中文摘要：

干旱区湖泊沉积可以有效记录区域湿度变化及粉尘活动历史,位于柴达木盆地德令哈南部的咸水封闭湖泊尕海具有恢复区域环境变化的潜力.该地区的长序列环境演变研究已开展了较多的工作,但缺乏短尺度、高分辨率的近代以来的环境变化湖泊记录.通过对尕海深水区短钻岩芯放射性核素210Pb和137Cs的年代测定和沉积物各指标分析,认为尕海沉积物碳酸盐含量可以反映区域湿度变化;而粗颗粒组分（〉66.9μm）主要由风力搬运入湖,其含量可以指示区域粉尘活动历史.区域近400 a的环境变化可划分为3个阶段：1633 1750 AD：各指标出现大幅度波动,表现出该时期气候环境的不稳定和干湿交替,其中1650 1720 AD的变化波动尤为显著,这与太阳活动进入Maunder极小期存在一定的联系.1750 1950 AD：区域气候环境无明显波动,碳酸盐含量逐渐降低,湿度增加.1950 2010 AD：各指标变动剧烈,区域虽降水增多,但由于蒸发加强,湿度降低;1974 AD以后粗颗粒组分含量急剧上升,表现出高强度尘暴事件.

英文摘要：

Lake sediments in arid area can record the change of regional humidity and dust history. Lake Gahai,a saline and hydrologically-closed lake in the south of Delingha,Qinghai Province,has the potential for reconstructing the local environmental change. Although many long-term environment evolution researches have been carried out in this area,short time-scale and highresolution records from lake sediments are still lacking. Here we present a nearly 400-year record from a short core taken form Lake Gahai. The chronology of the short core was established by ^210 Pb and ^137Cs analysis. Carbonate content,magnetic susceptibility and grain size were analysed. The variation of carbonate content can be used to indicate the change of local humidity and the coarser fraction（ 〉66. 9 μm） was mainly transported by winds,reflecting the dust storm events. The environmental change during the past 400 years can be divided into 3 stages. 1633 1750 AD： large fluctuations of proxies indicated an unstable dry and wet climate environment,especially during the 1650 1720 AD,and this obvious change was related to the solar activity. 1750 1950 AD：the decrease of carbonate content reflected an increasing local humidity. 1950 2010 AD： strengthened evaporation led to a low humidity although the regional precipitation increased. After 1974 AD,strong dust storm events were recorded by the coarser grain fraction.