CARBON DIOXIDE MONITORING IN A KARST RESOURCE

Carbon dioxide (CO2) in Carlsbad Cavern is being monitored to assess the park’s current conditions as a component of a Visitor Use Management (VUM) study. CO2 concentrations affect visitor safety, cave conservation, and visitor experience. This preliminary work establishes standard operating procedures for a future yearlong study. CO2 levels were monitored from June to July 2019 in three locations: at the base of the elevator shaft, Big Room Junction, and King's Palace at a 5 minute sampling interval. Two major limitations of this study are the sparsity and quality of data due to the short two-month monitoring period, various data losses, and the unreliability of the data due to mathematical corrections for automatic baseline calibrations. CO2 levels rose consistently in June and July of 2019. While the CO2 levels decreased in the evening, they did not return to starting levels. Visitor CO2 fluxes were cumulative over time during these two months. There was a positive correlation between daily visitation numbers and CO2 levels at the elevator and Big Room Junction. There was not enough data from the King’s Palace sensor for data analysis. Given the limitations of this study, these results are preliminary and should not be extrapolated past June and July of 2019. Carbon dioxide monitoring should be continued for at least a year; with more data, stronger conclusions and seasonal patterns can be determined.