Modern and fossil charcoal: aspects of structure and diagenesis

Cohen-Ofri, Ilit; Weiner, Lev; Boaretto, Elisabetta; Mintz, Genia; Weiner, Steve

doi:10.1016/j.jas.2005.08.008

Cited by 209 publications

(155 citation statements)

References 27 publications

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“…This allows us to infer that most charcoal contains domains composed of more highly ordered oxidation-resistant 'graphitic' material within a matrix of less ordered polyaromatic carbon, as has been demonstrated in other studies (Cohen-Ofri et al, 2006. The fact that crushing to <63µm produces a different response in different samples may suggest that crushing variably exposes different components of the samples to plasma oxidation compared to the 63-500µm fraction of the same sample.…”

Section: Most Oxidation Profiles Have a Quasi-exponential Form And Thsupporting

confidence: 56%

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Bird

Charville-Mort

Ascough

et al. 2010

Quaternary Geochronology

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This study investigates the potential of low-temperature oxygen plasma ashing as a technique for decontaminating charcoal and wood samples prior to radiocarbon dating. Plasma ashing is demonstrated to be rapid, controllable and surface-specific, and clear differences are identified in the rate of ashing in different organic materials. However, the ability of plasma ashing to selectively remove these different components is limited in heterogeneous sample matrices. This is because oxidation is confined to the

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Section: Most Oxidation Profiles Have a Quasi-exponential Form And Thsupporting

confidence: 56%

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Bird

Charville-Mort

Ascough

et al. 2010

Quaternary Geochronology

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“…This figure compiles data from surface horizons of 20 long-term field experiments (up to 23 years) in temperate climate, using 13 C labelling to trace the residence time of bulk SOM and of individual molecular compounds. The variation in turnover time is also seen in the compounds of microbial origin analysed for 13 fire-derived carbon does undergo oxidation and transport, as we now know from archaeological settings 28 , soils 29,30 , and from breakdown products in river 31 and ocean water 32,33 . In a field experiment, firederived residues were even observed to decompose faster than the remaining bulk organic matter, with 25% lost over 100 years (ref.…”

Section: Soil Humic Substancesmentioning

confidence: 94%

Persistence of soil organic matter as an ecosystem property

Schmidt

Torn

Abiven

et al. 2011

Nature

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Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily-and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.Understanding soil biogeochemistry is essential to the stewardship of ecosystem services provided by soils, such as soil fertility (for food, fibre and fuel production), water quality, resistance to erosion and climate mitigation through reduced feedbacks to climate change. Soils store at least three times as much carbon (in SOM) as is found in either the atmosphere or in living plants 1 . This major pool of organic carbon is sensitive to changes in climate or local environment, but how and on what timescale will it respond to such changes? The feedbacks between soil organic carbon and climate are not fully understood, so we are not fully able to answer these questions 2-7 , but we can explore them using numerical models of soil-organic-carbon cycling. We can not only simulate feedbacks between climate change and ecosystems, but also evaluate management options and analyse carbon sequestration and biofuel strategies. These models, however, rest on some assumptions that have been challenged and even disproved by recent research arising from new isotopic, spectroscopic and molecularmarker techniques and long-term field experiments.Here we describe how recent evidence has led to a framework for understanding SOM cycling, and we highlight new approaches that could lead us to a new generation of soil carbon models, which could better reflect observations and inform predictions and policies.

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“…For the modern charcoal sample, the thermal decomposition is around 540 °C (Table 3 in Cohen et al 2006). The broad peak around this temperature is not significantly modified by exposure to low and high pH solutions.…”

Section: Thermal Decomposition Upon Heatingmentioning

confidence: 93%

“…For modern charcoal, the observed weight loss after the first alkali treatment is likely to be due mainly to the breakdown of covalent bonds, since there are almost no carboxyl groups in the sample ( Figure 9 in Cohen et al 2006).…”

Section: Exposure To the First Alkali Treatmentmentioning

confidence: 99%

Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for ¹⁴C Sample Preparation and Charcoal Preservation

et al. 2008

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ABSTRACT. Chemical and structural similarities between poorly preserved charcoal and its contaminants, as well as low radiocarbon concentrations in old samples, complicate 14 C age determinations. Here, we characterize 4 fossil charcoal samples from the late Middle Paleolithic and early Upper Paleolithic strata of Kebara Cave, Israel, with respect to the structural and chemical changes that occur when they are subjected to the acid-base-acid (ABA) treatment. Differential thermal analysis and TEM show that acid treatment disrupts the structure, whereas alkali treatment results in the reformation of molecular aggregates. The major changes are ascribed to the formation of salt bridges at high pH and the disruption of the graphite-like crystallites at low pH. Weight losses during the treatments are consistently greater for older samples, implying that they are less well preserved. Based on the changes observed in vitro due to pH fluctuations, various methods for removing contamination, as well as a mechanism for preferential preservation of charcoal in nature, are proposed.

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Modern and fossil charcoal: aspects of structure and diagenesis

Cited by 209 publications

References 27 publications

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Persistence of soil organic matter as an ecosystem property

Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for ¹⁴C Sample Preparation and Charcoal Preservation

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Modern and fossil charcoal: aspects of structure and diagenesis

Cited by 209 publications

References 27 publications

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Assessment of oxygen plasma ashing as a pre-treatment for radiocarbon dating

Persistence of soil organic matter as an ecosystem property

Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for 14C Sample Preparation and Charcoal Preservation

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Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for ¹⁴C Sample Preparation and Charcoal Preservation