Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane

The second edition of The Biomarker Guide is a fully updated and expanded version of this essential reference. Now in two volumes, it provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes. Biomarkers and Isotopes in the Environment and Human History details the origins of biomarkers and introduces basic chemical principles relevant to their study. It discusses analytical techniques, and applications of biomarkers to environmental and archaeological problems. The Biomarker Guide is an invaluable resource for geologists, petroleum geochemists, biogeochemists, environmental scientists and archaeologists.

The Biomarker Guide

Contributors. Abbreviations. Introduction. 1. Stable isotope chemistry and measurement: a primer. Elizabeth W. Sulzman. Introduction. What isotopes are, what makes them distinct. Properties of ecologically useful stable isotopes. Technological advances and current trends in the ecological use of isotopes. Acknowledgments. References. 2. Sources of variation in the stable isotopic composition of plants. John D. Marshall, J. Renee Brooks, and Kate Lajtha. Introduction. Carbon isotopes. Nitrogen isotopes. Hydrogen and oxygen isotopes. Conclusions. References. 3. Natural 15N- and 13C-abundance as indicators of forest nitrogen status and soil carbon dynamics. Charles T. Garten, Jr, Paul J. Hanson, Donald E. Todd, Jr, Bonnie B. Lau, and Deanne J. Brice. Introduction. Significance of 15N-abundance to soil carbon sequestration. Vertical changes in soil 13C-abundance and soil carbon dynamics. Conclusions. Acknowledgments. References. 4. Soil nitrogen isotope composition. R. Dave Evans. Introduction. Sources of variation in soil 15N. Patterns of soil nitrogen isotope composition. Conclusions. References. 5. Isotopic study of the biology of modern and fossil vertebrates. Paul L. Koch. Introduction. Vertebrate tissues in the fossil record. Controls on the isotopic composition of vertebrate tissues. Preservation of biogenic isotope compositions by vertebrate fossils. Paleobiological applications. Conclusions. A post-script on workshops and literature resources. References. 6. Isotopic tracking of migrant wildlife. Keith A. Hobson. Introduction. Basic principles. Marine systems. Terrestrial systems (excluding deuterium). Using deuterium patterns in precipitation. Conclusions. References. 7. Natural abundance of 15N in marine planktonic ecosystems. Joseph P. Montoya. Introduction. Background. Isotopic variation in marine nitrogen. Source delineation and isotope budgets. Animal fractionation and food web processes. Isotopic transients in marine systems. Compound-specific nitrogen isotope analyses. Conclusions. Acknowledgment. References. 8. Stable isotope studies in marine chemoautotrophically based ecosystems: An update. Cindy Lee Van Dover. Introduction. Isotopic tracing of carbon at methane seeps. Whale falls. Hydrothermal vents. Conclusions. References. 9. Stable isotope ratios as tracers in marine food webs: An update. Robert H. Michener and Les Kaufman. Introduction. Methods of assessing food webs. Phytoplankton and particulate organic carbon. Phytoplankton and particulate organic nitrogen. Marine food webs. Stable isotopes in marine conservation biology. Conclusions. Acknowledgments. References. 10. Stable isotope tracing of temporal and spatial variability in organic matter sources to freshwater ecosystems. Jacques C. Finlay and Carol Kendall. Introduction. Overview of river food webs and stable isotope approaches. Stable isotope ratios of organic matter sources in stream ecosystems. C, N, and S isotopic variability and its applications in river ecology. Conclusions. Acknowledgments. References. 11. Stable isotope tracers in watershed hydrology. Kevin J. McGuire and Jeff McDonnell. Introduction. Basic concepts in watershed hydrology. Why are stable isotopes needed?. General concepts in isotope hydrology. Applications of isotope hydrology in watershed and ecosystem studies. Conclusions. Acknowledgments. References. 12. Tracing anthropogenic inputs of nitrogen to ecosystems. Carol Kendall, Emily M. Elliott, and Scott D. Wankel. Introduction. Isotopic compositions of major N sources to ecosystems. Processes affecting the isotopic composition of DIN. Separating mixing of sources from the effects of cycling. Applications to different environmental settings. What sources of agricultural and urban sources of nitrate can be distinguished using isotopes?. Other tools for tracing anthropogenic contaminants. Conclusions. References. 13. Modeling the dynamics of stable-isotope ratios for ecosystem biogeochemistry. William S. Currie. Introduction. Designing consistent model-data linkages and comparisons. Principles and techniques of stable isotope modeling. Conclusions. Acknowledgments. References. 14. Compound-specific stable isotope analysis in ecology and paleoecology. Richard P. Evershed, Ian D. Bull, Lorna T. Corr, Zoe M. Crossman, Bart E. van Dongen, Claire Evans, Susan Jim, Hazel Mottram, Anna J. Mukherjee, and Richard D. Pancost. Introduction. Why use compound-specific stable isotopes?. Analytical considerations in compound-specific stable isotope analysis. Applications of compound-specific stable isotope approaches in ecology and paleoecology. Conclusions. References. Index

