【作者】 陈功伟；

【导师】 倪才英；

【作者基本信息】 江西师范大学 ， 自然地理学， 2020， 硕士

【摘要】 水库是大气甲烷（CH₄）重要的排放源。为了揭示亚热带水库水体溶解性CH₄时空分异特征,本研究以福建省古田水库为研究对象,在水库的丰水期、枯水期与平水期对库区水体溶解性CH₄及其环境因子进行测定与分析。研究结果表明:（1）古田水库水体表层溶解性CH₄的浓度变化范围为0.05-0.40μmol·L^-1表现为:丰水期>枯水期>平水期。空间上,丰水期北部库区较高,东部库区较低。枯水期在水库出入口处浓度较低,中间区域浓度较高。平水期在北部、东部库区浓度较低,南部库区浓度较高,南北差异显著。丰水期溶解性CH₄和pH正相关与NO₃^–负相关,枯水期溶解性CH₄浓度分布与NH₄⁺和NO₃^–负相关。平水期溶解性CH₄浓度与叶绿素（Chla）和NO₃^–负相关。（2）丰水期库区水体溶解性CH₄的浓度高于上下游河流,但是库区水体NH₄⁺和NO₃^–显著低于上游河流。枯水期库区水体溶解性CH₄的浓度与上游河流浓度略低,较下游河流略高,库区水体溶解性无机碳（DIC）和NO₃^–浓度显著低于上下游河流。平水期上下游河流水体溶解性CH₄显著高于库区水体。三个时期库区水体的pH与Chla的浓度均高于上下游河流。（3）利用LM86、CW03、MY95和RC01四个模型计算水库水气界面CH₄通量结果分别为:0.41±0.29μmol·m^-2·h^-1、1.09±0.79μmol·m^-2·h^-1、1.33±0.99μmol·m^-2·h^-1和5.54±3.74μmol·m^-2·h^-1。与溶解性CH₄浓度不同,CH₄扩散通量时间上均表现为丰水期>平水期>枯水期。空间上,丰水期水气界面CH₄扩散通量与溶解性CH₄一致;枯水期和平水期南部库区较高,北部和东部库区CH₄扩散通量较低。以上研究结果表明,库区水体是CH₄的排放源。库区水体表层溶解性CH₄浓度以及模型估算的CH₄排放量在不同的时期,均呈现出较大的空间异质性,各个时期之间也存在较大的差异。水体中的NH₄⁺、NO₃^–、pH和Chla是引起溶解性CH₄时空分布差异的主要因素。在CH₄排放量估算和预测时,需要充分考虑水库的年内变化和水库水体溶解性CH₄的空间异质性。更多还原

【Abstract】 In order to reveal the spatial-temporal distribution of dissolved CH₄ in subtropical reservoirs,the study examined and analyzed of concentrations of dissolved CH₄ and its environmental factors in the water body of the Gutian reservoir,Fujian Province,and upper and lower reaches during the high flow,the low flow and the medium flow.The results show that:（i）The concentrations of dissolved CH₄ in Gutian Reservoir ranged from 0.05 to0.40μmol·L^-1,and listed as high flow>low flow>medium flow.During three periods,were higher during the high flow compared with dry and medium flow.During the high flow,the concentrations of dissolved CH₄ was higher in the north and lower in the east,while the concentrations were lower at the inlet and higher in the middle area during the dry season.During the medium flow,the concentrations of dissolved CH₄ were lowest in the north and east and highest in the south of the reservoir.The difference of the concentrations of dissolved CH₄ was significant between north and south.The concentrations of NO₃^–and pH were the main factors affecting the spatial differentiations of dissolved CH₄ concentrations during the high flow,the concentrations of NO₃^–and NH₄⁺were closely related to dissolved CH₄ concentrations in the low flow.Lastly,during the medium flow,the concentrations of dissolved CH₄ were mainly affected by the concentrations of Chla and NO₃^–.（ii）During the high flow,the concentrations of dissolved CH₄ in the reservoir were higher than those in the upstream and downstream,while the concentrations of NH₄⁺and NO₃^–are significantly lower than those in the upstream.During the low flow,the concentrations of dissolved CH₄ in the reservoir were comparable than those in the upstream and were slightly higher than those in the downstream.The concentration of DIC and NO₃^–in the reservoir area is significantly lower than that in the upstream and downstream rivers.During the medium flow,the concentrations of dissolved CH₄ were higher in the river compared with the reservoir.Across three periods,all the pH and the concentrations of Chla were higher in the reservoir than all the streams.（iii）According to the model LM86、CW03、MY95 and RC01,the CH₄ emission fluxes of reservoir were 0.41±0.29,1.09±0.79,1.33±0.99 and 5.54±3.74μmol·m^-2·h^-1.Different with the concentrations of dissolved CH₄,the CH₄ emission fluxes listed as follow:high flow>medium flow>low flow.During the high flow,the spatial distributions of CH₄ emission fluxes were similar with the concentrations of dissolved CH₄.During the other periods,the CH₄ emission fluxes were higher in the south and lower in the north and east of the reservoir.Combined,this result suggested that the reservoir is the source of CH₄ emission.The concentrations of dissolved CH₄ of the reservoir and the CH₄ emission fluxes changed across different periods and across the reservoir.The concentrations of NH₄⁺,NO₃^–and Chla and pH are the main environmental factors to determine the distributions of CH₄emission fluxes.In the future,the spatial-temporary changes of dissolved CH₄concentrations should be considered in the predicting CH₄ fluxes.更多还原