Vanessa and Franci, with some welcomed help from co-workers, have continued the monitoring of water and air at several points throughout the Postojna–Planina caves system. We have been relatively successful in organizing the sampling trips once every one to two weeks over the winter period. However, due to some periods with high water levels, we were not able to reach all sites on certain days. The good news is that the continuous monitoring instruments have so far survived and are providing good results, while the geochemical analyses are good quality.
Over the winter period the caves are well-ventilated, and thus, the CO2 concentrations of the cave air and water are characteristically low – towards atmospheric values. Compared with the summer values, the cave river waters generally had lower conductivities and higher pH values over the winter, while our cave pool showed the opposite trend. As such, we have gained important data that permits a thorough investigation into the dynamics of CO2 between the cave air and waters and the effects this has on the water geochemistry. As we move into spring the cave ventilation patterns should change to the summer regime, meaning that the next couple of months will be an exciting time for us, and so, monitoring and continuous data collection are ongoing and we are looking forward to gaining very interesting results over the transitional period.
Text: Vanessa E. Johnston
