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

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Related articles in JEQ Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed 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 (16) Citing Articles via Google Scholar Google Scholar Articles by Lu, Y. Articles by Pignatello, J. J. Search for Related Content PubMed PubMed Citation Articles by Lu, Y. Articles by Pignatello, J. J. GeoRef GeoRef Citation Agricola Articles by Lu, Y. Articles by Pignatello, J. J. Related Collections Humic Substances Volatile Organic Compounds Sorption/Exchange Organic Compounds Soil Pollution

TECHNICAL REPORTS

Organic Compounds in the Environment

Sorption of Apolar Aromatic Compounds to Soil Humic Acid Particles Affected by Aluminum(III) Ion Cross-Linking

Department of Soil and Water, Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT 06511

^* Corresponding author (Joseph.Pignatello{at}po.state.ct.us).

Received for publication May 19, 2003. Sorption of hydrophobic compounds in soils often shows nonlinearity, competition, and hysteresis. Since such behaviors have been associated with organic polymers in glassy state, it has been postulated that some forms of soil humic substances are glassy. The glassy state is favored by properties that decrease the flexibility of macromolecules, such as cross-linking, presence of unsaturated bonds, and high molecular weight. Polyvalent metal ions, which are abundant in soils, may cross-link humic substances by coordinating to multiple functional groups on different strands. Accordingly, we prepared an Al³⁺–cross-linked humic acid (Al-HA) from the H⁺ form (H-HA) of a soil humic acid by a flocculation technique that leaves Al ions bound to organic groups. Sorption of naphthalene and 1,2,4-trichlorobenzene (TCB) on H-HA was nonlinear, competitive, and slightly hysteretic, in agreement with previous studies showing glass transition temperatures of humic acids that lie above room temperature. Nonlinearity, competition, and hysteresis were all enhanced in Al-HA, validating the hypothesis that metal ion cross-linking enhances nonideal sorption. Application of a glassy polymer sorption model reveals that cross-linking increases the affinity of solutes for the hole domain relative to the dissolution domain. The results (i) indicate that isolated, purified soil humic acid behaves like a glassy solid, (ii) indicate that metal-ion cross-linking creates a more rigid-chain structure and supports a link between nonideal sorption and the glassy character of soil organic matter, and (iii) underscore the importance of metal ions on humic structure in relation to sorption of hydrophobic organic compounds.

Abbreviations: Al-HA, aluminum-ion-exchanged humic acid • DCB, 1,3-dichlorobenzene • DMM, dual-mode model • HA, humic acid • H-HA, hydrogen-ion-exchanged humic acid • OC, organic carbon • TCB, 1,2,4-trichlorobenzene

Related articles in JEQ:

This Issue in Journal of Environmental Quality

JEQ 2004 33: 1177-1182. [Full Text]  

This article has been cited by other articles:

				C. Gu and K. G. Karthikeyan Sorption of the antibiotic tetracycline to humic-mineral complexes. J. Environ. Qual., March 1, 2008; 37(2): 704 - 711. [Abstract] [Full Text] [PDF]

				J. J. Pignatello, Y. Lu, E. J. LeBoeuf, W. Huang, J. Song, and B. Xing Nonlinear and Competitive Sorption of Apolar Compounds in Black Carbon-Free Natural Organic Materials J. Environ. Qual., May 31, 2006; 35(4): 1049 - 1059. [Abstract] [Full Text] [PDF]

				A. A. MacKay and B. Canterbury Oxytetracycline Sorption to Organic Matter by Metal-Bridging J. Environ. Qual., October 12, 2005; 34(6): 1964 - 1971. [Abstract] [Full Text] [PDF]

				M. Sander, Y. Lu, and J. J. Pignatello A Thermodynamically Based Method to Quantify True Sorption Hysteresis J. Environ. Qual., May 11, 2005; 34(3): 1063 - 1072. [Abstract] [Full Text] [PDF]