[1] In order to evaluate the influence of soil permeability on soil CO 2 flux measurements performed with the dynamic concentration method, several tests were carried out using soils characterized by different permeability values and flow rates. A special device was assembled in the laboratory to create a one-dimensional gas flow through a soil of known permeability. Using the advective-diffusion theory, a physical model to predict soil concentration gradients was also developed. The calculated values of CO 2 concentrations at different depths were compared with those measured during the tests and a good agreement was found. Four soils with different gas permeability (3.6 Â 10 À2 to 1.23 Â 10 2 mm 2 ) were used. The CO 2 flux values were varied from 0.1 kg mOn the basis of these results, a new empirical equation for calculating very accurate soil CO 2 flux from dynamic concentration and soil permeability values was proposed. As highlighted by the experimental data, the influence of soil permeability on CO 2 flux measurements depends on various factors, of which the flow rate of the suction pump is the most important. Setting low values for the pumping flux (0.4-0.8 L min À1 ), the mean error due to soil permeability was lower than 5%. Finally, the method was tested by measuring the CO 2 flux in a grid of 48 sampling sites on Vulcano (Aeolian Islands, Italy), and the global error, affecting the CO 2 flux measurements in a real application, was evaluated.Citation: Camarda, M., S. Gurrieri, and M. Valenza (2006), CO 2 flux measurements in volcanic areas using the dynamic concentration method: Influence of soil permeability,
In this paper we have developed a new method for measuring in situ soil permeability, which is based on the theory of radial gas advection through an isotropic porous medium. The method was tested in the laboratory and at several locations on the island of Vulcano (Aeolian Islands, Italy). It consists of a special device which generates a gas source at a depth of 50 cm and it permits measurement of the relative induced pressure in nearby soil at different depths. The characteristic error of the method was less than 10%.Furthermore, soil permeability measurements were carried out in the island of Vulcano during different periods of the year (between May 2000 and June 2001). A strong decrease in permeability in the upper layers of the soil during and after rainfall was noted, with very poor correlations between the spatial distributions of soil CO 2 flux and shallow soil permeability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.