BAI Xiaoyong1,2, ZHANG Xinbao1,3*, and WANG Shijie1,2
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China; 2. Karst Ecosystem Observation and Research Station of Puding, Institute of Geochemistry, Chinese Academy of Sciences, Puding 562100, China; 3. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China)
Abstract The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of many depressions is not well understood. In this paper, the 137Cs technique was employed to investigate recent sedimentation rates in a Chinese polygonal karst depression. The results indicated that the sediment deposition rates ranged from 0.91 to 1.97 mm·a−1 in the period from 1963 to 2007, and the average sediment deposition rate and specific deposit yield of the catchment were estimated to be 1.47 mm·a−1 and 20 t·km−2·a−1, respectively. The results obtained were consistent with the local monitoring data of runoff plots, confirming the validity of the overall approach. It was shown that soil loss rates were very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the spacial distribution of surface soil and 137Cs inventories was affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon which exists widely in the karst areas and is significantly different from other places.
Keywords karst depression – deposition – caesium-137 – Southwest China
* Corresponding author, E-mail:zxbao@imde.ac.cn
CHINESE JOURNAL OF GEOCHEMISTRY Vol. 30, No. 1, 2011, page 84-92
© Science Press and Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg 2011
