Spatial Isotopic Analysis of Airborne CO2: Insights from Etna Volcano and Madonie Mountains, Italy, Surveys

Climate change is intricately linked to the carbon cycle. Both phenomena are examined across various temporal and spatial scales to clarify the processes of carbon exchange between the atmosphere and the Earth's surface in response to increasing greenhouse gas emissions, primarily CO₂. Anthropogenic CO₂ emissions emerge as the main driver of global warming, while natural CO₂ emissions into the atmosphere constitutes approximately 1% of annual CO₂ emissions, mainly resulting from volcanic activity.

This study relies on datasets gathered during surveys at Etna volcano and the Madonie mountains, Italy, to identify spatial variations in stable isotope composition and the concentration of airborne CO₂. The dataset was collected along a path specifically designed from the urban areas of Catania and Cefalù, both in Italy, to high altitudes (i.e., ~2200 m a.s.l.) at Mount Etna and the Madonie mountains, Italy, respectively. This dataset facilitates exploration of spatial variations in the sources of atmospheric CO₂ and patterns in the isotopic composition and concentration of airborne CO₂ with altitude.

The study's findings indicate that the primary sources of airborne CO₂ exhibit a biogenic isotopic carbon signature at Etna and the Madonie mountains, although a more ¹³C-enriched CO₂ source influences the isotopic signature of airborne CO₂ at Mount Etna. The concentration of airborne CO₂ and the carbon isotopic signature remain independent of altitude. However, a high correlation between altitude and oxygen isotopic signature suggests that variations in hydrology significantly impact the airborne CO₂.

Furthermore, the study underscores the complex relationship between environmental variables and airborne CO₂ concentration, indicating that the pattern in airborne CO₂ cannot be comprehensively investigated solely through concentration analysis due to the high background CO₂ concentration compared to relative spatial variations. Additionally, the carbon isotopic signature of CO₂ enables the differentiation of multiple sources of CO₂ at Mount Etna and the distinction of ¹³C-enriched volcanic CO₂ from background air at low airborne CO₂ concentrations.