MULTI-YEAR CAVE DRIPWATER FREQUENCY AND HYDROCHEMICAL MONITORING OF THREE CAVES IN EASTERN NORTH AMERICA: IMPLICATIONS FOR SPELEOTHEM PALEOCLIMATOLOGY

摘要

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 monitored 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 CO2 measurements were taken, revealing a seasonal ventilation cycle characteristic of temperate-region caves. Dripwaters from 12 sampling stations were collected throughout the first year, from which the isotopic results show the relationship between cave dripwaters and meteoric 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 flow-switching. Two are shown to have a seasonal-response and three demonstrated no response, characteristic of slow seepage flow. 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 sam