Establishing Criteria of Relative Abundance of Alkyl Polycyclic Aromatic Hydrocarbons (PAHs) for Differentiation of Pyrogenic and Petrogenic PAHs: An Application to Indian Sediment

Abstract

Various source materials such as crude oil, automobile exhaust, coal, and wood combustion products were analyzed for polycyclic aromatic hydrocarbons (PAHs) and hopanes. Hopanes were detected in coal combustion-derived soot, along with petrogenic sources. Based on the correlation between the alkylated PAHs/parental PAHs ratio with their respective C 30 hopane/PAHs ratio in these source materials, the criteria for differentiating the petrogenic and pyrogenic sources of PAHs were established. This study concluded that sediments contained exclusively pyrogenic PAHs when the following conditions were met: MP/P (methylphenanthrenes to phenanthrene) = 0.5, MPy/Py [(methylpyrenes + methylfluoranthenes) to (pyrene + fluoranthene)] = 0.15, and MC/C [(methylchrysenes + methylbenz[a]anthracenes) to (chrysene + benz[a]anthracene)] = 0.2. By contrast, the sediments contained exclusively petrogenic PAHs when the ratios of MP/P, MPy/Py, MC/C, and methyl PAHs (MPAHs)/PAHs exceeded 3.5, 1.5, 2.0, and 2.2, respectively. Based on these criteria, an intensive source apportionment of PAHs to sediments from three Indian metro cities, Chennai (n = 6), Mumbai (n = 6) and Kolkata (n = 12) (2003)(2004)(2005)(2006)(2007), was determined. This investigation found that sedimentary PAHs from India were depleted in alkylated PAHs with low MP/P ≈ 0.7, MPy/Py ≈ 0.14, and MC/C ≈ 0.3, which contrasted with other tropical Asian countries, where elevated values of these ratios were detected. Among the three cities, Kolkata waters were more strongly influenced by pyrogenic sources of PAHs with very low alkylated PAHs ratios than Chennai and Mumbai sediments. The compositional differences were attributed to the dominant coal and biomass in Kolkata compared to the dominant usage of petrogenic cooking fuel (e.g., kerosene) and automobile-derived sources in Chennai and Mumbai.

Seasonal Trends of Atmospheric PAHs in Five Asian Megacities and Source Detection Using Suitable Biomarkers

“…4). These ratios are described in our previous studies (Saha et al, 2009(Saha et al, , 2012, which show that vehicle exhausts have high values of these ratios (MP/P > 3.5, MPy/Py > 1.5, MC/C > 2.0, MPAHs/PAHs > 2.2), whereas high-temperature combustion of coal and wood produces low ratios (MP/P < 0.5, MPy/Py < 0.15, MC/C < 0.2, MPAHs/PAHs < 0.3).…”

“…The higher abundance of β isomers (17β21β(H)-C 30 [C 30 17β] and 17β21β(H)-C 29 [C 29 17β]hopanes) in winter aerosols of Beijing are identical to those in coal soot, in correspondence with the mass usage of coal during winter. Hopanes are generally found in petrogenic sources, but can be used as biomarkers of coal as well (Oros and Simoneit, 2000;Simoneit et al, 2007;Saha et al, 2012). The abundance of β homologues in the hopane profiles indicates a clear demarcation between coal-combustion-related hopanes and vehicle-exhaust-related hopanes; β isomers are usually found in higher abundance in coal-combustion-derived source than in vehicle-derived sources (Saha et al, 2012).…”

“…During combustion at high temperatures such as coal and wood combustions, alkyl PAHs is exhausted. Butin petroleum, which is diagenetically generated at low temperatures in the crust, they remain in abundance (Saha et al, 2009(Saha et al, , 2012. Thus, mixing of residual petroleum components with combustion products created higher ratios of methyl PAHs to parent PAHs in vehicle exhaust, whereas coal and wood combustion produced lower ratios (Fig.…”

“…Hence, it is important to understand the abundance, speciation, distribution, and potential sources of PAHs in aerosols so that the diverse effects of PM can be efficiently controlled. The adverse properties of PAHs, together with their still growing emission to the environment, make their monitoring a top priority in the evaluation of both human health risk and environmental hazards (Chetwittayachan et al, 2002;Saha et al, 2012).…”

“…The main source of PAHs in Kuala Lumpur, Malaysia, is vehicular emissions, since motor vehicles contribute as much as 82% of atmospheric pollutants (MEQR, 1996; Atmospheric PAHs can be formed by coal or wood combustion or by petroleum combustion. Petroleum-derived sources are evaluated by using hopane biomarkers (Zakaria et al, 2000(Zakaria et al, , 2001(Zakaria et al, , 2002Boonyatumanond et al, 2006;Saha et al, 2009Saha et al, , 2012Yu et al, 2016). Hopanes are pentacyclic C 27 to C 35 triterpenes and are ubiquitously present in crude oil.…”