粤西典型村域次降雨条件下非点源氮素排放特征  

Characteristics of Non-Point Source Nitrogen Emissions Under Individual Rainfall Events in a Typical Village Area in Western Guangdong,China

作　　者：徐垦 张芊芊 张思毅 郝贝贝 赵晓丽[3] 贺斌 XU Ken;ZHANG Qianqian;ZHANG Siyi;HAO Beibei;ZHAO Xiaoli;HE Bin(School of Environment,South China Normal University,Guangzhou 510006,China;Institute of Eco-Environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,China;State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China)

机构地区：[1]华南师范大学环境学院,广东广州510006 [2]广东省科学院生态环境与土壤研究所,广东广州510650 [3]中国环境科学研究院,环境基准与风险评估国家重点实验室,北京100012

出　　处：《环境科学研究》2024年第8期1725-1735,共11页Research of Environmental Sciences

基　　金：国家自然科学基金项目(No.42177065,41925031)。

摘　　要：粤西农业发达,施肥季降雨频繁,面源污染风险大。为研究粤西典型农业村镇不同土地利用类型在次降雨条件下的非点源氮素输出特征,采用降雨过程密集连续监测、雨后径流追踪监测的方法,结合降雨特征和土地利用类型分析降雨事件中氮素浓度及其形态的时空变化规律。结果表明:①监测点在降雨中总氮(TN)的事件平均浓度(EMC)为1.20~8.66 mg/L,其中溶解态氮(DN)占TN的比例最大,平均占比在43.23%~77.00%之间,DN又以溶解态氨氮(AN)为主,占比峰值达64.46%,氮素浓度表现为居民区>果园>农田。②结合氮浓度与径流量变化特征分析,发现氮素输出呈现两个峰值,其浓度随降雨时间的增加呈现先增后减的趋势,各形态氮素均存在初期冲刷效应,居民区最为显著,农田在整个降雨过程倾向于均匀输出。③降雨特征参数中,氮素浓度与前期干燥天数、降雨历时呈正相关,与最大降雨强度呈显著负相关,表明间隔多日的长时降雨会增加氮素输出风险,而雨强较大的降雨会起到稀释作用。氮素浓度受土地利用类型面积的影响,整体与农田、果园面积均呈显著负相关,与居民区面积呈显著正相关。④雨后氮素浓度在农田和果园呈先降后升的趋势,居民区则明显升高。农田沟渠对氮素存在消解作用,居民区是氮素的最大污染源。研究显示,粤西农业农村氮素面源污染要结合降雨和土地利用类型的污染特征对河道中(DN)进行精细化管控,同时要重视农村居民区的面源污染削减。The agriculture in western Guangdong Province,China,is highly developed,but frequent rainfall events in the fertilization season lead to a high risk of non-point source pollution.In order to study the characteristics of non-point source nitrogen output under different land use types in typical agricultural villages and towns in western Guangdong under single rainfall events,the methods of intensive continuous monitoring of the rainfall process and post rainfall runoff monitoring were adopted.The spatiotemporal changes in nitrogen forms and concentrations during rainfall events were studied by analyzing rainfall characteristics and land use type.The results showed that:(1)The event mean concentration of total nitrogen in rainfall was 1.20-8.66 mg/L,among which dissolved nitrogen accounted for the largest proportion of total nitrogen,with an average proportion of 43.23%-77.00%.Dissolved nitrogen was mainly dissolved ammonia nitrogen,accounting for 64.46%of the peak;the nitrogen concentration can be arranged in the order of residential area>orchard>farmland.(2)The coupling between different forms of nitrogen concentration and runoff characteristics indicated that the non-point source nitrogen output had two peaks;the nitrogen concentration first increased and then decreased with increasing rainfall duration.There was an initial scouring effect on all forms of nitrogen,especially in residential areas,and farmland often showed even output throughout the rainfall process.(3)Among the rainfall characteristic parameters,nitrogen concentration was positively correlated with the number of dry days in the early stage and the duration of rainfall;it was negatively correlated with the maximum rainfall intensity.This result indicates that long-term rainfall over many days increases the risk of nitrogen output,and rainfall events with higher rainfall intensity play a diluting role.The nitrogen concentration was greatly affected by the land use area,it was negatively correlated with farmland and orchard,and positively correlated

关 键 词：粤西 次降雨 氮素 非点源污染 事件平均浓度(EMC) 土地利用类型 

分 类 号：X592[环境科学与工程—环境工程]