散落核素~7Be和^(137)Cs在洱海和红枫湖沉积物中蓄积对比  

A comparative study on accumulation characteristics of ~7Be and ^(137)Cs in sediments of Lake Erhai and Lake Hongfeng, China

作　　者：白占国 万国江[2] 刘东生[3] 黄荣贵[2] 

机构地区：[1]中国农业科学院土壤肥料研究所农业部植物营养学重点实验室,北京100081 [2]中国科学院地球化学研究所环境地球化学国家重点实验室,贵州贵阳550002 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球化学》2002年第2期113-118,共6页Geochimica

基　　金：国家自然科学基金(49971053;49894170;49333040);中国科学院基金(KZ951-A1-402);国际科学基金IFSofSweden;A/2704-1)

摘　　要：沉积物柱芯分别采自滇西地区的洱海和黔中地区的红枫(及百花)湖,散落核素7Be和137Cs在沉积物中的蓄积特征对比分析表明,7Be在洱海及红枫湖沉积物中的累计值分别为(237±73)Bq/m2和(783±44)Bq/m2;按校正到沉降年代的数值,1986年以前137Cs的累计值分别为(519±26)Bq/m2及(3704±56)Bq/m2。由模式计算获知,(1)7Be和137Cs在红枫湖沉积物中的蓄积以侵蚀影响为主;在洱海的蓄积受直接散落控制。(2)在洱海和红枫湖地区7Be大气散落累计值分别为(0.07±0.02)Bq/cm2及(0.08±0.01)Bq/cm2;1986年以前137Cs大气散落累计值分别为(0.11±0.01)Bq/cm2及(0.37±0.01)Bq/cm2,显示出滇西与黔中地区之间137Cs散落的地区差异。这一现象可能反映出青藏高原对滇西地区存在着全球性大气扩散污染物散落的屏蔽效应。The sediment cores are collected from Lake Erhai in West Yunnan and Lake Hongfeng (and Lake Baihua) in Central Guizhou. The accumulation characteristics of the 7Be and 137Cs show that 7Be inventories in sediment cores of Lake Erhai and Lake Hongfeng (and Lake Baihua) are (237±73) Bq/m2 and (783±44) Bq/m2, respectively. On the basis of the activity values that are corrected to the deposition, prior to year 1986, 137Cs inventories in the lakes were (519±26) Bq/m2 and (3 704±56) Bq/m2, respectively. The model calculation indicated that (1) 7Be and 137Cs accumulations in Lake Hongfeng sediments are dominated by watershed erosion, but in Lake Erhai, they are mainly controlled by the directly atmospheric deposition, and (2) 7Be atmospheric fallout inventories in Lake Erhai and Lake Hongfeng are (0.07±0.02) Bq/cm2 and (0.08±0.01) Bq/cm2, respectively. Prior to 1986, 137Cs inventories were (0.11±0.01) Bq/cm2 and (0.37±0.01) Bq/cm2, respectively, indicating that 137Cs deposition has a regional difference in the two regions. This phenomenon would reflect that uplift of the Himalayas could have the barrier effect on the fallout of globally atmospheric pollutants in the western Yunnan.

关 键 词：^137CS ^7Be 湖泊沉积物 洱海 红枫湖 铍同位素 铯同位素 

分 类 号：P512.2[天文地球—地质学] P597