基于137Cs示踪法的青藏高原东南部土壤侵蚀状况

Soil erosion of Southeastern Qinghai-Tibet Plateau based on 137Cs tracer method

选取青藏高原东南部作为研究区域,根据流域从西到东划分为5个区域,通过野外采集43个表土样测量137Cs比活度、粒径、总有机碳(TOC)等指标,分析该区域的土壤侵蚀状况及其影响因素。结果表明,各样点的137Cs比活度为0~23.75 Bq/kg,平均为10.48 Bq/kg,小于背景值43.7 Bq/kg,所有样点处均发生侵蚀;所有区域均发生轻度侵蚀,区域三的侵蚀模数最大,为16.3 t(/hm^(2)·年),区域五的侵蚀模数最小,为7.8 t(/hm^(2)·年);研究区域内,侵蚀厚度随坡度的增加先增大后减小,在坡度为18°附近侵蚀厚度最大;侵蚀厚度与多年平均降水量、风速、植被覆盖度间无显著相关性;林地土壤的侵蚀厚度与TOC间存在显著的负相关性(P<0.05),草甸土壤处二者的负相关性不显著。

The Southeastern Qinghai-Tibet Plateau was selected as the research area,and it was divided into five areas from west to east according to the watershed.43 surface soil samples were collected to measure 137Cs activity,particle size,total organic carbon(TOC)and other data,and the soil erosion status and its influencing factors in this area were analyzed.The results showed that,the specific activity of 137Cs of the samples ranged from 0 to 23.75 Bq/kg,with an average value of 10.48 Bq/kg,which was less than the background value of 43.7 Bq/kg,and it revealed that erosion had occurred at all sample points.Slight erosion occurred in all five areas.The erosion modulus of Region III was the largest,and the value was 16.3 t(/hm^(2)·a).The erosion modulus of Region V was the least,and the value was 7.8 t(/hm^(2)·a).In the study area,the erosion thickness first increased and then decreased with the increase of the slope,and the erosion thickness was the largest near the slope of 18°.There was no significant correlation between erosion thickness and annual average precipitation,wind speed,and vegetation coverage.There was a significant negative correlation between the ero⁃sion thickness and TOC in forest soil,while the negative correlation between the two in meadow soil was not significant.