Biochemically altered charcoal residues as an important source of soil organic matter in subsoils of fire-affected subtropical regions

Velasco-Molina, Marta; Berns, Anne E.; Macı́as, Felipe; Knicker, Heike

doi:10.1016/j.geoderma.2015.08.016

Cited by 41 publications

(23 citation statements)

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“…The CP/MAS NMR spectra (Figure ) of the LF‐SOM pool was generally characterized by large alkyl (0–45 ppm) and O‐alkyl (60–95 ppm) peaks with variable contributions from aromatic moieties (110–145 ppm and 145–165 ppm), consistent with NMR spectra from forest and fire‐affected soil (e.g., Faria et al, ). The large aromatic and phenolic peaks across all NMR spectra are comparable to values reported in the literature for fire‐affected forests (~30% of signal) (Certini et al, ; Skjemstad et al, ; Velasco‐Molina et al, ). The apparent decrease in the aromatic peak between the September 2011 and October 2011 samples is likely due to an increase in deadfall (i.e., organic carbon delivery) following the fire that temporarily increased the relative contributions of the alkyl and O‐alkyl peaks.…”

Section: Resultssupporting

confidence: 84%

“…These aging processes may alter the vulnerability of charcoal to physical redistribution by changing charcoal physical properties, like density. PyC alteration in soil also renders PyC more vulnerable to such loss mechanisms as leaching (Velasco‐Molina et al, ), which is already an important PyC transport mechanism from soils (Güereña et al, ) and could be sped up by immediate soil incorporation, decreasing soil PyC contents. Additionally, if newly produced charcoal is anchored with roots at shallow, biologically active organic layers it cannot mix deeper in soils and could be at higher risk of re‐combustion in subsequent fires (Czimczik et al, ).…”

Section: Discussionmentioning

confidence: 99%

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Short‐Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility

et al. 2017

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Charcoal is a major component of the stable soil organic carbon reservoir, and the physical and chemical properties of charcoal can sometimes significantly alter bulk soil properties (e.g., by increasing soil water holding capacity). However, our understanding of the residence time of soil charcoal remains uncertain, with old measured soil charcoal ages in apparent conflict with relatively short modeled and measured residence times. These discrepancies may exist because the fate of charcoal on the landscape is a function not just of its resistance to biological decomposition but also its physical mobility. Mobility may be important in controlling charcoal landscape residence time and may artificially inflate estimates of its degradability, but few studies have examined charcoal vulnerability to physical redistribution. Charcoal landscape redistribution is likely higher than other organic carbon fractions owing to charcoal's low bulk density, typically less than 1.0 g/cm3. Here we examine both the physical and chemical properties of soil and charcoal over a period of two years following a 2011 wildfire in Texas. We find little change in properties with time; however, we find evidence of enhanced mobility of charcoal relative to other forms of soil organic matter. These data add to a growing body of evidence that charcoal is preferentially eroded, offering another explanation for variations observed in its environmental residence times.

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Section: Resultssupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Short‐Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility

et al. 2017

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“…For the first, evidences that this can occur have been reported from the Cerrado biome. 38 The latter has been observed in Atlantic Forest (Brazil) and Amazon biomes 39,40 and is assumed to be responsible for the fast recovery of Mediterranean soils after forest fires. 41 The favorable conditions for microbial degradation under the warm and humid conditions in the experimental region ( Figure 2) could have enhanced the complete or partial degradation of pyrogenic organic matter, and the leaching of the pyrogenic compounds may have been favored due to the high precipitation rates after burning ( Figure 2) and to the sandy character of the soil (Table 1).…”

Section: Chemical Composition Of Som Assessed By 13 C Nmrmentioning

confidence: 99%

Carbon in Physical Fractions and Organic Matter Chemical Composition of an Acrisol after Amazon Forest Burning and Conversion into Pasture

Leal¹,

Dick²,

Costa³

et al. 2018

J. Braz. Chem. Soc.

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The aim of this study was to investigate impacts of Amazon Forest (AF) fire and conversion to pasture on carbon accumulation in particle size fractions and organic matter (OM) composition of an Acrisol. Soil samples were collected (0.00-2.00 m depth) in three sites: native AF (NAF); AF under natural regeneration for two years after burning (BAF); 23-years old Brachiaria pasture after AF burning (BRA). Assuming NAF area as reference, BAF and BRA areas showed negative carbon balance when carbon emitted to the atmosphere at AF burning is taken into account. Soil OM aromaticity and hydrophobicity, assessed via 13 C nuclear magnetic resonance, in BRA and BAF were similar to that in NAF. Fire and post-fire land use altered the carbon distribution in sand, silt and clay along the soil profile and seem to have affected organo-mineral and OM self-assemblage interactions, since the relation between total soil carbon and carbon in clay was asymptotic in BAF and linear in NAF and BRA.

