Student: Rowan McCarthy, Undergraduate Student in Environmental Scientist, Earth Science, University of Northern Iowa
Research Mentor: Dr. Mohammad Iqbal
Preliminary Investigations into Wind Cave and Maquoketa Cave Hydrology
Scarce and complex, midwestern caves have been the subject of little hydrologic research. In association with the Iowa Space Grant Consortium, ongoing investigations are being conducted by the University of Northern Iowa within Wind Cave National Park. To better understand Wind Cave data, samples from Maquoketa Cave State Park have been collected and analyzed. Three water sources were identified by park staff and sampled by the researchers. One source (Dancehall) travels for hundreds of meters through a tall, vaulted cave. The second collection site (TD Spring) is a spring which trickles directly from the rock wall outside the lower Dancehall opening. The third site (Rainy Day) is an open-air stream in a much shorter, less ventilated cave. Notably, these sampling sites are very close to each other yet have strikingly different chemistries. Indicating that the latter two sampling sites are fed by shallow, conduit water sources, the pH levels of both hovered near 7.5, while the Dancehall site consistently had a pH above 8.0. Difference in pH is in many cases indicative of limestone buffering, the process by which water becomes more basic as it seeps through the limestone bedrock of Iowa. It is likely that despite it’s open-air nature, the Dancehall water source is predominantly fed by deep, diffuse flow, not shallow conduit sources. Conflictingly, the DO of this larger water source is higher on average than the DO of the other two Maquoketa sites studied. Ionically, both TD Spring and Dancehall samples have less Chlorine than Rainy Day. Both TD Spring and Dancehall also have significantly higher nitrate concentration than Rainy Day Cave. All sites have similar Sulfate concentrations when tested with an Ion Chromatograph. These data show that TD Spring and Dancehall Cave may have more in common than they share with Rainy Day, but a definitive source of the water that feeds these three systems has yet to be nailed down. After the park, now closed for bat hibernation, opens again in the Spring, a dye tracing will be organized to more fully and definitively ascertain the ways in which these water sources are fed. This data will be used in the Summer of 2022 in the performance of a dye tracing at Wind Cave National Park, a much more complex cave system from which researchers have already begun collecting data. Both Wind Cave and Maquoketa data suffer from a lack of long-term temporal analysis, which will be pursued in due course.