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Abstract
Earth's climate may be stabilized over millennia by solubilization of atmospheric carbon dioxide (CO2) as minerals weather, but the temperature sensitivity of this thermostat is poorly understood. We discovered that the temperature dependence of weathering expressed as an activation energy increases from laboratory to watershed as transport, clay precipitation, disaggregation, and fracturing increasingly couple to dissolution. A simple upscaling to the global system indicates that the temperature dependence decreases to ~22 kilojoules per mole because (i) the lack of runoff limits weathering and retains base metal cations on half the land surface and (ii) other landscapes are regolith-shielded and show little weathering response to temperature. By comparing weathering from laboratory to globe, we reconcile some aspects of kinetic and thermodynamic controls on CO2 drawdown by natural or enhanced weathering.
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Affiliation(s)
- S L Brantley
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA.,Department of Geosciences, Pennsylvania State University, University Park, PA, USA
| | - Andrew Shaughnessy
- Department of Geosciences, Pennsylvania State University, University Park, PA, USA
| | - Marina I Lebedeva
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA
| | - Victor N Balashov
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA
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Brantley SL, Vidic RD, Brasier K, Yoxtheimer D, Pollak J, Wilderman C, Wen T. Engaging over data on fracking and water quality. Science 2018; 359:395-397. [DOI: 10.1126/science.aan6520] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Brantley SL, Megonigal JP, Scatena FN, Balogh-Brunstad Z, Barnes RT, Bruns MA, Van Cappellen P, Dontsova K, Hartnett HE, Hartshorn AS, Heimsath A, Herndon E, Jin L, Keller CK, Leake JR, McDowell WH, Meinzer FC, Mozdzer TJ, Petsch S, Pett-Ridge J, Pregitzer KS, Raymond PA, Riebe CS, Shumaker K, Sutton-Grier A, Walter R, Yoo K. Twelve testable hypotheses on the geobiology of weathering. Geobiology 2011; 9:140-165. [PMID: 21231992 DOI: 10.1111/j.1472-4669.2010.00264.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Critical Zone (CZ) research investigates the chemical, physical, and biological processes that modulate the Earth's surface. Here, we advance 12 hypotheses that must be tested to improve our understanding of the CZ: (1) Solar-to-chemical conversion of energy by plants regulates flows of carbon, water, and nutrients through plant-microbe soil networks, thereby controlling the location and extent of biological weathering. (2) Biological stoichiometry drives changes in mineral stoichiometry and distribution through weathering. (3) On landscapes experiencing little erosion, biology drives weathering during initial succession, whereas weathering drives biology over the long term. (4) In eroding landscapes, weathering-front advance at depth is coupled to surface denudation via biotic processes. (5) Biology shapes the topography of the Critical Zone. (6) The impact of climate forcing on denudation rates in natural systems can be predicted from models incorporating biogeochemical reaction rates and geomorphological transport laws. (7) Rising global temperatures will increase carbon losses from the Critical Zone. (8) Rising atmospheric P(CO2) will increase rates and extents of mineral weathering in soils. (9) Riverine solute fluxes will respond to changes in climate primarily due to changes in water fluxes and secondarily through changes in biologically mediated weathering. (10) Land use change will impact Critical Zone processes and exports more than climate change. (11) In many severely altered settings, restoration of hydrological processes is possible in decades or less, whereas restoration of biodiversity and biogeochemical processes requires longer timescales. (12) Biogeochemical properties impart thresholds or tipping points beyond which rapid and irreversible losses of ecosystem health, function, and services can occur.
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Affiliation(s)
- S L Brantley
- Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA.
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Zerkle AL, Scheiderich K, Maresca JA, Liermann LJ, Brantley SL. Molybdenum isotope fractionation by cyanobacterial assimilation during nitrate utilization and N₂ fixation. Geobiology 2011; 9:94-106. [PMID: 21092069 PMCID: PMC3627308 DOI: 10.1111/j.1472-4669.2010.00262.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 10/14/2010] [Indexed: 05/30/2023]
Abstract
We measured the δ⁹⁸Mo of cells and media from molybdenum (Mo) assimilation experiments with the freshwater cyanobacterium Anabaena variabilis, grown with nitrate as a nitrogen (N) source or fixing atmospheric N₂. This organism uses a Mo-based nitrate reductase during nitrate utilization and a Mo-based dinitrogenase during N₂ fixation under culture conditions here. We also demonstrate that it has a high-affinity Mo uptake system (ModABC) similar to other cyanobacteria, including marine N₂-fixing strains. Anabaena variabilis preferentially assimilated light isotopes of Mo in all experiments, resulting in fractionations of -0.2‰ to -1.0‰ ± 0.2‰ between cells and media (ε(cells-media)), extending the range of biological Mo fractionations previously reported. The fractionations were internally consistent within experiments, but varied with the N source utilized and for different growth phases sampled. During growth on nitrate, A. variabilis consistently produced fractionations of -0.3 ± 0.1‰ (mean ± standard deviation between experiments). When fixing N₂, A. variabilis produced fractionations of -0.9 ± 0.1‰ during exponential growth, and -0.5 ± 0.1‰ during stationary phase. This pattern is inconsistent with a simple kinetic isotope effect associated with Mo transport, because Mo is likely transported through the ModABC uptake system under all conditions studied. We present a reaction network model for Mo isotope fractionation that demonstrates how Mo transport and storage, coordination changes during enzymatic incorporation, and the distribution of Mo inside the cell could all contribute to the total biological fractionations. Additionally, we discuss the potential importance of biologically incorporated Mo to organic matter-bound Mo in marine sediments.
