Continuous flux of dissolved black carbon from a vanished tropical forest biome

Dittmar, Thorsten; Rezende, Carlos Eduardo de; Manecki, Marcus; Niggemann, Jutta; Ovalle, Á. R. C.; Stubbins, Aron; Bernardes, Marcelo

doi:10.1038/ngeo1541

Cited by 209 publications

(219 citation statements)

References 21 publications

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“…Although, recent wildfire activity does not seem to have a significant effect on in-stream DBC Güereña et al, 2015;Wagner et al, 2015a), this material is continually exported from fire-impacted watersheds for decades after a burn event (Dittmar et al, 2012). This suggests that the aging of BC in soils may be a prerequisite to its dissolution and export to aquatic systems as DBC.…”

Section: Introductionmentioning

confidence: 97%

“…The ubiquity of fire and the refractory nature of condensed aromatics have resulted in the accumulation of BC in soils, where it comprises ∼14% of global soil C stores (Reisser et al, 2016). Despite the observed refractory nature of soil BC (Kuzyakov et al, 2014), the apparent solubilization and subsequent transport via rivers as DBC has been identified as a major loss process of BC from terrestrial environments (Dittmar et al, 2012;Jaffé et al, 2013;Stubbins et al, 2015). As such, it was estimated that DBC accounts for ∼10% of the total DOC flux exported annually by global rivers to the oceans .…”

Section: Introductionmentioning

confidence: 99%

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A New Perspective on the Apparent Solubility of Dissolved Black Carbon

2017

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Black carbon (BC), pyrogenic organic matter generated from the incomplete combustion of biomass, is ubiquitous in the environment. The molecular structures which comprise the BC pool of compounds are defined by their condensed aromatic core structures polysubstituted with O-containing functionalities (e.g., carboxyl groups). Despite the apparent hydrophobicity of BC molecules, a considerable portion of BC is translocated from terrestrial to aquatic systems in the form of dissolved BC (DBC). However, the specific biogeochemical mechanisms which control the transfer of BC from the land to the water remain elusive. In the current study, the apparent solubility of DBC was inferred from octanol-water partition coefficients (K ow ) modeled for proposed DBC structures with varying degrees of polycondensation and polar functionality. Modeled K ow values indicated that DBC molecules with small aromatic ring systems and high degrees of hydrophilic functionality may be truly solubilized in the aqueous phase. However, large and highly condensed DBC structures yielded high K ow values, which suggested that a considerable portion of the DBC pool which has been quantified in aquatic environments is not truly dissolved. We hypothesized that other DOM components may act as mediators in the solubilization of condensed aromatic molecules and serve to increase the solubility of DBC via hydrophobic, intermolecular associations. This hypothesis was tested through controlled leaching experiments to determine whether the mobilization of DBC from particulate soils and chars became enhanced in the presence of DOM. However, we observed that characteristics inherent to each sample type had a greater influence than added DOM on the apparent solubility of DBC. In addition, the direct comparison of molecular marker (benzenepolycarboxylic acids) and ultrahigh resolution mass spectral data (FT-ICR/MS) on leachates obtained from the same set of soils and char did not show a clear overlap in DBC quantification or characterization between the two analytical methods. Correlations between FT-ICR/MS results and BPCA were not significant possibly due to differences in the methodological windows and/or small sample size. Our results were unable to provide evidence in support of proposed hydrophobic interactions between DOM and DBC, suggesting that other physical/chemical mechanisms play important roles in the dissolution of BC.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

A New Perspective on the Apparent Solubility of Dissolved Black Carbon

2017

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“…This suggests that the hydrodynamic transport and depositional mechanism could also be an important factor affecting the occurrence of BC and TOC and their relationships, especially in the open GOT. Actually, this good correlation between BC and bulk OM was not only noticed in the particle phase (e.g., in soil, Glaser and Amelung, 2003;Cusack et al, 2012) but also in the dissolved phase and has been reported worldwide (e.g., Dittmar et al, 2012;Jaffe et al, 2013;Ding et al, 2013Ding et al, , 2015. The close relationship between BC and bulk OM in the dissolved phase could indicate that the release and subsequent sorption and desorption processes of BC are a complex function of environmental factors and particle properties, just as for bulk dissolved OM , which suggests that the mobilization of BC and bulk OM in various matrices is also mechanistically coupled.…”

