4 Characterization of Karst of the Midwestern U.S.: Problems with Unstable Ground and Groundwater Quality

Monday, 18 April 2016
8:00 AM - 12:00 PM
Technology Room

USING NUTRIENT DATA AND DYE TRACING TO INFER GROUNDWATER FLOW PATHS AND CONTAMINANT TRANSFER TIME IN GRAYSON-GUNNAR CAVE, MONTICELLO, KY

Paper number: 4-3
Program: Theme Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

This research comprises two related objectives in the study of Grayson Gunnar Cave system and enclosing epigenic karst aquifer in Southeast Kentucky: 1) to assess the connectivity between the cave system and potential point sources of anthropogenic contamination (e.g., septic systems and confined animal feeding operations—CAFOs); and 2) to determine the fate and travel time of nutrients within the cave. The vision is to use results from this study to contribute to a greater understanding of the critical zone, deeper groundwater, and the impact of changing land use on epigenic karst aquifers in the Cumberland Plateau.

The broader study included the analysis of principal ions, trace metals, stable isotopes, nutrient concentrations, specific UV absorption (SUVA), total phycocyanin, fluorescent dissolved organic matter (fDOM), and tracing by fluorescent dyes. In this presentation, we focus on nitrogen, phosphate data, and SUVA results from discrete samples, and phycocyanin and fDOM as monitored using an EXO2 multiparameter sonde. We also discuss the results from the qualitative dye traces using charcoal packets analyzed from the outflow spring of the karst aquifer.

Nitrogen and phosphate are elevated as expected. Nitrate concentrations are more dilute during storm events, but phosphate levels increase due to mobilization of sediment substrates. fDOM values spike during storm events and, combined with SUVA values, suggests the rapid transfer of organic matter from the land surface with limited degradation. In contrast, neither rhodamine WT dye injected into a well near a poultry CAFO or uranine dye injected into a domestic septic system, both in the headwaters of the karst aquifer, appeared at the spring after more than six weeks and multiple storm events. These results highlight the decoupling between fast flow routes through sinkholes and conduits and the more diffuse flow through the epikarst.

Geological Society of America Abstracts with Programs. Vol. 48, No. 5

doi: 10.1130/abs/2016NC-274826

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.