The application of caesium-137 measurements to estimate recent sedimentation rates in a typical karst depression of Guizhou Plateau,China |
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| Authors: | Xiaoyong Bai Xinbao Zhang Shijie Wang |
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| Institution: | (1) Institute of Geochemistry, Chinese Academy of Sciences, 46# Guanshui Road, Guiyang, 550002, Guizhou, China;(2) Institute of South China Karst, Guizhou Normal University, Guiyang, 550001, Guizhou, China |
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| 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. |
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| Keywords: | karst depression deposition caesium-137 Southwest China |
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