DISSOLVED INORGANIC CARBON SPECIES Speciation of Inorganic Carbon in Aqueous Phase as a Function of pH 1.0 0.9 0.8 0.7 0.6 CO - 2- 2 HCO3 CO3 0.5 0.4 0.3 0.2 Relative abundance of species Relative 0.1 0.0 3 4 5 6 7 8 9 10 11 pH Image by MIT OpenCourseWare. The relative distribution of the three major species of dissolved inorganic carbon in water as a function of pH. Note that at pH of seawater (~8.1), approximately 95% of the inorganic carbon is in the form of bicarbonate anion. 1 Carbon Cycle Fluxes and δ13C Values Atmosphere 102 778 (-7‰) 62 60 100 5 122 Surface Ocean Fossil Fuels Land biota 600 (1‰) 5,000 (-25‰) 1,600 (-25‰) 35 36 60 Dissolved bicarbonate Terrestrial soils deep ocean 1,600 (-25‰) 36,000 (0‰) 0.05 0.3 0.5 Organic C in seds/rocks Marine carbonate seds 15,000,000 (-25‰) 2,500 (0‰) 0.7 0.05 0.2 Atmosphere 0.06-0.7 0.03 Carbonate rocks 778 (-7‰) Mantle 60,000,000 (0-1‰) 324,000,000 (-5‰) 0.7 Continental Crust 7,000,000 (-5‰) FLUXES IN GIGATONS OF CARBON/YEAR 2 These tables have been removed due to copyright restrictions. Please see Table 3.1 and 3.2 in the book: Fundamentals of Geobiology. ISBN: 9781405187527. 3 Redox reactions Concepts: thermodynamic basis of microbial growth, sources of energy for microbial growth, utilization of natural chemical and light gradients, chemical profiles in aquatic environments and sediments, microbial processes and redox evolution of the environment, prediction of metabolisms supported by different environments, the influence of pH and environmental redox state on the formation of minerals Reading: Brock Biology of Microorganisms, Morel and Hering, Aquatic chemistry, Oremland et al. The microbial arsenic cycle in Mono Lake, California (2004), Lavik et al. (2009), Dolfing et al. (2008) 4 This image has been removed due to copyright restrictions. Please see the image on http://www.awi.de/fileadmin/user_upload/News/Press_Releases/2008/3._Quartal/Sedimentkerne_p.jg. 5 http://soundwaves.usgs.gov/2012/10/images/Methane3SulfidicMudDES-lg.jpg 6 Image courtesy of DOE. (Kessler et al., 2011) 7 Acid-mine drainage Image courtesy of NASA. Thiobacillus ferooxidans This image has been removed due to copyright restrictions. Please see the image on: http://www.torinoscienza.it/img/200x200/it/s00/00/0004/0000048c.png. 8 Energy Electrons Carbon Photo- Organo- Hetero- Litho- Auto- Chemo- Organo- Hetero- Litho- Auto- Mixotrophs: mixed sources of energy/carbon 9 ATP – energy currency of the cell 10 ATP SYNTHASE This image has been removed due to copyright restrictions. Please see the image on: http://www.bio.davidson.edu/courses/molbio/molstudents/spring2005/carlson/atp%20synthase1.html. 11 Redox reactions- terminology • Redox couple: any pair of species that have the same element in different oxidation states is a redox couple • Faraday constant: charge of 1 mole of electrons (96500 C) • Standard free energy of a reaction: 1 mole of reactants, std. conditions • Reductant: e- donor • Oxidant: e- acceptor • Oxidation: loss of e- • Reduction: gain of e- 12 5 rules for determining the formal charge of an atom 1. The elementary state has a redox state of 0 0 H2, O2, S 2. The oxidation state is equal to an ion’s charge Fe3+ = 3, H+ = 1 3. In most compounds… O = -2 and H = +1 4. A neutral molecule has zero net redox state H2O 5. A charged species has net redox state equal to its charge OH- = -1 13 Steps for balancing redox reactions 1. Write the unbalanced half-reactions for the oxidation and reduction 2. Balance all elements other than H and O 3. Balance O with H2O molecules 4. Balance H with H+ ions 5. Balance charge with e- 6. Balance number of e- in two half-reactions 7. Add the two half-reactions 8. Adjust for pH if necessary 9. Check that charge and atoms balance 14 pe pe0 Adapted from The P680* P680+ Carl Sagan Lecture - By Joe Kirschvink CH2 O CO2 –10 CO2 CH2 O + + H2 H H H2 0 + + NH4 N2 N2 NH4 CH4 CO2 CO2 CH4 H2 S S S H2 S 2– 2 – H2 S SO4 SO4 H2 S 2+ 2+ Fe Fe(OH)3 0 Fe(OH)3 Fe OXIDATION + – + NH4 NO3 NO3 NH4 – NO2 NO3 NO3 NO2 2 Mn2+ MnO2 MnO2 Mn + CO CO2 CO2 CO +10 – – N 2 NO3 NO3 N2 H2 O O2 O2 H2 O + P680 P680 + Courtesy of Joe Kirschvink. Used with permission. 15 Energy Electrons Carbon Photo- Organo- Hetero- Litho- Auto- Chemo- Organo- Hetero- Litho- Auto- Mixotrophs: mixed sources of energy/carbon 16 The electron tower generally explains porewater chemistry Lake Michigan Sediment Black Sea 17 Example of an anaerobic metabolism: Microbial growth in Mono Lake, CA © Google. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/. 18 Image courtesy of USGS. 19 Image courtesy of State of California. 20 This table has been removed due to copyright restrictions. Please see Table 3B-2 on page http://www.monobasinresearch.org/images/mbeir/dchapter3/table3b-2.pdf. 21 This image has been removed due to copyright restrictions. Please see Figure 3 (a) on page http://onlinelibrary.wiley.com/doi/10.1016/j.femsec.2003.12.016/full. 22 These images have been removed due to copyright restrictions. Please see Figure 3 (b) and (c) on page http://onlinelibrary.wiley.com/doi/10.1016/j.femsec.2003.12.016/full. 23 This table has been removed due to copyright restrictions. Please see Table 2 on page http://onlinelibrary.wiley.com/doi/10.1016/j.femsec.2003.12.016/full. (Oremland et al., 2004) 24 - 2- + Lactate +2HAsO4 + H - - - Acetate +HCO3 +2H2AsO3 -1 (∆G’0 = -156.8 kJ mol ). Image by MIT OpenCourseWare. (Oremland et al., 2004) 25 MIT OpenCourseWare http://ocw.mit.edu 12.007 Geobiology Spring 2013 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms..