太湖流域上游南苕溪水系夏秋季水体溶存二氧化碳和甲烷浓度特征及影响因素  

Characteristics and Drivers of Dissolved Carbon Dioxide and Methane Concentrations in the Nantiaoxi River System in the Upper Reaches of the Taihu Lake Basin During Summer-Autumn

作　　者：梁佳辉 田琳琳 周钟昱 张海阔 张方方[2] 何圣嘉 蔡延江 LIANG Jia-hui;TIAN Lin-lin;ZHOU Zhong-yu;ZHANG Hai-kuo;ZHANG Fang-fang;HE Sheng-jia;CAI Yan-jiang(State Key Laboratory of Subtropical Silviculture,Zhejiang A&F University,Hangzhou 311300,China;College of Environment and Resources,Zhejiang A&F University,Hangzhou 311300,China;College of Forestry and Biotechnology,Zhejiang A&F University,Hangzhou 311300,China)

机构地区：[1]浙江农林大学省部共建亚热带森林培育国家重点实验室,杭州311300 [2]浙江农林大学环境与资源学院,杭州311300 [3]浙江农林大学林业与生物技术学院,杭州311300

出　　处：《环境科学》2021年第6期2826-2838,共13页Environmental Science

基　　金：国家自然科学基金项目(41907268,41807154);长江水利委员会长江科学院开放基金项目(CKWV2019760/KY);浙江农林大学校科研发展基金项目(2018FR005,2018FR006,2018FR061)。

摘　　要：内陆水体是重要的活性碳(C)汇和温室气体潜在排放源.为查明太湖流域上游南苕溪水系夏秋季水体溶存二氧化碳(CO_(2))和甲烷(CH_(4))浓度特征及影响因素,于2019年7~11月进行水样采集,采用水-气顶空平衡-气相色谱法测定水体溶存CO_(2)浓度[c_(obs)(CO_(2))]和CH_(4)浓度[c_(obs)(CH_(4))],同步测定水体物理化学指标,分析水体c_(obs)(CO_(2))和c_(obs)(CH_(4))变化的主要影响因素.结果表明,观测期内南苕溪水体c_(obs)(CO_(2))及其饱和度[R(CO_(2))]和c_(obs)(CH_(4))及其饱和度[R(CH_(4))]的均值分别为(505.47±16.99)μg·L^(-1)、(256.31±8.32)%和(1.88±0.09)μg·L^(-1)、(5218.74±264.30)%;所有观测点位R(CO_(2))和R(CH_(4))均大于100%,表明南苕溪水体为CO_(2)和CH_(4)的潜在释放源.农业区水体c_(obs)(CO_(2))最高、居民点区次之、森林区最低,3种土地利用类型区水体间差异显著;居民点区水体c_(obs)(CH_(4))显著高于农业区与森林区.水体c_(obs)(CO_(2))、R(CO_(2))、c_(obs)(CH_(4))和R(CH_(4))均与氧化还原电位(ORP)负相关(P<0.01),与电导率(EC)正相关(P<0.01).叶绿素a(Chl-a)、硝态氮(NO_(3)^(-)-N)、总氮(TN)浓度和EC的差异是造成不同土地利用类型区水体c_(obs)(CO_(2))显著差异的主要原因;农业区和居民点区水体中较高的氮污染物浓度还可促进浮游植物生长并产生更活跃的呼吸作用,最终使两类型区水体c_(obs)(CO_(2))显著较高.居民点区水体中较高的可溶性有机碳(DOC)和铵态氮(NH_(4)^(+)-N)浓度及水温(WT)是导致该类型区水体c_(obs)(CH_(4))较高的主要原因.降雨对流域内不同土地利用类型区水体c_(obs)(CO_(2))和c_(obs)(CH_(4))都产生一定的影响,雨后农业区水体氮污染物浓度增大和居民点区水体DOC浓度增加分别是造成农业区水体c_(obs)(CO_(2))和居民点区水体c_(obs)(CH_(4))较高的主要原因.Inland waters are vital sinks for active carbon(C)and potential sources of greenhouse gas emissions.In this study,the characteristics of dissolved carbon dioxide(CO_(2))and methane(CH_(4))concentrations in the Nantiaoxi River system in the upper reaches of the Taihu Lake basin were observed between Jul.2019 and Nov.2019(summer and autumn)using headspace equilibration-gas chromatography.Simultaneously,physical and chemical parameters were also determined to understand the factors influencing dissolved CO_(2)and CH_(4)concentrations.The results showed that the mean dissolved CO_(2)concentrations and saturation levels in water were(505.47±16.99)μg·L^(-1)and(256.31±8.32)%,respectively,and the corresponding values for CH_(4)were(1.88±0.09)μg·L^(-1)and(5218.74±264.30)%,respectively.The saturation levels of dissolved CO_(2)and CH_(4)at all observation points were greater than 100%,indicating that the Nantiaoxi River system is a potential source of CO_(2)and CH_(4).The highest mean dissolved CO_(2)concentrations in water were found in agricultural areas followed by residential and forest areas,and there were significant differences among the three land-use types.The mean dissolved CH_(4)concentrations in the water in residential areas were significantly higher than those in agricultural area forest areas.The dissolved CO_(2)concentrations,saturation levels of CO_(2),dissolved CH_(4)concentrations,and saturation levels of CH_(4)in water were all negatively correlated with oxidation reduction potential(ORP)(P<0.01)and positively correlated with electrical conductivity(EC)(P<0.01).The discrepancies in chlorophyll(Chl-a),nitrate(NO_(3)--N),total nitrogen(TN),and EC were the main reasons for differences in dissolved CO_(2)concentrations among the different land use types.Phytoplankton growth could be promoted by the higher input of nitrogen pollutants into rivers in agricultural and residential areas,and respiration could be also enhanced,resulting in higher dissolved CO_(2)concentrations.The higher concentrations of

关 键 词：南苕溪 不同土地利用类型 溶存二氧化碳浓度 溶存甲烷浓度 空间差异 

分 类 号：X16[环境科学与工程—环境科学]