Unveiling urban atmospheres: a comprehensive study on CO2 dynamics, air quality, and volcanic impacts in Napoli and Pozzuoli

The atmospheric concentration of CO2 is crucial in urban areas due to its connection with air quality, pollution, and climate change. Monitoring airborne CO2 concentrations is vital for environmental management and public safety.  In the lower 50 meters of the atmosphere, CO2 emissions impact human health and ecosystems, making data at this level essential for addressing carbon-cycle and public-health questions. In volcanic zones, CO2 variations may correlate with volcanic activity, impacting local ecosystems and human health. In certain regions with high natural CO2 emissions, geogenic CO2 profoundly affects the environment. Despite volcanoes' local impact may be important, hydrocarbon combustion is the primary driver of increased atmospheric CO2 and global warming climate. This study presents survey results on stable isotope composition of carbon and oxygen of CO2 and airborne CO2 concentration in the Campi Flegrei caldera, a high volcanic risk area threatening the Naples metropolitan area. In the last 50 years, two major volcanic unrests (1969–72 and 1982–84) were monitored using seismic, deformation, and geochemical data. The current unrest started in 2005, involving pressurization of the underlying hydrothermal system as a causal factor of the current uplift in the Pozzuoli area. This research illustrates the use of a mobile laboratory to better understand emissions dynamics and quantify volcanic-origin emissions. Results shows that CO2 levels in Napoli's urban area exceed background atmosphere levels, indicating an anthropogenic origin from fossil fuel combustion. Conversely, in Pozzuoli's urban area, the stable isotope composition reveals a volcanic origin of the airborne CO2. This study demonstrates how a spatial survey of stable isotope composition of airborne CO2 is crucial for understanding emission dynamics. Distinguishing geogenic from anthropogenic emissions is challenging, especially through air CO2 concentration measurements alone. The findings emphasize the importance of monitoring atmospheric CO2, especially in areas with volcanic risks, contributing valuable insights for environmental and public health management.