Geogenic emission of methane and carbon dioxide at beciu mud volcano, (berca-arbănaşi hydrocarbon-bearing structure, eastern carpathians, Romania)

Abstract

As shown by previously performed flux measurements, the mud volcanoes of Berca-Arbănaşi hydrocarbon-bearing structure in Eastern Carpathians Foredeep, including Pâclele Mari, Pâclele Mici, and Fierbători, represent a main gas seepage system in Romania, with considerable emissions of methane. The present work completes these gas emission studies by reporting the flux of methane and carbon dioxide at Beciu mud volcano, belonging to the same structure, not measured previously. In total, 78 measurements were carried out in June 2011 (40 on the vents, 34 on the area covered by mud and 4 in the external area, covered by vegetation). Diffuse fluxes from mud were found ranging from 102 to 105 mg CH4 m-2 day-1, and 102-104 mg CO2 m-2 day-1; the emission from individual vents was in the range of 0.014 to 32 t CH4 year-1 and 0.003 to 2.9 t CO2 year-1. These values are comparable with those typically documented for mud volcanoes worldwide. Gas seepage occurs pervasively throughout the muddy cover, even if it appears to be saturated with water. The total emission of CH4 and CO2 from Beciu mud volcano is conservatively estimated to be at least 190 t year-1 and 35 t year-1, respectively. The Beciu output leads the total CH4 emission from the four Berca mud volcanoes to at least 1350 t year-1, a value comparable with that reported for a similar number of giant mud volcanoes in Azerbaijan. This work contributed to update the geogenic gas flux data-set of Romania and to extend the global data-set of methane and carbon dioxide emissions from mud volcanoes.