Radionuclides in soils along a mountain--Basin transect in the Koratepa Mountains of Uzbekistan

Abstract

T he weathering of mountain rocks and downhill movement of the resulting sediments form the building blocks of soil formation. Through eons of weathering and soil redistribution, complex landscapes are formed and reformed again in response to dynamic forces of geology, climate, and vegetation. Humans can also influence the formation of soils and landscapes through economic activities such as farming and pasturing livestock that disturb the stabilizing influence of native vegetation. As the global population increases, more and more of the earth's surface is impacted, and erosion of soil resources and sedimentation of the waterways is expected to increase. Assessing the rates of soil redistribution is a difficult endeavor. The spatial and temporal variabilities, at multiple scales, of the factors controlling erosion make simple measurements difficult, if not impossible (Chepil and Woodruff 1963; Stroosnijder 2005). Rainfall varies on timescales of minutes to decades, and wind speeds vary on timescales of seconds to months. Rainfall and other climatic factors also control the stabilizing influence of vegetation as long-term drought may result in bare unprotected landscapes. In the last few decades, fallout radionuclides, both natural and anthropogenic, have been used to assess rates of soil redistribution on time scales from a few weeks…