贵州红枫湖HF1-2孔沉积物的磁性特征及其土壤侵蚀意义

Magnetic properties of core HF1-2 from Lake Hongfeng in Guizhou Province and its implications for soil erosion

通过对红枫湖沉积物柱芯HF1-2磁性参数测量,总结出不同阶段沉积物磁性参数变化的特征,再结合137Cs、粒度、TOC(%)和C/N的分析结果,解译出红枫湖流域自1960-2003年的土壤侵蚀变化过程.从沉积物的分析得出,流域的土壤侵蚀经历了强弱交替的过程,两个明显土壤侵蚀增强的过程分别是1977-1980年和1987-1997年.初步探讨土壤侵蚀强烈的原因可能与降水量有关,但也明显存在着其它因素的影响.

Lake Hongfeng is a reservoir located in the center of Guizhou Province, which was built in 1960. A 35cm sediment core HFI-2 was sampled from the lake for analysis in 2004. Some mineral magnetism parameters such as SIRM, χif, IRM20mT, χARM, Hard, χfd% are measured, furthermore HIRM, ARM/SIRM, IRM20mT/SIRM, ARM/χIf, SIRM/χIf are calculated from them. Based on magnetic measurements of the core, we can find the changes of magnetic properties influenced by soil erosion in the catchments during the past 43 years from 1960 to 2003. Combination with the results of analyses of ^137Cs, grain size, TOC（%）and C/N, we divide the changes of soil erosion in the drainage area into several periods during these 43 years, the most seriously soil-erosion periods are during 1977 to1980 and 1987 to 1997. Compared with the rainfall data, we find the precipitation, especially summer precipitation may be the major reason of soil-erosion during 1977-1980, and there are some other unknown complex factors to affect the serious soil-erosion during period of 1987 to 1997.