Yue Yao, Ni Jinren, Ciais Philippe, Piao Shilong, Wang Tao, Huang Mengtian, Borthwick Alistair G L, Li Tianhong, Wang Yichu, Chappell Adrian, Van Oost Kristof
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China; School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, People's Republic of China;
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China;
Proc Natl Acad Sci U S A. 2016 Jun 14;113(24):6617-22. doi: 10.1073/pnas.1523358113. Epub 2016 May 31.
Soil erosion by water impacts soil organic carbon stocks and alters CO2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land-atmosphere CO2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt C⋅y(-1) of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO2 of 45 ± 25 Mt C⋅y(-1), equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the "hotspots," largely distributed in mountainous regions in the most intensive sink areas (>40 g C⋅m(-2)⋅y(-1)), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO2 sink. The erosion-induced CO2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO2 in the terrestrial budget, hence reducing the level of uncertainty.
水蚀作用影响土壤有机碳储量，并改变与大气交换的二氧化碳通量。侵蚀作为大气二氧化碳的净汇或源的作用仍存在很大争议，而且在大于小流域或区域的尺度上，相关信息很少。本研究试图在中国尺度上量化土壤碳的侧向运输以及随之而来的陆地 - 大气二氧化碳通量，中国已经经历了数十年的严重侵蚀。基于详细的全国调查得出的土壤侵蚀速率分布和土壤碳清单，我们在此表明，在过去二十年中，中国的水蚀作用使180±80 Mt C·y⁻¹的土壤有机碳发生转移，这导致陆地成为大气二氧化碳的净汇，为45±25 Mt C·y⁻¹，相当于中国此前评估的陆地碳汇的8 - 37%。有趣的是，“热点地区”主要分布在最强汇区（>40 g C·m⁻²·y⁻¹）的山区，仅占遭受水蚀总面积的1.
