Using 137Cs and 210Pbex to assess soil redistribution on slopes at different temporal scales
Using 137Cs and 210Pbex to assess soil redistribution on slopes at different temporal scales
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DOI：
10.1016/j.catena.2011.01.004
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发表时间：
2013-03
期刊：
影响因子：
6.2
通讯作者：
L. Gaspar;A. Navas;D. Walling;J. Machı́n;J. G. Arozamena
中科院分区：
文献类型：
--
作者：
L. Gaspar;A. Navas;D. Walling;J. Machı́n;J. G. Arozamena
由于气候变化，土壤流失的风险越来越大，因此需要关于不同时间尺度上侵蚀率的可靠信息。使用沉降放射性核素137 Cs，210 Pbexand7 Be作为示踪剂的沉积物的动员和再分布，使人们有可能获得估计土壤再分布率在一系列的时间尺度内未受干扰的和耕地景观。地中海景观的特点是地貌和土地利用的多样性很大，因此侵蚀和沉积模式在空间上变化很大。为了记录这种空间变异性，选择了位于半湿润前比利牛斯山脉（西班牙东北部）的一个坡面样带，使用137 Cs和210 Pbex评估中长期土壤再分布率。共收集了23个剖面土芯间隔50米沿着坡面样带，其中7Be先前已被用来记录土壤再分布所造成的一个单独的风暴事件。这两种放射性核素的含量有很大的差异，137 Cs的含量在409到6080 Bqm − 2之间，210 Pbex的含量在0到6734 Bqm − 2之间。根据137 Cs深度剖面，使用适当的转换模型，对土壤再分布的估计表明，沿样带的侵蚀速率沿着在2.6和31.9 Mgha − 1年−1之间变化，沉积速率在0.2和24.5 Mgha − 1年−1之间变化。最高的土壤流失发生在耕地，在样带的中坡区，而最高的沉积速率被发现在耕地内的下半部分的样带。210 Pbex的侵蚀速率在较低的斜坡上变化很大，介于0.1和83.7 Mgha − 1年− 1之间，而沉积速率在底部斜坡上也介于0.8和110 Mgha − 1年− 1之间。放射性核素沿着样带的空间分布反映了不同土地利用方式和坡度对水蚀的影响。所获得的结果证实了使用137Cs和210Pbex测量在不同的时间尺度在地中海环境的斜坡上评估土壤再分布的潜力。
Increasing risk of soil loss as a result of climate change, has generated a need for reliable information on erosion rates at different temporal scales. Use of the fallout radionuclides137Cs,210Pbexand7Be as tracers of sediment mobilization and redistribution makes it possible to obtain estimates of soil redistribution rates within both undisturbed and cultivated landscapes over a range of timescales. Mediterranean landscapes are characterized by a great diversity of physiography and land use, and as a consequence erosion and deposition patterns are highly variable spatially. To document such spatial variability, a slope transect located in the subhumid Pre-Pyrenean mountains (NE Spain) was selected to use137Cs and210Pbexto assess medium- and longer-term soil redistribution rates. A total of 23 sectioned soil cores spaced 50m apart were collected along the slope transect, where7Be had been previously used to document soil redistribution resulting from an individual storm event. The inventories of both radionuclides varied markedly, between 409 and 6080Bqm−2for137Cs, and between 0 and 6734Bqm−2for210Pbex. Estimates of soil redistribution, derived from the137Cs depth profiles, using appropriate conversion models, show that erosion rates along the transect vary between 2.6 and 31.9Mgha−1year−1, and that sedimentation rates vary between 0.2 and 24.5Mgha−1year−1. The highest soil losses occur in cultivated fields, within the midslope zone of the transect, while the highest deposition rates are found in tilled fields within the lower part of the transect. Erosion rates from210Pbexvaried widely between 0.1 and 83.7Mgha−1year−1on the lower slope, whereas sedimentation rates ranged between 0.8 and 110Mgha−1year−1also at the bottom slope. The spatial distribution of the radionuclides along the transect reflects the effects of different land use and slope gradient on water erosion. The results obtained confirm the potential for using137Cs and210Pbexmeasurements for assessing soil redistribution on slopes in the Mediterranean environment over different temporal scales.