The CREWS-JRW team will meet via WebEx on Monday, October 31, from 12 p.m. - 1 p.m.
Caitlin Mayernik, a Ph.D. candidate at MSU, will present "Riparian corridors control stream concentrations of nitrate and sulfate in semiarid dryland agricultural landscapes of the Judith River Watershed."
About the talk: In the JRW, leached nitrate accumulates in the Moccasin terrace shallow aquifers perched on impermeable shale, where groundwater concentrations in some locations exceed 20 mg N L-1, or twice the EPA public drinking water standard. Stream channels also exhibit sulfate concentrations that reflect contact with both weathered shale-derived soils upgradient on the terrace and weathered shale-derived alluvium deposited in the riparian corridors. The unique combination of chemistries driven by the interaction of human management with natural process domains provide an opportunity to parse the relative controls on water quality across this agricultural landscape. In this work, we ask how the hydrogeologic setting of a riparian corridor regulates hydrologic transport and biogeochemical transformation of nitrate and sulfate. We address this question using two years of solute data for stream channel and riparian groundwater across three ~700m reaches of two streams draining the Moccasin terrace landform centrally located in the JRW. Nitrate and sulfate concentrations in riparian groundwater vary within and across stream reaches indicating substantial and spatially variable biogeochemical processing of source waters. The geochemical signals imparted by stream incision into the terrace stratigraphy and the biochemical signals imparted by soil-saturated anoxic environments indicate the role of riparian corridors in influencing water quality in this semi-arid agricultural system.