Comparison of carbon emissions from the southern and northern tributaries of the Three Gorge Reservoir over the Changjiang River Basin, China

Abstract Greenhouse gas emissions from the Three Gorges Reservoir (TGR) have received an increasing amount of attention in recent years because of concerns related to regional climate change and clean energy production. The present study compared the greenhouse gas emissions from the Modaoxi and Shennongxi rivers as the southern and northern tributaries of the TGR. Results indicated that mean annual fluxes of carbon dioxide (CO2) and methane (CH4) were 55.8950 ± 92.9469 mg m−2 h−1 and 0.2544 ± 0.9066 mg m−2 h−1 along the Shennongxi River and 77.0298 ± 168.8724 mg m−2 h−1 and 0.2694 ± 1.1006 mg m−2 h−1 along the Modaoxi River, respectively. While more CO2 was released along the Modaoxi River, the methane emissions were similar for these two tributaries. Multivariate analysis indicated that water quality variables were more closely correlated with CO2 emissions along the Shennongxi River than along the Modaoxi. Conversely, methane emissions were more closely correlated with water quality variables along the Modaoxi River than along the Shennongxi. Carbon emissions in these two tributaries were mainly affected by inorganic carbon in the water. Organic carbon in the water had almost no effect on carbon emissions in these two tributaries. Further analysis showed that eutrophication and algal blooms may generate the largest amounts of greenhouse gas emissions from the Shennongxi River basin, while farming and carbon input from the drawdown area may be the crucial factors affecting carbon emissions in the Modaoxi River basin.