Transport of organic contaminants in a surficial sand aquifer--hydrogeologic and geochemical processes affecting transport movement

• Other Authors: Franks, Bernard Jeffrey.
• Format: Others
• Language: English
• Subjects: Hydrology
• Online Access: http://purl.flvc.org/fsu/lib/digcoll/etd/3161745

Transport of organic contaminants in a sand and gravel aquifer has been investigated in order to increase our understanding of hydrologic and geochemical processes affecting movement of selected organic solutes in groundwater. An abandoned wood-treatment facility in Pensacola, Florida, was chosen for the investigation. The geometry of the system, including locations of hydrologic sources and sinks, was documented in development of a calibrated three-dimensional model of groundwater flow. These data were then combined with contaminant distribution and groundwater velocity data in simulations of solute transport. === Both numerical and analytical transport simulations were performed, in order to compare and contrast results from each. Even with dispersion equal to zero, advective flow resulted in particle transport well beyond the boundaries of the site. All solutes investigated were shown to require both increased retardation (sorption) and increased decay (biodegradation) relative to a conservative constituent. Naphthalene was best simulated with retardation values between 2 and 4 and a decay constant between 0.001 and 0.002 d$\sp{-1}$. The phenolic compounds were best simulated with retardation values between 1 and 2 and a decay constant between 0.003 and 0.02 d$\sp{-1}$. === The complexities of solute migration in groundwater preclude any study from providing unique solutions. Available laboratory experiments on behavior of organic solutes and comparable field investigations at other sites support similarities among the studies. The existence of large vertical chemical concentration gradients which persisted after over 200 meters of lateral travel distance supported the idea of very small vertical dispersivities at the site. The small value for dispersivity suggests that results of vertically-averaged simulations should be used with caution in evaluation of organic transport in the subsurface. This investigation represented an effort to provide a conceptual framework for further studies, including predictions of changes to the environment, based on increased understanding of hydrologic and geochemical processes in the subsurface. === Source: Dissertation Abstracts International, Volume: 50-02, Section: B, page: 0474. === Major Professor: James Bryant Cowart. === Thesis (Ph.D.)--The Florida State University, 1988.