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“…Algumas pesquisas indicam que o processo de degradação de carvões inicia-se na escala de meses e inclui a oxidação dos anéis aromáticos e a inserção de grupos funcionais contendo oxigênio, como grupos carbonila e carboxila, (CHENG et al, 2006;KNICKER, 2011;VELASCO-MOLINA et al, 2015). Outros estudos, no âmbito da pirólise analítica, consideram que, PAH que se unem a outros produtos certamente mais transformados, como materiais de origem microbiana, na análise estatística fatorial, podem ser considerados degradados (MARQUES et al, 2015).…”

Section: Degradação Do Bcunclassified

Química da matéria orgânica e pedogênese em Latossolos húmicos sob vegetação de cerrado

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Química da matéria orgânica e pedogênese em Latossolos húmicos sob vegetação de cerrado Marina JustiDissertação apresentada para obtenção de título de Mestra em Ciências. RESUMO Química da matéria orgânica e pedogênese em Latossolos húmicos sob vegetação de cerradoA matéria orgânica do solo (MOS) representa um importante reservatório de carbono (C) nos ecossistemas terrestres. O conteúdo de C estocado no solo pode ser liberado para a atmosfera na forma de CO 2 , com a decomposição da MOS, ou pode ser aumentado com a entrada de resíduos e retenção da MOS. Nesse sentido, é importante entender os mecanismos de estabilidade e retenção da MOS para predizer como os solos respondem a mudanças, quer sejam elas induzidas por alterações climáticas ou por práticas de manejo. Dentro dos Latossolos, classe que ocupa cerca de 32 % do território brasileiro, há aqueles que possuem horizonte A húmico hiper espesso e, portanto, com maior estoque de C. Aspectos sobre a origem, formação e preservação do horizonte A húmico destes solos em suas ocorrências em diferentes biomas ainda não foram completamente elucidados e estão estritamente ligados à fonte, dinâmica e mecanismos de preservação e distribuição da MOS no solo. O objetivo deste trabalho é entender a gênese da MO dos Latossolos húmicos que ocorrem no Bioma Cerrado, por meio da caracterização molecular pela técnica da pirólise acoplada à cromatografia gasosa e espectroscopia de massas (pirólise -CG/EM). Para isso, foram coletadas amostras dos horizontes A em dois perfis de Latossolos com horizonte A húmico (LH1, LH2) e um perfil de Latossolo com horizonte A moderado (solo de referência; LNH) situados em superfície de aplanamento adjacente à Serra do Espinhaço, no município de Grão Mogol -MG, sob clima tropical semi-úmido e vegetação de cerrado sensu strictu. Por meio da descrição morfológica dos solos em diferentes níveis de observação (campo, lupa e microscópio) procurou-se entender melhor os mecanismos de espessamento do horizonte A e a distribuição de partículas de carvão ao longo do perfil. As amostras dos horizontes foram submetidas ao fracionamento físico e extração da MOS, gerando as seguintes frações: fração leve livre (FLL); fração leve oclusa (FLO), fração extraível com NaOH (EXT) e resíduo (RES). A morfologia dos perfis evidencia a intensa e longa atividade biológica (fauna e raízes) a que esses solos foram e estão submetidos. Isso explica a abundância de microagregados e a consequente macropososidade elevada, assim como a ampla distribuição de fragmentos de carvão em todo o horizonte A, e parte do B, com dimensões milimétricas a submilimétricas, sugerindo a fragmentação destes ao longo do tempo. Foi evidenciado o maior conteúdo de carvões nos dois LHs em comparação ao LNH. A distribuição da MOS nas frações estudadas foi a mesma para os três perfis estudados: RES>EXT>FLL>FLO, que mostra a importância da fração RES para estes solos. Produtos da carbonização (Black carbon; BC: hidrocarbonetos poliaromáticos) foram mais abundantes na fração RES e FLO, no entanto, a m...

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Biochemically altered charcoal residues as an important source of soil organic matter in subsoils of fire-affected subtropical regions

Cited by 41 publications

References 37 publications

Short‐Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility

Short‐Term Changes in Physical and Chemical Properties of Soil Charcoal Support Enhanced Landscape Mobility

Carbon in Physical Fractions and Organic Matter Chemical Composition of an Acrisol after Amazon Forest Burning and Conversion into Pasture

Química da matéria orgânica e pedogênese em Latossolos húmicos sob vegetação de cerrado

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