Soil erosion effects on soil organic carbon and an assessment within China

Soil erosion is a widespread geological process with strong capabilities to entrap, transport and redistribute surface soil. It is important to grade erosion intensity and estimate eroded soil mass. On the other hand, soil organic carbon pool (SOC), as the largest terrestrial carbon content, is prone to be affected by soil erosion. Soil erosion redistributes surface soil over landscape, and changes the physical environmental conditions. The consequences are depletion of SOC in eroded regions, emission of carbon dioxide during transportation and input of extra SOC in deposited sites. This paper quantified the effects of soil erosion on soil organic carbon through following three steps: firstly, soil erosion type and soil erosion intensity were determined by interpreting Landsat TM images. Secondly, through field investigation, soil type and soil profile data were collected, and SOC contents in the 0-20cm layer were constructed. Finally, supported by map algebra in Geographic Information System (GIS), soil organic carbon loss induced by soil erosion was calculated based on the national soil erosion modulus standard. Total annual SOC loss in China was about 1.595 x 10(8) ton-C yr(-1). Assuming 20% of SOC was oxidized, erosion induced CO2 emission was about 3.19 x 10(7) ton-C yr(-1).