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 ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (29) Citing Articles via Google Scholar Google Scholar Articles by Yates, L. M. Articles by von Wandruszka, R. Search for Related Content PubMed Articles by Yates, L. M., III Articles by von Wandruszka, R. GeoRef GeoRef Citation Agricola Articles by Yates, L. M. Articles by von Wandruszka, R.

DIVISION S-2-SOIL CHEMISTRY

Effects of pH and Metals on the Surface Tension of Aqueous Humic Materials

^a Dep. of Chemistry, Univ. of Idaho, Moscow, ID 83844-2343 USA

rvw{at}uidaho.edu

Humic substances play an important role in the transport and fate of xenobiotic materials in the environment. Since most of the relevant interactions take place in aqueous media, it is of prime importance to understand the behavior of these natural polymers in solution. In this study, surface tension measurements were used to elucidate conformational and structural changes in dissolved humic and fulvic acids under different conditions of pH, ionic strength, and the presence of certain metal ions. The measurements showed that the amphiphilic character of the humic solutes, which determines their surface activity, varied significantly with pH and metal content. The charge of the metal ion added was found to have an important effect in rendering the humic material sufficiently amphiphilic to migrate to the surface. As cation concentrations were increased, the formation of micelle-like humic structures led to the restoration of higher surface tensions. Measurements with materials of different molecular size indicated that these structures could arise from both intermolecular aggregation and intramolecular coiling. Kinetic measurements showed that the evolution of surface tension values in humic acid solutions followed a course that was consistent with the migration of metal ions within the humic structure. This is thought to involve the formation and subsequent disintegration of hydrophobic domains as the metal–humate interactions change during a period of hours.

Abbreviations: Da, daltons • DDIW, doubly deionized water • FA, fulvic acid • HA, humic acid • IHSS, International Humic Substances Society • LHA, leonardite humic acid • LHACB, leonardite humic acid crude blend • LSLHA, Latahco silt loam humic acid • SRFA, Suwannee River fulvic acid • SRHA, Suwannee River humic acid

This article has been cited by other articles:

				G. Arye, I. Nadav, and Y. Chen Short-term Reestablishment of Soil Water Repellency after Wetting: Effect on Capillary Pressure-Saturation Relationship Soil Sci. Soc. Am. J., April 5, 2007; 71(3): 692 - 702. [Abstract] [Full Text] [PDF]

				A. Gilboa, J. Bachmann, S. K. Woche, and Y. Chen Applicability of Interfacial Theories of Surface Tension to Water-Repellent Soils Soil Sci. Soc. Am. J., August 3, 2006; 70(5): 1417 - 1429. [Abstract] [Full Text] [PDF]

				R. H. Ellerbrock, H. H. Gerke, J. Bachmann, and M.-O. Goebel Composition of Organic Matter Fractions for Explaining Wettability of Three Forest Soils Soil Sci. Soc. Am. J., January 1, 2005; 69(1): 57 - 66. [Abstract] [Full Text] [PDF]