内蒙古巴丹吉林沙漠400年来大气沉降Hg的湖泊沉积记录  

Atmospheric Hg Deposition during the Past Four Centuries from the Lacustrine Sediment in the Badain Jaran Desert,Inner Mongolia,Northwest China

作　　者：刘斯文[1,2] 黄园英[1,2] 张玲金[1,2] 谭科艳[1,2] 田明中[3] 

机构地区：[1]国家地质实验测试中心,北京100037 [2]国土资源部生态地球化学重点实验室,北京100037 [3]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《现代地质》2015年第6期1319-1327,共9页Geoscience

基　　金：国家地质实验测试中心基本科研业务费项目(2015CSJ02;2013CSJ02)

摘　　要：Hg污染具有全球性,人类活动较少地区的湖泊沉积物对长距离输入的大气沉降Hg变化敏感。巴丹吉林沙漠中发育了约142个沙漠丘间湖泊,是研究大气沉降Hg记录的理想材料。选择巴丹吉林沙漠东南部的宝日陶勒盖湖泊进行湖泊钻探,结合210Pbuns和137Cs核素测年及THg沉积通量计算,重建了400年来巴丹吉林沙漠湖泊的THg沉积记录,并探讨了影响沙漠湖泊THg沉积的影响因素,评估了自然背景和人类活动的影响。结果表明:(1)沉积物中THg含量分布范围为1.5~17.5 ng/g,富集系数和沉积通量的分布范围分别为0.3~4.5和2.9~38.9μg/(cm^2·a)。THg含量、富集系数和沉积通量均表现为在岩心上部近几十年富集。(2)近400年来,湖泊沉积物中背景THg(THg_(岩石风化))通量变化相对稳定,主要受控于附近物源供给和区域风沙活动。大气沉降THg(THg_(大气))通量自20世纪30年代以来呈逐渐增加的趋势,很大程度上反映了近几十年来人为源大气沉降THg的增加。但20世纪30年代以来岩心局部的大气沉降THg通量的峰值可能还受全球变暖和湖泊生产力增加的影响,而20世纪30年代之前出现的峰值可能与"小冰期"冷期强烈的区域风沙活动有关。巴丹吉林沙漠湖泊400年来的THg大气沉积通量变化与全球Hg产量和冰心中的大气Hg含量变化记录一致,是沙漠地区大气沉降THg的可信纪录。The Hg pollution is a global problem. The lacustrine sediment in remote area is sensitive to atmospheric Hg deposition by long-distance transportation and they are ideal materials for studying atmospheric Hg cycling. The Badain Jaran Desert is located in the Northwest China where there are about 142 permanent interdune lakes,and lacustrine sediments from these lakes are ideal materials for study atmospheric Hg deposition in remote desert region due to less human activities. The inter-dune lake,the Baoritaolegai,in the southeast of the Badain Jaran Desert,was selected for this study. The sediment core（ BR-2） was dated by210Pbunsand137 Cs.Results derived from the sediment core BR-1 suggest that：（ 1） THg concentration ranges from 1. 5 to 17. 5 ng / g,the flux ranges from 2. 9 to 38. 9 μg /（ cm^2·a） and EF ranges from 0. 3 to 4. 5,respectively,and the THg content enriched in the recent decades;（ 2） The flux of THg in the Core BR-1 is composed of background（ THg_（lithogenic）） and atmospheric fractions（ THg_（atmospheric））. The flux variety of the THglithogenicfraction during 400 years is relative stable which are controlled mainly by nearby material source supply and regional aeolian activities. Gradually increasing flux of the THgatmosphericfraction since 1930 s,to a great extent,indicates the growth of anthropocentric THg in the recent decades. To the low background THg in the Badain Jaran Desert lake and the natural fluctuation affected by climate or the environmental change of the lacustrine sediment are considered.Peaks of the THgatmosphericflux occurring in the Core BR-1 after 1930 s may be relating with global warming and increasing lake productivity while THgatmosphericflux changes may link with the nearby material source and aeolian activities before 1930 s. Signals revealed by the 400 years＇ THgatmosphericflux from the inter-dune lacustrine sediment in the Badain Jaran Desert is consisting with global Hg production and a THg record from ice core from North American,which

关 键 词：汞 210Pb 137Cs 大气沉降 烧失量 巴丹吉林沙漠湖泊 

分 类 号：P534.63[天文地球—第四纪地质学]