Linked Life Data

15543742

Source:http://linkedlifedata.com/resource/pubmed/id/15543742

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
2004-11-16
pubmed:abstractText
Pesticide adsorption by soil clays can be dramatically influenced by the exchangeable cations present. Among the common exchangeable base cations in soils (Ca2+, Mg2+, K+, and Na+), K+-saturated clays frequently demonstrate the strongest affinity for pesticides. In the presence of multiple exchangeable cations in the system, we hypothesize that the magnitude of pesticide sorption to soil minerals is proportional to the fraction of clay interlayers saturated with K+ ions. To test this hypothesis, we measured sorption of three pesticides with different polarities (dichlobenil, monuron, and biphenyl) by homoionic K- and Ca-smectite (SWy-2) in KCl/CaCl2 aqueous solutions. The presence of different amounts of KCl and CaCl2 resulted in varying populations of K+ and Ca2+ on the clay exchange sites. The sorption of dichlobenil and, to a lesser extent monuron, increased with the fraction of K+ on clay mineral exchange sites. Ca- and K-SWy-2 displayed the same sorption capacities for nonpolar biphenyl. X-ray diffraction patterns indicated that at lower fractions of K+-saturation, exchangeable K+ ions were randomly distributed in clay interlayers and did not enhance pesticide sorption. At higher populations of K+ (vs Ca2+), demixing occurred causing some clay interlayers, regions, or tactoids to become fully saturated by K+, manifesting greatly enhanced pesticide sorption. The forward and reverse cation exchange reactions influenced not only K+ and Ca2+ populations on clays but also the nanostructures of clay quasicrystals in aqueous solution which plays an important, if not dominant, role in controlling the extent of pesticide sorption. Modulating the cation type and composition on clay mineral surfaces through cation exchange processes provides an environmental-safe protocol to manipulate the mobility and availability of polar pesticides, which could have applications for pesticide formulation and in environmental remediation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Biphenyl Compounds, http://linkedlifedata.com/resource/pubmed/chemical/Cations, http://linkedlifedata.com/resource/pubmed/chemical/Fungicides, Industrial, http://linkedlifedata.com/resource/pubmed/chemical/Herbicides, http://linkedlifedata.com/resource/pubmed/chemical/Methylurea Compounds, http://linkedlifedata.com/resource/pubmed/chemical/Nitriles, http://linkedlifedata.com/resource/pubmed/chemical/Potassium, http://linkedlifedata.com/resource/pubmed/chemical/Silicates, http://linkedlifedata.com/resource/pubmed/chemical/Smectite, http://linkedlifedata.com/resource/pubmed/chemical/Soil Pollutants, http://linkedlifedata.com/resource/pubmed/chemical/dichlobanil, http://linkedlifedata.com/resource/pubmed/chemical/diphenyl, http://linkedlifedata.com/resource/pubmed/chemical/monuron
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0013-936X
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5393-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Geochemical modulation of pesticide sorption on smectite clay.
pubmed:affiliation
Environmental Science and Policy Program, and Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't