tayebeh abdolmaleki

Katlekhour Cave near Garmab (Zanjan) and Saholan Cave in southeast Mahabad, two Iranian tourist caves, attract a large number of tourists annually. Indiscriminate entry and higher number of tourists into the fragile and sensitive environment of the caves increase the concentration of carbon dioxide and disturb the chemical equilibrium inside the cave and it also has devastating effects, like erosion and corrosion, on Karst forms inside the cave. Therefore, this paper attempts to investigate the annual dissolution rate of cave forms by simulating and reconstructing climatic conditions inside a controlled laboratory environment.

To achieve the objectives of the study, data on temperature, relative humidity and CO2 content within the caves in question during two 15-day periods in February due to low number of tourists and April due to high tourist presence inside the caves were collected using triple tool of temperature, humidity, and Co2 gauge model (AZ 77535). Next, by simulating the same conditions in a controlled laboratory environment, the amount of annual dissolution of the forms inside the caves was calculated using weighting method.

The amount of dissolution and scaling of forms is 0.9445 g / year for Katlekhour and 2.20 g / year for Saholan Cave. Of this amount, 0.7661 g is 81.12% of total dissolution for Katlekhour Cave and 1.6991 g is 84.45% for Saholan Cave are attributed to tourists’ presence.

Maximum presence of tourists in Katlekhour and Saholan Caves caused the micro-climates in which the increased level of the concentration of de-carbohydrate increases the temperature of cave and decreases the moisture. As a result of these changes, the formation process of karstic shapes within the caves is disrupted, resulting in the destruction and shattering of the forms.

The presence of tourists in the tourist- attracting caves has led to changes in the values of climatic elements in the caves, such as temperature and the percentage of relative humidity, as well as carbon dioxide concentration. Increasing the concentration of carbon dioxide resulting from the presence of tourists decreases the PH level of the environment and forms an acidic environment. Formation of an acidic environment inside the caves will give rise to dissolution and sheeting of the karstic structures within them. In order to investigate these changes, we selected the caves of Katale Khor and Saholan as two examples of caves of the country that are attracting a large number of tourists. In order to compare and investigate the influence of tourist on climate changing and carbon dioxide concentrations in caves, we collected data in February due to the low number of tourists and April due to the high presence of tourists inside the caves, by means of a three-purpose device for measuring temperature, humidity and CO2 (AZ 77535). Comparative findings regarding two months of February and April suggest that in both caves in April, as the number of tourists inside the caves increases, the concentration of carbon dioxide and the temperature have increased and the percentage of relative humidity has decreased. For example, in both caves the average of the highest carbon dioxide concentration in April is found in low altitude halls with its value 1508 PPM in Saholan cave and 1248 PPM in Katale Khor cave. The percentage of relative humidity is decreased in low altitude halls in the Saholan Cave by 2.5% and in the Kotal Khor Cave by 1.2%.

Caves, as important underground geosites, are considered among sensitive and fragile geomorphological structures (Mokhtari, 2015). The process of breathing in and out by the visitors causes a high accumulation of CO2 in the caves. Entering a great number of visitors into the caves increases the concentration of CO2. The more the time and presence of the visitors in the caves, the higher the accumulation and concentration of CO2 (Maleki et al, 2015). In this study, the Saholan Cave, as the second largest water cave, and the Katale Khor Cave, as the second popular tourist cave in Iran, that annually host a great number of visitors, were examined for changes in climate elements.

The data related to the concentration of CO2, temperature and relative humidity in maximum and minimum times for visitors’ presence was gathered. Considering changes in temperature, relative humidity and CO2 concentration in the halls and chambers of various sizes, and also for improving the accuracy, the space inside the caves were classed in three categories of low-height (height of ceiling between 0-2 meters from the surface of the ground), average-height (height of celling between 2-5meters), and very high (5 meters or more). Data collecting was done using a three-purpose device for measuring temperature, humidity and CO2 (AZ 77535) during two fifteen-day periods, was carried out, at the same time with, the minimum traffic of tourists in the caves (the Saholan and Katale Khor caves) in February and maximum tourist presence in the caves in April. Data collecting was done on a daily basis three times a day in the morning (before visitors’ arrival), at noon and night (after visitors’ departure) in both caves.
Discussion and

The data analysis showed that the presence of visitors in the cave during spring coincided with maximum walking of the visitors, increases CO2 concentration inside the halls, and the highest amount happens in small halls. Altogether, peak points registered for CO2 in different areas were exactly correspondent with days with highest number of visitors. Regarding the temperature, the range of changes showed an increasing trend from the morning until the night, and high temperatures in the corridors were correspondent with days with high numbers of visitors inside the caves. In the case of relative humidity percentage, there were times with a drop and decrease in humidity, that were exactly correspondent with maximum presence and high number of visitors inside the caves. Overall, relative humidity percentage inside the caves did not show much fluctuation.

Changing in climate elements inside the caves can produced following ramifications: corrosion of carbonate formations inside the cave. Impact on visitors’ health.. Maximum entering of the visitors into the caves creates sub-climates that according to the found results can increase CO2 concentration and cave temperature, and decrease the relative humidity. As a result of these changes, the process of karst formations inside the caves will be disrupted, and in some cases might cause destruction and fraction of these formations. Gradual destruction of amazing and well-shaped karst formations inside the caves slowly destroys and desolates the caves, and on the other hand disturbing the balance inside the cave and unleashing little amount of energy might upset the whole ecosystem of the cave. Thus, this phenomenon can endanger the condition of tourist caves of the country including Saholan and Katale Khor caves .
Keywords: Cave, Tourist, Saholan cave, Katale khor cave.