Impact of visits on the microclimates of caves, Experimental evidence from Škocjan Caves

IF 1 4区 地球科学 Q4 GEOSCIENCES, MULTIDISCIPLINARY
Vanja Debevec, J. Rakovec
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引用次数: 1

Abstract

Tourism activities in caves can result in changes in the microclimates of caves. The natural microclimate in closed caves is constant due to the balance between cave air and cave walls, while in open caves exchanges with outside air influence the microclimate. Visits to caves, especially in closed smaller caves, can thus endanger the natural balance if the microclimate does not return to natural conditions quickly enough.Continuous monitoring of the temperature and concentration of carbon dioxide in Škocjan Caves enables the assessment of the impact of visits. For this purpose, we used data measured in the relatively closed Silent Cave, at the locations named Calvary (Kalvarija), Tent (Šotor), and Passage (Prehod) in 2016, and in the wide open Murmuring Cave, at the locations named Bridge (Most) and Rimstone Pools (Ponvice), in 2013. The outdoor air temperature, as measured at the Škocjan meteorological station on the surface plateau, was considered in both cases. Along the tourist part of Škocjan Caves, the most closed part of the cave in Silent Cave is the location at Calvary, when the entrance doors through an artificially dug tunnel are closed. During the visits, the microclimate is subjected to draughts through open doors and to anthropogenic emissions. The data suggest that the influence of draughts predominates over direct anthropogenic emissions. In winter or on cold days air flows upwards and through the tunnel out of the cave, whereas in summer or on warm days it flows downwards. In such cases, the CO2 concentration decreases markedly due to the downwards chimney effect as the concentration in the outside air is much lower than in the cave. The data show that the temperature overnight and towards morning always returns to its natural value even in this rather small location in the cave. The changes in CO2 concentration persist for a longer period, until the time of the first visit the next morning, when it is again perturbed by a new visit. The data on time courses support the theoretically estimated characteristic of the exponential decline of disturbances backward towards natural conditions, depending on the size of a cave and on the efficiency of exchanges with its walls. For tem­perature, this characteristic time tT is about three to six hours at the Calvary site. The return of CO2 to natural conditions tCO2 is longer and its estimate less reliable than the one for temperature. In the wide-open and large Murmuring Cave, the impact of visits is negligible throughout the year. In this part of the cave we can observe the influence of external daily and annual changes, the amplitudes of which get smaller, and their phase lags bigger, deeper in the cave.
参观对洞穴小气候的影响,来自Škocjan洞穴的实验证据
洞穴中的旅游活动会导致洞穴小气候的变化。由于洞穴空气和洞穴壁之间的平衡,封闭洞穴中的自然小气候是恒定的,而在开放洞穴中,与外界空气的交换会影响小气候。如果小气候不能足够快地恢复到自然状态,参观洞穴,尤其是在封闭的较小洞穴中,可能会危及自然平衡。对Škocjan洞穴的温度和二氧化碳浓度进行持续监测,可以评估访问的影响。为此,我们使用了2016年在相对封闭的寂静洞穴(Calvarija)、帐篷(Šotor)和通道(Prehod)以及2013年在开阔的Murmuring洞穴(Bridge(Most)和Rimstone Pools(Ponvice))测量的数据。在这两种情况下都考虑了地面高原Škocjan气象站测得的室外气温。沿着Škocjan洞穴的旅游区,Silent cave洞穴最封闭的部分是Calvary,当时通过人工挖掘隧道的入口门是关闭的。在访问期间,小气候通过敞开的门受到气流和人为排放的影响。数据表明,干旱的影响超过了直接的人为排放。在冬天或寒冷的日子里,空气向上流动,穿过洞穴外的隧道,而在夏天或温暖的日子里则向下流动。在这种情况下,由于向下的烟囱效应,CO2浓度显著降低,因为外部空气中的浓度远低于洞穴中的浓度。数据显示,即使在洞穴中这个相当小的位置,夜间和接近早晨的温度也总是恢复到自然值。二氧化碳浓度的变化会持续更长的时间,直到第二天早上第一次就诊时,它再次受到新就诊的干扰。时间进程的数据支持了扰动向自然条件呈指数下降的理论估计特征,这取决于洞穴的大小和与墙壁的交换效率。就温度而言,这个特征时间tT在加略山遗址大约为三到六个小时。CO2恢复到自然条件的时间tCO2更长,其估计不如温度的估计可靠。在广阔开阔的Murmuring洞穴中,全年参观的影响微乎其微。在洞穴的这一部分,我们可以观察到外部日变化和年变化的影响,这些变化的振幅在洞穴中越来越小,相位滞后越来越大。
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来源期刊
Acta Carsologica
Acta Carsologica 地学-地球科学综合
CiteScore
1.50
自引率
14.30%
发文量
0
审稿时长
>12 weeks
期刊介绍: Karst areas occupy 10-20 % of ice-free land. Dissolution of rock by natural waters has given rise to specific landscape and underground. Karst surface features and caves have attracted man''s curiosity since the dawn of humanity and have been a focus to scientific studies since more than half of millennia. Acta Carsologica publishes original research papers and reviews, letters, essays and reports covering topics related to specific of karst areas. These comprise, but are not limited to karst geology, hydrology, and geomorphology, speleology, hydrogeology, biospeleology and history of karst science.
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