Source Characterization of Polycyclic Aromatic Hydrocarbons by Using Their Molecular Indices: An Overview of Possibilities - Reviews of Environmental Contamination and Toxicology - page 71

attributable to urban background, unless site- or region-specific survey data support
a different urban background concentration profile.
As with street dust, the most abundant of the 16 parent PAHs in storm water
(and in urban background) are fluoranthene and pyrene, and to a lesser extent,
phenanthrene and anthracene (Battelle Memorial Institute et al. 2003 ; Karlsson and
Viklander 2008 ). Urban background is generally enriched in four- to six-ringed
PAHs, and depleted in LMW PAHs (Battelle Memorial Institute et al. 2003 ). In
urban runoff, the pyrogenic homologues of fluoranthene and chrysene, and to a
lesser extent those of phenanthrene and anthracene exhibit the sloping pyrogenic
pattern. Therefore, urban background reflects pyrogenic characteristics that are dis-
tinct from those of other pyrogenic sources. Nevertheless, weathering may alter a
pyrogenic fingerprint (preferential elimination of LMW and parent PAHs over
HMW and alkylated PAHs) to resemble that of urban background (Battelle Memorial
Institute et al. 2003 ).

2.3 Biogenic/Diagenetic

Diagenetic PAHs are produced during the slow transformation of organic materials
in lake sediments, whereas biogenic PAHs are produced by plants, algae/phyto-
plankton and microorganisms (Venkatesan 1988 ). Perylene (PER) is produced
under several conditions: by diagenesis and biosynthesis from terrestrial precursors
(e.g., perylenequinone pigment) or other organic matter; under anoxic conditions;
and in soil and subtidal, marine and freshwater sediments (e.g., Boll et al. 2008 ;
Guo et al. 2007 ; Venkatesan 1988 ; Zakaria et al. 2002 ). In the tropics, termite nests
may act as a perylene source in soil (Barra et al. 2007 ; Mandalakis et al. 2004 ;
Wilcke et al. 2002 ).
If perylene does not correlate with the total organic carbon, then the perylene is
likely to have a natural origin (Luo et al. 2008 ). In such a case, perylene may not
yield its source of organic matter, although it can be a useful tracer for water and for
depositional conditions (Budzinski et al. 1997 ). For instance, assuming a biogenic
perylene origin, Page et al. ( 1996 ) used perylene depth gradients to show lack of
vertical mixing.
Other PAHs such as benzo[ b ]luoranthene (BbF), phenanthrene (P0) and naphtha-
lene (N0) can originate from vascular land plants or termite activity (Bakhtiari et al.
2009 ; Irwin et al. 1997 ; Tobiszewski and Namiesnik 2012 ). Benzo[ a ]pyrene can be
biosynthesized by certain bacteria and plants (Peters et al. 2005 ). Retene (RET) can
be produced from the anaerobic microbial degradation of dehydroabietic acid (pres-
ent in tire particles in urban areas) in soils and sediments (Mandalakis et al. 2004 ).
Perylene or biogenic-diagenetic PAHs also potentially have anthropogenic
sources. PER has been detected in trace amounts after pyrolytic processes
(Luo et al. 2008 ), such as coal pyrolysis in municipal incinerator waste products and
automotive emissions (Abrajano et al. 2003 ; Boll et al. 2008 ; Gogou et al. 2000 ).