Redistribution of Soil Organic Carbon Induced by Soil Erosion in the Nine River Basins of China

Global soil erosion redistributes a large amount of soil organic carbon (SOC) and is potential to significantly change the terrestrial carbon budget. However, there are large uncertainties in the redistribution of SOC within the terrestrial and aquatic ecosystems. Based on two national survey data sets on soil erosion and sediment measurements from hydrological stations, this study estimated the redistribution of sediment and SOC in the nine river basins of China during 1995-1996 and 2010-2012. Over these two periods, 3.55-4.50 Pg of soil and 68.42-77.32 Tg C of SOC were eroded each year. For the SOC budget, on average 57% and 47% of the eroded SOC was deposited over land, 25% and 44% was deposited in the channel, and 18% and 8% was delivered into the sea during 1995-1996 and 2010-2012, respectively. Compared with the corresponding magnitudes during 1995-1996, the eroded SOC, the SOC deposited over land, and the SOC discharged into the sea decreased during 2010-2012, and only the SOC deposited into the river channel increased (from 19.5 to 30.1 Tg C yr(-1)). The changes in SOC deposition in the channel of the Yangtze River and the Yellow River basins demonstrate that the influence of human activities is extensive. Our results show that the erosion-induced redistribution of SOC alters the carbon budget of China.