Determining the source of PAHs in sediment

S.D. Emsbo-Mattingly, A. Uhler, S. Stout, G. Douglas, K. McCarthy and A. Coleman

Abstract

The evaluation MGP tar impacts often requires a clear understanding of polycyclic aromatic hydro-carbon (PAH) origins in order to properly address issues of source control, nature and extent of contamination, and potential risk to biological receptors. Many redevelopment projects encounter problems in distinguishing PAHs from MGP and non-MGP sources at concentrations of total PAHs below 100 mg/kg (Table 1). While many of the issues discussed in this paper apply to soils, solids, oils and other media, the challenges for sediments are heightened because the tar residues must be distinguished in an environment where PAHs from many sources commonly commingle.

Distinguishing the origin of pyrogenic PAHs from multiple sources presents numerous technical challenges. In general, the PAH signatures of many natural, point, and non-point PAH sources are similar. The effects of environmental weathering on PAH residues and matrix interferences in environmental media often confuse the otherwise distinct source signature of PAHs. Consequently, multiple lines of evidence, including the innovative use of alternative measurement techniques, may be required to identify individual PAH source signatures in complex environmental media.

In this paper, data from a demonstration project and several field samples will illustrate the effective application of environmental forensics for assisting risk assessments and limiting MGP clean-up expenditures. The analytical methods featured include alkylated PAHs (GC/MS), saturate hydrocarbons (GC/MS), radiogenically dated sediment cores, and organic petrology. The interpretive techniques include chemical fingerprinting and source-specific diagnostic ratios.

Keywords: background, PAHs, sediments, source identification

© 2007 EPP Publications Ltd

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Article code 735