青藏高原东北部更尕海7—9月水-气界面CH_(4)、N_(2)O交换通量变化及其影响因素  

Variations in CH_(4)and N_(2)O Exchange Fluxes at theWater-Air Interface and Their Influencing Factors in Genggahai Lake in the Northeastern Qinghai-Xizang Plateau from July to September

作　　者：刘铖霖 金彦香 金鑫 林嘉欣 李渊 LIU Chenglin;JIN Yanxiang;JIN Xin;LIN Jiaxin;LI Yuan(Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation Ministry of Education,Qinghai Normal University,Xining,810008,China;Qinghai Provincial Key Laboratory of Physical Geography and Environmental Process,College of Geographical Science,Qinghai Normal University,Xining,810008,China;Academy of Plateau Science and Sustainability,Xining,810008,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,730000,China)

机构地区：[1]青海师范大学,青藏高原地表过程与生态保育教育部重点实验室,青海西宁810018 [2]青海师范大学地理科学学院,青海省自然地理与环境过程重点实验室,青海西宁810018 [3]高原科学与可持续发展研究院,青海西宁810018 [4]中国科学院西北生态环境资源研究院,甘肃兰州730000

出　　处：《盐湖研究》2024年第1期20-28,共9页Journal of Salt Lake Research

基　　金：国家自然科学基金(42201174);青海省应用基础研究项目(2023-ZJ-728)。

摘　　要：为了解青藏高原浅水草型湖泊水-气界面CH_(4)与N_(2)O通量的交换机制,以青藏高原东北部的更尕海为例,分别在2021年7月、8月、9月采用漂浮静态箱-气相色谱仪法对其水-气界面CH_(4)、N_(2)O交换通量进行连续、定点观测,并结合流域气象、湖泊水环境探讨其影响因素。结果表明:(1)更尕海水-气界面CH_(4)交换通量平均值为0.557 mg(/m^(2)·h),整体表现为源;N_(2)O交换通量平均值为-0.100μg(/m^(2)·h),整体表现为弱汇。(2)在空间上,受水生植物分布差异影响,更尕海黄苔分布区为水-气界面CH_(4)排放的热点区域,其次为狐尾藻分布区,无植被分布区最低。N_(2)O交换通量的变化受污染负荷的影响,粪便排放区是N_(2)O排放的热点区域。(3)在时间上,CH_(4)交换通量的变化则受温度影响,CH_(4)排放峰值主要出现于15:00时;N_(2)O交换通量的变化与沉水植物的光合作用有关。沉水植物光合作用向水体释放O_(2)并使pH升高,从而抑制了沉积物中的反硝化作用与微生物活性,使得湖泊整体表现为N_(2)O的“汇”。(4)相较于中国东部湖泊,青藏高原气压低,使得水体DO含量相对较低,减弱了水体对CH_(4)的氧化作用,还降低了水体中CH_(4)的溶解度,导致青藏高原湖泊CH_(4)排放通量显著高于中国东部湖泊。而青藏高原湖泊受人类活动的干扰较小,外源性污染较轻,造成该区域N_(2)O排放通量显著低于中国东部湖泊。Lakes in Qinghai-Xizang Plateau(QTP)account for more than 50%of the total lake area in China.However,due to the lack of fixed-point monitoring data from a variety of lakes,considerable uncertainty exists in CH_(4)and N_(2)O exchange mechanism in QTP lakes.Here we present CH_(4)fluxes(FCH_(4))and N_(2)O fluxes(FN_(2)O)at the water-air interface in Genggahai Lake(GGH Lake),a shallow macrophytic lake in northeastern QTP.The FCH_(4)and FN_(2)O were observed continuously during daytime from July to September in 2021 based on the floating chamber-gas chromatography method.In combination with meteoric data within the watershed,and the GGH lake water environmental parameters,the spatial-temporal change characteristics of FCH_(4)and FN_(2)O and their influencing factors were analyzed.The results showed that the average daily FCH_(4)was 0.557 mg(/m^(2)·h),and the GGH Lake was a source of atmospheric CH_(4);and the average daily FN_(2)O was-0.100μg(/m^(2)·h),and the GGH Lake was a weak sink of atmospheric N_(2)O.Because the distribution of aquatic plants species is different,there are differences in the FCH_(4)at the water-air interface in these different aquatic plants growth area.Among these areas,the FCH_(4)was the highest in yellow moss distributed area,whereas in none aquatic plants distributed area,the FCH_(4)was the lowest.Probably influenced by pollutant loads,variations in FN_(2)O showed great spatial heterogeneity.The fecal discharge zone is a hotspot area for N_(2)O.Affected by atmospheric temperature,the peak of FCH_(4)mainly occurred in 15:00.The daily variation in FN_(2)O was likely influenced by the photosynthesis of submerged aquatic plants.During photosynthesis,the submerged plants release O_(2)to the waterbody,which caused the pH increasing.Then denitrification and microbial activities in the lake sediment were inhibited,resulted in the significantly negative correlationship between FN_(2)O and pH and ORP.Due to the relatively lower local air pressure in theQTP,the contents ofDOin thewaterbody and the o

关 键 词：青藏高原 浅水草型湖泊 水-气界面 甲烷 氧化亚氮 

分 类 号：X511[环境科学与工程—环境工程]