Characterizing Aquifer Heterogeneity Using Bacterial and Bacteriophage Tracers

Abstract

Microorganisms constitute an almost exclusive form of life in the earth's subsurface environment (not including caves), particularly at depths exceeding the soil horizon. While of broad interest to ecology and geology, scientific interest in the fate and transport of microorganisms, particularly those introduced through the anthropogenic environment, has focused on understanding the subsurface environment as a pathway for human pathogens and on optimizing the use of microbial organisms for remediation of potable groundwater. This special section, inspired by the 2014 Ninth International Symposium for Subsurface Microbiology, brings together recent efforts to better understand the spatiotemporal occurrence of anthropogenic microbial groundwater contamination and the fate and transport of microbes in the subsurface environment: in soils, deep unsaturated zones, and within aquifer systems. Work includes field reconnaissance, controlled laboratory studies to improve our understanding of specific fate and transport processes, and the development and application of improved mechanistic understanding of microbial fate and transport processes in the subsurface environment. The findings confirm and also challenge the limitations of our current understanding of highly complex microbial fate and transport processes across spatiotemporal scales in the subsurface environment; they also add to the increasing knowledge base to improve our ability to protect drinking water resources and perform in situ environmental remediation.

Mycelial Effects on Phage Retention during Transport in a Microfluidic Platform

“…Previous work has highlighted the relevance of phages (i.e., viruses that infect bacteria) , as promising tracers for fecal contamination or for the evaluation of colloidal and water transport. − Although phage tracers have significantly improved our understanding of water and colloid movement in aquifers, information on the transport of phage tracers in the complex soil subsurface is still limited, yet highly needed. For example, accurate descriptions of microbial (colloid) transport and soil-related transport drivers are needed to assess the risk of pathogen contamination to drinking water supplies or to develop control strategies and treatment options.…”

Marine Phages As Tracers: Effects of Size, Morphology, and Physico–Chemical Surface Properties on Transport in a Porous Medium

“…Many phages (especially coli-phages such as MS2) have been tested since then either as potential surrogates for viral pathogens , or as a tool to trace the flow of water in hydrology. , An awkwardness of this usage was their differing adsorption behavior from the human adenoviruses (hAdVs) or the Norwalk virus as well as the isolation of both, coli-phages and their hosts from groundwater. , Moreover, strains of E. coli are listed as pathogenic bacteria of concern . Despite a large number of studies examining the transport of phages in the terrestrial subsurface, only very few studies evaluated marine phages, most often phage H40/1, − as microbial tracers . Marine phages are highly suitable for transport studies because they are virtually absent in the terrestrial ecosystem and nonpathogenic.…”

Microbial Transport and Fate in the Subsurface Environment: Introduction to the Special Section

“…Flynn et al (2015) reappraise solute and microbial tracer tests to characterize the ability of peri‐glacial sand and gravel aquifers to remove microbiological contaminants using a well characterized field site near Munich, Germany. The relative recovery of E. coli , the bacteriophage H40/1, and Pseudomonas putida varied strongly for transport distances of several tens of meters between injection and observation wells.…”