Understanding the dynamics and distribution of CO₂ in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO₂. We show (1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and (2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO₂. Namely, in the terminal chamber of the passage, the pCO₂ is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rates and pCO₂, which enter via small conduits and fractures embedded in a CO₂-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO₂ inflows, high and persistent gradients in pCO₂ are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m are observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.

了解碳酸盐岩溶地块地下大气中 CO ₂的动力学和分布，为了解溶解和降水过程、岩溶系统在全球碳循环中的作用以及利用洞穴沉积物进行古气候重建提供了重要的见解。我们讨论了斯洛文尼亚 Postojna Cave 通道的长期小气候观测，重点关注p CO _{2 的}高时空变化。我们表明 (1) 通过地块的气流是由烟囱效应和外部风的共同作用决定的，以及 (2) 气流方向、气流路径的几何形状和位置之间的关系观察点解释了观察到的p 的变化一氧化碳₂。即，在通道的末端腔室中，当外部空气通过大型开放通道系统流入现场时，在上升气流期间p CO ₂较低且均匀。当气流反向向下气流时，腔室由具有不同流速和p CO ₂的入口供给，这些入口通过嵌入在富含CO _{2 的}包气带中的小导管和裂缝进入。如果入口和出口的空间分布产生低和高之间的最小混合p CO ₂中流入，高和持久性梯度p CO ₂形成。腔室就是这种情况，在下降气流期间观察到高达 1000 ppm/m 的垂直梯度。这项工作中提出的结果提供了对地下大气动力学和组成的新见解，并证明了长期和空间分布观测的重要性。