Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment
Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment
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DOI：
10.1016/s0169-555x(02)00244-1
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发表时间：
2003-06
期刊：
影响因子：
3.9
通讯作者：
D. Walling;A. Collins;H. Sichingabula
中科院分区：
文献类型：
--
作者：
D. Walling;A. Collins;H. Sichingabula
用于收集侵蚀率和土壤重新分布信息的传统技术有许多重要的局限性。因此，使用环境放射性核素，更具体地说，137 Cs测量，近年来作为获取侵蚀和沉积率空间分布信息的一种手段，越来越受到关注。然而，在世界上一些地区，137Cs的含量很低，土壤和沉积物中137Cs的浓度很低，这给实验室分析带来了问题，因此137Cs方法的应用受到了阻碍。随着时间的推移，这些问题将越来越多，因为现有库存的放射性衰变，其中大部分是作为沉降物沉积的。四十年前本文探讨了在赞比亚南部上卡莱亚小流域（63平方公里）使用另一种沉降放射性核素，即未被污染的210铅，作为137铯的替代品的可能性，该流域137铯的存量已经很低。采用的方法与137 Cs的方法相似，尽管未被吸收的210 Pb随时间的推移基本上是恒定的沉降物，这意味着由此产生的侵蚀和土壤再分布率的估计反映了更长的时间（约100年）。100年，而不是。40年）。侵蚀和沉积速率的估计来自unaccounted210Pb测量用于构建典型的沉积物预算的三个主要土地利用类型在上卡莱耶流域，即商业种植，公共种植和灌木放牧。从uncharted210Pb获得的结果进行了比较，与同等结果的基础上137 Cs测量提供了以前的调查在研究集水区。两组结果高度一致。该研究报告证实了在这种环境中使用未被污染的210 Pb作为137 Cs的替代品的可行性，并表明联合使用这两种放射性核素可以提供有关研究区域侵蚀历史的额外信息。
Traditional techniques used to assemble information on rates of erosion and soil redistribution possess many important limitations. As a result, the use of environmental radionuclides, and more particularly137Cs measurements, has attracted increasing attention in recent years as a means of obtaining spatially distributed information on rates of erosion and deposition. The application of the137Cs approach is, however, hampered in some areas of the world where137Cs inventories are low and the low concentrations of137Cs found in soils and sediments cause problems for laboratory analysis. These problems will increase as time progresses due to the radioactive decay of the existing inventory, most of which was deposited as fallout ca. 40 years ago. This contribution explores the potential for using another fallout radionuclide, namely unsupported210Pb, as an alternative to137Cs, in the small (63 km2) Upper Kaleya catchment in southern Zambia where137Cs inventories are already very low. The approach employed with unsupported210Pb is similar to that used for137Cs, although the essentially constant fallout of unsupported210Pb through time means that the resulting estimates of erosion and soil redistribution rates reflect a longer period of time (ca. 100 years rather than ca. 40 years). The estimates of erosion and deposition rates derived from the unsupported210Pb measurements are used to construct typical sediment budgets for the three main land-use types in the Upper Kaleya catchment, namely, commercial cultivation, communal cultivation and bush grazing. The results obtained from the unsupported210Pb are compared with equivalent results based on137Cs measurements provided by a previous investigation undertaken in the study catchment. The two sets of results are highly consistent. The study reported confirms the viability of using unsupported210Pb as an alternative to137Cs in this environment and demonstrates that conjunctive use of both radionuclides can provide additional information on the erosional history of a study area.