Polycyclic aromatic hydrocarbons and amino acids in meteorites and ice samples from LaPaz Icefield, Antarctica

Abstract

Ice samples collected from directly underneath the meteorites were extracted. In addition, exhaust particles from the snowmobiles used during the expedition were collected to investigate possible contributions from this source. The meteorite samples, the particulate matter and solid-state extracts of the ice samples and the exhaust filters were subjected to two-step laser mass spectrometry (L2MS) to investigate the PAH composition. For amino acids analysis, the meteorites were extracted with water and acid hydrolyzed, and the extracts were analyzed with offline OPA/NAC derivatization combined with liquid chromatography with UV fluorescence detection and time of flight mass spectrometry (LC-FD/ToF-MS). PAHs in the particulate matter of the ice were found to be qualitatively similar to the meteorite samples, indicating that micron-sized grains of the meteorite may be embedded in the ice samples. The concentration levels of dissolved PAHs in all the ice samples were found to be below the detection limit of the L2MS. The PAH composition of the snowmobile exhaust is significantly different to the one in particulate matter, making it an unlikely source of contamination for Antarctic meteorites. The amino acids glycine, β-alanine and γ-amino-n-butyric acid that were detected at concentrations of 3 to 19 parts per billion (ppb) are probably indigenous to the Antarctic meteorites. Some of the LaPaz ice samples were also found to contain amino acids at concentration levels of 1 to 33 parts per trillion (ppt), in particular α-aminoisobutyric acid (AIB), an abundant non-protein amino acid of extraterrestrial origin found in some carbonaceous chondrites. We hypothesize that this amino acid could have been extracted from Antarctic micrometeorites and the particulate matter of the meteorites during the concentration procedure of the ice samples.

Contamination of Antarctic snow by polycyclic aromatic hydrocarbons dominated by combustion sources in the polar region

“…The firn pollution by PAHs was apparently not influenced by snowmobile exhaust, as PHE would be more prominent whereas NAP and M-NAPs would be negligible. [29] …”

“…[28] PAH patterns in ice were also studied in the context of meteorite research although concentrations were not reported (e.g. Botta et al [29] ).…”

Extraterrestrial Amino Acids

“…Ice from the Antarctic regions of Allan Hills [143,144] and La Paz [130,147] contained only trace levels of aspartic acid, serine, glycine, alanine, and g-ABA (less than 1 ppb of total amino acid concentration). Ice from the Antarctic regions of Allan Hills [143,144] and La Paz [130,147] contained only trace levels of aspartic acid, serine, glycine, alanine, and g-ABA (less than 1 ppb of total amino acid concentration).…”

Sources and fate of polycyclic aromatic hydrocarbons in the Antarctic and Southern Ocean atmosphere

“…Dachs (2014), Sources and fate of polycyclic aromatic hydrocarbons in the Antarctic and Southern Ocean atmosphere, Global Biogeochem. Cycles, 28, 1424-1436, doi:10.1002 to research stations [Cabrerizo et al, 2012;Aislabie et al, 1999;Mazzera et al, 1999], (ii) emissions from research and tourist vessels and accidental spills of fuel, (iii) secondary sources due to volatilization from soils and snow as recently demonstrated for persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) [Cabrerizo et al, 2013;Galbán-Malagón et al, 2013a, 2013b, and (iv) natural sources of PAHs in Antarctica due to natural losses or seeps of petroleum or coal deposits, meteorites, and biogenic production in soils, sediments, and the water column [Botta et al, 2008;Clemett et al, 1998;Naraoka et al, 2000;Wilcke, 2007;Cabrerizo et al, 2012]. This biogenic production could be related to the degradation of diterpenes from the organic matter pool.…”