Stable isotopes in ecology and environmental science

Methane is the most abundant organic chemical in Earth's atmosphere, and its concentration is increasing with time, as a variety of independent measurements have shown. Photochemical reactions oxidize methane in the atmosphere; through these reactions, methane exerts strong influence over the chemistry of the troposphere and the stratosphere and many species including ozone, hydroxyl radicals, and carbon monoxide. Also, through its infrared absorption spectrum, methane is an important greenhouse gas in the climate system. We describe and enumerate key roles and reactions. Then we focus on two kinds of methane production: microbial and thermogenic. Microbial methanogenesis is described, and key organisms and substrates are identified along with their properties and habitats. Microbial methane oxidation limits the release of methane from certain methanogenic areas. Both aerobic and anaerobic oxidation are described here along with methods to measure rates of methane production and oxidation experimentally. Indicators of the origin of methane, including C and H isotopes, are reviewed. We identify and evaluate several constraints on the budget of atmospheric methane, its sources, sinks and residence time. From these constraints and other data on sources and sinks we construct a list of sources and sinks, identities, and sizes. The quasi-steady state (defined in the text) annual source (or sink) totals about 310(±60) × 1012 mol (500(±95) × 1012 g), but there are many remaining uncertainties in source and sink sizes and several types of data that could lead to stronger constraints and revised estimates in the future. It is particularly difficult to identify enough sources of radiocarbon-free methane.

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Biogeochemical aspects of atmospheric methane

Methane is the most abundant hydrocarbon in the atmosphere, and it is an important greenhouse gas, which has so far contributed an estimated 20% of postindustrial global warming. A great deal of biogeochemical research has focused on the causes and effects of the variation in global fluxes of methane throughout earth's history, but the underlying microbial processes and their key agents remain poorly understood. This is a disturbing knowledge gap because 85% of the annual global methane production and about 60% of its consumption are based on microbial processes. Only three key functional groups of microorganisms of limited diversity regulate the fluxes of methane on earth, namely the aerobic methanotrophic bacteria, the methanogenic archaea, and their close relatives, the anaerobic methanotrophic archaea (ANME). The ANME represent special lines of descent within the Euryarchaeota and appear to gain energy exclusively from the anaerobic oxidation of methane (AOM), with sulfate as the final electron accept...

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Anaerobic Oxidation of Methane: Progress with an Unknown Process

A system has been developed at BGR for rapid and precise nitrogen isotopic ratio measurements on natural gases in northern Germany using a gas chromatograph coupled with an isotope ratio mass spectrometer (GC/IRMS). The main advantage of the GC/IRMS system relative to conventional techniques is the analysis of gases with varying nitrogen concentrations down to 0.1% in routine operation. Small sample size down to 10 nmol of nitrogen is sufficient for precise measurement within the 1 {sigma} range of {+-}0.3 to {+-}0.5%. Care was taken to avoid sample contamination by atmospheric nitrogen during measurement, which in other preparation systems occasionally yields systematic errors of up to several per mill. The system was designed for user friendly, fast operation with computer-aided data acquisition and calculations. A comparison of reanalyzed with already published {delta}{sup 15}N values for nitrogen gas from several natural gas fields in northwest and southern Germany reveals significant differences which depend on the nitrogen concentrations. A careful handling of the data is recommended. 18 refs., 9 figs., 2 tabs.

