Using Selected Operational Descriptors To Examine the Heterogeneity within a Bulk Humic Substance.

Hur, Jin; Schlautman, Mark A.

doi:10.1021/es030553k

Cited by 28 publications

(60 citation statements)

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“…Information on specific ultraviolet absorption (SUVA 254 ), an index of C aromaticity (Hur and Schlautman 2003), provides insight in the absence of detailed information on leachate chemistry. Leachate of A. excelsum was the only leachate found to increase phosphate sorption (which occurred in the litter addition soil) and also had greater SUVA 254 compared to the other four species (Fig.…”

Section: Mechanisms Underlying Phosphate Sorption Resultsmentioning

confidence: 99%

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Leaf litter inputs decrease phosphate sorption in a strongly weathered tropical soil over two time scales

2012

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In strongly weathered soils, leaf litter not only returns phosphorus (P) to the soil environment, it may also modify soil properties and soil solution chemistry, with the potential to decrease phosphate sorption and increase plant available P. Using a radioactive phosphate tracer ( 32 P) and 1 h laboratory incubations we investigated the effect of litter inputs on phosphate sorption over two time scales: (1) long-term field litter manipulations (litter addition, control and litter removal) and (2) pulses of litter leachate (i.e. water extracts of leaf litter) from five species. Leachate pulse effects were compared to a simulated throughfall, which served as a control solution. Soil receiving long-term doubling of leaf litter maintained five-fold more phosphate in solution than the litter removal soil. In addition to the quantity of phosphate sorbed, the field litter addition treatment decreased the strength of phosphate sorption, as evaluated through extraction of sorbed 32 P using a weakly acidic ammonium fluoride solution (Bray 1). In litter removal soil, leachate pulses significantly reduced phosphate sorption in comparison to the throughfall control for all five species evaluated. However, the ability of leachate pulses to reduce phosphate sorption decreased when soil had received field litter inputs. Across soils the effect of leachate pulses on phosphate sorption increased with net sorption of dissolved organic C, with the exception of leachate from one species that had a higher index of aromatic C concentration. These results demonstrate that litter inputs, as both long-term inputs and short-term leachate pulses, can decrease the quantity and strength of phosphate sorption, which may increase the biological availability of this key nutrient.

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Section: Mechanisms Underlying Phosphate Sorption Resultsmentioning

confidence: 99%

“…, were used as an index of C chemistry (Jaffrain et al 2007;Hur and Schlautman 2003) and measured on the diluted DOC samples (Hach DR 5000 UV-vis spectrophotometer).…”

Section: Leaf Litter Leachate and Soil Collectionmentioning

confidence: 99%

Leaf litter inputs decrease phosphate sorption in a strongly weathered tropical soil over two time scales

2012

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“…The standard humic and fulvic acids have been well-characterized in terms of elemental composition, acid functional group analysis, amino acid and carbohydrate content, 13 C-NMR estimates of carbon distribution, and 13 C-NMR, FTIR and fluorescence spectra. Humic materials available from commercial suppliers such as Fluka and Aldrich can be more problematic, as they have high and batch-variable ash contents (Malcolm and MacCarthy, 1986;Chin et al, 1994;Hur and Schlautman, 2003). Compared to soil and aquatic humic and fulvic acids, the 13 C-NMR spectra of commercial materials indicate lower carboxyl content, higher saturated aliphatic carbon content, and lower aromatic carbon content (Malcolm and MacCarthy, 1986).…”

Section: Terrestrial/aquatic Humic Substancesmentioning

confidence: 99%

“…Compared to soil and aquatic humic and fulvic acids, the 13 C-NMR spectra of commercial materials indicate lower carboxyl content, higher saturated aliphatic carbon content, and lower aromatic carbon content (Malcolm and MacCarthy, 1986). The commercial products also have relatively high average molecular weights; for example, MW estimates for Aldrich humic acid vary from about 4000 to more than 14 000 Da (Beckett et al, 1987;Chin et al, 1994;Hur and Schlautman, 2003).…”

