Aquifer microbial water quality evaluations are often performed by collecting groundwater samples from monitoring wells. While samples collected from continuously pumped sources are seldom disputed as representative of the aquifer, natural biofilm present in the vicinity of well screens may introduce unwanted microbial artefacts in monitoring wells that are only periodically sampled. The need for well water purging to obtain samples void of these artefacts has been widely recognized. However, purging methods are not standardized; many approaches presume that physico‐chemical water quality stability achieved through the removal of 3 to 5 well volumes is indicative of the stability of target analytes. Using a data set collected from a shallow unconfined aquifer in Southern Ontario, Canada, the need for using dedicated approaches that account for the time‐dependent nature of microbial water quality changes was demonstrated. Specifically, the utility of adenosine triphosphate (ATP) as a rapid, field‐ready biochemical indicator of microbial water quality stability was investigated. This work shows that ATP concentrations reflect time‐limited (bio)colloid transport processes that are consistent with other microbial water quality parameters monitored, but different from commonly measured physical and chemical water quality indicators of well purging adequacy. ATP concentrations occasionally fluctuated even after 3 or 4 h of purging, indicating that microbial artefacts attributable to biofilms in the vicinity of the well screen can still persist. The recurrence of characteristic ATP patterns in each well was systematically examined through the novel application of dynamic time warping (DTW), a nonparametric time series analysis approach. These patterns are believed to be linked with seasonal hydrogeological conditions, which warrant consideration in the design and interpretation of subsurface microbial water quality investigations.

中文翻译：

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三磷酸腺苷和动态时间规整方法照亮地下微生物的水质模式

含水层微生物水质评估通常是通过从监测井中收集地下水样本来进行的。尽管从连续抽水源收集的样品很少被争议为含水层的代表，但存在于井筛附近的天然生物膜可能会在监测仅定期采样的井中引入有害的微生物假象。人们已经广泛认识到需要进行井水冲洗以获得不含这些假象的样品。但是，清除方法尚未标准化。许多方法假定通过去除3至5孔的体积实现的理化水质稳定性表明了目标分析物的稳定性。使用从加拿大安大略省南部的一个浅水无限制含水层收集的数据集，证明了需要使用专门的方法来说明微生物水质变化的时间依赖性。具体来说，研究了三磷酸腺苷（ATP）作为微生物水质稳定性的快速，现成的生化指标的实用性。这项工作表明，ATP浓度反映了限时的（生物）胶体运输过程，该过程与所监测的其他微生物水质参数一致，但不同于通常测得的井水充足性的物理和化学水质指标。甚至在吹扫3或4小时后，ATP浓度仍会偶尔波动，这表明归因于井筛附近生物膜的微生物伪影仍然可以持续存在。通过动态时间规整（DTW）（一种非参数时间序列分析方法）的新颖应用，系统地检查了每口井中特征性ATP模式的重复性。这些模式被认为与季节性水文地质条件有关，因此在进行地下微生物水质调查的设计和解释时应考虑这些因素。