The application of caesium-137 measurements to estimate recent sedimentation rates in a typical karst depression of Guizhou Plateau, China  

作　　者：BAI Xiaoyong ZHANG Xinbao WANG Shijie 

机构地区：[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

出　　处：《Chinese Journal Of Geochemistry》2011年第1期84-92,共9页中国地球化学学报

基　　金：supported by the National Basic Research Program of China (973 Program) (Grant No. 2006CB403200);the National Natural Science Foundation of China(Grant No. 41001162);Knowledge Inno-vation Project of the Chinese Academy of Sciences (Grant No. KZCX2-YW-306);Provincial Governor Foundation of GuiZhou (Grant No. 2010);Opening Fund of State Key Labo-ratory of Environmental Geochemistry(Grant No. SKLEG9008);National Key Technology R & D Program (Grant Nos. 2006BAC01A09 and 2008BAD98B07)

摘　　要：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.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.

关 键 词：喀斯特洼地 沉积速率 产量估计 铯-137 中国 贵州高原 西南喀斯特地区 土壤侵蚀 

分 类 号：X591[环境科学与工程—环境工程] O233[理学—运筹学与控制论]