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1. Influence of pH on the balance between methanogenesis and iron reduction.

Author

Marquart KA, Haller BR, Paper JM, Flynn TM, Boyanov MI, Shodunke G, Gura C, Jin Q, and Kirk MF

Subjects
Bioreactors, Groundwater, Hydrogen-Ion Concentration, Oxidation-Reduction, Bacteria metabolism, Ferric Compounds metabolism, Iron metabolism, Iron Compounds metabolism, Methane metabolism, Minerals metabolism
Abstract

Methanogenesis and iron reduction play major roles in determining global fluxes of greenhouse gases. Despite their importance, environmental factors that influence their interactions are poorly known. Here, we present evidence that pH significantly influences the balance between each reaction in anoxic environments that contain ferric (oxyhydr)oxide minerals. In sediment bioreactors that contained goethite as a source of ferric iron, both iron reduction and methanogenesis occurred but the balance between them varied significantly with pH. Compared to bioreactors receiving acidic media (pH 6), electron donor oxidation was 85% lower for iron reduction and 61% higher for methanogenesis in bioreactors receiving alkaline media (pH 7.5). Thus, methanogenesis displaced iron reduction considerably at alkaline pH. Geochemistry data collected from U.S. aquifers demonstrate that a similar pattern also exists on a broad spatial scale in natural settings. In contrast, in bioreactors that were not augmented with goethite, clay minerals served as the source of ferric iron and the balance between each reaction did not vary significantly with pH. We therefore conclude that pH can regulate the relative contributions of microbial iron reduction and methanogenesis to carbon fluxes from terrestrial environments. We further propose that the availability of ferric (oxyhydr)oxide minerals influences the extent to which the balance between each reaction is sensitive to pH. The results of this study advance our understanding of environmental controls on microbial methane generation and provide a basis for using pH and the occurrence of ferric minerals to refine predictions of greenhouse gas fluxes., (© 2018 John Wiley & Sons Ltd.)

Published
2019
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2. Effect of Feedstock Concentration on Biogas Production by Inoculating Rumen Microorganisms in Biomass Solid Waste.

Author

Li N, Yang F, Xiao H, Zhang J, and Ping Q

Subjects
Animals, Cattle, Biofuels, Methane, Rumen microbiology, Sewage microbiology, Solid Waste
Abstract

A methane production system with continuous stirred-tank reactor, rumen liquid as inoculate microorganisms, and paper mill excess sludge (PES) as feedstock was studied. The work mainly focused on revealing the effect of feedstock concentration on the biogas production, which was seldom reported previously for the current system. The optimal fermentation conditions were found as follows: pH = 7, T = 39 ± 1 °C, sludge retention time is 20 days, sludge with total solids (TS) are 1, 2, 3.5, 5, 10, and 13% in weight. Daily gas yields were measured, and biogas compositions were analyzed by gas chromatograph. Under such conditions, the optimum input TS was 10 wt%, and the biogas yield and volume gas productivity were 280.2 mL/g·TS and 1188.4 mL L -1 ·d -1 , respectively. The proportions of CH 4 and CO 2 in the biogas were 65.1 and 34.2%. The CH 4 yield reached 182.7 mL/g VS (volatile suspended solid), which was higher than previously reported values. The findings of this work have a significant effect on promoting the application of digesting PES by rumen microorganisms and further identified the technical parameter.

Published
2018
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3. Anaerobic digestion of fines from recovered paper processing - Influence of fiber source, lignin and ash content on biogas potential.

Author

Steffen F, Requejo A, Ewald C, Janzon R, and Saake B

Subjects
Anaerobiosis, Carbohydrates chemistry, Crystallization, Dietary Fiber, Industrial Waste, Sewage, Temperature, Biofuels, Lignin chemistry, Methane chemistry, Paper, Refuse Disposal methods
Abstract

Fines concentration harms paper machine runability and output quality in recovered paper processing, hence, their extraction would be fundamentally beneficial. In this study, separated fines from an industrial recycled fiber pulp (RFP) were characterized and evaluated for their potential biogas yields with a focus on understanding the role of varying lignin and ash contents. Further, these results were compared with biogas yields from conventional chemical and mechanical pulps. Overall, methane yields of fines from mechanical pulps (21-28mL/gVS) and RFP (127mL/gVS) are relatively low compared to the high methane yields of 375mL/gVS from the chemical pulp fines. However, it was shown that the high ash content in RFP fines (up to 50%) did not negatively influence overall yield, rather, it was the presence of slowly biodegrading lignin-rich fiber fines., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Published
2016
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4. Influence of pH on the balance between methanogenesis and iron reduction

