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本项研究对位于亚拉巴马州北部石灰岩流域内土壤中~(137)C_s——一种核试验的放射性尘埃——进行了测量.研究的目的是:比较侵蚀区和沉积区土壤剖面中的~(137)C_s活性,②确定用~(137)C_s法计算的土壤侵蚀和沉积,与用USLE估算的侵蚀及与流域出口处测得的输沙量之间的关系.对代表轻微侵蚀区的分水岭、侵蚀区的边坡和沉积区的坡脚的耕地土壤样点46cm深的三维土壤剖面中~(137)C_s活性进行了分析.并把这些值与毗邻的未被干扰的林地中测得的~(137)C_s:活性(作为基数)进行了比较.对用~(137)C_s.活性损失值计算的侵蚀值与USLE计算的坡面侵蚀值进行了比较.对轻微侵蚀坡横断面,用~(137)C_s计算的年均(1954～1987年)土壤侵蚀速率与USLE计算值接近(28和26t/hm~2·a).~(137)C_s计算的侵蚀边坡上的侵蚀量比USLE计算值大27%～80%.984～1988年种植棉花期间,USLE计算的上游土壤流失量为9～52t/hm~2·a.在小流域坡脚沉积区以下测得的泥沙流失量仅为1～4t/hm~2·a.沉积区土壤剖面中的~(137)C_s活性为典型喀斯特地形区小流域产生的大量泥沙沉积提供了间接证据.
This study measured ~ (137) C_s, a nuclear test radioactive dust in soil in the limestone basins in the northern state of Alabama.The purpose of the study was to compare the soil profiles in the eroded and sedimentary soil profiles ~ (137) C_s activity, ②Determining the relationship between soil erosion and sediment calculated by ~ (137) C_smethod and erosion estimated by USLE and the sediment discharge measured at the outlet of the river basin, (137) C_s in 46-cm-depth soil samples from the slope of the eroded area and the slope foot of the sediment area were analyzed and compared with the adjacent undisturbed forest land survey (137) C_s: activity (as a base) were compared.Erosion values calculated from ~ (137) C_s. Activity loss values were compared with those calculated from USLE.Estimated values of the cross section of slightly eroded slope , And the annual average (1954-1987) soil erosion rate calculated by ~ (137) C_s is close to that calculated by USLE (28 and 26 t / hm ~ 2 · a). Erosion 27% ~ 80% larger than the value calculated by the USLE. During the cotton planting period from 984 to 1988, the USLE calculated upper soil loss was 9 ~ 52t / hm ~ 2 · a. The amount of sediment loss measured in the footwell below the footwell of the small watershed is only 1 ~ 4t / hm ~ 2 · a. The ~ (137) C_s activity in the soil profile of the sedimentary area is small in the typical karst topography The large amount of sediment deposition in the basin provides indirect evidence.