摘要
20世纪50—70年代核试验产生的137Cs尘埃,在现代冰川和非冰川湖泊沉积剖面中的深度分布存在明显差异.同理,大气宇宙射线成因的长半衰期10Be尘埃,在第四纪冰川和非冰川湖泊沉积剖面中的深度分布也应存在差异.第四纪冰川湖泊,冰期时流域内冰雪和10Be的累积量大于消融量,间冰期时冰雪和10Be的消融量大于累积量.因此,冰川湖泊冰期的10Be入湖通量小于间冰期.湖泊沉积剖面10Be浓度的波动,很可能表征流域内冰雪消融与累积的变化.非冰川湖泊,不存在冰川的累积与消融对10Be入湖通量的影响.开展第四纪冰川与非冰川湖泊沉积10Be含量变化的对比研究,有可能为破译中国东部中低山区古冰川和青藏高原大冰盖的世纪之争提供新的证据.
The shapes of depth distribution profiles of fallout { { } 137 Cs }, which were produced by nuclear weapon testing during the period of 1950-1970, are different in the deposits between non-glacial and glacial lakes. As fallout { { } 137 Cs } with a short half life of 30 ^17 a in modern lake deposits, depth distribution shapes of cosmogenic radionuclide 10 Be with a long half of 1.5 Ma should be different in the deposits between glacial and non-glacial lakes during Quaternary period. For a glacial lake, the amounts of accumulated ice layers and the containing 10 Be radionuclide are greater than the delivering values by meltwater over the catchment in glacial periods, while the amounts are less the delivering values in inter-glacial period. The fluctuations of 10 Be concentrations in deposit profiles of glacial lakes may reflect the changes of ice accumulation and melting during the quaternary period. For non-glacial lakes, there are no such effects of ice accumulation and melting on the { { } 10 Be } delivering yields from the catchment exist during the Quaternary period. A comparative study on { { } 10 Be } in deposits between glacial and non-glacial lakes may have great potential for solving the century s debate on the paleo-glaciers in the eastern low-middle mountain regions and on the ice sheet in the Tibet Plateau of China.
出处
《冰川冻土》
CSCD
北大核心
2005年第3期438-443,共6页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(40271015)
国家重点基础研究发展规划项目(2003CB415202
2004CB720200)资助
