Browsing by Author "Fay, Steffan R"

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    Optical Brightener Screening for Sewage Contamination of Water Table Aquifers in Southeastern Minnesota, USA
    (Published in: Proceeding of the International Association of Hydrogeologists XXVI International Congress, Edmonton, Alberta, Canada. June 1995., 1995-06) Spong, Ronald C; Fay, Steffan R; Alexander Jr., E. Calvin
    Novel screening methods for detecting optical brighteners, fluorescent organic blue dyes principally used in laundry detergents for whitening fabrics, have been developed for the monitoring of water table aquifers impacted by septic systems. Four rural residential communities characterized by private water supply and sewage systems were selected in southeastern Minnesota. Developments were chosen with a variety of saturated and unsaturated zone materials and thicknesses, water table and well depths, and topographic and cultural settings. Sampling sites were enrolled if wells were completed above regional aquitards. Sanitary surveys of sampling sites were completed with attention to drinking water usage and waste/wastewater disposal practices to uncover sources of crosscontamination. Water supplies were sampled and analyzed to determine aquifer sources, sanitary quality and natural backgrounds and anthropomorphic contributions of physicochemical and microbiological parameters of interest (e.g., nitrate, chloride and coliform bacteria). Filter holders containing untreated cotton, activated carbon and polysulfone/polyethersulfone membrane filters were installed as immersion-type detectors in toilet reservoirs. Syringe filter capsules comprised of polyethersulfone membranes were utilized for direct sampling. Exposure times ranged from minutes to months, and exposed filter media were analyzed in solid phase utilizing a scanning spectrofluorophotometer. Spectral data were computer-processed to objectively match peaks with the spectra obtained from pure fluorescent dyes and laundry detergent formulations. Detections were positive if matched peaks at 440 nm appeared above background fluorescence. Water supply test data and site survey information indicative of septic system contamination were moderately correlated with positive optical brightener detections.
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    Optical Brighteners: Sorption Behavior, Detection, Septic System Tracer Applications
    (Published in: Proceedings of the International Association of Hydrogeologists XXVI International Congress, Edmonton, Alberta, Canada. June 1995., 1995-06) Fay, Steffan R; Spong, Ronald C; Alexander, Scott C; Alexander Jr., E. Calvin
    Laboratory soil column experiments were used to evaluate the optical brighteners (fluorescent whitening agents) Tinopal3 CBS-X (ASTM designation DSBP-1) and Tinopal3 5BM-GX (ASTM designation DASC-4) and the fluorescent dye eosin Y (C.1. 45380) as adsorbing tracers in subsurface systems. In a low organic carbon content glacial outwash sand (foe = 0.0034, 97% sand by weight) the solid-water distribution coefficient (Kd) was determined to be 0.26 cm113/g for Tinopal CBS-X, 0. 78 cm113/g for Tinopal 5BM-GX, and 0.024 cm11 3/g for eosin Y. All three compounds had simple sigmoidal breakthrough curves. Optical brighteners can be detected in direct solution by fluorometry but suffer from interference associated with naturally occurring organic compounds. Unbrightened cotton can be used to qualitatively detect optical brighteners. Polyethersulfone filter media can be used to selectively remove optical brighteners from solution without changing the background fluorescence spectrum. The exposed filter medium can be analyzed as a solid sample in a scanning spectrofluorophotometer. The resulting spectrum can be used to measure the optical brightener concentration in the filtered sample. Polyethersulfone filters can be used to detect optical brighteners in samples collected in and around septic system drain fields at less than 1 ppb Tinopal 5BM-GX equivalent.