Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development
Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development
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高山流域的地下水惰性气体、年龄和温度特征：概念模型开发中的宝贵工具
DOI：
10.1029/2006wr005349
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发表时间：
2007
影响因子：
5.4
通讯作者：
J. Caine
中科院分区：
文献类型：
--
作者：
A. Manning;J. Caine
人们对高山流域的基岩地下水了解甚少，主要是因为高山地区缺乏水井。本文收集了科罗拉多州高山流域Handcart Gulch 3-342 m深度的泉水和井中地下水惰性气体、年龄和温度数据。温度剖面显示活跃的地下水循环至最大深度（含水层厚度）约200米，或地下水位以下约150米。溶解稀有气体数据显示基岩中异常高的过量空气浓度（>0.02 cm3 STP/g， ΔNe > 170%），与在流域上部观测到的异常大的季节性地下水位波动（高达50 m）相一致。表观3H/3He年龄与样品深度和过量空气浓度呈正相关。综合样本采集自干流附近的自流基岩井，并假定其近似于反映基岩含水层平均停留时间的流量加权样本。这些综合样品的指数平均年龄沿河流非常一致，5个样品中有4个在8至11年之间。示踪剂数据与其他水文和地质数据相结合，支持一个相对简单的流域地下水流动概念模型，其中：(1)渗透率主要是深度的函数；(2)水位波动随距离河流的远近而增大；(3)整个流域的补给、含水层厚度和孔隙度相对均匀，尽管其下方的元古代结晶岩地质复杂。
Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3–342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation to a maximum depth (aquifer thickness) of about 200 m, or about 150 m below the water table. Dissolved noble gas data show unusually high excess air concentrations (>0.02 cm3 STP/g, ΔNe > 170%) in the bedrock, consistent with unusually large seasonal water table fluctuations (up to 50 m) observed in the upper part of the watershed. Apparent 3H/3He ages are positively correlated with sample depth and excess air concentrations. Integrated samples were collected from artesian bedrock wells near the trunk stream and are assumed to approximate flow‐weighted samples reflecting bedrock aquifer mean residence times. Exponential mean ages for these integrated samples are remarkably consistent along the stream, four of five being from 8 to 11 years. The tracer data in combination with other hydrologic and geologic data support a relatively simple conceptual model of groundwater flow in the watershed in which (1) permeability is primarily a function of depth; (2) water table fluctuations increase with distance from the stream; and (3) recharge, aquifer thickness, and porosity are relatively uniform throughout the watershed in spite of the geological complexity of the Proterozoic crystalline rocks that underlie it.