Date of Completion
Penny Vlahos, Craig Tobias, Robert Mason
Field of Study
Master of Science
Passive sampling is a novel method of analyte concentration from the environment that strives to bring greater ease to field sampling regimes than traditional liquid-solid phase extractions (SPE). It is easier to deploy than a Niskin bottle or CTD rosette, and easier to recover than hoisting up dozens of liters of water. Passive sampling also offers the opportunity for wider exploratory studies, as compounds can be selectively extracted back in lab, rather than having to select a particular phase SPE and follow phase-specific elution methods. In this study, Ethylene Vinyl Acetate copolymer (EVA) was used as a marine sorption and collection media. Its efficacy was tested in both ambient munitions sampling for TNT and RDX, and for sulfate in porewaters. For the munitions subset of samples, the interaction between salinity, temperature, and percent acetate composition of the EVA samplers was explored. It was found that salinity had a large increase on Log KEVA from 0-5 PSU, then became nonlinear from 5-34 PSU. The initial increase was present for all EVA types, and the 5-34 PSU subset’s Log KEVA was affected in similar manner between EVA types. Increasing temperature was found to decrease munitions sorption over 5-25˚C, and it was found that EVA80 was the most efficient sorption media out of the EVA subtypes. This is likely due to dipole interactions from the increase in the polar acetate group. An EVA polymer seeded with barium containing organic compounds was tested for efficacy in sulfate precipitation to the film for use in isotopic sulfur measurements. Out of the many barium containing organic compounds selected for testing, barium oxalate was chosen for its efficiency at precipitating and trapping sulfate from the marine environment, while being able to be easily purified by an acid-catalyzed hydrolysis procedure. It was also proven that the EVA sampler does not add an isotopic bias through fractionation during precipitation to the film from the environment. Overall, it was proven that the Ethylene Vinyl Acetate copolymer is an effective passive sorption media for marine systems, for both munitions compounds and inorganic sulfate.
Warren, Joseph K, "Development of an In-situ Passive Sampling Device for Munitions Compounds and Sulfate" (2017). Master's Theses. 1132.