三江源区东西样带土壤侵蚀的^137Cs和^210Pbex示踪研究  

Study of Soil Erosion on the East-West Transects in the Three-Rivers Headwaters Region Using ^(137)Cs and ^(210)Pb_(ex) Tracing

作　　者：李俊杰[1,2,3] 李勇[3] 王仰麟[1,2] 吴健生[1,2] 

机构地区：[1]北京大学深圳研究生院,城市人居环境科学与技术重点实验室,广东深圳518055 [2]北京大学城市与环境学院,北京100871 [3]中国农业科学院农业环境与可持续发展研究所,北京100081

出　　处：《环境科学研究》2009年第12期1452-1459,共8页Research of Environmental Sciences

基　　金：国家自然科学基金项目(40671097,40771131);国际原子能机构项目(IAEA/RAS5043,TCCPR5015,Research ContractNo.12323)

摘　　要：运用137Cs和210Pbex联合示踪技术,考察青藏高原三江源区东西样带137Cs和210Pbex面积浓度的背景值和变化特征,以及东西样带土壤侵蚀速率、分布特征和主要影响因素.结果表明:①青藏高原三江源区东西样带137Cs和210Pbex面积浓度背景值分别为453~1 714和2 612~7 377 Bq/m2,137Cs和210Pbex背景值从西向东样带随海拔高度的变化差异明显.137Cs(x)和210Pbex(y)面积浓度的背景值区域分布呈显著线性相关,相关性关系式为y=3.587 2x+1 463.4,R2=0.951 7.②长江源区沱沱河137Cs的示踪结果表明,以沱沱河为中心的长江源区是典型的风蚀区,年侵蚀速率2.5 t/(hm2.a),该区是青藏高原重要的沙尘暴源区之一.③黄河源区玛多典型坡面137Cs和210Pbex的示踪结果表明,近40年来,玛多畜牧业为主的人类活动造成的土壤扰动比自然因素的影响大.④玛沁东倾沟乡和军牧场的比较研究结果表明,玛沁东倾沟乡高山草甸的水土保持效果较好,而玛沁军牧场的畜牧业活动造成了地表土壤的强烈扰动.⑤玛沁军功镇典型水蚀地貌土壤剖面137Cs和210Pbex的结果表明,20世纪50—60年代,该区的极端暴雨事件导致了严重的水土流失,土壤剖面中出现137Cs和210Pbex的空白区.植被破坏导致玛沁军功镇出现了严重水蚀,净侵蚀速率为8.0 t/(hm2.a).⑥近40年来,随着人类活动的加剧和全球气候变暖,导致青藏高原三江源区出现了沙尘暴的传输源地.A combination of 137Cs and 210 Pbex tracing is applied to ascertain the background value and change characteristics of 137Cs and 210 Pbex, soil erosion rate, distribution characteristics and main influencing factors of the East-West transects of the Three-Rivers Headwaters region of the Tibetan Plateau. The results indicate that： （1） in the East-West transects of the Three-Rivers Headwaters region of the Tibetan Plateau, the background values of 137 Cs and 210 Pbex. are in the range 453-1,714 and 2,612-7,377 Bq/m2 , respectively. With changes in elevation of the East-West transects, differences in the background values of 137 Cs and 210 Pboex are evident. The regional distribution of ,37 Cs （x） and 210 Pboex （y） background values shows significant correlation; the equation of the correlation is y = 3.587,2x ＋ 1,463.4, R2 = 0.951,7. （2） The 137Cs tracing result in the Tuotuo River at the Changjiang headstream region indicates that the Cbangjiang headstream region centered by the Tuotuo River is a typical wind erosion area, with soil erosion rate of 2.5 t/（ hm2 ·a）. This area is one of the important sources of dust storms on the Tibetan Plateau. （3） The results of 137 Cs and 210 Pboex tracing in the Maduo typical slope at the Yellow River headstream region indicate that in the last 40 years, livestock-based human activities in Maduo have caused more disturbance to the soil than the impact of natural factors. （4） Comparative study between Dongqinggou and Junmuchang in Maqin indicates that the alpine meadow in Dongqinggou is more effective in soil and water conservation than other vegetation studied, and the animal husbandry activities in Junmuchang have caused serious disturbance to the surface soil. （5） In the Jungongzhen region of Maqin, the 137 Cs and 210 Pboex results of soil profile from a typical site with serious water erosion show that the lack of 137 Cs and 210 Pboex was caused by heavy rain during extreme weather events in the region during the 1950s to 1960s. The water

关 键 词：三江源区 土壤侵蚀 137Cs和210Pbex示踪 

分 类 号：S151.3[农业科学—土壤学]