Carbon fixation in oceanic crust: Does it happen, and is it important?
Abstract
The carbon sources supporting a deep biosphere in igneous oceanic crust, and furthermore the balance of heterotrophy and autotrophy, are poorly understood. When the large reservoir size of oceanic crust is considered, carbon transformations in this environment have the potential to significantly impact the global carbon cycle. Furthermore, igneous oceanic crust is the most massive potential habitat for life on Earth, so understanding the carbon sources for this potential biosphere are important for understanding life on Earth. Geochemical evidence suggests that warm and anoxic upper basement is net heterotrophic, but the balance of these processes in cooler and potentially oxic oceanic crust are poorly known. Here, we present data from stable carbon isotope tracer incubations to examine carbon fixation in basalts collected from the Loihi Seamount, the Juan de Fuca Ridge, and the western flank of the Mid-Atlantic Ridge, to provide a first order constraint on the rates of carbon fixation on basalts. These data will be compared to recently available assessments of carbon cycling rates in fluids from upper basement to synthesize our current state of understanding of the potential for carbon fixation and respiration in oceanic crust. Moreover, we will present new genomic data of carbon fixation genes observed in the basalt enrichments as well as from the subsurface of the Juan de Fuca Ridge flank, enabling identification of the microbes and metabolic pathways involved in carbon fixation in these systems.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2014
- Bibcode:
- 2014AGUFM.B23G..04O
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0448 Geomicrobiology;
- BIOGEOSCIENCES;
- 0456 Life in extreme environments;
- BIOGEOSCIENCES;
- 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCES