Environmental Engineering Reference
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5.4.3
The Ratio of Benz[ a ]anthracene to Chrysene 6
Benz[ a ]anthracene (BaA) is preferentially produced over chrysene (C0) during the
combustion of fossil fuel or of biomass (Dvorska et al. 2011 ; Yunker et al. 2002 ).
Yunker et al. ( 2002 ) have suggested that BaA/C0 < 0.25 indicates petroleum sources,
0.25 < BaA/C0 ≤ 0.5 indicates mixed sources and BaA/C0 ≥ 0.5 indicates combus-
tion (e.g., vehicular emissions). In contrast, De Luca et al. ( 2004 ) have suggested
that the transition point from petrogenesis to pyrogenesis is at BaA/C0 = 1.
Nevertheless, the BaA/C0 ratio is well above 1 for gasoline and above 0.5 for coals
(Fig. 15 ). Examples of pyrogenic sources below the threshold of 0.5 are creosote
and the combustion of some coals, diesel and gasoline. Only anthracite combustion
and some combusted diesels have BaA/C0 values below 0.25.
The BaA/C0 ratio has sometimes been used in conjunction with the IP/ ghi ratio,
to distinguish between automobile and domestic heating sources (e.g., Dvorska
et al. 2011 ; Sofowote et al. 2008 ), or to apportion the contributions from coal tar and
paving bitumen to urban runoff and sediments (Ahrens and Depree 2010 ; Dupree
and Ahrens 2007 ). BaP/BbF (five-ringed PAHs) and BaA/C0 have been success-
fully used to differentiate Al smelter sludge from creosote pilings (Boehm and Saba
2008 ). The combination of A0/P0 (the inverse of P0/A0) and the BaA/C0 ratio can
be used to distinguish between pyrogenic sources and crude oils because both ratios
are higher for pyrogenic sources (Wang et al. 1999b , 2001 ). Sofowote et al. ( 2009 )
factorized both the A0/P0 and the BaA/C0 ratios into a new ratio that is more robust
than both constituent ratios. Zeng and Vista ( 1997 ) found that the BaA/C0 ratio cor-
related with the P1/P0 and P0/A0 ratios. However, the BaA/C0 ratio correlates only
weakly with the FL0/PY0 ratio (De Luca et al. 2004 ). Yunker et al. ( 2002 ) observed
negligible amounts of BaA in wood combustion and used the BaA/C0 ratio plus the
DMP ratio to trace wood combustion.
The BaA/C0 ratio is stable over different concentration ranges and aerobic deg-
radation and evaporation conditions (Costa and Sauer 2005 ; Uhler and Emsbo-
Mattingly 2006 ). However, caution is advised when only the BaA/C0 ratio is used
to distinguish different types of creosotes in sediments, especially if influences from
urban background (lower ratio) or weathering are possible (Mauro 2008 ; Stout et al.
2003 ; Yan et al. 2005 , 2006 ). Compared with C0, BaA is more easily photolyzed
and has a different environmental behavior (Dvorska et al. 2011 ; Tobiszewski and
Namiesnik 2012 ; Yunker et al. 2002 ). Yunker et al. ( 2002 ) reported that the photoly-
sis patterns for the BaA/C0 and the P0/A0 ratios were similar. Chrysene is the more
stable isomer and BaA can convert to C0 during degradation (De Luca et al. 2004 ;
Soclo et al. 2000 ). Therefore, the applicability of BaA/C0 in weathered sediments
may be questionable (Stout et al. 2003 ; Yan et al. 2005 ; Yunker et al. 2002 ).
6 The BaA/228 (i.e., the denominator is the sum of PAHs that have MW = 228) is sometimes used
instead of BaA/C0, because of the coelution of triphenylene (TPh) and chrysene (e.g., Gogou et al.
2000 ). In this paper no discrimination is made between the two ratios.
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