期刊名称：Journal of Integrative Environmental Sciences
印刷版ISSN：1943-815X
电子版ISSN：1943-8168
出版年度：2010
卷号：7
页码：31-38
DOI：10.1080/19438151003621359
语种：English
出版社：Taylor & Francis
摘要：Drylands are considered a net sink for atmospheric methane and a main component of global inventories for greenhouse gas budgets. However, a significant portion of drylands occur over sedimentary basins hosting natural gas and oil reservoirs, with gas migration to the surface (named “microseepage”) producing positive atmospheric CH4 fluxes. In this overview, we summarize the outcomes of microseepage surveys performed in different petroleum basins, describe how the microseepage area is estimated and what are the emission factors that can be used for a preliminary global emission estimate. Microseepage frequently overcomes methanotrophic consumption occurring in dry soil throughout large areas, and it is enhanced by faults and fractures in the rocks. Fluxes of a few tens to hundreds of mg m−2 d−1 are frequent for oil–gas fields, globally estimated at ∼4 million km2. However, microseepage may potentially exist over a wider area (∼8 million km2, i.e. 15% of global drylands), including the total petroleum system. Based on a relatively large and geographically dispersed data-set of emission factors from different hydrocarbon-prone basins in the USA and Europe, upscaling suggests that global microseepage emission exceeds 10 Tg y−1; it cannot be ignored in the atmospheric methane budget and in assessments for the sink potential of dry soil.
