An overview of the chemical composition of biomass

This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999GB001208

Black carbon in soils and sediments: Analysis, distribution, implications, and current challenges

The Marcellus Formation of Pennsylvania represents an outstanding example of an organic matter (OM)–hosted pore system; most pores detectable by field-emission scanning electron microscopy (FE-SEM) are associated with OM instead of mineral matrix. In the two wells studied here, total organic carbon (TOC) content is a stronger control on OM-hosted porosity than is thermal maturity. The two study wells span a maturity from late wet gas (vitrinite reflectance [Ro], 1.0%) to dry gas (Ro, 2.1%). Samples with a TOC less than 5.5 wt. % display a positive correlation between TOC and porosity, but samples with a TOC greater than 5.5 wt. % display little or no increase in porosity with a further increasing TOC. In a subset of samples (14) across a range of TOC (2.3–13.6 wt. %), the pore volume detectable by FE-SEM is a small fraction of total porosity, ranging from 2 to 32% of the helium porosity. Importantly, the FE-SEM–visible porosity in OM decreases significantly with increasing TOC, diminishing from 30% of OM volume to less than 1% of OM volume across the range of TOC. The morphology and size of OM-hosted pores also vary systematically with TOC. The interpretation of this anticorrelation between OM content and SEM-visible pores remains uncertain. Samples with the lowest OM porosity (higher TOC) may represent gas expulsion (pore collapse) that was more complete as a consequence of greater OM connectivity and framework compaction, whereas samples with higher OM porosity (lower TOC) correspond to rigid mineral frameworks that inhibited compactional expulsion of methane-filled bubbles. Alternatively, higher TOC samples may contain OM (low initial hydrogen index, relatively unreactive) that is less prone to development of FE-SEM–detectable pores. In this interpretation, OM type, controlled by sequence-stratigraphic position, is a factor in determining pore-size distribution.

Organic matter–hosted pore system, Marcellus Formation (Devonian), Pennsylvania

Preface 1 Carbon, the Earth and life: 11 Carbon and the basic requirements of life12 Chemical elements, simple compounds and their origins13 The origin of life14 Evolution of life and the atmosphere15 Major contributors to sedimentary organic matter 2 Chemical composition of biogenic matter: 21 Structure of natural products22 Carbohydrates23 Amino acids and proteins24 Lipids25 Lignins, tannins and related compounds26 Nucleotides and nucleic acids27 Geochemical implicatiions of compositional variation 3 Production, preservation and degradation of organic matter: 31 How and why organic-rich deposits form32 Controls on primary production33 Preservation and degradation of organic matter34 Depositional environments associated with accumulation of organic matter 4 Long-term fate of organic matter in the geosphere: 41 Diagenesis42 Humic material43 Coal44 Kerogen45 Catagenesis and metagenesis46 Temporal and geographical distribution of fossil organic carbon 5 Chemical stratigraphy 51 Biologically mediated transformations52 Examples of source indicators in recent sediments53 Diagenesis at the molecular level54 Source and environment indicators in ancient sediments and oil55 Thermal maturity and molecular transformations56 Palaeotemperature and age measurement57 Maturity of ancient sedimentary organic matter58 Isotopic palaeontology 6 The carbon cycle and climate 61 Global carbon cycle62 Changes in carbon reservoirs over geological time63 Palaeoclimatic variations64 Isotopic excursions at period boundaries65 Human influence on the carbon cycle 7 Anthropogenic carbon and the environment 71 Introduction72 Halocarbons73 Hydrocarbon pollution in aquatic environments74 Endocrine disrupting chemicals75 Environmental behaviour of selected xenobiotic compounds76 Factors affecting the rate of anthropogenic components Appendix 1: SI units usedAppendix 2: SI unit prefixesAppendix 3: Geological timescaleReferencesIndex

An introduction to organic geochemistry

An overview of the organic and inorganic phase composition of biomass

This book includes the origin of coal, its petrographic constitution, changes in the macerals during coalification, techniques of coal petrology and their application to problems of palaeobotany, geology, oil and gas prospecting, coal assessment, coal evaluation, and fuel technology. This is the Third Edition of this textbook. (DP)

Erich Stach

Papers

Stach's Textbook of coal petrology

Microscopy & Microanalysis 2022 in Portland, OR