An Ultraviolet Absorbance Method of Estimating the Percent Aromatic Carbon Content of Humic Acids

Traina, Samuel J.; Novak, Jeff; Smeck, N. E.

doi:10.2134/jeq1990.00472425001900010023x

Cited by 359 publications

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“…1, the UV-vis spectra of all HULIS fractions were featureless, while they displayed a generally decreasing absorbance as the wavelength increased. Such spectra are similar to the typical UV-vis spectra of atmospheric HULIS in previous studies (Havers et al, 1998;Varga et al, 2001;Kiss et al, 2002;Krivacsy et al, 2008;Baduel et al, 2009Baduel et al, , 2010Fan et al, 2012) and in naturally occurring humic substances (Traina et al, 1990;Peuravuori and Pihlaja, 1997;Chen et al, 2002;Domeizel et al, 2004). These results suggest that the primary HULIS in smoke PM 2.5 have a similar chemical structure to HULIS in atmospheric aerosols.…”

Section: Uv-vis Propertiessupporting

confidence: 86%

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

et al. 2016

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Abstract. Humic-like substances (HULIS) in smoke fine particulate matter (PM 2.5 ) emitted from the combustion of biomass materials (rice straw, corn straw, and pine branch) and fossil fuels (lignite coal and diesel fuel) were comprehensively studied in this work. The HULIS fractions were first isolated with a one-step solid-phase extraction method, and were then investigated with a series of analytical techniques: elemental analysis, total organic carbon analysis, UV-vis (ultraviolet-visible) spectroscopy, excitationemission matrix (EEM) fluorescence spectroscopy, Fourier transform infrared spectroscopy, and 1 H-nuclear magnetic resonance spectroscopy. The results show that HULIS account for 11.2-23.4 and 5.3 % of PM 2.5 emitted from biomass burning (BB) and coal combustion, respectively. In addition, contributions of HULIS-C to total carbon and water-soluble carbon in smoke PM 2.5 emitted from BB are 8.0-21.7 and 56.9-66.1 %, respectively. The corresponding contributions in smoke PM 2.5 from coal combustion are 5.2 and 45.5 %, respectively. These results suggest that BB and coal combustion are both important sources of HULIS in atmospheric aerosols. However, HULIS in diesel soot only accounted for ∼ 0.8 % of the soot particles, suggesting that vehicular exhaust may not be a significant primary source of HULIS. Primary HULIS and atmospheric HULIS display many similar chemical characteristics, as indicated by the instrumental analytical characterization, while some distinct features were also apparent. A high spectral absorbance in the UV-vis spectra, a distinct band at λ ex /λ em ≈ 280/350 nm in EEM spectra, lower H / C and O / C molar ratios, and a high content of [Ar-H] were observed for primary HULIS. These results suggest that primary HULIS contain more aromatic structures, and have a lower content of aliphatic and oxygen-containing groups than atmospheric HULIS. Among the four primary sources of HULIS, HULIS from BB had the highest O / C molar ratios (0.43-0.54) and [H-C-O] content (10-19 %), indicating that HULIS from this source mainly consisted of carbohydrate-and phenolic-like structures. HULIS from coal combustion had a lower O / C molar ratio (0.27) and a higher content of [Ar-H] (31 %), suggesting that aromatic compounds were extremely abundant in HULIS from this source. Moreover, the absorption Ångström exponents of primary HULIS from BB and coal combustion were 6.7-8.2 and 13.6, respectively. The mass absorption efficiencies of primary HULIS from BB and coal combustion at 365 nm (MAE 365 ) were 0.97-2.09 and 0.63 m 2 gC −1 , respectively. Noticeably higher MAE 365 values for primary HULIS from BB than coal combustion indicate that the former has a stronger contribution to the light-absorbing properties of aerosols in the atmospheric environment.

