干旱区生态环境知识资源中心(Arid): 近期人类活动对湖泊沉积记录的影响以托素湖为例

Arid

	近期人类活动对湖泊沉积记录的影响以托素湖为例
其他题名	RECENT HUMAN IMPACTS ON SEDIMENTARY RECORD: A CASE FROM LAKE TOSON
	付霞; 张家武; 王林; 崔雪莉; 马雪洋; 张玉枝
来源期刊	第四纪研究
ISSN	1001-7410
出版年	2016
卷号	36 期号:6 页码:1456-1465
中文摘要	现代湖泊沉积记录通常是定量化重建古环境气候参数时用于建立指标和气候要素定量关系必需的资料,但在人类活动较强的地区,现代湖泊沉积记录的指标受人类活动的影响程度及是否能用于建立定量关系研究缺少评估。文章选择位于德令哈的托素湖短钻岩芯(TSLC)沉积物,利用放射性核素~(210)Pb建立年代序列,将过去129年来沉积物碳酸盐含量和碳酸盐碳氧同位素与树轮重建的该区域降水量、区域孢粉A/C值及湖区52年来器测资料进行对比,评估人类活动对沉积记录的影响。结果显示,碳酸盐含量及其氧同位素指示的区域湿度变化在1883~1975年和2004~2011年与树轮重建的区域降水量及器测实际降水量有较好的对应关系;1975~2004年代用指标指示有效湿度降低与器测降水量增加、区域孢粉A/C值和树轮重建区域降水量增加整体相矛盾:指标显示区域有效湿度减小,而同期年平均风速减弱、年日照时数减少及年均相对湿度未发生显著变化使得蒸发量减少,区域有效湿度增加。沉积记录变干的原因主要是该阶段德令哈地区农业发展、农业耗水量增加导致托素湖补给量减少;2004年之后农业耗水量减少,指标记录与器测记录又趋于一致。因此在人类活动较强的地区利用湖泊沉积物代用指标重建气候要素时需先对人类活动影响强度进行评估。
英文摘要	Here we present a comparison between the proxies and observational data during the past decades using a short core (TSLC) from Lake Toson. Lake Toson (37°04’~37°13’N,96°50’~97°03’E) is a closed saline lake located in Delingha, NE Tibetan Plateau. The surface area of the lake is approximately 165.9km~2 with an elevation of 2808m a.s. 1. The maximum water depth is 23.6m. According to data from Delingha Meteorological Station, the mean annual temperature is 4℃,and the regional annual precipitation is about 160~170mm, most of which falls as rain from May to September. The potential evapotranspiration is about 2000mm. The current salinity of the lake water is ca.27.8g/L, and the pH of the lake water is 8.38. Modern vegetation in this region is dominated by desert plant communities. The lake is fed by water from Bayin River flowing through Lake Hurleg, which is 3km to the north of Lake Toson. Such a hydrologic pattern make it sensitive to climate change and human activities, hence being an ideal site to study human activities impact on sedimentary records. Core TSLC (37°07’36"N,96°57’01"E; 35.5cm in length) were recovered at the water depth of 23.6m in Lake Toson, and the resolution was 5mm and lcm of top to 20.5cm and 20.5cm below of the sample from the cores TSLC, respectively. The short core was dated using ~(210)Pb. Proxies including grain-size, carbonate content and carbonate oxygen isotopes (delta~(18)O_(carb)) were compared with instrumental data in Delingha in the last 52 years and the reconstructed regional precipitation by tree-ring and A/C ratio of Lake Gahai. The delta~(18)O_(carb) values were attributed to changes in precipitation/evaporation (P/E) ratios (effective humidity). High (low) authigene carbonate content indicated salinization (desalination) of Lake Toson,and carbonate content changes was consistent with delta~(18)O_(carb) which could reveal the changes of effective humidity of lake areas. During the period of 1883 ~ 1975A.D.,proxies indicated a low effective humidity and a gradual increasing trend,but effective humidity decreased and then increased during 1960 ~1970 A.D. Effective humidity increased during 2004 ~ 2011 A.D. Results revealed that regional effective humidity indicated by proxies was consistent with the precipitation reconstructed by tree-ring and the observed precipitation during 1883 ~ 1975A.D. and 2004~2011 A.D. During the period of 1975 ~2004A.D.,however, proxies was indicating a reduced P/E ratio, conflicting with the increased precipitation suggested by both the instrumental data, the tree-ring-based reconstruction and A/C ratio of Lake Gahai. During this period the regional evaporation decreased due to reduced wind speed and the annual sunshine hours, though the temperature was increasing. The resulted effective humidity, therefore, was increasing. The inconsistency between the reduced effective humidity recorded by proxies and the increased humidity by the observational data was caused by the regional agriculture development. Increased water consumption for irrigation during this period reduced the water supply for Lake Toson through the Bayin River. After 2004A.D., the agricultural water consumption reduced and the climate indicated by proxies became consistent with the instrumental data again. Our result suggests that recent human impacts should be evaluated before the relationship between proxies and climate factors are used for paleoclimate reconstruction in regions with intensive human activities. Meanwhile, the resolution of observational data should be match with proxies resolution when we analyze observational data.
中文关键词	湖泊沉积 ; 代用指标 ; 器测资料 ; 人类活动 ; 托素湖
英文关键词	lake sediment environmental proxies instrumental data human activities Lake Toson
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOSCIENCES MULTIDISCIPLINARY ; GEOLOGY
WOS研究方向	Geology
CSCD记录号	CSCD:5847556
来源机构	兰州大学
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/234148
作者单位	兰州大学资源环境学院, 西部环境教育部重点实验室, 兰州, 甘肃 730000, 中国
推荐引用方式 GB/T 7714	付霞,张家武,王林,等. 近期人类活动对湖泊沉积记录的影响以托素湖为例[J]. 兰州大学,2016,36(6):1456-1465.
APA	付霞,张家武,王林,崔雪莉,马雪洋,&张玉枝.(2016).近期人类活动对湖泊沉积记录的影响以托素湖为例.第四纪研究,36(6),1456-1465.
MLA	付霞,et al."近期人类活动对湖泊沉积记录的影响以托素湖为例".第四纪研究 36.6(2016):1456-1465.