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Titre :
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Gas partitioning of dissolved volatile organic compounds in the vadose zone: Principles, temperature effects and literature review
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Auteurs :
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J. Washington
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Type de document :
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article/chapitre/communication
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Année de publication :
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1996
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Format :
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p.709-718
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Langues:
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= Anglais
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Catégories :
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QUALITE DE L'EAU
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Mots-clés:
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MILIEU NON SATURE
;
POLLUTION DE L'EAU
;
MATIERE VOLATILE
;
COMPOSE ORGANIQUE
;
TEMPERATURE
;
DILUTION
;
HYDROCARBURE
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Résumé :
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Enthalpy and entropy of volatilization from dilute aqueous solutions for 26 volatile organic compounds (VOCs) have been determined using Henry's Law values reported in published literature. Based on the linearity of van't Hoff plots, for the temperature ranges common in soils, the differences in heat capacities of volatilization for reactants and products are very small for the VOCs studied. When volatile solutes such as VOCs are present in soil water, soil-gas concentration often nearly is in equilibrium with the dissolved solute. Setchinow salting coefficients are linearly related to dissolved partial molar volumes for halogenated aliphatic compounds. Based in part on approximations from this linear relationship, equilibrium deviations from Henry's Law behavior for dilute VOC concentrations due to capillary tension or the presence of ionic solutes are small for common soil conditions. Since gas/water partitioning of VOCs if temperature-sensitive and since annual soil moisture and temperature patterns vary geographically in documented fashion, geographically specific temporal patterns in soil-gas VOC concentrations are predictable in vadose zones containing dissolved VOCs. A U.S.
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Source :
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Ground water, vol.34, n°4
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