9.4 Polycyclic Aromatic Hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs) are polluting our environment through
point and non-point sources. Basically, these compounds are the by-products of
many combustion processes of human beings, for example, residential heating
systems, industrial power generation, incineration, manufacturing, agricultural burning and petroleum combustion (Johnsen et al. 2005; Fu et al. 2012; Kim et al. 2013,
Stogiannidis and Laane 2015; Maletic et al. 2019). The most important industries
releasing PAHs are coke and carbon production, petroleum processing, aluminium
and sintering. Besides, the partial combustion and pyrolysis of fossil fuels or timber,
and the release of petroleum products are other sources of contamination. Additionally, further sources of PAHs are petroleum spills, oil seepage and diagenesis of
organic matters (Readman et al. 1987; Ke et al. 2002; Kriipsalu et al. 2008; Oyo-Ita
et al. 2016; Zhao et al. 2016). Other sources are unregulated fires such as agricultural, recreational and naturally occurring fires, crematoria, cigarette smoking,
volatilisation from soils and vegetation (Vione et al. 2004; Garcia-Falcon et al.
2006; Vane et al. 2013). Additional potential sources include medicinal dyes,
plastics and pesticide discharges. Also, extraterrestrial sources for PAHs are
discussed in the literature as prerequisites for the creation of life processes (Becker
et al. 1997; Snow et al. 1998; Salama et al. 1999; Ehrenfreund et al. 2011; Sabbah
et al. 2017). Although the core groups of polycyclic aromatic hydrocarbons (PAHs)
are not chiral, transformation products and associated PAH derivatives are reported
as chiral contaminants (Pangrekar et al. 2003; Platt and Grupe 2005; Hecht et al.
2010; Greene et al. 2017). Chiral PAH transformation products are today actively
used as bio-tracers for the elucidation of carcinogenic PAHs (i.e. Benzo[a]pyrene)
during microsomal transformation in mammals and humans (Mushtaq et al. 1986;
Luch et al. 1999; Pangrekar et al. 2003; Platt and Grupe 2005).
For 2007, a total global release of 504 Gg PAH was estimated by Shen et al. in
2013 (Shen et al. 2013). It is, hence, acknowledged that anthropogenic sources of
emissions are greater than natural ones (forest fires and volcanic eruptions) and that
these PAHs are inter-continentally transported via the atmosphere (Gilbert 1994;
Pozzoli et al. 2004; Kim et al. 2013; Mesquita et al. 2014; Li and Duan 2020). Chiral
PAH transformation products are currently investigated as tracers for the environmental mobility, biodegradability and toxicity assessment of their corresponding
parent compounds (Lai et al. 1989; Platt et al. 1990; Moody et al. 2003; Hecht and
Hochalter 2014). The major sources of PAHs are summarised in Table 9.3.
Table 9.2 Major sources for pesticide release into the environment
Point sources
Non-point sources (Diffusive)
Industrial production and discharge
Agricultural and forestry
Rural and urban sewage sludge
Evaporation
Municipal and industrial wastewater discharges
Spray drift, diffusive re-evaporation
Agricultural drainage
Ground and surface waters
Domestic release and municipal applications
Atmospheric distribution
9.4 Polycyclic Aromatic Hydrocarbons
259
Polycyclic aromatic hydrocarbons (PAHs) are polluting our environment through
point and non-point sources. Basically, these compounds are the by-products of
many combustion processes of human beings, for example, residential heating
systems, industrial power generation, incineration, manufacturing, agricultural burning and petroleum combustion (Johnsen et al. 2005; Fu et al. 2012; Kim et al. 2013,
Stogiannidis and Laane 2015; Maletic et al. 2019). The most important industries
releasing PAHs are coke and carbon production, petroleum processing, aluminium
and sintering. Besides, the partial combustion and pyrolysis of fossil fuels or timber,
and the release of petroleum products are other sources of contamination. Additionally, further sources of PAHs are petroleum spills, oil seepage and diagenesis of
organic matters (Readman et al. 1987; Ke et al. 2002; Kriipsalu et al. 2008; Oyo-Ita
et al. 2016; Zhao et al. 2016). Other sources are unregulated fires such as agricultural, recreational and naturally occurring fires, crematoria, cigarette smoking,
volatilisation from soils and vegetation (Vione et al. 2004; Garcia-Falcon et al.
2006; Vane et al. 2013). Additional potential sources include medicinal dyes,
plastics and pesticide discharges. Also, extraterrestrial sources for PAHs are
discussed in the literature as prerequisites for the creation of life processes (Becker
et al. 1997; Snow et al. 1998; Salama et al. 1999; Ehrenfreund et al. 2011; Sabbah
et al. 2017). Although the core groups of polycyclic aromatic hydrocarbons (PAHs)
are not chiral, transformation products and associated PAH derivatives are reported
as chiral contaminants (Pangrekar et al. 2003; Platt and Grupe 2005; Hecht et al.
2010; Greene et al. 2017). Chiral PAH transformation products are today actively
used as bio-tracers for the elucidation of carcinogenic PAHs (i.e. Benzo[a]pyrene)
during microsomal transformation in mammals and humans (Mushtaq et al. 1986;
Luch et al. 1999; Pangrekar et al. 2003; Platt and Grupe 2005).
For 2007, a total global release of 504 Gg PAH was estimated by Shen et al. in
2013 (Shen et al. 2013). It is, hence, acknowledged that anthropogenic sources of
emissions are greater than natural ones (forest fires and volcanic eruptions) and that
these PAHs are inter-continentally transported via the atmosphere (Gilbert 1994;
Pozzoli et al. 2004; Kim et al. 2013; Mesquita et al. 2014; Li and Duan 2020). Chiral
PAH transformation products are currently investigated as tracers for the environmental mobility, biodegradability and toxicity assessment of their corresponding
parent compounds (Lai et al. 1989; Platt et al. 1990; Moody et al. 2003; Hecht and
Hochalter 2014). The major sources of PAHs are summarised in Table 9.3.
Table 9.2 Major sources for pesticide release into the environment
Point sources
Non-point sources (Diffusive)
Industrial production and discharge
Agricultural and forestry
Rural and urban sewage sludge
Evaporation
Municipal and industrial wastewater discharges
Spray drift, diffusive re-evaporation
Agricultural drainage
Ground and surface waters
Domestic release and municipal applications
Atmospheric distribution
9.4 Polycyclic Aromatic Hydrocarbons
259