Abstract The use of tritium in the identification of the “age” of groundwater is being used since the discovery of its potential for this purpose in 1954. The present work sought to apply and discuss the use of the different types of lumped parameter models (LPM) in the Caue and Gandarela aquifers, in order to obtain the groundwater mean residence time based on tritium data. Water samples from several discharges related to the Caue and Gandarela aquifers were collected during the month of September of 2017. The reconstruction of the historical series of tritium contents in the precipitation at the GNIP station CDTN-Belo Horizonte was carried out based on data from the Kaitoke (New Zealand) and Adelaide (Australia) stations in addition to the Brazilian stations Brasilia, Rio de Janeiro and Salvador. The sample results and the data of the reconstructed historical series of the tritium concentration in the CDTN station during the period between 1953 and 2017, served as the basis to use the lumped parameter models with the aid of the software TracerLPM, provided by the United States Geological Survey. From the overlap of some sample points with tritium samples collected in different years by different authors, an adjustment of some models of residence time distribution was possible. The models used were exponential (EM), exponential-piston (EPM), and dispersive (DM). The model that best fit to data was the EPM model. The mean transit time for the EPM model in the analyzed points varies from 63 to 95 years, with a median value of 73 years. Differences between values of the EPM ratio parameter were verified. However, all values indicate an exponential flow component greater than the piston flow component. The EPM model suggests a long retention time of the tracer in the aquifer system. It can be used as an approximation of the retention time for environmental contamination. The exponential model (EM) and piston flow model (PFM) were used together. Based on the data of a single tritium sample collected in time, and the average value of residence time provided by each model, a first approximation of the mean residence time value can be obtained. The results suggest that this is a better approximation than assuming a pure exponential model or piston flow model to describe the data of a single tritium sample in time as were made by previous local works. In general, a short residence time was estimated for the Caue aquifer as a whole with some discharges with long residence time that drains regional flows from the deepest part of the Caue aquifer, reflecting the complex structural geology fabric.

中文翻译：

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使用巴西米纳斯吉拉斯州 Quadrilátero Ferrífero 的 Moeda Synclyne 环境氚的单一和时间序列数据进行地下水测年

摘要 自 1954 年发现氚用于此目的的潜力以来，一直在使用氚来确定地下水的“年龄”。目前的工作试图应用和讨论不同类型的集总参数模型 (LPM) 的使用。 ) 在 Caue 和 Gandarela 含水层中，为了获得基于氚数据的地下水平均停留时间。2017 年 9 月收集了与 Caue 和 Gandarela 含水层相关的几个排放水样。 GNIP 站 CDTN-Belo Horizo​​nte 降水中氚含量的历史序列重建是基于来自除巴西站巴西利亚、里约热内卢和萨尔瓦多外，还有 Kaitoke（新西兰）和阿德莱德（澳大利亚）站。1953-2017年CDTN台氚浓度历史序列重建的样本结果和数据，为利用美国提供的TracerLPM软件辅助使用集总参数模型提供了依据。地理调查。从一些样本点与不同作者不同年份收集的氚样本的重叠来看，一些停留时间分布模型的调整是可能的。使用的模型是指数 (EM)、指数活塞 (EPM) 和分散 (DM)。最适合数据的模型是 EPM 模型。分析点中 EPM 模型的平均传输时间从 63 年到 95 年不等，中值为 73 年。验证了 EPM 比率参数值之间的差异。然而，所有值都表示指数流量分量大于活塞流量分量。EPM 模型表明示踪剂在含水层系统中的保留时间很长。它可以用作环境污染保留时间的近似值。指数模型（EM）和活塞流模型（PFM）一起使用。根据及时采集的单个氚样品的数据，以及各模型提供的停留时间平均值，可以得到平均停留时间值的一阶近似值。结果表明，这比假设一个纯指数模型或活塞流模型来及时描述单个氚样品的数据是更好的近似，如先前的本地工作所做的那样。一般来说，