闽江河口表层水体氧化亚氮释放时空变化特征及其影响因素  

Spatial and temporal variations and influencing factors of nitrous oxide emissions from surface water in Min River Estuary

作　　者：漆梦婷 罗柳 洪晓静 钱伟[1,2] 仝川[1,2] 李小飞[1,2] QI Mengting;LUO Liu;HONG Xiaojing;QIAN Wei;TONG Chuan;LI Xiaofei(School of Geography Science,Fujian Normal University,Fuzhou 350007;Key Laboratory of Humid Subtropical Eco-geographical Processes of Ministry of Education,Fujian Normal University,Fuzhou 350007)

机构地区：[1]福建师范大学地理科学学院,福州350007 [2]福建师范大学湿润亚热带生态-地理过程教育部重点实验室,福州350007

出　　处：《环境科学学报》2022年第7期489-500,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.42071130,41701548);福建省自然科学基金(No.2020J01184)。

摘　　要：以闽江口水体为研究对象,研究了闽江河口上段(城市河口段)、河口中段和河口下段(口外海滨段)不同季节水体N_(2)O的溶存浓度、水-气界面通量及其环境影响因子.结果表明,闽江口水体N_(2)O溶存浓度为0.99~55.92 nmol·L^(-1),N_(2)O饱和度为8.0%~396%,水-气界面N_(2)O释放通量为-5.21~7.91μg·m^(-2)·h^(-1).从季节差异看,7月(夏季)、9月(秋季)和12月(冬季)水体中N_(2)O过饱和,表现为N_(2)O的排放“源”;4月(春季)水体中N_(2)O不饱和,表现为N_(2)O“汇”.水-气界面N_(2)O释放通量呈夏、秋和冬季高,春季低的季节变化规律.在空间变化上,水-气界面N_(2)O释放通量从河口上段到下段降低,与氮含量变化趋势一致.N_(2)O间接性释放因子为0.004%~0.128%,低于IPCC推荐值(0.25%).温度、盐度、pH、NO_(3)^(-)、DO、悬浮颗粒物浓度是影响N_(2)O溶存浓度与释放通量的主要影响因素.因此,季节性变化和人类活动导致河口N_(2)O释放存在较大的时空差异性,从而增加了河口N_(2)O排放评估的不确定性.In this study,seasonal variability of N_(2)O concentrations and fluxes and associated environmental factors were investigated in the upper section(urban estuary),the middle section and the lower section(coastal section outside the estuary)of Min River Estuary.The results indicated that N_(2)O concentrations,N_(2)O saturations and N_(2)O fluxes were in a range of 0.99~55.92 nmol·L^(-1),8.0%~396%,and-5.21~7.91μg·m^(-2)·h^(-1).Water N_(2)O was supersaturated in July(summer),September(autumn)and December(winter),representing the"source"of N_(2)O emission.However,N_(2)O emissions exhibited the"sink"in April(spring).N_(2)O fluxes were significantly higher in summer,autumn and winter than in spring,and decreased from the upper to lower estuary.Indirect N_(2)O emission factors ranged from 0.004%to 0.128%,which was significantly lower than the IPCC default value(0.25%).Temperature,salinity,pH,NO_(3)^(-),DO and suspended particulate matter were the crucial factors affecting dissolved N_(2)O concentrations and fluxes.Therefore,seasonal changes and human activities can trigger the large variability of N_(2)O emissions,leading to the increasing uncertainty of N_(2)O projections.

关 键 词：氧化亚氮 溶存浓度 通量 温度 闽江口 

分 类 号：X171[环境科学与工程—环境科学]