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DESCOPE: Role of Minerals in Prebiotic Chemistry (Tasks 1 & 2 only)
PI: Schoonen, Martin
Minerals may have promoted both prebiotic synthesis and degradation or decomposition reactions. The proposed effort, which will support one graduate student, builds on earlier work and is organized in three tasks. The objective of task one, Mineral-promoted Dinitrogen Reduction, is to determine the kinetics of the reduction of dinitrogen to ammonium in the presence of NiFe alloys. NiFe alloys, such as the mineral awaruite, are formed during serpentinization and would have been present on the prebiotic Earth. Flow-through and batch experiments with a suite of synthetic alloys with compositions ranging from pure Fe to pure Ni will be conducted over a temperature ranging from 80 to 150°C. Experiments will be conducted with and without dissolved CO 2 to evaluate the effect of this electron acceptor on the efficiency of the N2-reduction process. The objective of the second task, Modeling water-rock interaction on the Hadean Earth, is to determine the conditions necessary for the formation of secondary minerals with catalytic potential. Thermodynamic data for NiFe alloys, such as awaruite, will be added to the data base. Reaction-path modeling will explore a range of conditions for both komatiite and tonalite, two starting materials representing ultramafic and more felsic components of the Hadean Earth surface. The objective of task 3, Mineral-promoted degradation of biomolecules, is to evaluate if minerals can promote the degradation or decomposition of biomolecules through radical reactions. This work builds on our earlier work in which we showed that pyrite can spontaneously produce radicals and decompose RNA. Radical reactions lead to fragmentation of large biomolecules. These fragments may recombine to form a suite of new organic molecules (so called cross coupling reactions). Batch experiments will be conducted in which the fate of model compounds in a monomineralic slurry of relevant minerals is studied. Besides the loss of the model compound, we will also analyze the composition of the products, using Electrospray Ionization Mass Spectrometry.
The results of the first two task will deepen our understanding of the role minerals may have played in prebiotic chemistry and which minerals may have been present on the prebiotic earth. The results of the third task may have implications for the interpretation of fossil biomolecules. Biomolecules may be transformed and complex molecules may form abiotically through cross coupling reactions.
