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Use of bacteria community analysis to distinguish groundwater recharge sources to shallow wells
Author(s) -
Higgins Mark A.,
Robbins Gary A.,
Maas Kendra R.,
Binkhorst Gordon K.
Publication year - 2020
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.1002/jeq2.20150
Subject(s) - groundwater recharge , groundwater , environmental science , hydrogeology , indicator bacteria , nitrate , water quality , contamination , water well , hydrology (agriculture) , environmental chemistry , ecology , biology , geology , fecal coliform , chemistry , aquifer , geotechnical engineering
In this study, bacteria community analysis was performed to supplement a preexisting evaluation of nitrate contamination in drinking water wells at a coastal site in Old Lyme, CT. Given well usage and coastal hydrogeologic conditions, the source(s) of nitrate contamination in domestic wells could not be discerned between local septic systems or a nearby farm where organic fertilizers were used. Groundwater bacteria communities are known to be sensitive to a variety of environmental conditions. As such, they are potentially useful in distinguishing groundwater recharge sources. Groundwater samples collected from wells were analyzed using polymerase chain reactions (PCR) and 16S rRNA sequencing to determine the bacteria distributions in each well. The biostatistical analysis of the data using Bray–Curtis nonmetric multidimensional scaling and permutational multivariate analysis of variance revealed three distinct bacteria community distributions that coincided with three different areas on the site. Additionally, principal component analysis (PCA) of the water quality data revealed that wells with similar bacteria shared similar water quality, all of which was indicative of local recharge. These findings suggested that the domestic well nitrate contamination was derived from local septic systems rather than the farm. Septic indicator analysis using ultra‐performance liquid chromatography–tandem mass spectrometry determined the presence of caffeine in domestic wells, which was consistent with the conclusions from the bacteria analysis, PCA, and the known hydrogeologic conditions. The low cost, ease of sample collection, and growing availability of bioinformatics laboratory services and software are conducive to the application of microbial community analysis as a supplemental tool for groundwater investigations.