干旱区研究2012，Vol.29Issue(5)：898-906,9.
甘肃梨园河流域地下水来源及其水化学特征
The Sources and Hydrochemical Properties of Groundwater in the Liyuan River Basin, Gansu Province
摘要
Abstract
The Liyuan River Basin is located in an arid inland in northwest China and it is an important agricul-tural area in the Hexi Corridor, Gansu Province. As a tributary stream of the Heihe River, the Liyuan River is of significance in promoting economic and ecological development in the Zhangye Basin. The ecosystem in the region is highly vulnerable and strongly affected by the hydrochemical composition of water. For this reason, it is necessa- ry to monitor the hydrochemical evolution in this area so as to avoid the degeneration of the local ecological environ- ment. As surface water resources are limited, groundwater has gradually become as an indispensable water source in people＇s daily life and agriculture. A lack of understanding of the mechanisms of groundwater evolution may lead to unwise utilization of groundwater, and thus have a negative impact on local sustainable development may be re-sulted in. In this paper, the relationships between hydrochemical properties and stable isotopes were analyzed. The transformation of surface water and groundwater was lucubrated so as to provide the government with decisional sup-port concerning groundwater conservation. It was assumed that groundwater flowed in the same path from the south- west to the northeast based on considering the flow direction of the Liyuan River. The results showed that the TDS values of groundwater increased from the southwest to the northeast. The highest TDS value was 1 258 mg/L, which was too high for drinking use ; this was the result of water-rock interaction and the salinization caused by the infiitra-tion of irrigation water. Along with the flow path, the hydrochemical type of deep groundwater changed from Ca - HCO3 to Ca - Mg - HCO3, Mg - SO4 and Na - SO4, that of shallow groundwater changed from Ca - HCO3 to Mg - HCO3 - SO4 and Mg - SO4, and that of surface water remained as Ca - HCO3 without change. Among the hyrdo-chemical changes, the increasing content of Na ＋ was the most apparent. There were two reasons for the increase of Na^＋ content along the flow path： the first was that Ca^2＋ in groundwater exchanged with Na ^＋ in minerals in the cat-ion-exchange process, and the second was the weathering of silicate minerals that produced Na^ ＋ The results simu- lated with Phreeqc software identified that there were the main water-rock interactions in groundwater along the flow path. In deep groundwater, calcite was precipitated at first, and then dissolved; whereas CO2 gas, gypsum, dolo-mite and halite were dissolved. In shallow groundwater, calcite was dissolved at first, and then precipitated, while gypsum and halite were dissolved. The modeling results were the evidences of the hydrochemical processes. The tracer elements of 2^H and 18^O in water molecules were used in this paper to analyze the water resources and re-charge patterns. By comparing the ^18δO - δ^2H relation line of surface water and groundwater, global meteoric water line （GMWL） and local meteoric water line （ LMWL）, it was concluded that groundwater was recharged by precip-itation or snowmeh water via surface runoff from the mountain area. Deep groundwater migrated upward to recharge shallow groundwater and surface water.关键词
地下水/水文地球化学/Phreeqc软件/氢氧稳定同位素/梨园河流域/甘肃Key words
groundwater/hydrogeochemistry/Phreeqc software/stable isotope/Liyuan River Basin/Gansu分类
天文与地球科学引用本文复制引用
张清寰,齐识,马金珠..甘肃梨园河流域地下水来源及其水化学特征[J].干旱区研究,2012,29(5):898-906,9.基金项目
科技部“973”项目 （）
国家自然科学基金项目（40872161）共同资助 （）
