Vol15 No.2: 254-263
【Title】Spatial differentiation in stable isotope compositions of surface waters and its environmental significance in the Issyk-Kul Lake region of Central Asia
【Author】MA Long1,2*; JILILI Abuduwaili1,2; LI Yao-ming1,2
【Addresses】1 State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; 2 CAS Research Center for Ecology and Environment of Central Asia, Urumqi 830011, China
【Citation】Ma L, Jilili A, Li YM (2018) Spatial differentiation in stable isotope compositions of surface waters and its environmental significance in the Issyk-Kul Lake region of Central Asia. Journal of Mountain Science 15(2). https://doi.org/10.1007/s11629-017-4499-4
【Abstract】Stable isotope values of oxygen (18O) and hydrogen (2H) of surface waters were used to study the origin and environmental significances in the Issyk-Kul basin of Kyrgyzstan in Central Asia, which is the most important intermountain basin in the modern Tien Shan orogen. This study is the first analysis of hydrochemical spatial differentiation in the stable isotopes of surface waters in this watershed. 75 samples were collected from rivers, springs, lakes, rain and snow during the rainy season in July and August of 2016. Stable isotopes of 18O and 2H were studied for all samples, and cation ratios (Sr/CaandMg/Ca) were also determined for lake water samples. Stable isotope values from precipitation scattered around the Local Meteoric Water Line (determined from Urumqi Station of the global network of isotopes in precipitation (GNIP)), together with values of the Deuterium excess parameter (d) from 15.3‰ to 30.5‰, with an average of 19.8‰, indicating that the moisture sources are primarily from regions with low relative humidity. The δ18O and δ2H values were significantly different between the river and lake samples, indicating that regional evaporation caused the isotopicenrichment of lake water. Geospatial autocorrelation, measured by Moran's I coefficient, indicated weak spatial autocorrelation within stable isotopes of oxygen and hydrogen in the surface waters of the studied area, which is primarily an effect of climate during the water chemistry evolution. The cation ratios Sr/Ca and Mg/Ca in lake water samples were not correlated with the concentration of total dissolved solids, but did show correlation with stable isotopic values, which is significant for paleoenvironmental reconstruction.
【Keywords】Spatial differentiation; Stable isotope; Moisture Sources; Geospatial autocorrelation; Issyk-Kul Lake; Central Asia