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Project Progress

MBGC Simulations:

The newly completed methanogenesis component of the model MBGC (MicrobialBioGeoChemistry) was used to examine the effects of competition between methanogens and sulfate-reducing bacteria on metabolism and gas flux in the microbial mat.

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Diffusion and boundary conditions:

A more detailed diffusive boundary layer model was developed that relies on water velocity overlying the mat to determine the thickness of the diffusive boundary layer, which will influence flux calculations of MBGC. Temperature and salinity equations were added to the diffusion coefficients to refine the environmental sensitivity of MBGC flux calculations.

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A skeleton model of eddy flux and flux across the water — air interface was constructed to prepare for future inclusion in a VPL (Virtual Planetary Laboratory) simulation.

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Salinity effects:

Metabolic consequences of salinity changes were added to the model. Each microbial guild and metabolism type was modified uniquely using equations that expressed an optimum salinity and a description of the changes that occurred due to changes in salinity. Simulations of moderate and highly hypersaline conditions indicated that community composition, gas flux, and chemical profile within the mat are highly sensitive to changes in salinity.

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Microbial mats of ice-covered lakes:

A collaboration was initiated with the laboratory of Slawek Tulaczyk (UC Santa Cruz) to model the microbial mats of ice-covered lakes. A proposal was written to fund a graduate student (Camas Tung) in support of the work, which will examine the biogeochemistry of microbial mats in Antarctic ice-covered lakes.