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 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 (17) Citing Articles via Google Scholar Google Scholar Articles by Hyun, S. Articles by Rao, P. S. C. Search for Related Content PubMed PubMed Citation Articles by Hyun, S. Articles by Rao, P. S. C. GeoRef GeoRef Citation Agricola Articles by Hyun, S. Articles by Rao, P. S. C. Related Collections Organic Compounds Soil Chemistry

TECHNICAL REPORTS
Organic Compounds in the Environment

Significance of Anion Exchange in Pentachlorophenol Sorption by Variable-Charge Soils

^a Dep. of Agronomy, Purdue Univ., West Lafayette, IN 47907-2054
^b School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907-2051

^* Corresponding author (lslee{at}purdue.edu)

Received for publication May 14, 2002. Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH- and pK_a–dependent chemical speciation and using two organic carbon–normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl₂, CaSO₄, Ca(H₂PO₄)₂ as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl₂ and Ca(H₂PO₄)₂ solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides.

Abbreviations: AEC, anion exchange capacity • CEC, cation exchange capacity • PCP, pentachlorophenol • PZNC, point of zero net charge

Related articles in JEQ:

This Issue in Journal of Environmental Quality

JEQ 2003 32: 745-750. [Full Text]  

This article has been cited by other articles:

				S. Hyun and L. S. Lee Factors Controlling Sorption of Prosulfuron by Variable-Charge Soils and Model Sorbents J. Environ. Qual., July 1, 2004; 33(4): 1354 - 1361. [Abstract] [Full Text] [PDF]