Volcanic Degassing of Hazardous Gases and Their Atmospheric Dispersion: A Case Study of Vulcano Island, Aeolian Archipelago, Italy

Gaseous emissions from active volcanic systems constitute a primary natural source of global atmospheric pollution. Typically, these fluids are dominated by high concentrations of water vapor (H2O) and carbon dioxide (CO2), which together account for more than 90% of the total emission volume. These are followed by sulfur species, specifically SO2 and H2S, within a range of a few percentage points. The remaining fluid emissions comprise minor species—including HCl, HF, CO, H2, He,and  N2 alongside numerous other trace elements. Many of these gases, particularly SO2, H2S, CO2, and CO, are hazardous to human health and exhibit various deleterious effects. Consequently, extensive environmental research has been conducted in recent years to evaluate the impact of these gases on public health. The primary objective of this study is to characterize the atmospheric dispersion of gaseous emissions from the volcanic system of Vulcano Island, originating from the main degassing centers: the crater area and the hydrothermal system of the Levante Bay. Atmospheric concentrations of sulfur dioxide SO2 were monitored using a quasi-continuous network based on Scanning Differential Optical Absorption Spectroscopy (Scan-DOAS) technology. Concurrently, H2S and CO2 concentrations in the Levante Bay area were measured using Multi-GAS instrumentation.By integrating SO2 flux data derived from Scan-DOAS measurements with atmospheric dispersion maps generated via AERMOD modeling software, we estimated the spatial distribution of SO2 across the volcanic crater and inhabited regions, including Vulcano Village and Vulcano Piano. This investigation provided critical insights into areas where anomalous concentrations of SO2, H2S, and CO2 exceed the threshold limits established by the World Health Organization (WHO) and the European Union (EU). Findings indicate that these thresholds are frequently surpassed within and adjacent to the crater zone.