Author

Ben R. Haller, Qusheng Jin, Ganiyat Shodunke, Colleen M. Gura, Maxim I. Boyanov, Matthew F. Kirk, Theodore M. Flynn, Janet M. Paper, and Kyle A. Marquart

Subjects
Goethite, 010504 meteorology & atmospheric sciences, Methanogenesis, Iron, 010502 geochemistry & geophysics, Ferric Compounds, 01 natural sciences, Methane, chemistry.chemical_compound, Bioreactors, medicine, Groundwater, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, General Environmental Science, Minerals, Oxide minerals, Bacteria, biology, Hydrogen-Ion Concentration, biology.organism_classification, Anoxic waters, chemistry, Environmental chemistry, visual_art, visual_art.visual_art_medium, General Earth and Planetary Sciences, Ferric, Clay minerals, Oxidation-Reduction, Iron Compounds, medicine.drug, Geobacter
Abstract

Methanogenesis and iron reduction play major roles in determining global fluxes of greenhouse gases. Despite their importance, environmental factors that influence their interactions are poorly known. Here, we present evidence that pH significantly influences the balance between each reaction in anoxic environments that contain ferric (oxyhydr)oxide minerals. In sediment bioreactors that contained goethite as a source of ferric iron, both iron reduction and methanogenesis occurred but the balance between them varied significantly with pH. Compared to bioreactors receiving acidic media (pH 6), electron donor oxidation was 85% lower for iron reduction and 61% higher for methanogenesis in bioreactors receiving alkaline media (pH 7.5). Thus, methanogenesis displaced iron reduction considerably at alkaline pH. Geochemistry data collected from U.S. aquifers demonstrate that a similar pattern also exists on a broad spatial scale in natural settings. In contrast, in bioreactors that were not augmented with goethite, clay minerals served as the source of ferric iron and the balance between each reaction did not vary significantly with pH. We therefore conclude that pH can regulate the relative contributions of microbial iron reduction and methanogenesis to carbon fluxes from terrestrial environments. We further propose that the availability of ferric (oxyhydr)oxide minerals influences the extent to which the balance between each reaction is sensitive to pH. The results of this study advance our understanding of environmental controls on microbial methane generation and provide a basis for using pH and the occurrence of ferric minerals to refine predictions of greenhouse gas fluxes.

