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Use of Molecular Markers to Compare Escherichia coli Transport with Traditional Groundwater Tracers in Epikarst
Author(s) -
Bandy Ashley,
Cook Kimberly,
Fryar Alan E.,
Polk Jason
Publication year - 2018
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 - 10.2134/jeq2017.10.0406
Subject(s) - karst , groundwater , aquifer , contamination , tracer , environmental chemistry , environmental science , hydrology (agriculture) , surface water , water table , hydrogeology , water quality , chemistry , environmental engineering , geology , ecology , biology , paleontology , physics , geotechnical engineering , nuclear physics
Bacterial contamination of karst aquifers is a global concern as water quality deteriorates in the face of decreasing water security. Traditional abiotic groundwater tracers, which do not exhibit surface properties similar to bacteria, may not be good proxies for risk assessment of bacterial transport in karst environments. This study examined the transport and attenuation of two isolates of Escherichia coli in relation to traditional groundwater tracers (rhodamine WT dye and 1‐μm‐diam. latex microspheres) through ∼30 m of epikarst in western Kentucky. Differential movement of the four tracers was observed, with tracer behavior dependent on flow conditions. Dye arrived at the sampling site prior to particulates. Molecular biology techniques successfully detected bacteria in the cave and showed attenuation was greater for a bacterial isolate with high attachment efficiency compared with an isolate known to have low attachment efficiency. Microspheres were first detected simultaneously with the low‐attachment isolate but attained maximum concentrations during increases in discharge >11 d post‐injection. Bacteria were remobilized by storm events >60 d after injection, illustrating the storage capacity of epikarst with regard to potential contaminants. The two bacterial strains were not transported at the same rate within the epikarst, showing breakthroughs during differing storm events and illustrating the importance of cell surface chemistry in the prediction of microorganism movement. Moreover, this study has shown that molecular analysis can be successfully used to target, quantify, and track introduced microbial tracers in karst terrains. Core Ideas Differential movement of bacteria, dye, and microspheres was evident in epikarst. Surface chemistry should be considered for prediction of bacterial movement in karst. Molecular analysis can be used to track microbial tracers in karst terrains.