Fossil charcoal as evidence of past atmospheric composition

Cope, M. J.; Chaloner, W. G.

doi:10.1038/283647a0

Cited by 140 publications

(46 citation statements)

References 10 publications

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“…This notion is based on several observations including the high degree of resistance of EC to a range of chemical oxidants [Smith et al, 1973;Cachier et al, 1989; Heard and Senfile, 1984; Bird and GrOcke, 1997; Wolbach and Anders, 1989; Skjemstad eta/., 1993, 1996], its preservation for long periods of time in the geologic record [Cope and Chaloner, 1980], and the observation that fine EC in marine sediments is not lost to an appreciable extent over millions of years [Herring, 1985]. It is known that charcoal and EC are significant components of many soils where the overlying vegetation is subject to periodic burning, and it is also known from radiocarbon dating that charcoal and EC can persist for thousands of years once incorporated into the soil [e.g., Hopkins et al, 1990;Pessenda et al, 1996], and also for thousands of years in sediments or the dissolved organic carbon pool prior to its ultimate burial in the deep ocean [e.g., Masiello and Druffel, 1998].…”

Section: Introductionmentioning

confidence: 99%

Stability of elemental carbon in a savanna soil

Bird¹,

Moyo²,

Veenendaal³

et al. 1999

Global Biogeochemical Cycles

268

190

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Abstract. We have investigated the stability of oxidation-resistant elemental carbon (OREC) in a sandy savanna soil at the Matopos fire trial site, Zimbabwe. The protection of some soil plots from fire for the last 50 years at this site has enabled a comparison of OREC abundances between those plots which have been protected from fire and plots which have continued to be burnt. The total 0-5 cm OREC inventory of the soil protected from fire is estimated to be 2.0-k-_0.5 mg cm-2; approximately half the "natural" OREC inventory at the study site of 3.8+0.5 mg cm '2 (the mean for plots burnt every 1-5 years). The associated half-life for natural OREC loss from the 0-5 cm interval of the protected plots is calculated to be <100 years, with the half-life for large carbonized particles (>2000 gm) in the soil being considerably <50 years. These results suggest that at least in well-aerated tropical soil environments, charcoal and OREC can be can be significantly degraded on decadal to centennia• timesca,es. OREC abundance and carbon-isotope data suggest that OREC in coarse particles is progressively degraded into fmer particle sizes, with a concomitant increase in resistance to oxidafive degradation of OREC in the fmer particle sizes due to the progressive loss of more readily degraded OREC. It remains unclear whether the OREC that is degraded is oxidized completely to CO2 and subsequently emitted from the soil, reduced to a sufficiently small particle size to be illuviated to deeper parts of the soil profile, solubilized and lost from the profile as dissolved organic carbon or transmuted into a chemical form which is susceptible to attack by the acid-dichromate reagent. The conclusion that a significant proportion of OREC can undergo natural degradation in well-aerated environments on decadal/centennial timescales suggests that only a fraction of the total production of OREC from biomass burning and fossil fuel combustion is likely to be sequestered in the slow-cycling "geological" carbon reservoir.

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Section: Introductionmentioning

confidence: 99%

Stability of elemental carbon in a savanna soil

Bird¹,

Moyo²,

Veenendaal³

et al. 1999

Global Biogeochemical Cycles

268

190

View full text Add to dashboard Cite

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“…The estimate for char age from Cope and Chaloner (1980) was not included in the average of 300 million years, because it was not an estimate of turnover time, but it does reflect the view that PyC would reside in soil for very extended periods of time. Also, note that the x-axis is not numeric.…”

Section: Erosion As a Driver Of C Dynamics In Soilmentioning

confidence: 99%

Pyrogenic Carbon Erosion: Implications for Stock and Persistence of Pyrogenic Carbon in Soil

Abney

Berhe

2018

Front. Earth Sci.

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Pyrogenic carbon (PyC) constitutes an important pool of soil organic matter (SOM), particularly for its reactivity and because of its assumed long residence times in soil. In the past, research on the dynamics of PyC in the soil system has focused on quantifying stock and mean residence time (MRT) of PyC in soil, as well as determining both PyC stabilization mechanisms and loss pathways. Much of this research has focused on decomposition as the most important loss pathway for PyC from soil. However, the low density of PyC and its high concentration on the soil surface after fire indicates that a significant proportion of PyC formed or deposited on the soil surface is likely laterally transported away from the site of production by wind and water erosion. Here, we present a synthesis of available data and literature to compare the magnitude of the water-driven erosional PyC flux with other important loss pathways, including leaching and decomposition, of PyC from soil. Furthermore, we use a simple first-order kinetic model of soil PyC dynamics to assess the effect of erosion and deposition on residence time of PyC in eroding landscapes. Current reports of PyC MRT range from 250 to 660 years. Using a specific example-based model system, we find that ignoring the role of erosion may lead to the under-or over-estimation of PyC MRT on the centennial time scale. Furthermore, we find that, depending on the specific landform positions, timescales considered, and initial concentrations of PyC in soil, ignoring the role of erosion in distributing PyC across a landscape can lead to discrepancies in PyC concentrations on the order of several 100 g PyC m −2 . Erosion is an important PyC flux that can act as a significant control on the stock and residence time of PyC in the soil system.

