δ18O and electrical conductivity (EC) were used successfully to trace the spatial distribution of whole-lake groundwater-lake exchange for a small (four ha) groundwater-fed lake situated in a low relief and low hydraulic gradient area. The method relies on quick sampling of shallow groundwater, direct analysis of EC in the field, and relatively in-expensive analysis of δ18O in the laboratory. Ternary uncertain end-member mixing analysis (precipitation, groundwater, and lake water) quantified the composition of water discharging to and recharging from the lake. The tracer distribution and mixing analysis were in agreement with the interpreted groundwater flow near the lake. The use of only one tracer (either δ18O or EC) gave the same results for the recharge segments, but the discharge segments changed the origin of the water from being groundwater to precipitation controlled. The two tracers complemented each other, especially with different signals in precipitation and groundwater. The uncertain end-members were assessed based on local (groundwater and lake water) and off-site (precipitation) data. The off-site data were found to be useful if it contained representative information on local-site seasonality (uncertainty, variance). Final end-member concentrations could explain the transience of the hydrology at the site (i.e., flooding of the area adjacent to the lake during periods with high precipitation, and variability of the δ18O signal in precipitation). This methodology potentially represents a new option to study groundwater-lake systems. The tracer information collected over only two days is useful by itself for developing the next steps like the quantification of fluxes based on other standard methods (Darcy approach, seepage meters, or temperature). The tracer information can provide quantitative estimation of inputs and outputs by using the mixing analysis.

中文翻译：

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使用 d18O 和电导率以及不确定的端部混合分析追踪低水力梯度系统中地下水和湖水全湖交换的空间分布

δ18O 和电导率 (EC) 已成功用于追踪位于低地势和低水力梯度区域的小型（四公顷）地下水补给湖的全湖地下水-湖交换的空间分布。该方法依赖于浅层地下水的快速采样、现场直接分析 EC 以及实验室中相对便宜的 δ18O 分析。三元不确定端元混合分析（降水、地下水和湖水）量化了流入湖和从湖补给的水的组成。示踪剂分布和混合分析与湖附近解释的地下水流一致。仅使用一种示踪剂（δ18O 或 EC）对补给段给出了相同的结果，但是排放段将水的来源从地下水变为受降水控制的水。这两种示踪剂相辅相成，尤其是在降水和地下水中具有不同的信号。不确定的最终成员是根据当地（地下水和湖水）和场外（降水）数据进行评估的。如果场外数据包含有关当地季节性（不确定性、方差）的代表性信息，则发现该数据很有用。最终的端元浓度可以解释该地点水文的瞬态（即，在高降水期间邻近湖泊区域的洪水，以及降水中 δ18O 信号的变化）。这种方法可能代表了研究地下水-湖泊系统的新选择。仅在两天内收集的示踪剂信息本身对于开发后续步骤非常有用，例如基于其他标准方法（达西方法、渗流计或温度）的通量量化。示踪信息可以通过混合分析提供输入和输出的定量估计。