Fate and transport of 17 beta-estradiol in karst aquifers

17 β-estradiol (E2), the most potent natural estrogen, has been linked to a number of health and reproductive problems in aquatic species. A karst aquifer, with its solution channels and preferential flow paths, allows for rapid movement of contaminants through the system and is a habitat for numerous aquatic species. E2 is present within waters of karst aquifers, indicating that the aquatic species are at risk of developing health or reproductive disorders.; I addressed the risk associated of E2 through the examination of four possible pathways for E2 through a karst system. The sediment within the conduits (Pathway 1) may serve as a source of E2 that could be slowly released E2 into the conduit; however, E2 loses activity within the sediment because of either degradational loss or sorption to the sediment. During high flow events, the sediment does not serve as reservoir for either E2 or water. Degradation of E2 over 13 days (Pathway 2) was not observed in karst spring waters. There are no losses of E2 for any differences in holding conditions (i.e. the presence/absence of light or extreme holding temperatures). The movement of fluid and solute is confined to the conduit; during high flow, only a minor flux of fluid and solute (Pathway 3) may move into the matrix. Transport in the conduit (Pathway 4) is dependent upon the geometry of the conduits, the proportion of infiltration into the system, and the physical properties of the system. Flow routing is highly sensitive to the length of the conduits and to the width of the conduits. Without knowledge of the internal system, modeling of fluid and solute transport will produce inaccurate results.