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Section: Uv-vis Propertiessupporting

confidence: 86%

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

et al. 2016

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“…Or in other words, an increase in the hydrogen content indicates a greater number of aliphatic carbons (CH 2 ) than aromatic carbons (C=C). 39 The values of the H/C atomic ratios for samples of AHS vary between 1.17 and 1.33 (Table 2).These values are close to the ones cited in literature for related researchers (Table 3). The samples indicate carbon atoms having more aliphatic characteristics when compared with the data of Leenheer 36 and Ertel et al 37 However, in relation to the data obtained by Sargentini et al, 40 the samples present more aromatic characteristics.…”

supporting

confidence: 82%

Section: Resultsmentioning

confidence: 99%

The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Oliveira¹,

Sargentini²,

Rosa³

et al. 2007

J. Braz. Chem. Soc.

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Neste trabalho, substâncias húmicas foram extraídas de amostras de água coletadas mensalmente na Bacia do Rio Negro-AM para estudar suas propriedades no ambiente amazônico e interações com íons mercúrio, considerando a influência da variação sazonal na sua formação. Os parâmetros razões atômicas C/H, C/N e C/O, grupos funcionais, radicais livres do tipo semiquinona, pH, índices pluviométricos e fluviométricos, concentrações de mercúrio foram interpretados por análise hierárquica de cluster (AHC) e análise de componentes principais (ACP). As análises estatísticas mostraram que, quanto maior o índice pluviométrico e menor o índice fluviométrico maior o grau de humificação das substâncias húmicas aquáticas. A seguinte ordem decrescente do grau de humificação das SHA coletadas mensalmente pode ser estabelecida: Nov/02 a Fev/03 > Mar/02 a Mai/02 > Jun/02 a Out/02. As maiores concentrações de mercúrio foram determinadas nas amostras mais humificadas, sugerindo que devido a rearranjos inter e/ou intramoleculares, quanto maior o grau de humificação maior a afinidade dos íons Hg(II) pelas substâncias húmicas aquáticas.In this work, humic substances were extracted from water samples collected monthly from the Negro River basin in the Amazon state (Brazil) to study their properties in the Amazonian environment and interactions with the mercury ion considering the influence of seasonalness in this formation. The C/H, C/N and C/O atomic ratio parameters, functional groups, concentration of semiquinone-type free radicals, pH, pluviometric and fluviometric indices, and mercury concentrations were interpreted using hierarchical cluster analysis (HCA) and principal component analysis (PCA). The statistical analyses showed that when the pluviometric index was greater and the fluviometric index was smaller, the degree of humification of aquatic substances was greater. The following decreasing order of the degree of humification of the AHS collected monthly was established: Nov/02 to Feb/03 > Mar/02 to May/02 > Jun/02 to Oct/02. The greatest concentrations of mercury were detected in more humidified samples. These results suggest that due to inter and/or intra-molecular rearrangements, the degree of humification of aquatic humic substances is related to its affinity for Hg(II) ions.Keywords: aquatic humic substance, seasonality, Negro River, Amazon, mercury IntroductionFresh water streams have an important function in the global carbon cycle in that they conduct organic matter (OM) of terrestrial origin and transfer it to the oceans. 1 The Amazonian region is home to the most extensive fluvial system which also has greatest liquid mass of the whole earth and it is covered by the largest pluvial tropical forest. According to Bluntschli, 2 the circulation of marine water through the atmospheric compartment above the forest and then from the forest across the fluvial plains again to the sea has a decisive 861 Oliveira et al. Vol. 18, No. 4, 2007 function in the Amazonian ecosystem. According to Sioli, 3 the forest and the regimes...

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“…The lower H/C ratio indicates a larger amount of unsaturated structures. In other words, an increase in the hydrogen content indicates a greater number of aliphatic carbons (CH2) than aromatic carbons (C=C) (Traina et al, 1990). Among the AHS and HSP fractions, F1 and F2 showed lower H/C atomic ratios, indicating more aromatic fractions.…”

