Impact of water exhaled out by visitors in show cave: a case study from the Balcarka Cave (Moravian Karst)
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| Year of publication | 2024 |
| Type | Conference abstract |
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| Description | The anthropogenic impact of the water and CO2 exhaled by visitors was studied in the Balcarka Cave, the show cave in the Moravian Karst (Czech Republic). For calculation of the personal CO2/absolute humidity fluxes, two alternative models were proposed. The first model was based on detailed modeling of the CO2/absolute humidity concentration in the atmosphere of the monitored chamber. The chamber represented a homogeneous reservoir with input and output fluxes. The CO2 fluxes included (1) the advective input flux from the exterior or/and an adjacent cave space, (2) the anthropogenic flux, and (3) the advective output flux out of the chamber. Following the CO2 model, the model of absolute humidity evolution was advanced by (4) the flux associated with the condensation of anthropogenic water vapor. The second model used the known/presumed composition of the air that was breathed off and the physical activity of the visitors. The CO2 fluxes of 2.4 × 10-4 and (2.0–3.9) × 10-4 mol person-1 s-1 and the water vapor fluxes of (3.2–8.9) × 10-3 and (0.6–1.2) × 10-2 g person -1 s-1 were found for a slightly increased physical load. Based on the number of visitors, mean tour time, and personal anthropogenic flux, the total volume of exhaled water was estimated for (i) the winter season, (ii) the summer season, and (iii) the whole season. For the available data on attendance and accessibility period, the total mass of water vapor exhaled by visitors in the Balcarka Cave was estimated to be in the range of (2.2–4.5) × 107 g with significant seasonality (the summer total mass of (2.1–4.2) × 107 g significantly exceeded the winter total mass of (1.5–2.9) × 106 g). According to the geochemical model, this mass of water is capable of dissolving 3160 to 6321 g of calcite, assuming a mean winter and summer CO2 concentration in the cave air of 1000 and 3000 ppmv. The larger extent of water condensation can lead to the so-called condensation corrosion, whereas the lower extent of condensation probably causes a recrystallization of calcite on the surface of speleothems and rocks. The effect could be a potential risk, for example, for prehistoric cave paintings. The results indicate the importance of improving cave management to keep the cave microclimatic parameters close to natural conditions. Possible proposals could be to reduce the number of visitors in groups and/or shorten the period of cave tours. |