,the average runoff reduction was 70.58%,the worst effect was exerted by Castanea mollissima+Bromus japonicus,but Castanea mollissima+Bromus japonicus still reduced the runoff by 56%compared with the single Castanea mollissima species;(2)the intercropping model of Sophora flavescens,Medicago sativa,Menthahaplocalyx,Buchloe dactyloides and Castanea mollissima could effectively reduce the loss of phosphorus in slope farmland,and the intercropping model of Bromus japonicus and Castanea mollissima could reduce the nitrogen loss of slope farmland to a certain extent;in addition to Bromus japonicus and Castanea mollissima intercropping plots,the reduction rates of COD,BOD5 and TOC in runoff of other intercropping plots were 29.10%~95.04%,31.49%~93.60%and 16.76%~62.17%,respectively;(3)intercropping Castanea mollissima and Sophora flavescens had the best effect on reducing TN,TP and other non-point source pollution indicators,and its allocation effect was the best.Comprehensive evaluation was the most suitable for large-scale promotion.