Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

Organic compounds at different depths in a sandy soil and their role in water repellency

Organic compounds at different depths in a sandy soil and their role in water repellency The causes of soil water repellency are still only poorly understood. It is generally assumed that hydrophobic organic compounds are responsible, but those concerned have not previously been identified by comparison between samples taken from a water repellent topsoil and the wettable subsoil. In this study we separated, characterised, and compared the organic compounds present at 4 different depths in a sandy soil under permanent grass cover that is water repellent in the upper 0.30 m but wettable below this. Soil samples were extracted using a mixture of isopropanol and aqueous ammonia (7 : 3 v : v). Samples were wettable after extraction and re-application of the extract from each sample onto wettable sand induced water repellency. The chloroform-soluble portions of the extracts were analysed by gas chromatography and gas chromatography-mass spectrometry. The compounds identified at all soil depths included long-chain carboxylic acids (C 16 –C 24 ), amides (C 14 –C 24 ), alkanes (C 25 –C 31 ), aldehydes or ketones (C 25 –C 29 ), and more complex ring-containing structures. 1 H and 13 C nuclear magnetic resonance spectroscopy, and the carbon/hydrogen ratio as determined by microanalysis, confirmed the predominantly aliphatic character of the extracts. Both wettable and water repellent samples contained hydrophobic compounds. The 3 water repellent samples contained far more organic material, although the amount extracted was not related to the degree of water repellency. Perhaps more importantly, they contained polar compounds of high relative molecular mass, which were almost absent from the wettable subsoil. It may be speculated that these are the compounds in this soil whose presence in significant amounts is necessary for water repellency to be exhibited. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Soil Research CSIRO Publishing

Organic compounds at different depths in a sandy soil and their role in water repellency

Download PDF
11 pages

Loading next page...
 
/lp/csiro-publishing/organic-compounds-at-different-depths-in-a-sandy-soil-and-their-role-BVEcsULcef

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
CSIRO Publishing
Copyright
CSIRO
ISSN
1838-675X
eISSN
1838-6768
DOI
10.1071/SR04094
Publisher site
See Article on Publisher Site

Abstract

The causes of soil water repellency are still only poorly understood. It is generally assumed that hydrophobic organic compounds are responsible, but those concerned have not previously been identified by comparison between samples taken from a water repellent topsoil and the wettable subsoil. In this study we separated, characterised, and compared the organic compounds present at 4 different depths in a sandy soil under permanent grass cover that is water repellent in the upper 0.30 m but wettable below this. Soil samples were extracted using a mixture of isopropanol and aqueous ammonia (7 : 3 v : v). Samples were wettable after extraction and re-application of the extract from each sample onto wettable sand induced water repellency. The chloroform-soluble portions of the extracts were analysed by gas chromatography and gas chromatography-mass spectrometry. The compounds identified at all soil depths included long-chain carboxylic acids (C 16 –C 24 ), amides (C 14 –C 24 ), alkanes (C 25 –C 31 ), aldehydes or ketones (C 25 –C 29 ), and more complex ring-containing structures. 1 H and 13 C nuclear magnetic resonance spectroscopy, and the carbon/hydrogen ratio as determined by microanalysis, confirmed the predominantly aliphatic character of the extracts. Both wettable and water repellent samples contained hydrophobic compounds. The 3 water repellent samples contained far more organic material, although the amount extracted was not related to the degree of water repellency. Perhaps more importantly, they contained polar compounds of high relative molecular mass, which were almost absent from the wettable subsoil. It may be speculated that these are the compounds in this soil whose presence in significant amounts is necessary for water repellency to be exhibited.

Journal

Soil Research – CSIRO Publishing

Published: May 25, 2005

Keywords: hydrophobicity, gas chromatography.

References

  • Water repellency of sieve fractions from sandy soils and relationships with organic material and soil structure.
    Bisdom EBA
  • The influence of the microflora on physical properties of soils. I. Effects associated with filamentous algae and fungi.
    Bond RD
  • Isolation, fractionation, functionalities and concepts of structures of soil organic macromolecules.
    Clapp CE
  • Water repellency in soils: a historical overview.
    DeBano LF
  • Actual water repellency and critical soil water content in a dune sand.
    Dekker LW
  • Fingered flow: the creator of sand columns in dune and beach sands.
    Dekker LW
  • Variation in water content and wetting patterns in Dutch water repellent peaty clay and clayey peat soils.
    Dekker LW
  • Effect of drying temperature on the severity of soil water repellency.
    Dekker LW
  • Extent and significance of water repellency in dunes along the Dutch coast.
    Dekker LW
  • On standardising the ‘Water Drop Penetration Time’ and the ‘Molarity of an Ethanol Droplet’ techniques to classify soil hydrophobicity: a case study using medium textured soils.
    Doerr SH
  • Water repellency of soils: the influence of ambient relative humidity.
    Doerr SH
  • Extraction of compounds associated with water repellency in sandy soils of different origin.
    Doerr SH
  • Spatial variability of soil water repellency in fire prone eucalyptus and pine forests, Portugal.
    Doerr SH
  • Soil water repellency: its causes, characteristics and hydro-geomorphological significance.
    Doerr SH
  • Hydrocarbon constituents of the wax coating of plant leaves: a taxonomic survey.
    Edlington G
  • The development of water repellency in sands: studies on the physico-chemical and biological mechanisms.
    Franco CMM
  • Hydrophobic properties and chemical characterisation of natural water repellent materials in Australian sands.
    Franco CMM
  • Subcritical water repellency of aggregates from a range of soil management practices.
    Hallett PD
  • Humic substances: progress towards more realistic concepts of structures.
    Hayes MHB
  • Procedures for the isolation and fractionation of humic substances.
    Hayes MHB
  • Hydrophobic compounds in sands in New Zealand—extraction, characterisation and proposed mechanisms for repellency expression.
    Horne DJ
  • Comparative studies of wettable and nonwettable soils from Agrostis palustris Huds. sand greens.
    Hudson RA
  • Organic matter comparison of wettable and nonwettable soils from bentgrass sand greens.
    Hudson RA
  • High humidity-induced increase in water repellency in some sandy soils.
    Jex GW
  • Measurement of contact angle, water drop penetration time, and critical surface tension.
    Letey J
  • Extraction and characterisation of water repellent materials from Australian soils.
    Ma’shum M
  • The effect of plant top material on the water repellence of fired sands and water repellent soils.
    McGhie DA
  • Causes of repellency. I. The nature of the hydrophobic compounds found in a New Zealand development sequence of yellow-brown sands.
    McIntosh JC
  • Increased sequestration of organic carbon in soil by hydrophobic protection.
    Piccolo A
  • Water repellency and its role in forming preferred flow paths in soils.
    Ritsema CJ
  • Flexible conformation in organic matter coatings: an hypothesis about soil water repellency.
    Roy JL
  • Petroleum residues as water-repellent substances in weathered nonwettable oil-contaminated soils.
    Roy JL
  • Substances contributing to fire induced water repellency in soils.
    Savage SM
  • Supercritical gas extraction of a soil with solvents of increasing polarities.
    Schnitzer M
  • Soil water repellency.
    Wallis MG
  • Adverse effects of drying temperature on the persistence of water repellency in Greek soils.
    Ziogas AK