Source Characterization of Polycyclic Aromatic Hydrocarbons by Using Their Molecular Indices: An Overview of Possibilities - Reviews of Environmental Contamination and Toxicology - page 62

For this reason, it is suggested that highly alkylated PAHs (e.g., P4 or P3-phenan-
threnes) be selected and used for identifying the source of PAHs in distilled oil
products such as diesel and jet fuel samples (Wang et al. 1999a ).
Some coal PAHs have been characterized, as occasionally has their contribution
to sediment contamination (Achten and Hofmann 2009 ; Boehm et al. 2001 ; Dzou
et al. 1995 ; Peters et al. 2005 ; Radke et al. 1982 ; Stout and Emsbo-Mattingly 2008 ).
Lower rank coals (lignite and sub-bituminous coal) may contain significant amounts
of perylene. Dibenzothiophenes may also be abundant in coals (Stark et al. 2003 ).
Coal PAHs are generally not bioavailable and the concentrations at which they exist
are below risk limits. However, they are of practical interest in forensic studies, and
for understanding potential sources of PAHs (Stout and Emsbo-Mattingly 2008 ).
The PAH distribution patterns in coals seem to be a function of coal rank (Fig.
S27, Supporting Material; Radke et al. 1982 ; Stout and Emsbo-Mattingly 2008 ).
The higher the coal rank, the more dominant are the LMW compounds over the
HMW ones (petrogenic characteristic). However, the homologous series of phenan-
threnes (minus retene), fluoranthenes and chrysenes show a bell-shaped PAH profile
in low rank coals (typical of petrogenic PAHs). In higher coal ranks, this bell-shaped
profile shifts to a pyrogenic-like skewed pattern that is dominated by parent PAHs
(Fig. S27, Supporting Material).
Leakage, spillage and dumping of fresh and used lubricating oils (Fig. 1e ; Figs.
S12-S15, Supporting Material) are major sources of PAHs in the aquatic environ-
ment of Malaysia (Zakaria et al. 2002 ). “Fresh” lubricants are severely depleted of
HMW PAHs and contain small amounts of LMW PAHs, such as dibenzothiophenes
(Denton 2006 ; Sicre et al. 1987 ; Wang et al. 2004 ; Zakaria et al. 2002 ). In contrast,
the PAH content of used lubricating oil is three orders of magnitude higher than that
of fresh lubricating oil. The “extra” PAHs are derived both from the accumulation
of PAHs formed in the engine combustion chamber (Pyrogenic HMW compounds)
and from the incorporation of petrogenic PAHs from unburned fuel (gasoline or
diesel alkyl-homologues such as P1) into the lubricating oil (Boonyatumanond et al.
2007 ; Douglas et al. 2007a ; Zakaria et al. 2002 ). For example, methylphenanthrenes
are less abundant in diesel than in used lubricating oils (Boonyatumanond et al.
2007 ). Thus, lubricants used in fuel combustion chambers might be classified as a
mixed source of PAHs that show an enhanced pyrogenic profile (Fig. 1e and Figs.
S12-S15, Supporting Material).
A significant amount of liquid fuel used in vehicles or in other combustion pro-
cesses may be unburned (up to 1.2%), and therefore may contain the initial petro-
genic fingerprint (Fig. 4 , Figs. S16, S17, Supporting Material) of the fuel as vapor
(Bucheli et al. 2004 ; Lehndorff and Schwark 2009 ; Simoneit 1985 ; Wang et al.
1999b ; Williams et al. 1986 ; Zeng and Vista 1997 ). For example, automobile and
boat engine exhausts contain both petroleum residues and incomplete combustion
products (Zeng and Vista 1997 ). In Tokyo, Japan, alkyl PAHs and the street dust of
heavily traveled roads contained a greater abundance of alkyldibenzothiophenes than
the street dust from roads in residential areas (Takada et al. 1990 ). Diesel fuel con-
tributes more alkylated, sulfur and three-ringed PAHs (petrogenic fingerprint) to the
atmosphere than does gasoline (Hwang et al. 2003 ; Lehndorff and Schwark 2009 ).