南苕溪河岸带景观格局对水体氮素浓度的影响  

ffects of landscape pattern in riparian buffer on water nitrogen concentrations in the South Tiaoxi River

作　　者：陈学兵 王烁 刘富平 马小雪 田琳琳 陈健[1,3,7] 李彦 蔡延江 CHEN Xue-bing;WANG Shuo;LIU Fu-ping;MA Xiao-xue;TIAN Lin-lin;CHEN Jian;LI Yan;CAI Yan-jiang(National Key Laboratory for Development and Utilization of Forest Food Resources,Zhejiang A&F University,Hangzhou 311300,China;College of Environmental and Resource Sciences,Zhejiang A&F University,Hangzhou 311300,China;College of Forestry and Biotechnology,Zhejiang A&F University,Hangzhou 311300,China;CAS Key Laboratory of Aquatic Botany and Watershed Ecology,Wuhan Botanical Garden,Chinese Academy of Sciences,Wuhan 430074,China;College of Geosciences,Jiangsu Second Normal University,Nanjing 210013,China;Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 211135,China;Tianmushan Forest Ecosystem National Orientation Observation and Research Station of Zhejiang Province,Hangzhou 311300,China)

机构地区：[1]浙江农林大学,森林食物资源挖掘与利用全国重点实验室,浙江杭州311300 [2]浙江农林大学环境与资源学院、碳中和学院,浙江杭州311300 [3]浙江农林大学林业与生物技术学院,浙江杭州311300 [4]中国科学院武汉植物园,中国科学院水生植物与流域生态重点实验室,湖北武汉430074 [5]江苏第二师范学院地理科学学院,江苏南京210013 [6]中国科学院南京地理与湖泊研究所,江苏南京211135 [7]浙江天目山森林生态系统国家定位观测研究站,浙江杭州311300

出　　处：《中国环境科学》2025年第4期1925-1938,共14页China Environmental Science

基　　金：国家自然科学基金资助项目(41907268,42406234);浙江省领雁研发攻关计划项目(2022C02019);浙江农林大学校科研发展基金资助项目(2018FR005,2018FR006,2018FR061)。

摘　　要：基于2019~2022年太湖流域上游南苕溪流域的实测数据,分别利用冗余分析(RDA)和非参数变点分析(nCPA)确定流域氮(N)素浓度与不同尺度河岸带景观格局指数的关系和影响水体硝态氮(NO_(3)^(-)-N)浓度变化的关键景观阈值区间(景观格局指数阈值).结果显示:南苕溪流域总氮(TN)浓度超过地表水Ⅴ类标准,NO_(3)^(-)-N是主要N污染物赋存形态.湿季水体TN、溶解性总氮(DTN)、NO_(3)^(-)-N和溶解性有机氮(DON)浓度均显著高于干季,而铵态氮(NH_(4)^(+)-N)浓度则相反;上游河段N素浓度低于下游河段.400和200m河岸带缓冲区内景观格局指数分别对湿季和干季水体N素浓度解释度最高(89.49%和90.97%).在确定降低流域水体NO_(3)^(-)-N污染风险的关键景观格局指数阈值分析的基础上,建议在400m河岸带缓冲区内调控耕地、建设用地面积占比及香农多样性指数(SDHI)分别低于0.25%、1.75%和0.77;在200m河岸带缓冲区内调控耕地面积占比和边缘密度(ED)分别应低于0.5%和39m/hm^(2),且林地面积占比应高于91.0%.Based on field data from 2019 to 2022 in the South Tiaoxi River Watershed in the upper reaches of the Taihu Lake Basin,redundancy analysis(RDA)and non-parametric breakpoint analysis(nCPA)were employed to analyze the relationships between riverine nitrogen(N)concentrations and landscape pattern indices at different buffer scales,and identity the critical landscape threshold ranges affecting the river nitrate(NO_(3)^(-)-N)concentration.The results showed that the total nitrogen(TN)concentration in the South Tiaoxi River exceeded the Class V surface water quality standard,with NO_(3)^(-)-N as the predominant N pollutant.During the wet season,the concentrations of TN,dissolved total nitrogen(DTN),NO_(3)^(-)-N,and dissolved organic nitrogen(DON)were significantly higher than those in the dry season,whereas ammonium nitrogen(NH_(4)^(+)-N)concentrations were lower.N concentrations were lower in the upstream compared to downstream.The landscape pattern indices in the buffer zones of 400m and 200m explained the largest variance in river N concentrations during the wet and dry seasons,respectively(89.49%and 90.97%).Based on the identified key thresholds of landscape pattern indices for significantly reducing the risk of NO_(3)^(-)-N pollution in the watershed,the following suggestions are provided:the proportion of farmland,construction land,and Shannon diversity index(SDHI)in the buffer zone of 400m should be controlled within 0.25%,1.75%,and 0.77,respectively;and the proportion of farmland and edge density(ED)in the buffer zone of 200m should be kept within 0.5%and 39m/hm^(2),simultaneously with the proportion of forest area exceeding 91.0%.

关 键 词：硝态氮(NO_(3)^(-)-N) 河岸缓冲带 景观组成 景观配置 景观格局指数阈值 尺度效应 

分 类 号：X524[环境科学与工程—环境工程]