Mathematics – Logic
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufm.p52b..02f&link_type=abstract
American Geophysical Union, Fall Meeting 2002, abstract #P52B-02
Mathematics
Logic
0400 Biogeosciences, 1030 Geochemical Cycles (0330), 1040 Isotopic Composition/Chemistry, 1055 Organic Geochemistry, 4267 Paleoceanography
Scientific paper
In the study of life on earth, isotopic analyses of organic biomarkers provide essential insight to their biological and environmental provenance. Isotopic analyses of organic materials on other planets present a number of challenges, both analytical and interpretive. Prebiotic planetary organic materials can derive from condensation reactions and by delivery through meteorites or interplanetary dust, with the relative importance of each influenced by the oxidation state of the atmosphere. Material delivered to planets can have an interstellar origin, although it is dominated by compounds influenced by the formation of the solar system. Each of these processes impact molecular isotopic signatures and must be considered in life-detection strategies. Pronounced effects are observed for hydrogen isotopes, with smaller fractionations observed for other elements. Theoretical, laboratory and observational studies of non-terrean materials are essential to further understand molecular isotopic heterogeneity associated with these exclusively abiotic processes. Studies of Archean-aged samples provide an important resource for interpreting molecular isotopic patterns as signatures of life processes. Carbon assimilation and biomass synthesis from simple precursor compounds typically discriminate against 13C. This generality, however, is complicated by the observations of a wide range of fractionation factors associated with important microbial carbon-uptake processes. Metabolic processes further distribute isotopic signatures, such that wide isotopic heterogeneity is observed among cellular biochemical constituents. In addition, preservation/contamination concerns dominate studies of very ancient organic matter, as they likely will in life-detection studies. However, both biochemical heterogeneity and sample integrity can be addressed by considering patterns from different paleoenvironments. Molecular results demonstrate that Late Archean microbial life on this planet was diverse, and ecological controls on element cycling dominate interpretations of molecular isotopic signatures. Is ecology universal? The answer may be the key to understanding life signatures elsewhere.
Eigenbrode Jennifer L.
Freeman Katherine H.
House Christopher H.
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