Using isotopes of dissolved inorganic carbon species and water to separate sources of recharge in a cave spring, northwestern Arkansas, USA Blowing Spring Cave

Abstract

Using isotopes of dissolved inorganic carbon species and water to separate sources of recharge in a cave spring, northwestern Arkansas, USA Blowing Spring Cave in northwestern Arkansas is representative of cave systems in the karst of the Ozark Plateaus, and stable isotopes of water (δ 18 O and δ 2 H) and inorganic carbon (δ 13 C) were used to quantify soil-water, bedrock-matrix water, and precipitation contributions to cave-spring flow during storm events to understand controls on cave water quality. water samples from recharge-zone soils and the cave were collected from March to May 2012 to implement a multicomponent hydrograph separation approach using δ O only changed by approximately 3‰ and 1‰, respectively. The isotopic compositions of precipitation and pre-event (i.e., soil and bedrock matrix) water were isotopically similar and the two-component hydrograph separation was inaccurate, either overestimating (>100%) or underestimating (<0%) the precipitation contribution to the spring. During the storm event, spring DIC and δ creased to a minimum of 8.6 mg/L and -16.2‰, respectively. If the contribution from precipitation was assumed to be zero, soil water was found to contribute between 23 to 72% of the total volume of discharge. Although the assumption of negligible contributions from precipitation is unrealistic, especially in karst systems where rapid flow through conduits occurs, the hydrograph separation using inorganic carbon highlights the importance of considering vadose-zone soil water when analyzing storm chemohydrographs.

Quantifying the variability in Escherichia coli (E. coli) throughout storm events at a karst spring in northwestern Arkansas, United States

“…The size of the recharge area was calculated using the normalized base-flow method (Brahana 1997) and found to be between 2.9 and 6.1 km 2 (Knierim et al 2013). Karst groundwater flow paths can cross topographic divides; therefore, spring recharge areas do not always coincide with surface-water drainage basins (Brahana 1997;Ford and Williams 2007b).…”

“…Using the normalized base-flow method (Brahana 1997), the recharge area for BS was calculated to be between 2.9 and 6.1 km 2 (Knierim et al 2013). Soils in the recharge area of BS are predominantly extremely gravelly silt loam, generally less than 2 to 3 m thick, with a high capacity to transmit water, from approximately 5 to 15 cm/h (Natural Resources Conservation Service 2013).…”

“…Blowing Spring (BS) discharges from the Boone Formation and includes 2.4 km of mapped cave passage (Knierim et al 2013). Using the normalized base-flow method (Brahana 1997), the recharge area for BS was calculated to be between 2.9 and 6.1 km 2 (Knierim et al 2013).…”

Monitoring Atmospheric, Soil, and Dissolved CO2 Using a Low-Cost, Arduino Monitoring Platform (CO2-LAMP): Theory, Fabrication, and Operation

“…The two sites represent karst environments within the Springfield Plateau physiographic province overlying the Springfield Plateau aquifer (Kresse et al, 2014). The Springfield Plateau province can be characterized as a mantled karst terrain consisting of a cherty regolith overlying the Boone Formation, a cave forming Paleozoic carbonate unit (Brahana et al, 1999;Knierim et al, 2013;Al-Qinna et al, 2014;Jarvie et al, 2014).…”

Epikarst Hydrogeochemical Processes in Telogenetic Karst Systems in South-Central Kentucky

“…Dissolved inorganic carbon is expressed as a concentration, assigned to natural waters, either surface or subsurface, and designed to identify the reaction constituents and/or products within a given system (either CO2 or dissolved CaCO3, respectively) (White 1988;Clark and Fritz 1997;Drever 1997;Palmer 2007a). Several studies have explored the concentrations of DIC in surface and karst spring water (Emblanch et al 2003;Liu et al 2010;Shin et al 2011;Charlier et al 2012;Faimon et al 2012a;Faimon et al 2012b;Yang et al 2012;Knierim et al 2013;Osterhoudt 2014;McClanahan 2016;Salley 2016;Zhang et al 2016) to determine the seasonal and storm event fluctuations.…”