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Uptake of Sulfate by Freshwater Animals from Ambient Water
Citation:
Griffith, M., Jim Lazorchak, AND H. Haring. Uptake of Sulfate by Freshwater Animals from Ambient Water. 2020 SETAC North America Annual Meeting, Virtual, November 15 - 19, 2020.
Impact/Purpose:
Relatively little is known about the ionoregulation of sulfate in freshwaters. To understand how the sulfate anion may contribute to adverse effects associated to elevated ionic strength in freshwater, we conducted a series of experiments to measure the uptake and efflux of sulfate in representatives of 4 freshwater groups. If there is no uptake of sulfate from ambient waters, increasing water concentrations of sulfate would not increase internal sulfate concentrations and directly affect organismal sulfate concentations and ionic balances. Effects would only occur due to osmotic imbalances. However, we did observe sulfate uptake and excretion in all 4 species, suggesting the presence cellular transporters for sulfate. This research is intended to assist OW, OST in decisions relating to the development of ambient water quality criteria for individual ions, such as sulfate.
Description:
To understand how the anion, sulfate (SO42-), may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO42- in representatives of 4 freshwater groups: a fish, Pimephales promelas, and 3 invertebrates, the unionid mollusk, Utterbackia imbecillis, the crayfish, Procambarus clarkii, and a mayfly, Hexagenia bilineata. Using δ(34S/32S) stable isotope ratios and concentrations of S and SO42-, we measured the SO42− influx rate, net flux, and efflux rate during a 24-hr exposure period to water containing two concentrations of 34S-enriched NaSO4. For all 4 species, the mean estimates of SO42− influx were positive, and SO42− influx was significantly greater than 0 at both SO42− concentrations in the fish and mollusk and at the lower SO42- concentration in the crayfish. The estimates of SO42− efflux and net flux were much more variable than those for SO42− influx, but several species by SO42- concentration combinations for efflux and net flux were negative, which suggests net excretion of SO42- by the animals. The results of our experiments suggest there is more uptake and excretion of SO42- in freshwater animals than had been recognized.
