Persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil

Environ Sci Pollut Res Int. 2015 Jan;22(2):1344-56. doi: 10.1007/s11356-014-3386-6. Epub 2014 Aug 21.

Abstract

Halogenated carbazoles have recently been detected in soil and water samples, but their environmental effects and fate are unknown. Eighty-four soil samples obtained from a site with no recorded history of pollution were used to assess the persistence and dioxin-like toxicity of carbazole and chlorocarbazoles in soil under controlled conditions for 15 months. Soil samples were divided into two temperature conditions, 15 and 20 °C, both under fluctuating soil moisture conditions comprising 19 and 44 drying-rewetting cycles, respectively. This was characterized by natural water loss by evaporation and rewetting to -15 kPa. Accelerated solvent extraction (ASE) and cleanup were performed after incubation. Identification and quantification were done using high-resolution gas chromatogram/mass spectrometer (HRGC/MS), while dioxin-like toxicity was determined by ethoxyresorufin-O-deethylase (EROD) induction in H4IIA rat hepatoma cells assay and multidimensional quantitative structure-activity relationships (mQSAR) modelling. Carbazole, 3-chlorocarbazole and 3,6-dichlorocarbazole were detected including trichlorocarbazole not previously reported in soils. Carbazole and 3-chlorocarbazole showed significant dissipation at 15 °C but not at 20 °C incubating conditions indicating that low temperature could be suitable for dissipation of carbazole and chlorocarbazoles. 3,6-Dichlorocarbazole was resistant at both conditions. Trichlorocarbazole however exhibited a tendency to increase in concentration with time. 3-Chlorocarbazole, 3,6-dibromocarbazole and selected soil extracts exhibited EROD activity. Dioxin-like toxicity did not decrease significantly with time, whereas the sum chlorocarbazole toxic equivalence concentrations (∑TEQ) did not contribute significantly to the soil assay dioxin-like toxicity equivalent concentrations (TCDD-EQ). Carbazole and chlorocarbazoles are persistent with the latter also toxic in natural conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacteria / drug effects
  • Bacteria / growth & development
  • Bacteria / isolation & purification
  • Carbazoles / chemistry
  • Carbazoles / toxicity*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Dioxins / analysis
  • Dioxins / toxicity
  • Dodecenoyl-CoA Isomerase
  • Gas Chromatography-Mass Spectrometry
  • Rats
  • Soil / chemistry
  • Soil Microbiology
  • Soil Pollutants / chemistry
  • Soil Pollutants / toxicity*

Substances

  • Carbazoles
  • Dioxins
  • Soil
  • Soil Pollutants
  • carbazole
  • Dodecenoyl-CoA Isomerase