Date of Thesis

5-10-2017

Thesis Type

Honors Thesis (Bucknell Access Only)

Degree Type

Bachelor of Science

Department

Geology

First Advisor

Ellen K. Herman

Abstract

Studying variability in karst spring water chemistry, specifically Mg/Ca ratios and PCO2, during storm events is useful in identifying recharge sources and flowpaths for karst systems. Analyzing hysteresis plots make flow component arrival time comparisons possible and allow for the identification of water types, such as soil water, epikarst water, point recharge storm event water, and matrix water. Mg/Ca and PCO2 hysteresis at two central Pennsylvania karst springs was observed during the summers of 2015 and 2016. Clockwise Mg/Ca hysteresis is observed at both springs, suggesting that matrix water is arriving at the springs before event water. This is likely the result of piston flow. Both springs experienced storm-induced hysteresis during relatively wet antecedent conditions and minimal to no storm-induced hysteresis during relatively dry antecedent conditions. This suggests that antecedent precipitation conditions strongly impact recharge and flow through fluviokarst systems, especially with regard to storm events. During wet antecedent conditions, clockwise Mg/Ca hysteresis was observed at Smullton Sinks, suggesting that piston flow is causing matrix water to arrive at the spring before storm event water. In contrast, during dry antecedent conditions, storm event water does not arrive at either spring and a soil water signature is not observed. These data and observations serve as a starting point for the development of a comprehensive karst spring classification system that takes into account both flow and recharge. This research is important because understanding how water flows through karst systems and knowing where it comes from is a crucial component of effective water supply management and contamination protection of these systems.

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