Microbial degradation of street dust polycyclic aromatic hydrocarbons in microcosms simulating diffuse pollution of urban soil

Anders R. Johnsen, Julia R. de Lipthay, Søren J. Sørensen, Flemming Ekelund, Peter Christensen, Ole Andersen, Ulrich Karlson, Carsten S. Jacobsen

Research output: Contribution to journalArticleResearchpeer-review

43 Citations (Scopus)

Abstract

Diffuse pollution with polycyclic aromatic hydrocarbons (PAHs) of topsoil in urban regions has caused increasing concerns in recent years. We simulated diffuse pollution of soil in microcosms by spiking sandy topsoil (A-horizon) and coarse, mineral subsoil (C-horizon) with street dust (PM63) isolated from municipal street sweepings from central Copenhagen. The microbial communities adapted to PAH degradation in microcosms spiked with street dust in both A-horizon and C-horizon soils, in spite of low PAH-concentrations. The increased potential for PAH degradation was demonstrated on several levels: by slowly diminishing PAH-concentrations, increased mineralization of 14C-PAHs, increasing numbers of PAH degraders and increased prevalence of nah and pdo1 PAH degradation genes, i.e. the microbial communities quickly adapted to PAH degradation. Three- and 4-ring PAHs from the street dust were biodegraded to some extent (10-20%), but 5- and 6-ring PAHs were not biodegraded in spite of frequent soil mixing and high PAH degradation potentials. In addition to biodegradation, leaching of 2-, 3- and 4-ring PAHs from the A-horizon to the C-horizon seems to reduce PAH-levels in surface soil. Over time, levels of 2-, 3- and 4-ring PAHs in surface soil may reach equilibrium between input and the combination of biodegradation and leaching. However, levels of the environmentally critical 5- and 6-ring PAHs will probably continue to rise. We presume that sorption to black carbon particles is responsible for the persistence and low bioaccessibility of 5- and 6-ring PAHs in diffusely polluted soil.

Original languageEnglish
Pages (from-to)535-545
Number of pages11
JournalEnvironmental Microbiology
Volume8
Issue number3
DOIs
Publication statusPublished - Mar 2006

Programme Area

  • Programme Area 2: Water Resources

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