Isotopic and Hydrochemical Characteristics of Groundwater in the Golmud River Basin

On the basis of rule of hydr ochemical components cycling in the corresponding drainage basins having different isotope compositions, H and O isotopes analysis for natural water in the Golmud River basin, indicates that lixiviation of groundwater chemical components is strengthened, HCO₃^- decreases gradually, and Cl^- increases as flowing distance increases.By using DD, D¹⁸O and ³H to establish a linearequation for drainage basin atmosphere precipitation and confirm mountain rivers are not supplied in the current year and mainly supplied by groundwater and then by ice-snow melt and atmosphere precipitation.Averages DD and D¹⁸O values in the mountainous precipitation are lower than those in the plain areas.This indicates that the isotopes of precipitation in plain areas are influenced by evaporation and heavy isotopes are enriched.That the average DD and D¹⁸O values in mountainous precipitation are identical to those in the plain areasi shows that groundwater in plain areas is rechar ged by stream from mountains.The DD and D¹⁸O values of confined flow water are substantially similar with phreatic water.Age determined by ³H value is older than phreatic water, its age will change from young to old with increase of buried depth.