Section: Terrestrial/aquatic Humic Substancesmentioning

confidence: 99%

Atmospheric HULIS: How humic-like are they? A comprehensive and critical review

2006

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Abstract.A class of organic molecules extracted from atmospheric aerosol particles and isolated from fog and cloud water has been termed HUmic-LIke Substances (HULIS) due to a certain resemblance to terrestrial and aquatic humic and fulvic acids. In light of the interest that this class of atmospheric compounds currently attracts, we comprehensively review HULIS properties, as well as laboratory and field investigations concerning their formation and characterization in atmospheric samples. While sharing some important features such as polyacidic nature, accumulating evidence suggests that atmospheric HULIS differ substantially from terrestrial and aquatic humic substances. Major differences between HULIS and humic substances, including smaller average molecular weight, lower aromatic moiety content, greater surface activity, better droplet activation ability, as well as others, are highlighted. Several alternatives are proposed that may explain such differences: (1) the possibility that mono-and di-carboxylic acids and mineral acids abundant in the atmosphere prevent the formation of large humic "supramolecular associations"; (2) that large humic macromolecules are destroyed in the atmosphere by UV radiation, O 3 , and OH − radicals; 3) that "HULIS" actually consists of a complex, unresolved mixture of relatively small molecules rather than macromolecular entities; and (4) that HULIS formed via abiotic and short-lived oxidative reaction pathways differ substantially from humic substances formed over long time periods via biologically-mediated reactions. It should also be recalled that the vast majority of studies of HULIS relate to the water soluble fraction, which would include only the fulvic acid fraction of humic substances, and exclude the humic acid (base-soluble) and humin (insoluble) fractions of humic substances. A significant effort towards Correspondence to: E. R. Graber (ergraber@volcani.agri.gov.il) adopting standard extraction and characterization methods is required to develop a better and meaningful comparison between different HULIS samples.

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“…Actually, the decrease of absorbance has already been observed in different fractionation processes (Burba et al, 1995;Aster et al, 1996;Schimpf and Petteys, 1997;Lin et al, 1999Lin et al, , 2000Kitis et al, 2002;Hoque et al, 2003;Hur and Schlautman, 2003;Alberts and Takács, 2004;Zanardi-Lamardo et al, 2004;Richard et al, 2004) or changed in their aggregation through acidic treatment (Piccolo et al, 1999;Cozzolino et al, 2001;Baigorri et al, 2007) but mostly left without explanation. Piccolo explained that absorbance decrease is a consequence of the disruption of weak intermolecular bonds; holding aggregates together (Piccolo et al, 1996b).…”

Section: Resultsmentioning

confidence: 99%

Fluorescence quenching as an indicator of the conformational change of humic<br>acids

Franko

2013

Emir. J. Food Agric

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Humic acids as a water soluble fraction of humus play important role in the plant growth. Even though structure of humic acids is not clear, their spectroscopic properties can reveal us useful information. To investigate influence of humic acids reorganization, HPSEC fractionation at mild fractionation conditions has been carried out. Reconstruction of secondary chromatograms of separated fractions showed molecular size increase and increased response on fluorescence detector, although neither molecular size change nor significant absorbance increase was observed on UV-VIS detector. However, bigger aggregates, that didn't fluoresce in the unfractionated sample started to fluoresce. The reason for this behavior is not some change of spectral properties of a specific fraction, but a general fluorescence increase indicating humic acid reorganization. Therefore spectroscopic changes can be used as a tool for monitoring their reorganization, which might play an important role in nutrients soil plant mobility and should be studied in more details from that perspective.

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Using Selected Operational Descriptors To Examine the Heterogeneity within a Bulk Humic Substance.

Cited by 28 publications

References 0 publications

Leaf litter inputs decrease phosphate sorption in a strongly weathered tropical soil over two time scales

Leaf litter inputs decrease phosphate sorption in a strongly weathered tropical soil over two time scales

Atmospheric HULIS: How humic-like are they? A comprehensive and critical review

Fluorescence quenching as an indicator of the conformational change of humic<br>acids

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