Which geological feature can cause seasonal changes to radon levels?

Karst geology is characterized by features such as limestone, sinkholes, and caves that can significantly influence radon levels in the environment. The porous nature of limestone allows for the movement of groundwater and gases, including radon, which is produced through the natural decay of uranium found in certain geological formations. Seasonal changes in temperature and rainfall can affect groundwater levels and the movement of gases, leading to fluctuations in radon emissions from the soil into the atmosphere. For example, during wet seasons, increased groundwater can enhance the mobilization of radon from the soil, causing higher levels in indoor air.

Desert landscapes, mountain ranges, and river deltas do not have the same geological conditions conducive to the regular and significant migration of radon. While they may have an impact on local radon levels, they do not exhibit the same pronounced seasonal variability due to their different geological characteristics and hydrological processes. Thus, karst geology stands out as the geological feature most likely to cause seasonal changes in radon levels.