农村多水塘系统景观结构对非点源污染中氮截留效应的影响  

Effect of Different Multi-pond Network Landscape Structures on Nitrogen Retention Over Agricultural Watersheds

作　　者：李玉凤 刘红玉 刘军志 娄彩荣 王娟 LI Yu-feng1 , LIU I-Iong-yu1 , LIU Jun-zhi1 , LOU Cai-rong1, WANG Juan1(1. College of Marine Science and Engineering, Nanjing Normal University, Nanjing 210023, China; 2. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, State Key Laboratory Cultivation Base of Geographical Environment Evolution, College of Geographical Science, Nanjing Normal University, Nanjing 210023, China)

机构地区：[1]南京师范大学海洋科学与工程学院,南京210023 [2]南京师范大学地理科学学院江苏省地理信息资源开发与利用协同创新中心江苏省地理环境演化国家重点实验室培育建设点,南京210023

出　　处：《环境科学》2018年第11期4999-5006,共8页Environmental Science

基　　金：国家自然科学基金项目(41871188;31570459;41601413);江苏省基础研究计划(自然科学基金)项目(BK20140921);江苏省高校自然科学研究重点项目(15KJA170002);江苏省重点研发计划项目(BE2018681)

摘　　要：多水塘系统在滞留和降解农业面源污染中发挥着巨大作用.不同景观结构特征的多水塘系统对农业面源污染的截留率也存在差异.本文针对多水塘系统的功能及特点,选择4个不同景观结构的小流域作为研究区域,分析降雨前后多水塘系统水环境的变化特征及其对氮元素的截留情况,并揭示其截留率与水塘系统景观结构之间的关系.结果表明:(1)雨前水塘水体中总氮(TN)浓度的变化范围在1. 32～6. 32 mg·L^(-1)之间,雨后TN质量浓度增加到2. 8～16. 99 mg·L^(-1)之间,其中,硝氮(NO_3^--N)占TN的质量分数为20%～74%;(2)多水塘系统对TN、NO_3^--N和氨氮(NH_4^+-N)的平均截留率分别为50. 09%、48. 71%和52. 75%;(3)小流域1中的水塘系统对氮的截留率最低,平均次降水过程中小流域2中的水塘系统对氮的截留量最低,仅为56. 10kg,远低于小流域4中水塘系统对氮的截留量324. 43kg;(4)多水塘系统对氮的截留率受到水塘个数、面积及水塘与水塘之间沟渠密度的影响,其中沟渠密度对氮截留率的影响最大.本研究结果可为农村多水塘系统的管理及规划提供科学依据.Nitrogen（ N） loss from agricultural fields can cause eutrophication in downstream freshwater systems,but the use of multipond networks can mitigate N losses from agricultural runoff. This study presents an analysis of the relationships between N retention and land use before and after rainfall events with the goal of identifying differences in agricultural runoff in four sub-watersheds with 3,3,7,and 7 ponds,respectively. The total N concentrations before rainfall ranged from 1. 32 mg·L^-1 to 6. 32 mg·L^-1,and total N（ TN） levels in the ponds after rainfall varied from 2. 8 mg·L^-1 to 16. 99 mg·L^-1 and typically contained 20%-74% nitrate（ NO3^--N）. The mean concentration retention efficiencies in the four sub-watersheds for TN,NO3^--N,and ammonium（ NH4^＋-N） were50. 09%,48. 71%,and 52. 75%,respectively. The N retention efficiency in sub-watershed 1（ 3 ponds） was the lowest among the four sub-watersheds. The N retention mass in sub-watershed 2（ 3 ponds） was only 56. 10 kg,and this value was far lower than that of sub-watershed 4（ 324. 43 kg,7 ponds）. The number of ponds in the sub-watersheds was not the only factor that contributed to the effective retention of non-point source N in-situ,but pond area and ditch density also significantly affected N retention. Thus,pond area and ditch density should be increased for similar multi-pond areas. However,managing multi-ponds to maximize N retention requires dynamic monitoring and management over the long term.

关 键 词：多水塘系统 非点源污染 氮截留 农村流域 景观结构 

分 类 号：X52[环境科学与工程—环境工程]