Development of a Colloid Sampling Technique for Suboxic Groundwaters in Memphis, TN

Techniques for colloid isolation have been relatively well documented to date, but have been conducted primarily under oxic conditions. New methods to resolve sub- or anoxic conditions must be developed to facilitate further advances in understanding colloidal behaviors across all environments. Suboxic (diss. O2 ~ 45-57 μg/L) conditions, characteristic of groundwater from the Memphis Aquifer (Memphis, TN), have been observed to generate iron precipitates via oxidation upon exposure to the atmosphere. It is believed this will confound any attempts toward the large volume (>1000 L) sampling of the colloid phase of groundwater flow using cross-flow filtration (CFF) methods. Integration of a high-pressure (40 psi) reservoir to the recycle loop design in CFF is proposed to concentrate colloids from groundwater samples. The results represent the testing of the modified Pellicon ultrafilter design, including a robust recharacterization of collection efficiency and establishment of the system's capacity to preserve in-situ oxygen concentrations sampled from non-oxic subsurface environments.