Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production
Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production
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DOI：
10.1038/ngeo2721
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发表时间：
2016-07-01
影响因子：
18.3
通讯作者：
Pozzer, Andrea
中科院分区：
文献类型：
--
作者：
Helmig, Detlev;Rossabi, Samuel;Pozzer, Andrea
乙烷等非甲烷碳氢化合物是对流层臭氧和气溶胶的重要前体。使用来自全球地面网络和大气柱观测的数据，我们表明，乙烷摩尔分数从20世纪70年代(1-3)开始的稳定下降在2005年至2010年期间在北半球大部分地区停止，此后逆转。我们计算出，从2009年年中到2014年年中，北半球乙烷排放量每年增加0.42(+/-0.19)Tg Yr(-1)。乙烷和寿命较短的丙烷的增幅最大的是美国中部和东部，其空间分布表明，北美石油和天然气开发是增加排放的主要来源。如果计入其他共同排放的石油和天然气非甲烷烃，我们估计北半球非甲烷烃年排放总量将增加1.2(+/-0.8)tg/a。大气化学传输模型表明，这些排放可能会使石油和天然气生产区附近的夏季平均地表臭氧每摩尔增加几个纳摩尔。甲烷/乙烷石油和天然气的排放比率可能表明相关的甲烷排放显著增加；然而，这一增加与产区观察到的泄漏率和甲烷全球同位素比率的变化不一致。
Non-methane hydrocarbons such as ethane are important precursors to tropospheric ozone and aerosols. Using data from a global surface network and atmospheric column observations we show that the steady decline in the ethane mole fraction that began in the 1970s(1-3) halted between 2005 and 2010 in most of the Northern Hemisphere and has since reversed. We calculate a yearly increase in ethane emissions in the Northern Hemisphere of 0.42 (+/- 0.19) Tg yr(-1) between mid-2009 and mid-2014. The largest increases in ethane and the shorter-lived propane are seen over the central and eastern USA, with a spatial distribution that suggests North American oil and natural gas development as the primary source of increasing emissions. By including other co-emitted oil and natural gas non-methane hydrocarbons, we estimate a Northern Hemisphere total non-methane hydrocarbon yearly emission increase of 1.2 (+/- 0.8) Tg yr(-1). Atmospheric chemical transport modelling suggests that these emissions could augment summertime mean surface ozone by several nanomoles per mole near oil and natural gas production regions. Methane/ethane oil and natural gas emission ratios could suggest a significant increase in associated methane emissions; however, this increase is inconsistent with observed leak rates in production regions and changes in methane's global isotopic ratio.