188 • Journal of Cave and Karst Studies, September 2019 Jessica B. Kelley, Harry Rowe, Gregory S. Springer, Yongli Gao. Multi-year cave dripwater frequency and hydrochemical monitoring of three caves in Eastern North America. Journal of Cave and Karst Studies, v. 81, no. 3, p. 188-202. DOI:10.4311/2017ES0110 MULTI-YEAR CAVE DRIPWATER FREQUENCY AND HYDROCHEMICAL MONITORING OF THREE CAVES IN EASTERN NORTH AMERICA: IMPLICATIONS FOR SPELEOTHEM PALEOCLIMATOLOGY Jessica B. Kelley 1,C , Harry Rowe 2 , Gregory S. Springer 3 , and Yongli Gao 1 Abstract A cave monitoring program of three caves in southeastern West Virginia, USA, was undertaken from September 2011 to December 2013. Culverson Creek Cave, Buckeye Creek Cave, and Lost World Caverns were continuously moni- tored for temperature and relative humidity, revealing a highly-stable environment year-round. The caves were visited approximately every three months during the study period, when discrete CO 2 measurements were taken, revealing a seasonal ventilation cycle characteristic of temperate-region caves. Dripwaters from 12 sampling stations were collect- ed throughout the frst year, from which the isotopic results show the relationship between cave dripwaters and mete- oric precipitation. Two sampling periods, those of March 2012 and October 2012, were distinctly different than most of the other isotope values that fell on, or very near, the Global Meteoric Water Line (GMWL). The March 2012 dripwater isotopes were very negative, resulting from several days of heavy meteoric precipitation preceding the collection time that likely pushed water through the vadose zone that had accumulated in the previous winter months. The October 2012 samples displayed a positive linear trend, falling to the right of the GMWL, indicating that those samples were comprised of waters with evaporative loss. Drip frequency loggers placed above the cave allow a direct comparison between surface precipitation and six cave drip-frequency loggers, placed strategically throughout the study caves. These frequency data help to characterize the drips, where one was shown to be highly responsive and underwent fow-switching. Two are shown to have a seasonal-response and three demonstrated no response, characteristic of slow seepage fow. Stalagmites formed as a result of the latter are generally regarded as the most suitable for long-term paleoclimate studies. Monitoring programs performed prior to stalagmite collection for paleoclimate reconstructions could aid in the selection of suitable samples, thereby preserving priceless cave formations, as well as aiding in the interpretation of geochemical proxy variations in speleothem calcite. Introduction Speleothems as paleoclimate archives have been increasingly utilized over the past few decades (Baker et al., 1997; Dorale et al., 1998; Roberts et al., 1998; Hellstrom and McCulloch, 2000; Wang et al., 2001; Poore et al., 2003; Dykoski et al., 2005; Cheng et al., 2006; Spötl et al., 2006; Vollweiler et al., 2006; Borsato et al., 2007; Cruz et al., 2007; Mattey et al., 2008; Lambert and Aharon, 2010; Stríkis et al., 2011). Stalagmites are the product of cave dripwaters, which have complex surface-to-cave hydrologic pathways, seasonal distributions, and unique hydrochemical histories. Isotopic and trace element variation between coeval speleothems underscores the importance of an understanding of dripwater variability, as speleothem records may represent different aspects of the climate system. The complexity of hydrologic evolution from the soil zone through the vadose and phreatic zones in the epikarst has prohibited a com- plete understanding of the hydrologic histories of individual cave drips. However, the dripwater frequency and modern hydrochemistry of dripwaters can give clues as to the hydrologic pathway of the individual drips and may aid in the interpretation of stalagmite records. Speleothems form due to the CO 2 degassing of supersaturated waters, which is governed by soil gas CO 2 and the cave air CO 2 concentrations (Fairchild et al., 2006). Upon entering the cave atmosphere, the dripwaters with high CO 2 encounter the lower-CO 2 cave air, thereby driving the precipitation and deposition of calcite as the CO 2 degasses. Den- sity-driven seasonal ventilation exerts a signifcant control on the annual growth distribution of calcite laminae, as the concentration of cave air CO 2 is generally highest in the warmer months, because the relatively colder cave air remains in the topographic lows of the cave. In contrast, the cold, dense air of the colder months sinks into the cave, thereby increasing ventilation and lowering cave air CO 2 (Fairchild and Baker, 2012). Previous work on karst vadose hydrology and speleothem geochemistry has focused on three major themes: drip variability and fow regimes (Smart and Friederich, 1986; Baker et al., 1997; Baker and Brunsdon, 2003), hydrochemical studies of dripwaters (Huang et al., 2001; Tooth and Fairchild, 2003; McDonald et al., 2004, 2007; Karmann et al., 2007; Lambert and Aharon, 2010, 2011), and experimental/quantitative models of calcite deposition and/or isotopic evolu- tion (Buhmann and Dreybrodt, 1985; Dreybrodt, 1996; Wackerbarth et al., 2010). Many recent studies have included 1 Department of Geological Sciences, The University of Texas at San Antonio, San Antonio, TX 78249, USA 2 Premier Oilfeld Laboratories, Houston, TX 77041, USA 3 Department of Geological Sciences, Ohio University, Athens, OH 45701, USA C Corresponding author: jessica.kelley@utsa.edu