Section: Relationships Between Bc Toc and Sediment Grain Size And Pomentioning

confidence: 99%

Distribution, input pathway and mass inventory of black carbon in sediments of the Gulf of Thailand, SE Asia

Shi

Bai

et al. 2016

Estuarine, Coastal and Shelf Science

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a b s t r a c tThe coastal margins around Southeast Asia (SE Asia) may serve as an ideal location to study the sourcesink process of sedimentary black carbon (BC) because SE Asia has been identified as one of the major BC emission source regions in the world. This study provides an extensive picture of recent regional-scale sedimentary BC sequestration in the Gulf of Thailand (GOT), a tropical marine system in SE Asia. Generally, the sedimentary BC concentrations (0.07e3.99 mg/g) were in the low to moderate ranges of those obtained in other coastal sediments around the world. Regional variability of the BC and its correlation with the sediment grain size and total organic carbon (TOC) content indicated a general hydrodynamic constraint on BC occurrence in the lower Gulf in contrast to the upper Gulf with a more source dependence due to the direct land-based input. BC/TOC% values and the varied BC components (char and soot), as well as their correlations suggested that char was the predominant constituents of sedimentary BC both in the upper and lower Gulf, which could be mainly derived from biomass burning and entered into the nearshore region through direct fluvial transport and surface run-off. The estimated BC burial flux (~212 mg/cm 2 /y) and mass inventory (~200 Gg/y) in the GOT on the hundred-year timescale were of the same order of magnitude compared with other oceanic margins, and thus the tropical shelf sediments from SE Asia could serve as an important sink of land-emitted BC.

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“…Furthermore, wildfire accelerates carbon and nitrogen mineralization and modifies the chemical composition of the detritus layer, converting lignin and polysaccharide rich and relatively degradable carbon pools to polycyclic aromatic, charcoal-rich, and recalcitrant black carbon. 19,20 Such an extreme change in the DOM source is expected to extensively alter DOM structure and its reactivity in forming DBPs. Recently, Writer et al 7 studied water quality and DOM reactivity in forming DBPs after the High Park wildfire in Colorado and found no consistent differences in DOC level and DBP formation between burned and nonburned watersheds.…”

Section: ■ Introductionmentioning

confidence: 99%

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

Wang

Dahlgren

Erşan

et al. 2015

Environ. Sci. Technol.

107

105

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Wildfire occurrence and intensity are increasing worldwide causing severe disturbances to forest watersheds used for potable water supply. The effects of wildfire on drinking water quality are not well understood, especially in terms of terrestrial dissolved organic matter (DOM) and DOM-associated formation of disinfection byproducts (DBP). As the forest floor layer is a major source of terrestrial DOM, we investigated characteristics and DBP formation of water extractable organic matter (WEOM) from the 0−5 cm depth of nonburned detritus (control) and burned detritus with black ash (moderate severity) and white ash (high severity) associated with the 2013 Rim Fire in California. Spectroscopic results suggested that the aromaticity of WEOM followed white ash > control > black ash and fluorescence region II (excitation 220−250 nm; emission 330−380 nm) of the emission-excitation-matrix was identified as a potential burn severity indicator. Compared to the control, WEOM from white and black ashes had lower reactivity in forming trihalomethanes (55%-of-control) and haloacetic acids (67%-of-control), but higher reactivity in forming the more carcinogenic haloacetonitrile after chlorination (244%-of-control) and N-nitrosodimethylamine after chloramination (229%-of-control). There was no change in reactivity for chloral hydrate formation, while WEOM from black ash showed a higher reactivity for haloketone formation (150%-of-control). Because wildfire consumed a large portion of organic matter from the detritus layer, there was lower water extractable organic carbon (27%-of-control) and organic nitrogen (19%-of-control) yields in ashes. Consequently, the wildfire caused an overall reduction in water extractable terrestrial DBP precursor yield from detritus materials.

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Continuous flux of dissolved black carbon from a vanished tropical forest biome

Cited by 209 publications

References 21 publications

A New Perspective on the Apparent Solubility of Dissolved Black Carbon

A New Perspective on the Apparent Solubility of Dissolved Black Carbon

Distribution, input pathway and mass inventory of black carbon in sediments of the Gulf of Thailand, SE Asia

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

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