Changes and potential drivers of CO2 emissions from inland waters in the Yangtze River Basin

Knowledge about the dynamics of carbon emissions from inland waters is crucial for robust estimates of land-atmosphere carbon fluxes under global change. However, it remains unknown how global change and regional human activities will affect carbon dioxide (CO2) emissions from inland waters in large river basins. Here, we quantify the seasonal surface water area, CO2 flux and annual CO2 emissions from lotic and lentic systems throughout the Yangtze River Basin during the 1980s and 2010s. We also employ the Random Forest model to assess the relative importance of various natural and anthropogenic factors on riverine CO2 partial pressure (pCO2). Our results indicate an expansion in reservoirs (+2680 km2 in water surface area) and a decline in river and lake areas (-1702 km2) between the 1980s and 2010s. We observe a substantial decline in CO2 emissions, decreasing from 52.69 +/- 13.11 Tg C yr- 1 in the 1980s to 31.20 +/- 5.37 Tg C yr- 1 in the 2010s. Our findings suggest a diminished influence of Gross Domestic Product (GDP) on riverine pCO2, coupled with the growing importance of natural factors (latitude, temperature and soil types), reflecting a significant shift from anthropogenic to natural control over river CO2 levels. This study highlights the importance of comprehending the intricate interactions between human activities and inland-water CO2 emissions in developing countries, which may contribute to the achievement of carbon neutrality goals.