Instrumental enhancement to study Mt Etna ecosystem: Carbon dioxide measurements using Eddy Covariance and flux chambers (PON-GRINT project)

The PON-GRINT project, led by INGV, is aimed at strengthening the Research Infrastructures and Italian facilities involved in the EPOS implementation plan and defining possible expansions of data, products and services. IGG-CNR was involved in the project with the goal to investigate CO2 fluxes at the soil-vegetation atmosphere interface in the Mt Etna environment and assess the balance between volcanic and biological CO2 . Two fixed stations for measuring CO2 soil emission and an Eddy Covariance system for measuring net CO2 exchange in the Mt Etna ecosystem have been installed since december 2021 and April 2022, respectively. These installations are located in the Valle del Bove (Piano Bello, Milo) at 1100 m above sea level in a relatively flat area. The main wind direction is W-E, and permanent outgassing occurs from the four summit craters that are upwind to the stations. The area is dominated by the endemic Genista aetenensis. Fixed CO2 accumulation chambers are dedicated to the measurements of ecosystem respiration and consist of opaque automatic chambers with a diffusion infrared Vaisala sensors for CO2 measurement, a data-logger and a sensor for the measure of soil moisture and temperature. Data on CO2 flux are acquired at an hourly sampling interval (length of a single measurement = 4 minutes).The Eddy Covariance station allows to measure the net ecosystem exchange, and includes an enclosed path gas analyzer for the measurements of CO2 , H2 O, latent and sensible heat, a sonic anemometer for the measurements of wind and turbulence parameters, sensors for both the total and photosintetically active radiance, a thermohygrometer, a set of probes for atmospheric pressure, soil humidity and temperature. All the Eddy Covariance sensors record raw data at a sampling rate of 10 Hz, while final eddy covariance turbulent fluxes are computed as 30 minutes averages. Data are trasmitted by West Systems to the IGG-CNR server. In addition, field campaigns performed at both sampling sites by a mobile accumulation chamber in light and dark configurations allow to measure both gross primary production and ecosystem respiration, thus integrating previous techniques measurements. Data acquired from the new stations allow high temporal and spatial resolution of CO2 , H2 O, latent and sensible heatfluxes at Piano Bello. Moreover, since few Eddy Covariance towers are reported in the literature for active volcanic contex due to the harshness of the environment (Werner et al., 2003; Lewicki et al., 2012), the new installation at Mt Etna will represent a new innovative challenge in the national panorama. The data will be of interest to the international community dedicated to the study of natural CO2 emissions at the soil-vegetation-atmosphere interface, and will be integrated in EPOS. Our long-term goal is an interdisciplinary study of volcanic, biological, ecological, biogeochemical, climatic, and biogeographic aspects, including anthropogenic impact on the environment. The new activities on Mt Etna benefit from collaboration the Etna Park Authority and the Regional Department of Rural and Territorial Development in Catania.