摘要
随着云南大理洱海西侧冲积扇和湖相沉积层平原区域旅游业和农业快速发展,扇缘农业种植活动和扇中人类活动产生大量三氮污染物,由苍山18溪入渗补给使得受氮素污染地下水不断向洱海排泄,使得高原湖泊水体富营养化风险进一步增大。河床潜流带对于入渗的地表水具有净化作用,为了深入研究冲积扇河床潜流带对氮素迁移及转化机制,通过模拟河床潜流带渗滤系统,结合扇中城镇生活污水下渗污染、扇缘农田施肥垂直下渗污染以及扇顶基流地表水和地下水交替补给迁移污染,为河床潜流带地下水氮素污染防治奠定基础。试验结果表明河床潜流带对氮素迁移转化影响明显,扇中NH4+-N和NO3--N在垂向入渗时主要是通过反硝化作用进行脱氮达到水质净化的目的,总体划分为正面效应和负面效应两类,正效应包括阴阳离子交替吸附作用、硝化与反硝化作用的脱氮行为,导致污染物浓度降低使水净化的过程,主要以反硝化作用为主硝化反应为辅进行脱氮;负面效应则是硝化作用和阴阳离子吸附作用使总硬度随着水体析出的Ca2+、Mg2+浓度的升高而升高。扇顶交替流作用下,NO3--N的迁移转化通过以反硝化作用为主,DNRA为辅去氮达到水质净化的过程。
With the rapid development of tourism and agriculture in the alluvial fan and lacustrine sedimentary plain on the western side of Erhai Lake in Dali,Yunnan Province,large amounts of NH-N,NO,-N,and NO,-N pollutants have been generated by agricultural cultivation at the margins of the alluvial fan and by human activities within the alluvial fan.The infiltration of the 18 streams in the Cangshan Mountains drives the nitrogen-contaminated groundwater to continuously discharge into Erhai Lake,which further increases the risk of eutrophication of the water bodies of the alpine lake.The hyporheic zone has a purifying effect on the infiltrated surface water.To investigate the migration and removal patterns of nitrogen in the hyporheic zone in the alluvial fan,a simulated infiltration system of the hyporheic zone was designed,including three hydrological processes affecting the migration of the aforementioned nitrogen pollutants,namely,the infiltration of urban domestic sewage in the alluvial fan,the vertical infiltration of fertilizer applied at the margins of the alluvial fan,and the alternate recharge of the hyporheic zone by surface water and groundwater at the apex of the alluvial fan.The experimental results revealed that the hyporheic zone has good NH,t-N and NO;-N removal efficiencies.Their removal in the alluvial fan mainly relies on denitrification during their vertical infiltration,which generally involves two processes with opposite effects:(1)a positive-effect process involving the alternate adsorption of anions and cations in the hyporheic zone,accompanied by nitrification and denitrification,where denitrification is the primary nitrogen removal step and nitrification plays a supplementary role,leading to pollutant concentration reduction and water purification,and(2)a negative-effect process involving nitrification and anion/cation adsorption followed by the release of Ca*and Mg*into the aqueous phase,leading to increased total hardness of the water.During the alternate recharge of the hyporheic zone by sur
作者
覃荣高
陈祥森
曹广祝
李金荣
强毅
路艳峰
QIN Ronggao;CHEN Xiangsen;CAO Guangzhu;LI Jinrong;QIANG Yi;LU Yanfeng(School of Land and Resources Engineering,Kunming University of Science and Technology,Kunming 650031 China;Key Laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area of Ministry of Natural Resources,Kunming 650228,China;College of Ecology and Environment,Zhengzhou University,Zhengzhou 450001,China)
出处
《环境科学与技术》
CAS
CSCD
北大核心
2023年第6期16-24,共9页
Environmental Science & Technology
基金
国家自然科学基金项目(42167052,42267063)。
关键词
高原湖泊
河床潜流带
溶质迁移
氨氮
硝态氮
地表水-地下水
plateau lake
hyporheic zone
solute transport
ammonia nitrogen
nitrate nitrogen
surface water-groundwater