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Affiliation(s)
- A L Zerkle
- Department of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA.
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Hausrath EM, Brantley SL. Basalt and olivine dissolution under cold, salty, and acidic conditions: What can we learn about recent aqueous weathering on Mars? ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010je003610] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hausrath EM, Treiman AH, Vicenzi E, Bish DL, Blake D, Sarrazin P, Hoehler T, Midtkandal I, Steele A, Brantley SL. Short- and long-term olivine weathering in Svalbard: implications for Mars. Astrobiology 2008; 8:1079-1092. [PMID: 19191538 DOI: 10.1089/ast.2007.0195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Liquid water is essential to life as we know it on Earth; therefore, the search for water on Mars is a critical component of the search for life. Olivine, a mineral identified as present on Mars, has been proposed as an indicator of the duration and characteristics of water because it dissolves quickly, particularly under low-pH conditions. The duration of olivine persistence relative to glass under conditions of aqueous alteration reflects the pH and temperature of the reacting fluids. In this paper, we investigate the utility of 3 methodologies to detect silicate weathering in a Mars analog environment (Sverrefjell volcano, Svalbard). CheMin, a miniature X-ray diffraction instrument developed for flight on NASA's upcoming Mars Science Laboratory, was deployed on Svalbard and was successful in detecting olivine and weathering products. The persistence of olivine and glass in Svalbard rocks was also investigated via laboratory observations of weathered hand samples as well as an in situ burial experiment. Observations of hand samples are consistent with the inference that olivine persists longer than glass at near-zero temperatures in the presence of solutions at pH approximately 7-9 on Svalbard, whereas in hydrothermally altered zones, glass has persisted longer than olivine in the presence of fluids at similar pH at approximately 50 degrees C. Analysis of the surfaces of olivine and glass samples, which were buried on Sverrefjell for 1 year and then retrieved, documented only minor incipient weathering, though these results suggest the importance of biological impacts. The 3 types of observations (CheMin, laboratory observations of hand samples, burial experiments) of weathering of olivine and glass at Svalbard show promise for interpretation of weathering on Mars. Furthermore, the weathering relationships observed on Svalbard are consistent with laboratory-measured dissolution rates, which suggests that relative mineral dissolution rates in the laboratory, in concert with field observations, can be used to yield valuable information regarding the pH and temperature of reacting martian fluids.
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Affiliation(s)
- E M Hausrath
- Department of Geosciences, Pennsylvania State University, University Park, PA, USA.
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Lewicki JL, Evans WC, Hilley GE, Sorey ML, Rogie JD, Brantley SL. Shallow soil CO2flow along the San Andreas and Calaveras Faults, California. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb002141] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J. L. Lewicki
- Department of Geosciences; Pennsylvania State University; University Park Pennsylvania USA
| | - W. C. Evans
- U.S. Geological Survey; Menlo Park California USA
| | - G. E. Hilley
- Institut für Geowissenshaften; Universität Potsdam; Potsdam Germany
| | | | - J. D. Rogie
- Department of Geosciences; Pennsylvania State University; University Park Pennsylvania USA
- U.S. Geological Survey; Menlo Park California USA
| | - S. L. Brantley
- Department of Geosciences; Pennsylvania State University; University Park Pennsylvania USA
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Werner C, Brantley SL, Boomer K. CO2emissions related to the Yellowstone volcanic system: 2. Statistical sampling, total degassing, and transport mechanisms. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jb900331] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Foster AL, Brown GE, Parks GA, Tingle TN, Voigt DE, Brantley SL. XAFS Determination of As(V) Associated with Fe(III) Oxyhydroxides in Weathered Mine Tailings and Contaminated Soil from California, U.S.A. ACTA ACUST UNITED AC 1997. [DOI: 10.1051/jp4:1997244] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Koepenick KW, Brantley SL, Thompson JM, Rowe GL, Nyblade AA, Moshy C. Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00173] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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