Study on the Climatic and Environmental Implication of Stable Nitrogen Isotopes from the Lacustrine Sediments in Typically Westerly-Influenced Balikun Lake in Xinjiang

The significance of climatic implication of the sediments nitrogen isotopes from Balikun Lake, which is located in typically westerly-influenced northeastern Xinjiang, is studied in this paper. Values of δ15N values of a 250 cm-deep section which is located at the center of the lake, fluctuate from 6.0‰ to 22.9‰ with an average value of 12.0‰. Supported by multi-proxy records including bulk organic carbon isotopes (δ13Corg), organic matter content (OM), and the ratio of TOC and total nitrogen (C/N), higher δ15N values could reflect relatively wet conditions, whereas lower δ15N suggests relatively dry conditions is inferred. Based on the δ15N record, five climatic periods in the past 9400 years could be identified, i.e., relatively dry condition from 9400 cal. a BP to 7300 cal. a BP; relatively wet conditions between 7300 cal. a BP and 5900 cal. a BP; relatively dry period between 5900 cal. a BP and 3100 cal. a BP; a wetter period from 3100 cal. a BP to 1100 cal. a BP, and after 1100 cal. a BP, strengthened human activity may exert strong influence on nitrogen isotopes. The results indicate that the nitrogen isotopes bear valuable potential to indicate past climatic changes in the westerly-influenced arid Xinjiang, NW China.