Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice
Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice
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南极火星陨石、碳质球粒陨石和极地冰中的多环芳烃 (PAH)
DOI：
10.1117/12.278782
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发表时间：
1997
影响因子：
3.4
通讯作者：
J. Bada
中科院分区：
文献类型：
--
作者：
L. Becker;D. Glavin;J. Bada
最近对火星陨石ALH84001中存在的碳酸盐球的分析发现，多环芳烃(PAHs)的含量达到了ppm级。在ALH84001中观察到的多环芳烃的分布被解释为与陆地来源不一致，并声称是陨石原生的，可能来自古老的火星生物群。我们研究了南极雪戈特陨石EETA79001中的多环芳烃，也被认为来自火星，以及几个南极碳质球粒陨石。我们发现，在ALH84001碳酸盐球粒中检测到的许多相同的多环芳烃存在于南极碳质球粒陨石中，以及EETA79001的基质和碳酸盐(Druse)组分中。我们还研究了极地冰层中的多环芳烃，发现碳酸盐是冰水中多环芳烃的有效清除剂。此外，南极Allan Hills冰的碳酸盐萃取物中多环芳烃的分布与EETA79001和ALH84001中的分布非常相似。据报道，在EETA79001德鲁兹陨石物质中存在明显来自陆地的L氨基酸，这表明这块陨石受到陆地有机物的污染，这些有机物可能来自南极冰川融水渗入陨石。我们的数据表明，在ALH84001和EETA79001中观察到的多环芳烃要么来自于有机物向火星的外源输送，要么来自冰融水中存在的地外和陆地多环芳烃，或者更有可能来自这些来源的混合物。多环芳烃似乎不是寻找火星上已灭绝或现存生命的有用生物标记物。
Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level. The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life in Mars.