Table 2.

Summary of key findings from three lines of evidence used in support of PAH source apportionment in NS SCH sediments.

Approach	Details	Key Finding (s)	Estimated Source
Diagnostic Ratio	Fluoranthene/(Fluoranthene + Pyrene)	All regions present values >0.5	Wood/grass/coal combustion (Yunker et al., 2002)
	Anthracene/(Anthracene + Phenanthrene)	All regions present values >0.1	Combustion (Yunker et al., 2002)
	Benzo[a]anthracene/(Benzo[a]anthracene + Chrysene)	All regions present values >0.35	Combustion (Yunker et al., 2002)
	Indeno[1,2,3-cd] pyrene/(Indeno [1,2,3cd] pyrene + Benzo[g,h,i]perylene).	Gulf, Eastern and Combined present values between 0.2–0.5, while Southwest region is >0.5	0.2–0.5 indicates petroleum combustion, while >0.5 supports wood/grass/coal combustion (Yunker et al., 2002)
	LMW PAHs/HMW PAHs	HMW PAHs dominate NS SCHs, all regions demonstrate a ratio value of <1.	Combustion (Hwang and Foster, 2006; Zhang et al., 2008)
Unmix Optimum Receptor Modeling	Unmix Optimum identified four sources which best fit NS SCH data.	Source 1 presents high loadings of including BaP, BkF, BbF, BaA. Source 1 contributes 32% to total PAHs.	Coal combustion/vehicle emissions
		Source 2 presents high loadings of Flu and Pyr. Source 2 contributes 47% to total PAHs.	Coal/biomass combustion
		Source 3 presents high loadings of Phe and Ant. Source 3 contributes 11% to total PAHs.	Mixed petrogenic source
		Source 4 presents high loadings of Phe, Ace, and Fl. Source 4 contributes 10% to total PAHs.	Mixed source of petrogenic and pyrogenic origins.
Compositional Analysis	Assessment (%) of 2–6 ring PAHs across Gulf, Eastern, and Southwest regions.	4-ring PAHs compose over 50% of all PAHs among regions. HMW PAHs (4–6 rings) form the greatest proportion among all regions.	The abundance of HMW PAHs suggests combustion origin (McCready et al., 2000)
	Correlation analysis of PAHs [∑Comb] and ∑PAH16	Strong positive relationship between ∑Comb and ∑PAH16 (r2= 0.958)	Combustion derived PAHs dominate the total PAH profile