城市小型景观水体溶存N;O浓度及排放通量特征  

Spatiotemporal variations and influencing factors of N;O concentration and flux from urban small landscape waters

作　　者：庞吉丽 王晓锋 刘婷婷[4] 吴胜男 黄婷 赵舒宁 吴文洁 陈彦蓉 PANG Jili;WANG Xiaofeng;LIU Tingting;WU Shengnan;HUANG Ting;ZHAO Shuning;WU Wenjie;CHEN Yanrong(Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River,Chongqing 401331,China;Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station,Chongqing 405400,China;College of Geography and Tourism,Chongqing Normal University,Chongqing 401331,China;State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200241,China)

机构地区：[1]长江上游湿地科学研究重庆市重点实验室,重庆401331 [2]三峡库区地表生态过程重庆市野外科学观测研究站,重庆405400 [3]重庆师范大学地理与旅游学院,重庆401331 [4]华东师范大学河口海岸研究所,上海200241

出　　处：《生态学报》2021年第22期8991-9007,共17页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(41807321);重庆市基础研究与前沿探索项目(cstc2018jcyjAX0672);重庆市教委研究项目(KJQN201800530);重庆师范大学博士科研启动项目(17XLB023)。

摘　　要：淡水生态系统是大气中N_(2)O的重要排放源,受到国内外广泛关注。城市小型景观水体作为区域淡水系统的重要组成,具有环境容量小,受人类活动干扰强烈,其N_(2)O排放特征及影响机制并不清楚。选择重庆大学城8个典型景观水体和2个城市外围的自然水体(对照)作为研究对象,利用顶空法和漂浮箱法对水体溶存N_(2)O浓度及排放通量进行季节性监测,并通过分析生境特征及水环境特征,探究城市小型景观水体N_(2)O排放特征及关键影响因素。结果表明:1)小型景观水体TN、NO_(3)^(-)-N、NH_(4)^(+)-N、NO_(3)^(-)-N含量总体偏低但变异性极强(变化范围分别为0.31-1.47 mg/L、0.05-0.79 mg/L、0.03-0.14 mg/L、0.00-0.04 mg/L),硝态氮是主要的氮形态;景观水体氮丰度远高于外围的自然水体;2)10个小型水体N_(2)O浓度范围为16.51-158.96 nmol/L,平均为(47.60±21.47)nmol/L,均处于过饱和状态;漂浮箱法实测8个景观水体N_(2)O排放通量均值为(0.13±0.05)mmol m^(-2)d^(-1),是对照水体的1.3-5.2倍,高于大部分已有研究结果,是大气N_(2)O的排放热源;3)景观水体N_(2)O排放通量与水体各形态氮含量呈显著的正相关关系,较高的N负荷和强烈的氮转化过程是导致景观水体成为N_(2)O排放热源的主要因子,水体N含量可以作为景观水体N_(2)O排放强度的有效指示因子;同时水生植物分布对水体N_(2)O排放影响显著,有植物分布的水域比开敞水域高1.4倍;4)漂浮箱法和边界层模型法对小型景观水体N_(2)O排放通量的监测结果呈较好的线性关系,但不同季节仍存在着一定差异,需要进一步优化模型估算方法;5)水体N_(2)O排放通量对温度的季节性变化较为敏感,呈夏季最高,春、秋季次之,冬季最低的季节模式。本研究强调,城市小型景观水体具有较高的N_(2)O排放速率,在区域氮循环及全球淡水系统温室气体排放清单中具有不可忽视的作用,在未来研究中应得�Nitrous oxide(N_(2)O)is an important greenhouse gas that contributes to climate change and stratospheric ozone destruction.Freshwater ecosystem,acting as a sink of the terrestrial and anthropogenic nitrogen,continuously processes nitrogen loading and emits N_(2)O to atmosphere.Human perturbation of the global nitrogen cycle has seriously increased nitrogen loading and N_(2)O emission from aquatic ecosystems and gained widespread attention.Urban small-scale landscape water bodies,as a significant component of the regional freshwater systems but small environmental capacity,are strongly disturbed by human activities and have an unclear nitrogen processing efficiency.As result of small area,the N_(2)O emission from urban small landscape waters has not been concerned world widely.In this study,we selected eight typical landscape water bodies and two natural water bodies in Chongqing,and carried out four seasonal investigations of the dissolved N_(2)O concentrations and N_(2)O fluxes from the surface water by floating chamber method and headspace method in order to clarify the spatiotemporal variations and the key influencing factors of N_(2)O emission from small landscape waters.The results showed that:1)TN,NO_(3)^(-)-N,NH_(4)^(+)-N,and NO_(3)^(-)-N concentrations in the sampling water bodies were generally low but significantly different from each other with range of 0.31-1.47 mg/L,0.046-0.789 mg/L,0.031-0.141 mg/L,0.003-0.041 mg/L,respectively.NO_(3)^(-)-N was the main nitrogen form in landscape waters.Besides,the nitrogen abundance of landscape waters was significantly higher than that of the natural waters.2)The dissolved N_(2)O concentrations in all sampling waters ranged from 16.51-158.96 nmol/L,average of(47.60±21.47)nmol/L,and were all observably oversaturated with N_(2)O relative to atmospheric equilibrium,acting as net N_(2)O sources to the atmosphere.The N_(2)O concentrations in the eight landscape waters were two times higher than those in the tow natural water bodies.The average N_(2)O fluxes measured b

关 键 词：景观水体 氮形态 N O排放通量 时空变异性 影响因素 

分 类 号：X52[环境科学与工程—环境工程]