METEOROLOGICAL MEASUREMENTS OF THREE SOUTH TEXAS CAVES IN DIFFERING GEOLOGICAL FORMATIONS

The amount of carbon dioxide emitting into the outer atmosphere was examined from three caves in the San Antonio area from the Austin Chalk, Glenrose Limestone, and Edwards Limestone. These caves are close geographically, stacked near each other in geologic sequence. Data taken from within these caves assisted in discovering how their meteorological effects differ, and what quantity of CO₂ may be venting to the outer atmosphere. The first hypothesis made was that there would be more CO₂ present in the Austin Chalk cave due to geologic differences and because of the reports of difficulty breathing in Austin Chalk caves. Since the Austin Chalk formation was expected to have higher levels of carbon dioxide, it was also expected to emit more CO₂ into the atmosphere. Within each cave, data loggers were set up to gather carbon dioxide, barometric pressure, temperature, and airflow data. Daily cycles were examined to determine if significant differences in any of the parameters were present within each cave environment. Results showed differences in temperature between and within the caves. The temperature changes appeared to correlate with changes in barometric pressure. Area differences between the passage sizes were found to be a great contributing factor to CO₂ volumes exiting in each cave. Data has shown from the daily cycles that each cave has an inhalation and exhalation period during the day. Calculations revealed the quantity of carbon dioxide estimated to be released during the exhalation cycles from the caves, showing the contribution that is made to atmospheric carbon dioxide levels. The Austin Chalk cave was found to have a greater volume of CO₂ within its entrance passages however, the Glenrose cave emitted more CO₂ into the atmosphere. Comparisons of data between summer collections and winter collections are also discussed.