USE OF NEXT-GENERATION SEQUENCING AND BACTERIAL COMMUNITY ANALYSIS IN PRIVATE GROUNDWATER WELLS TO IDENTIFY COMMON RECHARGE SOURCES

This study uses microbial community analysis methods on groundwater samples to identify common recharge sources between private shallow wells which contain varying levels of nitrate. Bacterial community composition in soil and water is controlled by measurable environmental factors such as pH, geochemical properties, climatic variables, and common water quality parameters (dissolved oxygen, electrical conductivity, total dissolved solids). Additionally, bacteria can be carried by water from source areas into major groundwater flow paths as a biological colloidal particle. Understanding bacterial transport and biogeography coupled with new rapid techniques for characterizing bacteria populations through 16S rRNA sequencing have made bacterial communities useful as a practical tracer tool for identifying common sources of groundwater recharge. In this study, groundwater samples were collected from ten private wells in southern Connecticut. The microbial communities were extracted from the samples and underwent 16S rRNA sequencing on an Illumina MiSeq Sequencer. Correlations between bacterial community composition, water quality data, and geospatial data were used to determine which groundwater wells shared similar recharge sources. The results of this study provide a foundation for future work involving this novel method of using bacteria as a groundwater tracer.