Radon emissions as indicators of changes in tropical Andean ecosystems emerging after glacial retreat under climate forcing

This study examines radon emissions as potential proxies for environmental change in tropical Andean ecosystems undergoing rapid glacier retreat due to climate forcing. The research was conducted in the proglacial zone of the Yana Ucsha glacier in the Peruvian Andes, where field campaigns between July and November 2023 yielded radon measurements at approximately 28-day intervals across ten monitoring sites (M1–M10). Radon flux was measured using LR115 detectors and complemented by analyses of soil texture and the topographic wetness index (TWI) to assess the influence of environmental variables. Results demonstrate that radon emissions are strongly modulated by soil moisture, which in turn is regulated by regional air temperature and glacier runoff. A significant inverse relationship was identified between radon exhalation and regional air temperature, indicating that warmer periods suppress radon release due to increased soil moisture from enhanced glacier melt. Conversely, the coldest monitoring interval (second period) exhibited markedly higher radon exhalation, reaching up to 0.45 and 0.32 Bq m^-2 h^-1 at sites M1 and M4, respectively—approximately four to five times greater than the baseline range (0–0.10 Bq m^-2h^-1) observed during other periods. This pronounced temporal anomaly coincided with lower regional air temperatures, reduced glacier runoff, and drier soil conditions, highlighting strong climatic control on radon emissions. These findings suggest that ongoing glacier retreat and climate change may constrain or reduce radon emission rates in Andean proglacial environments, with important implications for environmental monitoring and ecosystem dynamics. Overall, this study provides novel insights into the interactions among cryospheric, atmospheric, and radon dynamics in the tropical Andes.