Analysis of tsagaan lake sediment, valley of the gobi lakes, Mongolia, to determine past environmental changes and the effect of ongoing global warming

Abstract

The arid region of Mongolia is sensitive to climate change. Understanding of climate variations in the past plays an important role in predicting further climate changes. In this study, we aim to investigate the relationship between the climatic factor and sedimentation history in the late Holocene. We analyzed the 18TS1 core sample (136 cm in length) from the Tsagaan lake in the Valley of the Gobi Lakes, Mongolia. The sediment core mainly consists of clay and silt sediments, occasionally interrupted by the sand-dominated layers. 210Pb dating method is applied and indicates that the upper 24 cm sediment spans the sedimentation history of the last 87 years. Along-core variations in sediment characteristics such as organic matter, carbonate, and amorphous silica abundance are indicative of the drought -inducing period based on the significant correlations between sediment characteristics and Self-calibrated Palmer Drought Severity Index. Moreover, the enrichment of carbonates is a great indicator of shallow lake conditions prior to the lake disappearance during the dry period. The chemical composition of sand-dominated units in the sediment core well agrees with that of sand sheets and sand dunes in the catchment. Modern expansion and migration of sand sheets are identified by aerial photo imagery. The insufficient sediment chronology is limiting our interpretation, though; the comparison with the other paleoclimate records helps the establishment of environmental changes in the last millennium.