地质甲烷对大气甲烷源与汇的贡献

地质甲烷是除湿地外最大的一类自然源,主要包括微渗漏、泥火山、海底渗漏、火山地热区和温泉等,这些地质源每年向大气释放约42～64 Mt甲烷气体,在整个大气甲烷收支平衡中具有重要意义.IPCC第四次报告(2007年)以前由于相关调查研究的欠缺,甚至基本数据的匮乏(包括未发现的源)以及甲烷地质成因的复杂性,对地质甲烷等烃类气体向大气的排放通量估算严重偏低.最近几年,国外相关研究者进行了一定规模的系统调查和科学研究,补充完善了有效数据库,改变了估计偏低的现状,并且使IPCC将地质来源的甲烷单独列项.相对来讲,我国在这一领域的研究还刚刚起步,与国际水平相差甚远,包括泥火山等地质甲烷释放通量的原位测量和科学研究仍属空白.因此,适时总结国内外相关研究的现状和发展趋势,将有利于为开展中国地质源甲烷的研究提供有益的参考.

Contributions of Geologic Methane to Atmospheric Methane Sources and Sinks

Geologic methane plays an important role in atmospheric methane balance and its emission is the second biggest sources of the atmospheric methane just after wetland at present.It has recently been recognized that the geologic emission of methane was estimated as much as about 42-64 Mt/y,including micro-seepages,mud volcanism,Sub-marine seeps,geothermal flux(volcanoes and hot springs) and so on.The emission flux of geologic methane and other gaseous hydrocarbons might be estimated very lowly before IPCC AR4(2007) as for lacking of sufficient field investigation(unknown resources) and complexity of geologic causes.Along with a considerable scale and systematic survey and research,it would be globally implemented for complement effective database and reducing calculation errors.These works have been made geological methane as an important source by IPCC.However,there are very limited field investigations and academic researches performed in China by far,being far behind the international level in this field.Some international investigation results and academic research progresses in this field will be summarized in this paper in order to lay a foundation for the study on geologic emissions of methane in China.