Source Characterization of Polycyclic Aromatic Hydrocarbons by Using Their Molecular Indices: An Overview of Possibilities - Reviews of Environmental Contamination and Toxicology - page 68

Lower coal combustion temperatures (e.g., domestic stoves) yield more PAHs than
do high-temperature processes, such as in coal power plants (Chen et al. 2005 ; Oros
and Simoneit 2000 ). Therefore, in addition to coal content, the combustor is crucial
when calculating coal PAH emissions.
Much attention has been paid to increased creosote PAH contamination in
sediments, particularly in the U.S. (Brenner et al. 2002 ; Stout et al. 2001a , 2003 ).
Coal tar, creosote and coal tar pitch contain very large quantities of pyrogenic PAHs
(>10%). As a result, small amounts of these materials greatly influence the distribu-
tion of PAHs in sediments (Stout et al. 2001b ). Two- and three-ringed PAHs are
abundant in creosote. For example, parent PAHs, such as naphthalene (N0), ace-
naphthene (AE), fluorene (F0), phenanthrene (P0), fluoranthene (FL0) and pyrene
(PY0) (see also Fig. S28a, Supporting Material), dominate over four- to six-ringed
PAHs (Stout et al. 2001a and references therein).
Creosote degradation (Fig. S28b-d, Supporting Material) results in the loss of
LMW PAHs and a PAH signature dominated by four to six rings (increasing abun-
dance of benz[ a ]anthracenes, chrysenes, benzofluoranthenes, benzopyrenes)
(Brenner et al. 2002 ; Stout et al. 2003 ). This fingerprint is hardly distinguishable
from the urban background, which contains mainly pyrolytic sources. Therefore,
creosote is classified as a pyrogenic PAH source (Stout et al. 2001b ).
Industrial activities such as coke and steel production have released large quanti-
ties of not only pyrogenic PAHs (Orecchio 2010 ; Saber et al. 2005 ), but also of
LMW PAHs such as naphthalene (Fig. S31), and all of these PAHs eventually end up
in soil or sediment (Karlsson and Viklander 2008 ; Morillo et al. 2008b ). Distillation
of tars (e.g., coal tar) alters the pyrogenic PAH composition (depending on the PAH
boiling point), leading to mixtures enriched in LMW PAHs, as occurs with creosote
(Neff et al. 2005 ). Coal tar PAHs are present in pavements and asphalt, and result
from high-temperature baking of hard coal in a reducing atmosphere to produce
coke and manufactured gas. These sources (i.e., those rich in PAHs such as benz[ a ]
anthracene, chrysene, indeno[ 1 , 2 , 3 - cd ]pyrene and benzo[ ghi ]perylene), show a
characteristic pyrogenic profile (Fig. 5e ), and are likely to be washed out by rain and
end up in sediments (Douglas et al. 2007a ; Neff et al. 2005 ; Yunker et al. 2002 ).
PAH patterns in paving materials show distributions of both LMW PAHs (petro-
genic) and HMW PAHs (pyrogenic) (Fig. 5 ). Such patterns reflect the blending that
occurs with different types of heavy petroleum products (Fig. 1c, d ), paving materials
(Fig. 5a ) and coal tar (Fig. 5e ) (Douglas et al. 2007a ). In general, PAHs heavier than
fluoranthene or pyrene (and to a lesser extent anthracene, phenanthrene, and acenaph-
thene) are dominant in such materials, although coal tar pitch or tar residues may be
enriched in naphthalenes, phenanthrenes, and possibly dibenzothiophenes (Figs. S29,
S30; Supporting Material; Saber et al. 2006 ). The HMW PAH tar fingerprint is mini-
mally changed, even after degradation (Uhler and Emsbo-Mattingly 2006 ), making it
possible to use HMW PAHs to characterize coal tars (Costa et al. 2004 ).
Street dust is transported in sediments, rivers, wastewater treatment plants and
estuaries via street runoff, which is an important source and pathway of how PAHs
reach sediment, particularly in regions that have high and intense rainfall events