Nicolae FRUNZETI¹, Mircea MOLDOVAN^1*, Bety-Denissa BURGHELE¹, Constantin COSMA¹, Calin BACIU¹, Botond PAPP¹, Gabriela Emilia POPITA¹ & Laurentiu Cristian STOIAN^2
1Babeş-Bolyai University, Faculty of Environmental Science and Engineering, Fantanele street, 30, 400294, Cluj-
Napoca, Romania. *E-mail: mircea.moldovan@ubbcluj.com
²Babeş-Bolyai University, Faculty of Geography, Clinicilor Street, 5-7, 400006, Cluj-Napoca, Romania

FLUX MEASUREMENTS OF ²²²Rn, CH₄ AND CO₂ ALONG WITH SOIL GAS CONCENTRATIONS (²²²Rn, CO, NO₂ AND SO₂) OVER A METHANE RESERVOIR IN TRANSYLVANIA (ROMANIA)

Full text

The Transylvanian Basin is well known for its large and good quality methane accumulations. In many sites these accumulations are not completely sealed, and methane leaks into the atmosphere through faults or fractures. A soil gas survey was carried out after a rainy season at Sărmăşel, the largest methane seep in Transylvania. This study presents the first results of soil ²²²Rn concentration measurements in relation with CH₄ flux, in an attempt to better understand the spatial distribution of soil gas concentrations and migration toward the surface in this area. Taking into account the particular situation in the field, the study area was divided in two sub-areas corresponding to the two main seeps with high methane emissions and everlasting fires. Accordingly, two sets of measurements were performed. The first set was distributed on a 36 meters transect with respect to seep 1. The soil gases concentrations (²²²Rn, CO, NO₂ and SO₂) were measured at 80 cm depth along with CH₄ and CO₂ fluxes. The maximum values of ²²²Rn concentration from soil was found at 17.5 kBqm^-3 and quite high concentrations of other gases, such as 19 ppm of CO, 1 ppm of SO₂ and 0.7 ppm of NO₂. The results suggest that concentrations of CO, NO₂ and SO₂ correlate with CH₄ and CO₂ fluxes. Radon concentration in soil seems to be more dependent on soil permeability than on the CH₄ flux. For the second set of measurements, the CH₄ and ²²²Rn fluxes were randomly distributed around the main vents. It was observed a relatively high ²²²Rn flux with a maximum value of 119.3 mBqm^-2s^-1 and an average of 58.4 mBqm^-2s^-1, over an area with high CH₄ emission.