A Deep Carbon Observatory project
PI : Bernard Marty
CRPG participants :
Determining the flux of volcanic CO2 between the deep Earth and the surface is one ogf the major goals of the DCO initiative. A dominant fraction of this CO2 degassing flux is undetected, because magmatic bodies not only degas in the atmosphere or in the hydrosphere through volcanic conduits, but also release mantle-derived volatiles through the volcanic edifices ( 50 % of the total magmatic CO2 flux in the case of Mount Etna ; A major difficulty in quantifying this cryptic CO2 flux is the high atmospheric CO2 background (380 ppm vol., which overcomes the natural emissions as soon as they are diluted by air. This project will develop the detection and the quantification of slight excess in air above volcanic zones of the rare isotope. Sampling of air will be carried above individual volcanoes and regionally in volcanic/tectonic areas : Erta Ale in Afar, Ethiopia, Mt Etna area, Kilauea at Hawaii.. For a given volcanic/tectonic environment, the ratio between 3He and CO2 does not vary much, so that quantification of the regional CO2 degassing flux will be made based on 3He excesses in air.
Sampling air in the plume of the Erta Ale active lava lake, Jan. 2011