巴音河流域水化学与氢氧同位素特征研究

Hydrochemical Property and H ydrogen and O xygen I soto pes in the Bayin River Basin

【目的】分析巴音河流域水化学与氢氧同位素特征,揭示流域内不同水体间的转换关系。【方法】结合水化学与稳定同位素技术,分析巴音河流域不同水体的水化学特征,探讨水体中离子来源及控制因素,进而识别不同水体间的补给机制。【结果】流域水体pH平均值、TDS平均值及DO平均值分别为7.53、399 mg/L和5.46 mg/L;河水、泉水中阴离子以SO_(4)^(2-)为主,地下水中阴离子以Cl^(-)为主;所有水体阳离子均以Ca^(2+)为主。水体中Na^(+)(/Na^(+)+Ca^(2+))的比值点主要分布在蒸发-结晶作用带和岩石风化带之间,远离大气降水带;巴音河流域水体蒸发线的斜率(4.94)显著小于当地及全球大气降水线斜率;河水氢氧稳定同位素的平均值介于流域北部山区大气降水和地下水的氢氧稳定同位素平均值之间。【结论】蒸发结晶作用和岩石风化作用是控制流域水体水化学特征的主要因素,且蒸发岩和碳酸盐的风化溶解是流域水体离子的主要来源。上游地下水接受地表水渗漏和侧向径流补给,比例分别为43.36%、56.64%;中游地下水接受地表水和河流上游补给,比例分别为69.51%、30.49%;下游地表水接受地下水和泉水补给,比例分别为10.26%、89.74%。

【Objective】The Bayin river basin is located in Qinghai province;the physical and chemical properties of its water vary with many factors.In this paper,we analyze the hydro-chemical properties and hydrogen and oxygen isotopes in different reaches of the basin.【Method】Water samples were taken from different locations in the basin,and the hydrochemical property and stable isotopes in each sample were analyzed using standard laboratory methods.【Result】①The average pH,TDS and DO of the water samples are 7.53,399 mg/L and 5.46 mg/L respectively.The predominant anion in the surface water and groundwater is SO_(4)^(2-) and Cl^(-),respectively,while the main cation in the waters is Ca^(2+),in spring.②The Na^(+)/(Na^(+)+Ca^(2+))ratio is distributed mainly between the evaporation crystallization zone and the rock weathering zone,far away from the atmospheric precipitation zone.③The slope of the water evaporation line is 4.94,significantly lower than that of local and global atmospheric precipitation lines.The average stable hydrogen and oxygen isotopes in the river water are between the average atmospheric precipitation and the groundwater in the mountainous region in north of the basin.④Evaporation crystallization and rock weathering are the main factors controlling hydro-chemical property of the basin water,and rock weathering and dissolution of evaporite and carbonate are the main sources of the ions.⑤Recharge to the upstream groundwater is surface water leakage and lateral runoff,accounting for 43.36%and 56.64%of the total recharge,respectively,while recharge to the groundwater in the middle reach is surface water and upstream river water,accounting for 69.51%and 30.49%of the toral recharge,respectively.In the downstream reach,groundwater recharges the river and spring,accounting for 10.26%and 89.74%of their total recharges,respectively.