Environmental aging of polycyclic aromatic hydrocarbons on soot and its effect on source identification

Abstract

Soot associated PAHs were exposed to simulated sunlight to investigate disappearance rates under environmental aging conditions and to examine the robustness of diagnostic ratios for PAH source apportionment. Naphthalene, acenaphthylene, acenaphthene, and fluorene showed an obvious twophase disappearance in all experiments while phenanthrene and anthracene exhibited this behavior for all but the highest soot loading. The first phase loss is 5-40 times faster than the second phase loss and occurred within 3 h for naphthalene, acenaphthylene, acenaphthene, and fluorene and within 10 h for phenanthrene and anthracene. Two-phase disappearance was not observed for any of the higher molecular weight PAHs with 4-6 rings. Each PAH has a unique loss rate via photodegradation and volatilization and these rates of some PAHs were affected by soot loadings; phenanthrene and anthracene showed similar rates in the first phase and increased loss rates in the second phase as soot loading increased. In the absence of light, the loss of PAHs was related to both temperature and molecular characteristics. Due to differences in disappearance rates of individual PAHs under illumination over extended times, prolonged exposure to sunlight could change the interpretation of some diagnostic ratios used previously for PAH source identification. This result indicates that more consistent and accurate methods that take into consideration the longevity of particulate PAHs are needed for reliable source apportionment.

An integrated approach for the evaluation of technological hazard impacts on air quality: the case of the Val d'Agri oil/gas plant

“…The formation of this cluster can be explained by incomplete combustion processes as a common source of all the three parameters, and highlights the strong interaction between the particle phase represented by BC and the organic molecular species contained in UVPM. These molecules, quantitatively determined by THC concentration measurements, are verified to have a high probability to be adsorbed on BC particles surfaces (Kim et al, 2009). From concentration values in Table 3, it can be easily verified that more than 90 % of THC consists of methane, and therefore a good correlation between BC, UVPM and CH 4 can be inferred from CA.…”

Polycyclic aromatic hydrocarbons in deep sea sediments: Microbe–pollutant interactions in a remote environment

“…Sorption also increases with increasing soil organic carbon content (Wang et al, 2001) and decreasing pore size (Semple et al, 2003). In soot, a carbon-rich matrix, pyrolytic PAHs are highly sorbed and occluded, which reduces their degradation in comparison to other surfaces (Kim et al, 2009). At DSS organic carbon content is lower than at coastal marine sediments (Nagata et al, 2010) thus PAHs are more bioavailable.…”

Phototransformation rate constants of PAHs associated with soot particles

“…In this work we apply the same approach, but for PAH photodegradation in bulk deposits of soot particles collected onto Teflon filters, using our recently published disappearance profiles of illuminated PAHs on soot (Kim et al, 2009). Applying eq.…”