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

It would he beneficial to better understanrl the emission conditions through measuring the greenhouse gas (CHG)emission from the Xiangxi River,an anabranch of Three Corges Reservoir,as well as to study the influence of the alga bloom on the CHG 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 resuits of other studies in various regions of Three Corges Reservoir,the average CH₄ emission from the Xiangxi River is low,which is obviously different from the(alculation based on some international approach based on the average for the entire region of the reservoir area.