1. Geomicrobiology at the Sevilleta Predicting the metabolic energy available to aqueous microorganisms By Samantha Adelberg Mentors: Laura Crossey and Amy Williams

2. Water Sources of Water at the Sevilleta – Rio Grande – Precipitation – Groundwater Wells and Springs

3. Groundwater 25 wells and springs Minimal Knowledge Some Previous Research

4. Research Question Water chemistries varying dramatically within the Sevilleta due to local geology But how much does the varying water chemistry affect the thermodynamics of the different springs and wells?

5. Thermodynamics All reactions want to move towards an equilibrium state Natural waters such as the ones at the Sevilleta are not in equilibrium Energetically favorable for these reactions to move from one state to another – Spontaneous reactions, - delta G But there is no set time limit Affinity = RT ln(K/Q) Equilibrium constant Gas constant Temperature

6. Role of Microorganisms Act as catalysts in these reactions Speed up the electron transfers Must spend energy making enzymes that can perform these reactions Facilitate these reactions because they gain a determined amount of energy through each transaction Amount of energy gained changes

7. Chemo-litho-auto-trophChemo-litho-auto-troph Energy Source: Chemical reactions Electron Donor: Inorganic Carbon source: Inorganic “Eater of” Heterotroph Photoautotroph Chemolithoautotroph

8. Gibbs Free Energy

9. Study Area: Sevilleta Springs and Wells

10. Methods In the Field – pH, conductivity, TDS, temp – Bottles for cations, anions, stable isotopes, nutrients, delta 13C In the Lab – Alkalinity (endpoint titrations) – ICP: cations and trace elements – IC: anions – Nutrients Analysis – Geochemical modeling software Phreeqc – Thermodynamics code to determine electron affinity

11. PICTURE of LOCAL GEOLOGY

14. Cibola San Acacia Tomasino Rio Salado Box Springs Silver Creek West Mesa

15. Deeply Derived Waters San Acacia Spring Rio Salado Box Springs CoCorp Siesmic Line, Lewis and Baldridge 1994

16. Results

17. ReactionsAFFINITIES (kJ/mol/e) Electron Acceptor 9Fe2+ + NO 2 - + 10H2O -> 3Magnetite + NH4+ + 16H+108.3213633 Nitrite 2Fe2+ + NO 3 - + 2H2O -> Hematite + NO2- + 4H+65.70072061Nitrate Pyrite + NO 3 - + 2H+ -> 2Sulfur + Fe2+ + NO2- + H2O42.97850923Nitrate Pyrite + 7NO 3 - + H2O -> Fe2+ + 2SO42- + 7NO2- + 2H+37.70280148 Nitrate S + 3NO 3 - + H2O -> SO42- + 3NO2- + 2H+37.21998924 Nitrate Top 5 Reactions for all Springs/Wells

18. What does this show? What reactions can occur The potential energy yield of the different reactions What niche spaces are available for use Trends between the geology, water chemistry, and affinity coefficients

19. Affinity Trends Chloride Dominated Waters (San A-C, RSB12) have nearly identical affinity coefficients P value =.94

20. The Chloride Dominated Waters San Acacia SpringRio Salado Box Spring

21. Affinity Trends Geographically similar location (SdC1, TW) Distinct water types – Sulfate Dominated (Cibola Spring) – Mixed Ion Water (Tomasino Well) P value =.925

22. PICTURE of LOCAL GEOLOGY Cibola Tomasino

23. Affinity Trends Bicarbonate Dominated Waters (WMW, SC2) P value =.665

24. Nutrient Readings C:N ratios limiting nutrients whose presence greatly affects the health of a water system > 14.6 severe N deficiency 8.3 –14.6 moderate deficiency <8.3 no deficiency Only Tomasino Well does not have a severe N deficiency All Springs/Wells have high TOC readings which predict the presence of chemolithoheterotrophs Spring/WellC:N Fish & Wildlife Well4635.96354 San Lorenzo Spring 276.86617 McKenzie Well23.56353 Cibola Spring426.27735 Canyon Well25.24335 Gibbs Well53.93346 Tule Well1651.51884 Rio Salado (downstream)1453.10889 Rio Salado Box spring11293.03585 Rio Salado Box spring12285.04539 Silver Creek seep 2189.86399 San Lorenzo Spring 1158.53682 Tomasino Well9.65792 San Acacia brine pool35.35470 Nunn Well77.92092 West Mesa Well66.00071 Canyon del Ojito Spring39.41307 San Acacia spring170.15187

25. Discussion Nitrate is the dominant electron acceptor Nutrient reading show that all but one spring/well is deficient in N – This is probably because NO 3 is being used nearly entirely in these metabolic reactions Surprisingly, in the springs/wells with O 2, Nitrate continues to have a higher energy yield – Perhaps because O 2 is so limited that it isn’t optimal for microorganisms to use this pathway Feedback effect between microbs and water Gibbs Free Energy

26. Lower than atmos. pCO2 yet saturated with respect to calcite Higher than atmos. pCO2 yet under saturated with respect to calcite Higher than atmos. pCO2 and saturated with calcite

27. Crossey, unpublished

28. Why use thermodynamic modeling? Future geomicrobiology research and sampling Provides explanations Similarities to Mid Ocean Ridge thermal vents Rio Grande Rift; Crossey et al., in prep. Lost City Hydrothermal area, Kelley et al., 2005 Continental spring systems Marine vent systems

29. Acknowledgements - Laura Crossey -Amy Williams -Frankie Reyes - All the REU’s! - Jennifer Johnson - Scott Collins -Fish and Wildlife Services -NSF -Sevilleta LTER -Ara Kooser -Brandi Cron -Amanda Martinez -Cathy! -Mehdi and Kim in the analytical chemistry lab -Amanda Schaupp, my statistician!

30. QUESTIONS?