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Project Progress

The 2009 field campaign to Yellowstone National Park generated 224 water samples with coordinated dissolved gas samples. In Year 2, these were analyzed for major anions and cations, trace elements, dissolved inorganic and organic carbon concentrations and isotopic values. Interpretation is underway. During 2010 field work, an additional 190 coordinated water, dissolved gas, and sediment/biofilm samples were collected across physical and geochemical gradients, including changes in temperature, pH, dissolved gas concentration (esp. H₂), total sulfide concentration, and degree of gas-phase and liquid-phase hydrothermal input in order to better understand the interplay of biological processes and geochemical changes. Dissolved inorganic and organic carbon concentrations and isotopic signatures are nearly finished. Trace element analysis of water samples is underway. Major anion and cation analysis awaits an Ion Chromatography system upgrade. Analysis for dissolved H₂ is complete (collaborative with Tori Hoehler’s lab, NASA Ames), and analysis for other dissolved gases, will begin after installation of two new GC systems in Shock’s lab (funded by NSF). Samples were selected for initial DNA and RNA analysis.

Extended Redifeld Ratio (ERR) analysis continues on sediment and mat samples collected in 2009 from 110 of the 224 sites. Currently, C, N, and P concentrations and isotopic ratios for C and N are complete. Trace element analysis is nearing completion; data will be interpreted relative to the water samples. Samples for ERR have been collected for 2010, but analysis has not yet begun.

During the 2009 field season, we performed over 200 4-hour-long ¹⁵N tracer incubations at 5 hydrothermal features in Yellowstone National Park. These features comprised a range of geochemical compositions. These experiments generated over 1000 samples, the analysis of which was ongoing in Year 2. Data collected thus far have provided evidence and rates for several target processes including denitrification, nitrate and ammonium uptake.

During the 2010 field season, we revisited many of the same sites and conducted overnight (24-hour) incubations better suited to tracking N-cycle processes with rates that were too slow to detect in 4-6h incubations. We expect to complete all analyses by June 2011, by which point we will have a detailed inventory of all major N-cycling processes at these sites.

Also during the summer of 2010, 24-hour incubation nutrient-addition experiments were performed at 4 YNP hot springs at 2 temperatures per spring, above and below the photosynthetic fringe. Sediment or mat and spring water were collected and divided between 24 vented bottles and amended with N, P and Fe in a full factorial design. The sediment or mat was frozen for later molecular analysis. Dissolved elements are analyzed and method development has begun to assess nucleic acid ratios (RNA/DNA).

To investigate the use of one-carbon compounds by microbial communities, ¹³C-tracer experiments were conducted at four hot springs. Sediment and/or microbial mat samples were incubated in bottles amended with unlabeled and ¹³C-labeled methanol for 24 hours. Control samples of no methanol addition were also incubated. After incubation, sediment and/or microbial mat, hot spring water, and headspace gas samples were collected to determine the fate of the labeled methanol. Sample processing has started and preliminary data (elemental analysis) suggests that methanol assimilation occurred at one location. Sample processing underway includes (1) carbon and nitrogen contents and their isotopes by elemental analysis, (2) ¹³C-carbon dioxide in the headspace gas samples, (3) ¹³C in the dissolved organic carbon and dissolved inorganic carbon pools of hot spring water, and (4) detecting ¹³C-labeled nucleic acids in the sediments.

Finally, we continued efforts to catalyze the development of novel sensor technologies to characterize the chemistry of extreme hot spring environments. In Year 1, this effort consisted of involving engineering faculty and graduate students in the YNP field expedition. In Year 2, we supported students working on the development of sensors in the laboratory.