HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by Li, L. Articles by Fu, J. Search for Related Content PubMed Articles by Li, L. Articles by Fu, J. Agricola Articles by Li, L. Articles by Fu, J. Related Collections Humic Substances Soil Organic Matter Soil Chemistry

DIVISION S-2—SOIL CHEMISTRY

Chemical and Molecular Heterogeneity of Humic Acids Repetitively Extracted from a Peat

^a State Key Lab. of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
^b Dep. of Civil, Architectural, and Environmental Engineering, Drexel Univ., Philadelphia, PA 19104

^* Corresponding author (weilin.huang{at}drexel.edu)

Eight humic acid (HA) fractions obtained by repetitive base extraction of a peat soil were characterized in terms of chemical compositions, functionalities, and molecular sizes using an elemental analyzer, infrared spectrometry (IR), solid-state ¹³C-nuclear magnetic resonance spectrometry (¹³C-NMR), and high performance size-exclusion chromatography (HPSEC). Large variations in chemical, functional, and molecular properties were observed among the eight humic fractions. The elemental analysis data showed that, from the first (Fr1) to the eighth fraction (Fr8), the O/C atomic ratio decreased from 0.52 to 0.36 whereas the H/C atomic ratio increased from 1.1 to 1.5. The measured average apparent molecular size (M_w) increases from 7.7 to 22.1 kDa as a function of the extent of extraction. Carbon-13 NMR and FTIR spectra of the fractions indicated that the contents of oxygen-containing and aromatic functional groups decreased and the contents of aliphatic groups increased from Fr1 to Fr8. The results suggested that two subunits of HAs might exist: an aliphatic subunit having larger apparent M_w and an aromatic subunit having smaller apparent M_w. We proposed that each of the eight HA fractions is a mixture of these two subunits.

Abbreviations: ¹³C-NMR, solid-state ¹³C-nuclear magnetic resonance spectrometry • HA, humic acids • HPSEC, high performance size exclusion chromatography • IHSS, International Humic Substances Society • IR, infrared spectrometry • M_W, apparent molecular size

This article has been cited by other articles:

				A. Farenhorst Importance of Soil Organic Matter Fractions in Soil-Landscape and Regional Assessments of Pesticide Sorption and Leaching in Soil Soil Sci. Soc. Am. J., April 19, 2006; 70(3): 1005 - 1012. [Abstract] [Full Text] [PDF]

				K. Wang and B. Xing Structural and Sorption Characteristics of Adsorbed Humic Acid on Clay Minerals J. Environ. Qual., January 1, 2005; 34(1): 342 - 349. [Abstract] [Full Text] [PDF]