title: Molecular Features of Humic Acids and Fulvic Acids from Contrasting Environments.
abstract: Insight in the molecular structure of humic acid (HA) and fulvic acid (FA) can contribute to identify relationships between their molecular properties, and further our quantitative abilities to model important organic matter functions such as metal complexation and association with mineral surfaces. Pyrolysis gas chromatography/mass spectrometry (Py-GC-MS) is used to compare the molecular composition of HA and FA. A systematic comparison was obtained by using samples from different environmental sources, including solid and aqueous samples from both natural and waste sources. The chemical signature of the pyrolysates was highly variable and no significant difference between HA and FA was found for major chemical groups, that is, carbohydrates, phenols, benzenes, and lignin phenols, together accounting for 62-96% of all quantified pyrolysis products. However, factor analysis showed that within each sample, FAs consistently differed from corresponding HAs in a larger contribution from mono- and polyaromatic hydrocarbons and heterocyclic hydrocarbons, together accounting for 3.9-44.5% of the quantified pyrolysis products. This consistent difference between FAs and corresponding HAs, suggests that their binding properties may, in addition to the carboxyl and phenolic groups, be influenced by the molecular architecture. Py-GC-MS may thus contribute to identify relationships between HA and FA binding- and molecular-properties.
authors.affiliation: Department of Soil Science (LSO), "Luiz de Queiroz" College of Agriculture (ESALQ), University of São Paulo (USP) , Av. Pádua Dias, 11 Caixa Postal 9 Piracicaba/SP 13418-900, Brazil.
authors.forename: Judith
authors.identifier: 0000-0001-8364-7034
authors.initials: J
authors.lastname: Schellekens
authors.affiliation: Department of Soil Quality, Wageningen University , P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Buurman
authors.affiliation: Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.|Soil Resources and Land Use, Technical University Dresden , Pienner Strasse 19, D-01737 Tharandt, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Kalbitz
authors.affiliation: Energy research Centre of The Netherlands, P.O. Box 1, 1755 ZG Petten, The Netherlands.
authors.forename: Andre van
authors.initials: AV
authors.lastname: Zomeren
authors.affiliation: Department of Soil Science (LSO), "Luiz de Queiroz" College of Agriculture (ESALQ), University of São Paulo (USP) , Av. Pádua Dias, 11 Caixa Postal 9 Piracicaba/SP 13418-900, Brazil.
authors.forename: Pablo
authors.initials: P
authors.lastname: Vidal-Torrado
authors.affiliation: Soil Resources and Land Use, Technical University Dresden , Pienner Strasse 19, D-01737 Tharandt, Germany.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cerli
authors.affiliation: Department of Soil Quality, Wageningen University , P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Rob N J
authors.initials: RN
authors.lastname: Comans
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D004777:Environment; D008401:Gas Chromatography-Mass Spectrometry; D006812:Humic Substances; D008031:Lignin; D009930:Organic Chemicals
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D009930:Organic Chemicals; D008031:Lignin