Soil CO2 flux measurements in volcanic and geothermal areas

The accumulation chamber methodology allows one to obtain reliable values of the soil CO2 flux, phi(soil) (CO2), in the range 0.2 to over 10 000 g m(-2) d(-1) as proven by both laboratory tests and field surveys in geothermal and volcanic areas. A strong negative correlation is observed between Delta phi(soil) (CO2)/ Delta t and Delta P-atm/Delta t. Maps of classes of log phi(soil) (CO2) for the northern sector of Vulcano Island, Solfatara of Pozzuoli, Nea Kameni Islet and Yanbajain geothermal field evidence that active faults and fractures act as uprising channels of deep, CO2-rich geothermal or magmatic gases. The total diffuse CO2 output was evaluated for each surveyed area. (C) 1998 Elsevier Science Ltd. All rights reserved.