Published
2018

5. Regional trends and drivers of the global methane budget

Author

Naveen Chandra, Akihiko Ito, Philippe Ciais, Peter A. Raymond, Jurek Müller, Ann R. Stavert, Joe R. Melton, Marielle Saunois, Phillipe Bousquet, Adrian Gustafson, Yosuke Niwa, Robert B. Jackson, Shushi Peng, Qianlai Zhuang, Hanqin Tian, Aki Tsuruta, George H. Allen, Benjamin Poulter, Joe McNorton, Bo Zheng, Yi Yin, Prabir K. Patra, Thomas Kleinen, Pierre Regnier, Peter Bergamaschi, Ronny Lauerwald, Shamil Maksyutov, Misa Ishizawa, Arjo Segers, William J. Riley, Josep G. Canadell, Zhen Zhang, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université libre de Bruxelles (ULB), This paper is the result of a collaborative international effort under the umbrella of the Global Carbon Project, a Global Research Project of Future Earth and a research partner of the World Climate Research Programme. We acknowledge primary support for the methane budget from the Gordon and Betty Moore Foundation through Grant GBMF5439 'Advancing Understanding of the Global Methane Cycle' to Stanford University (P.I. Rob Jackson, co- P.I.s Philippe Bousquet, Marielle Saunois, Josep Canadell, Gustaf Hugelius, and Ben Poulter). Josep Canadell acknowledges the support of the Australian National Environmental Science Program – Earth Systems and Climate Change. Prabir K Patra and Neveen Chandra acknowledge support from Environment Research and Technology Development Funds of the Environmental Restoration and Conservation Agency of Japan (JPMEERF20182002, JPMEERF20172001). Jurek Müller thanks for support by the Swiss National Science Foundation (#200020_172476). Peter Bergamaschi acknowledges the support of ECMWF providing computing resources under the special project 'Improve European and global CH4 and N2O flux inversions (2018-2020)'. Pierre Regnier acknowledges the support from the VERIFY project under European Union's Horizon 2020 research and innovation program grant agree-ment no. 776810. The TM5-CAMS inversions are available from https://atmos phere.copernicus.eu, Arjo Segers acknowledges the support from the Copernicus Atmosphere Monitoring Service, implemented by the European Centre for Medium-Range Weather Forecasts on be-half of the European Commission (grant no. CAMS73). William Riley acknowledges support by the US Department of Energy, Office of Science, Biological and Environmental Research, Regional and Global Climate Modeling Program through the RUBISCO Scientific Focus Area under contract DE-AC02- 05CH11231 to Lawrence Berkeley National Laboratory. The authors gratefully acknowledge those re-sponsible for the global network of atmospheric observations used in this study including Donald R Blake and Isobel Simpson, University of California Irvine, USA, Gordon Brailsford, NIWA, Cyril Crevosier, LMD, France, New Zealand, Paul Krummel and Ray Langenfelds, CSIRO, Australia, Toshinobu Machida, Yasunori Tohjima and Yukio Yoshida, NIES, Japan, Ronald Prinn, MIT, USA, Simon O’Doherty, University of Bristol, UK, Michel Ramonet, LSCE-IPSL, France, Atsushi Takizawa, JMA, Japan, Ray Weiss, Scripps Institute of Oceanography, USA and Doug Worthy, Environment Canada, Canada. We would also like to thank Lena Höglund-Isaksson, IIASA, Austria, Greet Janssens- Maenhout EC-JRC, Italy and Steven Smith, PNNL-JGCR, USA for their assistance with the anthropogenic inventory data. The authors also acknowledge the significant contribution of Goulven G. Laruelle, Department Geoscience, Environment & Society, Université Libre de Bruxelles, Brussels, Belgium who, with P. Regnier, developed the re-gionally distributed estuarine flux data set., and European Project: 776810,H2020,H2020-SC5-2017-OneStageB,VERIFY(2018)

Subjects
China, Municipal solid waste, Livestock, 010504 meteorology & atmospheric sciences, methane emissions, Oceans and Seas, 010501 environmental sciences, 7. Clean energy, 01 natural sciences, Methane, 12. Responsible consumption, bottom-up, Atmosphere, chemistry.chemical_compound, Enteric fermentation, Environmental protection, source sectors, Environmental Chemistry, Animals, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, regional, Ecology, business.industry, Coal mining, Biological Sciences, Climate Action, natural emissions, Carbon project, chemistry, 13. Climate action, Greenhouse gas, top-down, Environmental science, anthropogenic emissions, business, Environmental Sciences
Abstract

The ongoing development of the Global Carbon Project (GCP) global methane (CH4 ) budget shows a continuation of increasing CH4 emissions and CH4 accumulation in the atmosphere during 2000-2017. Here, we decompose the global budget into 19 regions (18land and 1 oceanic) and five key source sectors to spatially attribute the observed global trends. A comparison of top-down (TD) (atmospheric and transport model-based) and bottom-up (BU) (inventory- and process model-based) CH4 emission estimates demonstrates robust temporal trends with CH4 emissions increasing in 16 of the 19 regions. Five regions-China, Southeast Asia, USA, South Asia, and Brazil-account for >40% of the global total emissions (their anthropogenic and natural sources together totaling >270Tg CH4 yr-1 in 2008-2017). Two of these regions, China and South Asia, emit predominantly anthropogenic emissions (>75%) and together emit more than 25% of global anthropogenic emissions. China and the Middle East show the largest increases in total emission rates over the 2000 to 2017 period with regional emissions increasing by >20%. In contrast, Europe and Korea and Japan show a steady decline in CH4 emission rates, with total emissions decreasing by ~10% between 2000 and 2017. Coal mining, waste (predominantly solid waste disposal) and livestock (especially enteric fermentation) are dominant drivers of observed emissions increases while declines appear driven by a combination of waste and fossil emission reductions. As such, together these sectors present the greatest risks of further increasing the atmospheric CH4 burden and the greatest opportunities for greenhouse gas abatement.

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