Chemical heterogeneity of humic substances: characterization of size fractions obtained by hollow-fibre ultrafiltration Export

@article{Christl2000, abstract = {To investigate the chemical heterogeneity of humic substances in relation to molecular size, fulvic and humic acids were extracted and purified from the surface horizon of a Humic Gleysol in northern Switzerland. A fractionation scheme using hollow-fibre ultrafiltration cartridges was developed and used to obtain four size fractions of the humic acid with nominal molecular weight ranges \> 300 kDa, 1002013300 kDa, 302013100 kDa, and 10201330 kDa. The fulvic acid and all humic acid fractions were characterized by size exclusion chromatography, elemental analysis (C, H, N, S), as well as spectroscopic techniques including UV-VIS, CP-MAS 13C-NMR, FT-IR, and fluorescence spectroscopy. Clear chemical differences between the humic acid size fractions were observed. Smaller size fractions of the soil humic acid contained more chargeable functional groups and a larger percentage of aromatic carbon than the larger size fractions. Conversely, the percentage of aliphatic carbon increased with increasing apparent molecular weight. The chemical composition of the smallest humic acid fraction differed clearly from the fulvic acid fraction, despite similar apparent molecular size and carboxyl carbon content. Small humic acids contained much more aromatic carbon and less aliphatic carbon than the fulvic acid fraction. Apparently, humic size fractions differ in their chemical composition, which can have important implications for their environmental behaviour.}, address = {Institute of Terrestrial Ecology, Swiss Federal Institute of Technology, Grabenstrasse 3, 8952 Schlieren, Switzerland, and ; Department of Soil Science, Technische Universitt Mnchen, 85350 Freising-Weihenstephan, Germany}, author = {Christl, I. and Knicker, H. and K\"{o}gel-Knabner, I. and Kretzschmar, R.}, citeulike-article-id = {4035244}, citeulike-linkout-0 = {http://dx.doi.org/10.1111/j.1365-2389.2000.00352.x}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/120715572/ABSTRACT}, doi = {10.1111/j.1365-2389.2000.00352.x}, journal = {European Journal of Soil Science}, keywords = {aromatisation, humic, sectroscopy, substances, uv, vis}, number = {4}, pages = {617--625}, posted-at = {2009-02-11 14:20:40}, priority = {2}, title = {Chemical heterogeneity of humic substances: characterization of size fractions obtained by hollow-fibre ultrafiltration}, url = {http://dx.doi.org/10.1111/j.1365-2389.2000.00352.x}, volume = {51}, year = {2000} }

TY - JOUR ID - Christl2000 L3 - citeulike-article-id:4035244 N2 - To investigate the chemical heterogeneity of humic substances in relation to molecular size, fulvic and humic acids were extracted and purified from the surface horizon of a Humic Gleysol in northern Switzerland. A fractionation scheme using hollow-fibre ultrafiltration cartridges was developed and used to obtain four size fractions of the humic acid with nominal molecular weight ranges > 300 kDa, 1002013300 kDa, 302013100 kDa, and 10201330 kDa. The fulvic acid and all humic acid fractions were characterized by size exclusion chromatography, elemental analysis (C, H, N, S), as well as spectroscopic techniques including UV-VIS, CP-MAS 13C-NMR, FT-IR, and fluorescence spectroscopy. Clear chemical differences between the humic acid size fractions were observed. Smaller size fractions of the soil humic acid contained more chargeable functional groups and a larger percentage of aromatic carbon than the larger size fractions. Conversely, the percentage of aliphatic carbon increased with increasing apparent molecular weight. The chemical composition of the smallest humic acid fraction differed clearly from the fulvic acid fraction, despite similar apparent molecular size and carboxyl carbon content. Small humic acids contained much more aromatic carbon and less aliphatic carbon than the fulvic acid fraction. Apparently, humic size fractions differ in their chemical composition, which can have important implications for their environmental behaviour. IS - 4 JF - European Journal of Soil Science AD - Institute of Terrestrial Ecology, Swiss Federal Institute of Technology, Grabenstrasse 3, 8952 Schlieren, Switzerland, and ; Department of Soil Science, Technische Universitt Mnchen, 85350 Freising-Weihenstephan, Germany EP - 625 TI - Chemical heterogeneity of humic substances: characterization of size fractions obtained by hollow-fibre ultrafiltration VL - 51 SP - 617 KW - aromatisation KW - humic KW - sectroscopy KW - substances KW - uv KW - vis AU - Christl, I AU - Knicker, H AU - Kögel-Knabner, I AU - Kretzschmar, R PY - 2000/// UR - http://dx.doi.org/10.1111/j.1365-2389.2000.00352.x ER -