137Cs法在风沙过程研究中的应用前景

¹³⁷Cs法在土壤侵蚀与泥沙沉积研究中已得到普遍的应用,但在风沙过程研究中尚未引起足够的重视。针对风沙过程研究中存在的有关问题,对¹³⁷Cs法的应用前景作了展望,并提出了¹³⁷Cs应用的若干建议。

PROSPECTS OF CAESIUM-137 USED IN THE STUDY OF AEOLIAN PROCESSES

Aeolian processes that involve the mobilization, transport and deposition of material by wind are the key to understand desert geomorphology and the characteristics of aeolian sediments. In the study of aeolian processes, a great amount of results ranging from the entrainment of an individual grain to the movement of dunes composed of many hundreds of thousands of tones sand have achieved by means of field investigation, wind tunnel experiment, remote sensing, sedimentology and theoretical modelling etc.. However, as to the time scales, these methods always concern with either the ancient geological variation of desert environment or the instantaneous grain saltation, unfortunately ignoring the precise measurement of recent or modern aeolian processes which regarded as more sensitive response to the global change. Up now, the aeolian processes with middle time scale of 10s yr. remain to be gaps relatively. In accordance with the above limitation, a new tracing method of caesium-137 to estimate the modern aeolian processes is introduced in this paper. The world-fallout of caesium-137 associated with the nuclear weapons tests during 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. The concentration of fallout of caesium-137 in surface horizons and its low leachability have allowed this radioisotope to be used as a geologic dateline to determine the rates of soil erosion. At present, the use of caesium-137 as tracer of soil water erosion and sediment deposition has developed rapidly and widespreadly around the world, meanwhile the estimation of wind erosion and sedimentation has adopted the method a little. Therefore, on the basis of the tracing principles of caesium-137, some advantages and disadvantages of using the tracer in the study of aeolian processes are discussed.