Section: Doc Content In the Ahs And Hsp Fractionsmentioning

confidence: 99%

Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

Rigobello¹,

Campos²,

Azevêdo³

et al. 2017

Rev. ambiente água

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This paper compares the structural characteristics of aquatic humic substances (AHS) with humic substances from peat (HSP) through different analytical techniques, including elemental analysis, solid state 13 C cross polarization/magic-angle-spinning nuclear magnetic resonance spectroscopy ( 13 C CP-MAS NMR), ultraviolet/visible (UV/Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy and total organic carbon (TOC). The AHS were extracted from water collected in a tributary of the Itapanhaú River (Bertioga/SP) using XAD 8 resin, and the HSP were extracted from peat collected in the Mogi Guaçu River bank (Luis Antonio/SP) with a KOH solution. After dialysis, both AHS and HSP extracts were filtered in membrane of 0.45 µm pore size (Fraction F1: < 0.45 µm) and fractioned by ultrafiltration in different apparent molecular sizes (AMS) (F2: 100 kDa-0.45 μm; F3: 30 kDa-100 kDa and F4: < 30 kDa). The extracts with the lowest AMS (F3 and F4) showed a higher number of aliphatic carbons than aromatic carbons, a higher concentration of groups containing oxygen and a higher percentage of fulvic acids (FA) than humic acids (HA) for both AHS and HSP. However, the AHS presented higher FA than HA content in relation to the HSP and distinct structural properties.Keywords: fulvic acid, humic acid, humic substances, ultrafiltration. 775Comparative characterization of humic substances … Rev. Ambient. Água vol. 12 n. 5 Taubaté -Sep. / Oct. 2017 Caracterização comparativa de substâncias húmicas extraídas de água e de turfa de diferentes tamanhos moleculares aparentes RESUMOEste artigo compara as características estruturais das substâncias húmicas aquáticas (SHA) com substâncias húmicas de turfa (SHT) usando diferentes técnicas analíticas, incluindo análise elementar, espectro de polarização cruzada de estado sólido 13 C/ espectroscopia de ressonância magnética nuclear ( 13 C CP-MAS RMN), espectroscopia no ultravioleta/visível e infravermelho com transformada de Fourier e carbono orgânico total (COT). As SHA foram extraídas de água coletada em um afluente do rio Itapanhaú (Bertioga/SP), utilizando resina XAD 8 e as SHT foram extraídas de turfa coletadas na margem do rio Mogi-Guaçu (Luis Antonio/SP) com uma solução de KOH. Após a diálise, ambos extratos de SHA e SHT foram filtrados em membrana com 0,45 m de tamanho de poro (Fração F1: < 0,45 m) e após fracionados através de ultrafiltração em diferentes tamanhos moleculares aparentes (F2: 100 kDa-0,45 m; F3: 30 -100 kDa e F4: < 30 kDa). Os extratos de menor tamanho (F3 e F4) apresentaram um maior número de átomos de carbono alifáticos do que de carbonos aromáticos, uma maior concentração de grupos contendo oxigênio e uma percentagem mais elevada de ácidos fúlvicos do que os ácidos húmicos para ambas as frações de SHA e de SHT. No entanto, as SHA apresentaram maior quantidade de ácidos fúlvicos que ácidos húmicos em relação às SHT e propriedades estruturais distintas.Palavras-chave: ácidos fúlvicos, ácidos húmicos, substâncias húmicas, ultrafiltração.

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An Ultraviolet Absorbance Method of Estimating the Percent Aromatic Carbon Content of Humic Acids

Cited by 359 publications

References 0 publications

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

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An Ultraviolet Absorbance Method of Estimating the Percent Aromatic Carbon Content of Humic Acids

Cited by 359 publications

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Comprehensive characterization of humic-like substances in smoke PM&lt;sub&gt;2.5&lt;/sub&gt; emitted from the combustion of biomass materials and fossil fuels

Comprehensive characterization of humic-like substances in smoke PM&lt;sub&gt;2.5&lt;/sub&gt; emitted from the combustion of biomass materials and fossil fuels

The influence of seasonalness on the structural characteristics of aquatic humic substances extracted from Negro River (Amazon State) waters: interactions with Hg(II)

Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

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Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels

Comprehensive characterization of humic-like substances in smoke PM<sub>2.5</sub> emitted from the combustion of biomass materials and fossil fuels