Evolution of Lake Ailike (northern Xinjiang of China) during past 130 years inferred from diatom data

Abstract

We have studied diatom assemblages of a 42-cm-long sediment core obtained from Lake Ailike in northern Xinjiang of China to reconstruct the hydrological and ecological variations of the past 130 years. Three environmental parameters of lake water (i.e., diatom-inferred pH, diatom-inferred total phosphorus and diatom-inferred conductivity) were estimated by comparing the fossil diatom assemblages from the Lake Ailike core with the modern diatom assemblages in the European Diatom Database. The reconstruction exhibited two major stages: stage A (1884–1960) was a “natural” stage and stage B (1960–2013) was a “human” stage. The “natural” stage can be further divided into two sub-stages: A-1 (1884–1920) was characterized by an averagely low lake area and A-2 (1920–1960) was a stably high lake-area period. The comparison between the reconstructed lake-area variations from Lake Ailike with the treering-recorded Palmer Drought Severity Index (PDSI) variations from nearby Hutubi shows that the low lake area from 1884 to 1920 was correspondent with a dry period and that the high lake area from 1920 to 1960 with a wet period. The similarity between PDSI from Hutubi and the Atlantic Multidecadal Oscillation (AMO) implies a climatic linkage. The linkage is revealed by the tight in-phase relationship between AMO and SWP (Siberian warm-season precipitation), that is, the AMO-promoted SWP might have extended its influence to northern Xinjiang. The “human” stage can also be divided into two sub-stages: B-1 (1960–2000) was a regressing stage and B-2 (2000–2013) was a transgressing stage. The man-made regression led to dramatic increases in TP of the lake water, TOC and TN of the sediments and also in the resulted decrease in lake water pH. Fortunately, the Irtysh-Karamay Canal started to inject water into the lake in 2001, resulting in a constant expansion of lake-covered area and also in a constant improvement of ecological conditions.