(2020) Nitrogen Isotope Ratios Trace High pH in a Terrestrial Mars Analog Site
Tino C, Stüeken E, Arp G, Jung D & Lyons T
01b: Room 1, Tuesday 23rd June 00:06 - 00:09
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Has this proxy been applied to Curiosity SAM data? Does the proxy work the same for biotic vs abiotic sources of ammonia?
The short answer is no, because while indigenous, oxidized nitrogen compounds have been found with SAM (Stern et al., PNAS 2015), definitive measurements of N isotope ratios and reduced nitrogen contents from Gale's crustal materials is thus far an unresolved endeavor. This is primarily a result of labile nitrogen compounds (those that evolve below 300C) having too much potential interference with derivatives of the N-bearing compound MTBSTFA (a silylation agent needed for GC analyses), as well as isobaric interference with compounds like CO. The proxy should work with any ammonia source, as it is essentially a physicochemical function of all free ammonium/ammonia compounds. While abiotic systems (e.g., experimental) may show greater fractionation, biogenic materials produced under anoxic conditions may be the best way to bury and preserve appreciable nitrogen signals. Understanding preservation potential is a research focus going forward. Feel free to reach out for more!
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