Gas flux to the atmosphere from mud volcanoes in eastern Romania

Abstract

Gas flux measurements have for the first time been taken from vents and soil of eastern Romania mud volcanoes, the largest geological structures in Europe releasing methane into the atmosphere. In the quiescent phase, the methane emission from single vents is up to 28 t yr−1. Diffuse soil microseepage is of the order of 102−105 mg m−2 day−1. A total output of at least 1200 tonnes of CH4 per year can be conservatively estimated over the area investigated alone (∼ 2.3 km2). Helium fluxes are up to five orders of magnitude higher than the average flux in a stable continental area, pointing to a close link between mud volcanoes and crustal degassing through faults crossing the deep hydrocarbon reservoirs. These data represent a key contribution towards refining global CH4‐emission estimates, which indicate mud volcanoes as a significant and unavoidable source of greenhouse gases for the atmosphere.

Monitoring methane emission of mud volcanoes by seismic tremor measurements: a pilot study

“…Low permeability of clays in mud-volcano areas (Kopf, 2002) suggests that, in the lack of large mud outflow (typical of quiescent phases), gas propagation from the reservoir should mainly occur by the uprise of bubbles (Etiope and Martinelli, 2002;Albarello, 2005). Actually, visual monitoring of bubbling at the surface of emitting vents was considered for estimating gas outflow at mud volcanoes (Etiope et al, 2004a). The basic limitation of this last approach is that it is feasible when strictly localized emission occurs, without any other dry seepage.…”

Geochemistry of dissolved gases from the Eastern Carpathians - Transylvanian Basin boundary

“…Althaus et al 2000;Vaselli et al 2002;Etiope et al 2004;Baciu et al 2007). The chemical composition of the dissolved gases extracted from the water samples shows the ubiquitous presence of CO 2 .…”

“…Mountains are mainly volcanic (Althaus et al 2000;Vaselli et al 2002) while the south-eastern Transylvanian Basin is characterized by crustal-type helium associated to methane reservoirs (Etiope et al 2004;Baciu et al 2007). The highest He isotopic ratios of the area have been detected at the proximity of the volcanic arc, at Bálványos, where R/Ra values from 3.04 to 3.19…”

Inventory of Onshore Hydrocarbon Seeps in Romania (HYSED-RO Database)

“…A new approach based on gas flux measurements in seeping areas, combined with molecular and isotopic analyses has developed gradually after the year 2000 [34][35][36]. The first isotopic composition of methane from a Romanian seep was published in 2008 [37].…”

“…Consequently, the seeps are located on lineaments following the same direction. A relevant example is the Berca-Arbanasi hydrocarbon-bearing structure (Figure 7), where the largest Romanian mud volcanoes are located [35]. Four mud volcanoes (from North to South: Beciu, Paclele Mici, Paclele Mari and Fierbatori) are positioned on the axis of the faulted anticline, generally at the intersection with transversal faults.…”