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Response to O'Reilly et al. (2014)


Key Points

  • O'Reilly et al. (2013) made several errors in their paper regarding environmental forensic techniques for pyrogenic polycyclic aromatic hydrocarbons (PAHs).
  • Their use of alkylated PAHs in forensic evaluations to determine petrogenic (i.e., oil-based) sources of PAHs is limited for urban sediments that are frequently classified as pyrogenic (i.e., combustion sources).
  • O'Reilly et al. (2013) used a small number of samples from multiple sources in their principal components analysis figures and they simply do not have enough data to use this statistical technique.
  • The authors recommended using both the USEPA's chemical mass balance and Unmix models for evaluating the source apportionment of PAHs in sediment data sets; however, this will not be feasible for most studies because the Unmix model requires a large sample size.