Effects of Environmental Perturbations and Seasonal Dynamics upon Microbial Populations in Serpentinite-hosted Groundwater
Abstract
Fractured and uplifted ultramafic rock, found in structures known as ophiolites, is a common feature at continental margins throughout the world. As these structures undergo water-rock reactions through a process known as serpentinization they generate high pH (>10), highly reducing, volatile-rich fluids that can provide energy sources for subsurface microbial communities. At the same time, as ophiolites weather into serpentine soils, they interact with carbon reservoirs in complex ways through processes such as abiogenic hydrocarbon formation, carbonate precipitation, and microbial processing of organic matter. A recent study of the Coast Range Ophiolite Microbial Observatory (CROMO) well network in northern California documented the relationships between aqueous geochemistry and microbial metagenomes in serpentinization-influenced groundwater, highlighting the influence of pH, methane, and carbon monoxide concentrations upon the abundance of certain populations. The extremely low diversity of microbial communities at the site provided a tractable model to evaluate ongoing biogeochemical processes. New work at CROMO has studied temporal changes in microbial abundance and community composition in groundwater relative to hydrological and geochemical properties. Between 2014 and 2016, in situ dataloggers at CROMO have captured perturbations in the region such as earthquakes, wildfires, droughts, and floods. These perturbations impact physico-chemical properties of the groundwater (e.g. redox, nutrient concentrations) in ways that are reflected in the microbial ecology of the site. Initial results of the multi-year integration of groundwater microbiology, geochemistry, and hydrology at CROMO will be presented in terms of their consequences for carbon cycling activities. Developing a predictive model of these feedbacks is essential as serpentine-hosted environments are subjected to land-use change, mining activities, and are being targeted for geological carbon sequestration.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.B31H0570S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0452 Instruments and techniques;
- BIOGEOSCIENCESDE: 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCESDE: 1830 Groundwater/surface water interaction;
- HYDROLOGY