A mobile downhole fluorometer was used to detect zones of preferential groundwater tracer transport into an observation well. Identification of such zones is not possible if individual samples are collected over the well's entire screened interval. Laboratory-based tests using the fluorometer, and a purpose-built apparatus demonstrated that the fluorometer could be used with tracers to characterise well water flow regimes. During field investigations in a porous aquifer, the fluorometer monitored tracer concentrations in an observation well with a 12-m-long screen, 10 m down the hydraulic gradient from a fully penetrating injection well. Test results showed that the tracer occurred in the observation well over a discrete 2.5-m-thick interval. Single-well dilution test and vertical-flow data indicated that water entered the well at additional depths, but no tracer was detected at these levels. A numerical model reproducing dilution test concentration profiles indicated that water entered the well in many of these horizons at comparable velocities to those in the tracer-bearing zone. These data suggest that groundwater flow direction varied with depth in the aquifer under investigation. Moreover, simulations of tracer arrival indicated that the tracer distribution observed in the observation well was derived from a horizon that may be no thicker than 0.5 m.RØsumØ Un fluorim tre a ØtØ utilisØ pour dØtecter les zones d'Øcoulement prØfØrentiel d'un traceur dans un puits d'observation. Les identifications de telles zones n'est pas possible si les Øchantillons individuels sont collectØs sur toute les longueurs des parties crØpinØes du puits. Les tests de laboratoire utilisant un fluorim tre et un dispositif adØquat ont montrØ que les fluorim tres pouvaient servir à dØfinir les rØgimes d'Øcoulement de l'eau dans les puits. Durant les investigations de terrain dans un aquif re poreux, le fluorim tre a enregistrØ les concentrations du traceur dans un puits d'observation avec une crØpine de 12 m. de long, 10 m sous le gradient hydraulique dans un puits à pØnØtration totale. Les rØsultats des tests ont montrØ que le traceur apparaissait dans un interval discret de 2.5 m de long. Un test de dilution en puits unique et des donnØes d'Øcoulement vertical ont indiquØ que l'eau rentrait dans le puits à d'autres profondeurs, mais le traceur n'a pas ØtØ dØtectØ à ces niveaux. Un mod le numØrique reproduisant le test de dilution et le profil de concentration a indiquØ que l'eau entrait dans le puits à ces niveaux à des vitesses comparables de celle du traceur. Ces donnØes sugg rent que l'Øcoulement des eaux souterraines varie avec la profondeur dans l'aquif re sous la zone d'investigation. D'ailleurs, les simulations de l'arrivØe du traceur ont montrØ que la distribution des concentrations du traceur dans le puits ne pouvaient pas Þtre dues à une couche plus fine que 0.5 m.Resumen Se utilizó un fluorómetro móvil descendente para detectar zonas de transporte preferencial de trazadores de agua subterrµnea en un pozo de observ...
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.