巴丹吉林沙漠包气带Cl^-示踪与气候记录研究  

Chloride as a Tracer and Climatic Change Record from Unsaturated Zone of Badain Jaran Desert

作　　者：马金珠[1] 李丁[1] 李相虎[1] Edmunds W M 

机构地区：[1]兰州大学西部环境教育部重点实验室中德干旱研究中心,甘肃兰州730000 [2]British Geological Survey, Wallingford, Oxfordshire, UK

出　　处：《中国沙漠》2004年第6期674-679,共6页Journal of Desert Research

基　　金：国家自然科学基金项目(40302031);国家重点基础研究发展规划"973"项目(G2000048701)资助

摘　　要：Cl-是自然界中最稳定的示踪剂,包气带水Cl-浓度与降水中Cl-浓度的差异可以反映降水的有效入渗补给量和包气带水的年龄。基于CMB的氯累积年龄可以用36Cl/Cl在三个时间尺度上校正。利用CMB研究了巴丹吉林沙漠南缘的两个钻孔剖面的Cl-与含水量的分布状况,计算了800a以来的地下水补给量及其所反映的气候波动特征。在该地区,多年平均降雨量为89mm,而平均补给量仅为1 3mm。干旱沙漠地区最近800a气候明显经历了4个干期和3个湿期。1500—1530年是干旱区气候突变的时期,18世纪末至19世纪初是气候环境演化的又一个十分重要的时间界限,自此以后的漫长时间,干旱化进程进一步加剧。Chloride (Cl^(-)) is ubiquitous in groundwater and soil water. One of the most useful properties of the Cl^(-) ion is that highly soluble and therefore is a conservative tracer. The Cl^(-) ion also has the advantage of simple analysis and of being conserved during the recharge process so that the Chloride Mass Balance (CMB) approach can be used to estimate the paleo-recharge and can provide a record of oscillating climate events at the decadal or longer scale. The (()^(36)Cl)/Cl can be well successfully used to estimate the pore water residence time over three different time scales, and well be used for validation of chloride cumulative age. The history of groundwater recharge and climatic changes during the last 800 years has been estimated and reconstructed using environmental chloride from unsaturated zone profile in the southeast Badain Jaran desert, NW China. By using a steady-state model for duplicate unsaturated zone chloride profiles, the long-term recharge at the site was estimated to be 1.3 mm·a^(-1). From one profile, which reached the water table, the climatic change events of 10～20 years duration were well preserved. There are 3 wet phases and 4 dry episodes during the recent 800 years according to the peaks and troughs of recharge rate calculated via chloride concentration and moisture content. It was a dry episode before 1290 AD. The time of 1500～1530 AD, which is an important period when climate occurred violent change from drought to wet. At the beginning of 1800s, the important turning events of the local climate from wet to dry occurred and then the climate deteriorated severely during the last 200 years. The unsaturated profile was compared with the Guliya ice core records. The agreement of wet and dry phases from 1200 to 1900 AD is quite good, whilst the conversely trends recorded during the last 100 years. It seems that the large-scale climate difference take place between mountain regions and the desert basin in the NW China during the 20^(th) century, which are closely correspond to t

关 键 词：气候记录 补给量 示踪 巴丹吉林沙漠 包气带 平均降雨量 气候突变 入渗 干旱 Cl^- 

分 类 号：P641[天文地球—地质矿产勘探] P467[天文地球—地质学]