ETBC: Organic Geochemical Transformations and the Deep Biosphere--Identifying the Food Sources for Microbes in Sedimentary Systems

Project: Research project

Description

This supplement request was recommended by the NSF program directors. It will support undergraduate students who will be fully integrated into the research effort. These undergraduates will conduct experiments and perform calculations, and we expect that senior thesis research projects will emerge from this effort. Intellectual Merit This research will explore how geochemical processes support microbes living deep in the crust of the Earth. One enigma of the deep biosphere in sediments and sedimentary rocks is the identity and source of organic compounds that are consumed by subsurface microbes. While some of these compounds are likely to be produced by other subsurface microbes, a plausibly large portion of the consumable inventory of organic compounds comes from abiotic geochemical transformations of organic matter. The hypothesis to be tested is that reactions at great depths, many of which occur at temperatures and pressures higher than microbial life can withstand, produce organic solutes that can be transported to the inhabited zones of the subsurface. Specifically, the focus of this research is on how reactions between hot water and organic matter generate small organic compounds that ultimately feed the deep biosphere. The approach involves two complementary experimental efforts examining hydrothermal organic reactions. Phase I will focus on well-known reactions involved in the transformation of simple hydrocarbons into alcohols, ketones, and carboxylic acids, at elevated temperatures and pressures. Phase II explores these same reactions but in the context of a more realistic and thus complex geologic system that includes the clay minerals found in sediments and sedimentary rocks. Many of these reactions have never been systematically studied under geologically realistic conditions, so their mechanisms in nature are currently a matter of speculation.
StatusFinished
Effective start/end date9/1/081/31/14

Funding

  • National Science Foundation (NSF): $1,528,590.00

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biosphere
organic compound
food
sedimentary rock
organic matter
ketone
carboxylic acid
sediment
clay mineral
alcohol
solute
student
hydrocarbon
crust
experiment
temperature
thesis
programme
calculation
research project