Improved Stable Nitrogen Isotope Ratio Measurements of Natural Gases

In this paper the installation and long-term operation of a system for continuous monitoring of fumarolic gases is described. Several physicochemical and gas-geochemical parameters such as the concentration of CO2, H2S and CO in the fumarolic emissions, as well as the temperatures of the hydrothermal steam and soil in close vicinity of the fumarole and steam pressure are measured in short-time intervals (typically 15 seconds). Data are logged on-site and in parallel transferred to a remote station by digital telemetry. Specially developed software enables the real-time observation of the local conditions in the crater and full bidirectional control of the monitoring system. Fluctuations in the monitored parameters are also reported. From the data presented it can be concluded that environmental conditions (direction and strength of wind, precipitation) will interact with some of the parameters monitored. These influences can only be revealed by continuously operated monitoring systems.

Continuous, Direct Gas-Geochemical Monitoring in Hydrothermal Vents : Installation and Long-Term Operation on Nisyros Island (Greece)

A technique has been developed to determine C12/C13 and D/H isotopic ratios on small quantities of methane through pentane hydrocarbons and has been applied to natural gases from various genetic sources (i.e., early-diagenetic, oil-associated, late-catagenic and mixed-gas sources). Carbon isotopes measured from 27 natural gases have ^dgr13C range of 23, 15, and 20^pmil for the C1 to C3 alkanes and maximum ^dgr13C values of -35.1, -26.8, and -20.8 ^pmil respectively. With a smaller sample base, butane and pentane vary within 16 and 4 ^pmil, respectively, for those samples with the most positive ^dgr13C = -26.5 and -26.9 ^pmil. Deuterium isotopes exhibit greater isotopic variation than the corresponding carbon values. D/H variations clearly decrease toward the higher homologues with ^dgrD ranges of 182, 110, 75, 43, and 29 ^pmil for C1 through C5. Most negative D/H measurements also decrease with carbon number from ^dgrD = -311 ^pmil for methane to -128 ^pmil for pentane. These relative changes in carbon and hydrogen isotopic contents for the higher homologues are useful in the classification of natural gases, particularly those of mixed origin. End_of_Article - Last_Page 316------------

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Hydrogen and Carbon Isotopes of C1 to C5 Alkanes in Natural Gases: ABSTRACT

We report the results of a first attempt to monitor the gas emission from two distinct vents of two mud volcanoes in Azerbaijan, representing in both cases a fraction of the total amount of gas emitted by these structures. One monitoring station was placed on a salse lake in the crater area of the Dashgil mud volcano. It recorded methane flux from December 2003 to March 2006 and additionally radon emission in 2004. The second monitoring station was placed in October 2004 on the Perikushkul mud volcano. Both vents show significant variations in gas output with time. Month-long phases of near-constant gas output and periods characterized by large-scale daily variations were both observed. We proposed that fluctuations in gas output are connected with short-term variations in vent geometry (Dashgil) or with periodic buildups of methane at depth and sudden discharges (Perikushkul). Methane emission from the vent at Dashgil shows a well-developed periodicity of 24.05 hr, whereas no periodicity at Perikushkul was observed. During the observational period, both vents exhibited slowly decreasing gas output with time.

First Approach in Quantifying Fluctuating Gas Emissions of Methane and Radon from Mud Volcanoes in Azerbaijan

In this paper the installation and operation of a system for continuous monitoring of fumarolic gases are described. Several physicochemical and gas parameters such as the concentration of CO 2 , H 2 S and Rn in the fumarolic emissions, as well as the temperature of the fumarolic gas and its pressure are measured in intervals of seconds and transferred to a remote station by digital telemetry. Variations in the monitored parameters which were observed during a short flurry of seismic activity in close vicinity to Nisyros are also reported.

Eckhard Faber

Papers

Improved Stable Nitrogen Isotope Ratio Measurements of Natural Gases

Continuous, Direct Gas-Geochemical Monitoring in Hydrothermal Vents : Installation and Long-Term Operation on Nisyros Island (Greece)

Hydrogen and Carbon Isotopes of C1 to C5 Alkanes in Natural Gases: ABSTRACT

First Approach in Quantifying Fluctuating Gas Emissions of Methane and Radon from Mud Volcanoes in Azerbaijan

Real time monitoring of gas-geochemical parameters in Nisyros fumaroles