Peer Reviewed: Investigating Humic Acids in Soils

Steelink, Cornelius

doi:10.1021/ac022040m

Cited by 55 publications

(36 citation statements)

References 19 publications

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“…The elemental composition of humic acid used in this study is quite similar to the average percentages reported for elemental composition of soil humic acids (28). UV-Visible spectral absorbances of humic acid and their ratios at particular wavelengths are shown in Table 3.…”

Section: Resultssupporting

confidence: 76%

“…After a 48 h equilibration at pH 12.8, the variability in spectroscopic data was very low, indicating the stabilisation of humic acid structure in solution. The ratio of absorbances at 465 nm and 665 nm (A 465 /A 665 ) is used as a measure of aromaticity or humifi cation: a low ratio (~3.0) indicates a high aromatic character, and a high ratio (~8) a high aliphatic character of humic acid; humifi cation is indicated by lower A 465 /A 665 ratio (28). Absorption of light at 254 nm reflects the presence of UVabsorbing functional groups and absorption at 436 nm of the coloured (yellow/brown) ones.…”

Section: Resultsmentioning

confidence: 99%

“…Aqueous (27)(28)(29). The acidity of humic acid was determined by measuring the pH in the supernatant of samples prepared by overnight equilibration of 0.025 g (in experiments with chlorophenols) or 0.010 g (in experiments with triazines) of sorbent with 3 cm 3 of deionised water.…”

Section: Compoundmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Organic and Mineral Soil Fractions on Sorption Behaviour of Chlorophenol and Triazine Micropollutants

Stipičević

Fingler

Drevenkar

2009

Archives of Industrial Hygiene and Toxicology

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This article compares the sorption behaviour of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, chlorotriazine atrazine, methylthiotriazine ametryn, methoxytriazine atratone, hydroxyatrazine, and didelakylated atrazine in a topsoil and an aquifer sediment before and after removal of sorbent organic matter and in humic acid. Freundlich isotherm coeffi cients K f and 1/n and free energy change (∆G°) were calculated for all compounds in all sorbents. According to sorbent pH values, chlorophenolate anions and uncharged triazine species dominated in all sorption experiments with topsoil and aquifer sediment. In experiments with humic acid, chlorophenols, atrazine, and didealkylated atrazine existed almost completely as neutral species, whereas protonated species dominated for hydroxyatrazine, atratone, and ametryn. In addition to a hydrophobic partition, sorption of all compounds in native soil and sediment sorbents includes specifi c, more polar interactions, which greatly depend on sorbate acidity/ basicity, specifi c properties of the sorbent organic matter and of mineral surface, as well as on the system pH. A signifi cantly greater sorption intensity of all compounds in "organic-free" than in the native aquifer sediment confi rmed the importance and possible dominance of mineral surface in the sorption process. Sorption intensity of chlorophenol and triazine compounds in humic acid was closely related to compound hydrophobicity. Greater sorption of almost completely protonated hydroxyatrazine than of the more hydropohobic but uncharged atrazine indicated different humic acid reaction sites for two compounds and consequently different sorption mechanisms.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

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Effect of Organic and Mineral Soil Fractions on Sorption Behaviour of Chlorophenol and Triazine Micropollutants

Stipičević

Fingler

Drevenkar

2009

Archives of Industrial Hygiene and Toxicology

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“…On the other hand, the diversification of supramolecular structures of allochthonous fulvic or humic acids and of autochthonous fulvic acids are familiar phenomena in the field of organic geochemistry. They are generally composed of a variety of functional groups such as OH (phenols, alcohols and carbohydrates), COOH (aromatic or aliphatic acids), as well as aldehydes (-CHO), ketones (C=O), ethers (R-O-R′), esters (COOR), methoxylates, and so on [4,6,9,19]. Such functional groups may all be generated, at least in part, by the reaction of O 2  (and/or its related ROS) with the components of plants or algal biomass.…”

Section: Canadian Chemical Transactionsmentioning

confidence: 99%

Biological Formation of Organic Substances from Particulate Organic Matter

Mostofa¹,

Liu²,

Minella³

et al. 2015

Can. Chem. Trans.

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Biological degradation of terrestrially derived macromolecules including lignin and cellulose has been shown to produce a large number of environmentally relevant phenolic compounds. It has demonstrated that extracellular superoxide (O 2  ) is produced by heterotrophic bacteria that are common in lakes, soil, hydrothermal vents, marine sediments, estuaries and oceans. Rates of superoxide production normalized to the proportion of metabolically active cells vary between 0.02  0.02 amol cell −1 hour −1 (mean ± standard error) and 19.4  5.2 amol cell −1 hour −1 . Such findings provide insights into the mechanism of two key and yet unclear processes, including the biological degradation of particulate organic matter (POM) that can form dissolved organic substances, and the structural diversification of dissolved organic substances originated from POM such as plant material or algal biomass.

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“…HSs are anionic polyelectrolytes that represent 65%-75% of the total organic matter in soils. Average molecular weight ranges from 2 to 400 kDa, depending on the determination method [2]. An empirical formula for the basic structure of humic acids (HSs) has been proposed [3]: C 72 H 43−95 O 30 N 4 ·0-38H 2 O.…”

Section: Introductionmentioning

confidence: 99%