Publication Date:
1999-05-01
Description:
Some soils develop severe water repellency several years or decades following oil contamination. We previously reported on the characteristics of three such soils. Here we report on the characteristics of putative water-repellent substances in them. We examined the effectiveness of various polar, nonpolar and amphiphilic solvents for removal of water-repellent substances in three nonwettable soils. Only the amphiphilic solvent mixture isopropanol/14.8 M ammonia (7:3, vol/vol) (IPA/NH4OH) completely eliminated soil water repellency in all three soils. We thus define putative water-repellent substances as those substances whose removal from soil by IPA/NH4OH removes water repellency. High-resolution CPMAS 13C-NMR spectroscopy and thermal desorption followed by conventional gas chromatography/mass spectroscopy with electron impact ionization (GC/EI/MS) and GC/MS with chemical ionization (GC/CI/MS) were used to characterize extracted putative water-repellent substances. We conclude that: (i) the identified representatives of these substances consist mostly of homologous series of long-chain and polycyclic aliphatic organic compounds; namely, n-fatty acids, n-alkanes, and cycloalkanes, and that (ii) they are of petroleum origin rather than plant or microbial origin. Key words: Soil hydrophobicity, petroleum hydrocarbons, soil water repellency, amphiphilic solvents, crude oil, nonwettable soil
Print ISSN:
0008-4271
Electronic ISSN:
1918-1841
Topics:
Geosciences
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Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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