三峡水库香溪河支流水域温室气体排放通量观测

Observation on greenhouse gas emissions from Xiangxi River in Three Gorges Region

开展对香溪河支流水体的温室气体排放观测,有助于增加对三峡水库支流温室气体排放情况的了解以及水华对温室气体排放的影响。研究采用静态箱-气相色谱法,于2009年10月至2010年10月先后11次开展对香溪河支流水体3种温室气体(二氧化碳、甲烷、氧化亚氮)排放强度的观测,结果表明:观测期间香溪河支流的二氧化碳平均排放通量约为76.52 mg/(m2.h),排放强度与水体中叶绿素a浓度呈显著负相关,支流水华期间,二氧化碳排放通量小于0,表现为对大气中二氧化碳的吸收;支流甲烷平均排放通量约为0.244 9 mg/(m2.h);氧化亚氮平均排放水平约为0.011 7 mg/(m2.h)。通过将甲烷平均排放水平与三峡水库其它区域开展的研究结果进行对比表明:三峡水库的甲烷排放水平很低,明显不同于已有基于国外水库平均排放水平对三峡水库全区甲烷排放的估算结果。

It would be beneficial to better understand the emission conditions through measuring the greenhouse gas（GHG） emission from the Xiangxi River,an anabranch of Three Gorges Reservoir,as well as to study the influence of the alga bloom on the GHG emission.Using floating chambers,CO2,CH4 and N2O emissions from the Xiangxi River were measured by 11 times field observations from October 2009 to October 2010.The observational result shows that the average CO2 emission is 76.52mg/（m2 · h）,and the intensity is negatively correlated to the chl-a concentration.The CO2 intensity falls below zero during the alga bloom,showing absorption.While the CH4 and N2O emissions,the average values are 0.244 9 mg/（m2 · h） and 0.011 7 mg/（m2 · h）,respectively.Compared to the results of other studies in various regions of Three Gorges Reservoir,the average CH4 emission from the Xiangxi River is low,which is obviously different from the calculation based on some international approach based on the average for the entire region of the reservoir area.