A Virological Perspective on the Use of Bacteriophages as Hydrological Tracers

Abstract

Hydrological tracers, commonly used for characterizing water flow paths and sources, do not often meet all the requirements of an ideal tracer. Trans-disciplinary approaches are advocated as the way forward to enlarge the number of tracers available for investigating hydrological processes. Since the 19th century, hydrological tracers have been increasingly used, particularly in underground areas. The tracer toolbox at hand includes a large variety of options, including fluorescent dyes, isotopes, salts or bacteriophages, with each tracer offering specific qualities and complementarities. While their potential for hydrological studies has been studied in karstic environments since the 1960s, bacteriophages remain insufficiently understood. According to the selection methodology used in this review, more than thirty experiments have been listed, involving in total around seventeen different bacteriophages. These have facilitated the investigation of groundwater, surface water (i.e., river, lake and marine water), wetland and wastewater hydrological processes. The tracing experiments have also highlighted the possible interaction between bacteriophages and the surrounding environments. Bacteriophages have successfully helped researchers to understand the water flow within watersheds. Certain advantages, such as the sensitivity of detection, the ease of producing high concentrations of bacteriophages to be injected, their specificity for a host and their non-pathogenicity for human and animal cells, make bacteriophages appreciable tracer candidates for tracing experiments. However, the adsorption process or environmental factors such as temperature, pH and UV light considerably impact the fate of bacteriophages, thereby leading to an attenuation of the phage signal. Considering both the flaws and the qualities of bacteriophages, their use as hydrological tracers requires new insight and further discussions regarding experimental tracing conditions.

Investigating rare earth elements and water stable isotopes dynamics in forest ecosystems

“…new methods for sampling tree sap; REEs as tracers of tree water uptake; and a multi-tracer and multidisciplinary approach that also considers the biochemical and physiological variables as a fundamental part of tracers' studies. From this perspective, this project is in line with other recent studies that have used a multidisciplinary and/or multi-tracer approaches for hydrological research (e.g., Antonelli et al, 2017;Pfister et al, 2017;Abbott et al, 2016;Florent et al, 2022;Barbeta et al, 2022), opening the doors to new avenues of research in the field of eco-hydrology. The biochemical interactions between water and organic molecules (Yakir and DeNiro, 1989;Yakir et al, 1990;Cormier et al, 2018) are complex processes that lead to modifications in the isotopic signature of the various water compartments in trees, making it difficult to recognize the original source.…”