The objective of this work is to investigate the hydrochemical compositions of the geothermal wa-ter,lake water,river water,and ice-and snow-melt water as well as control factors of provenance in the Daggyia geothermal field of Tibet.The field surveys and sampling were conducted in August 2014.The main cations and anions of samples were measured using the ICP-OES and UV-visible spectrophotometer.The iso-topic ratios of dissolved inorganic carbon (DIC)were analyzed using a gas stable isotope ratio mass spectrom-eter.The results show that the concentrations of total dissolved solids (TDS)range from 977.13 mg/L to 1 279.50 mg/L for geothermal water,and K+ and Na+ are the main cations,and HCO 3 - and Cl- are the main anions.The concentrations of TDS of the lake waters range from 77.81 mg/L to 810.94 mg/L,Ca2 + ,Na+ , HCO 3 - (CO 3 2 - )and SO 4 2 - occupy the majority of ions.The hydrochemical types of both geothermal water and lake water are the type of bicarbonate-sodium.The ion concentrations of river and melt water are low, and the hydrochemical type is bicarbonate-calcium.The concentrations of DIC in geothermal water range from 9.2 mmol/L to 15.4 mmol/L,and that of δ1 3 CDIC ranges from -9.09‰ to -0.95‰.The concentra-tions of DIC in lake water are 1.1 mmol/L to 9.7 mmol/L,theδ1 3 CDIC values are -8.84‰ to -0.27‰.The Gibbs boomerang envelope of water samples indicates that the hydrochemical characteristics are mainly con-trolled by silicate rocks weathering in the area,and the major processes are the albite and potash feldspar weathering,while the hydrochemical compositions of geothermal water are also affected by dissolution of e-vaporation of salt rocks.The carbon sources of silicate weathering around the lakes are mainly soil carbon di-oxide.Meanwhile the deep carbon dioxide input is the main source of silicate hydrolysis in hot spring areas.%为探究青藏高原搭格架地热区地热水、湖水、河水、冰雪融水等天然水体的水化学组成及物质来源控制因子,于2014年8月对该地区进行了考察和取样。利用紫外-可见光分光光度计和 ICP-OES 测定了水样中各阴、阳离子含量,利用 Gas Bench 连接同位素质谱仪测定了水样中溶解无机碳(DIC)同位素比值。结果表明,地热水中总溶解固体(TDS)含量为977.13~1279.50 mg/L,阳离子以 K+和 Na+为主,阴离子以HCO 3-和 Cl-为主,湖水的 TDS 含量为77.81~810.94 mg/L,阳离子以 Na+和 Ca2+为主,阴离子以 HCO 3-(CO 32-)和 SO 42-为主,地热水和湖水的水化学类型为 HCO 3-Na 型；河水和冰雪融水的各离子含量较低,水化学类型为 HCO 3- Ca 型；地热水的 DIC 浓度范围为9.2~15.4 mmol/L,δ13 CDIC 值为-9.09‰~-0.95‰；湖水的 DIC 浓度为1.1~9.7 mmol/L,δ13 CDIC 值为-8.84‰~-0.27‰。根据水化学 Gibbs 分布模式图判断出区域水化学特征主要受硅酸盐岩风化控制,以钠长石和钾长石风化为主,但是地热水的水化学组分受到硅酸盐岩和蒸发盐岩共同控制。通过碳同位素比值分析对区域主要风化过程中 CO 2的来源示踪表明,湖区周围的硅酸盐风化其碳源主要为土壤 CO 2,热泉区硅酸盐水解其碳源为地球深部 CO 2输入。
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