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“…Biomass burning can be traced back to the earliest secondarily thickened terrestrial vascular plants (Upper Devonian) and even earlier (Lower Devonian) in the form of fusain, a fossil derived from charcoal, or charcoal itself (Komarek, 1971(Komarek, , 1973Cope & Chaloner, 1980, 1981, 1985Clark & Russell, 1981 ;Edwards, Fanning & Richardson, 1986 ;Chaloner, 1989 ;Robinson, 1989 ;Behrensmeyer et al, 1992 ;Clark & Robinson, 1993) (Fig. 1).…”

Section: (3) Spatial and Temporal Variations In Combined N In The Atmmentioning

confidence: 99%

The past, present and future of nitrogenous compounds in the atmosphere, and their interactions with plants

Raven

Yin

1998

New Phytologist

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Ammonia was necessary for the origin of life. However, NH3 would not have been a significant component of the neutral or mildly reducing (N2, CO2, H2O) atmosphere which characterized the Hadean earth (>3·8 Gyr ago), especially in view of the u.v. lability of NH3, the greater u.v. output of the young sun than pertains today, and the absence of an atmospheric u.v. screen. Heterogeneous phase reactions, following atmospheric chemistry, have been proposed as a prebiotic NH3 source. Lightning, or bolides (meteorites and comets), generated NOx., and Fe2+ in the sea could have reduced NO2− resulting from the NOx. to NH4+; this disequilibrium NH4+ level could have supported the production of the nitrogenous organic building blocks of life. NOx. and NHy thus could both have had important roles in the origin and evolution of life. Burgeoning biota could soon have depleted abiotically generated NH4+, and biological N2 fixation could have evolved in its present Fe‐demanding, O2‐sensitive forms in the Archaean O2‐free, Fe2+‐rich environment. Organic matter could have driven biological denitrification reactions based on NO2− and NO3− generated abiologically using some redox components which evolved in earlier chemolithotrophs and photolithotrophs, regenerating atmospheric NOx. and producing N2O. Any atmospheric NH3 leaking from oceanic biology would have been subject to u.v. breakdown and rain‐out. Although O2‐evolving photosynthesis probably began in the Archean some 3·5 Gyr ago, any O2 accumulation was local until 2·0 Gyr ago (Proterozoic) due to consumption by oxidation of Fe2+ and S2−. However, localized O2 accumulation before 2·0 Gyr ago could account for the observed early evolution of cytochrome oxidase and the possibility of O2‐consuming chemolithotrophic and chemoorganotrophic nitrification, with further possibilities of NOx. production. Oxygen accumulation globally from 2·0 Gyr onwards coincided approximately with the evolution of eukaryotes, which contributed phagotrophy to the reactions of the N cycle as well as the nutrification‐like aerobic production of NO. by nitric oxide synthetase, while lightning and bolides could now generate NO. from N2 and O2. Evidence for terrestrial ecosystems is found from 1·0 Gyr onwards; NOx. and NH3 generated by terrestrial biota stands a greater chance of escaping to the atmosphere than do these compounds generated in the sea where recycling within the water body is likely. As CO2 levels fell and O2 levels rose, NH3 cycling in the photorespiratory carbon oxidation cycle might have been evident as early as 1 Gyr ago, although this does not seem to be a major contributor to atmospheric NH3 today. Embryophyte evolution on land 450 Myr ago, together with symbionts and biophages, increased primary productivity and N cycling on land, with greater quantitative possibilities for NOx. and NH3 escape to the atmosphere. The evolution of lignin (and related phenylpropanoids) at least 400 Myr ago, with associated NH3 recycling in vascular land plant, does not seem (on present evidence) to incre...

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Fossil charcoal as evidence of past atmospheric composition

Cited by 140 publications

References 10 publications

Stability of elemental carbon in a savanna soil

Stability of elemental carbon in a savanna soil

Pyrogenic Carbon Erosion: Implications for Stock and Persistence of Pyrogenic Carbon in Soil

The past, present and future of nitrogenous compounds in the atmosphere, and their interactions with plants

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