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This article in JEQ

  1. Vol. 31 No. 6, p. 1963-1971
     
    Received: Oct 16, 2001


    * Corresponding author(s): Hubert.deJonge@agrsci.dk
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doi:10.2134/jeq2002.1963

Transport of Di(2-ethylhexyl)phthalate (DEHP) Applied with Sewage Sludge to Undisturbed and Repacked Soil Columns

  1. H. de Jonge *a,
  2. L. W. de Jongea,
  3. B. W. Blicherb and
  4. P. Moldrupb
  1. a L.W. de Jonge, Danish Institute of Agricultural Sciences, Dep. of Crop Physiology and Soil Science, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark
    b Dep. Environmental Engineering, Aalborg University, Sohngaardsholmvej 57, DK-9000 Aalborg, Denmark

Abstract

Municipal sewage sludge is often used on arable soils as a source of nitrogen and phosphorus, but it also contains organic contaminants that may be leached to the ground water. Di(2-ethylhexyl)phthalate (DEHP) is a priority pollutant that is present in sewage sludge in ubiquitous amounts. Column experiments were performed on undisturbed soil cores (20-cm depth × 20-cm diameter) with three different soil types: a sand, a loamy sand, and a sandy loam soil. Dewatered sewage sludge was spiked with 14C-labeled DEHP (60 mg kg−1) and bromide (5 g kg−1). Sludge was applied to the soil columns either as five aggregates, or homogeneously mixed with the surface layer. Also, two leaching experiments were performed with repacked soil columns (loamy sand and sandy loam soil). The DEHP concentrations in the effluent did not exceed 1.0 μg L−1, and after 200 mm of outflow less than 0.5% of the applied amount was recovered in the leachate in all soils but the sandy loam soil with homogeneous sludge application (up to 3.4% of the applied amount recovered). In the absence of macropore flow, DEHP in the leachate was primarily sorbed to mobilized dissolved organic macromolecules (DOM, 30.3 to 81.3%), while 2.4 to 23.6% was sorbed to mobilized mineral particles. When macropore flow occurred, this changed to 16.5 to 37.4% (DOM) and 36.9 to 40.6% (mineral particles), respectively. The critical combination for leaching of considerable amounts of DEHP was homogeneous sludge application and a continuous macropore structure.

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Copyright © 2002. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.31:1963–1971.