3.1.1 Emissions to the Atmosphere
Urban and industrial PAH emissions to the atmosphere were estimated based on the
INERIS (French National Institute for Environmental Technology and Hazards)
database. A recurrent spatial inventory of atmospheric pollutant emissions including
PAHs has been made since 2003 by the INERIS. It includes emissions from
all reported sources, whether anthropogenic or natural. Since source types were
specified, the PAH emissions related to household heating, road traffic and industrial
activities were estimated independently. Thus, household heating and road
traffic, respectively, amounted to E5a ¼ 11 tons year
À1 (Σ16, naphthalene included)
and E5b ¼ 4 tons year
À1 (Σ16) of PAHs, leading to total urban emissions of
E5 ¼ 15 tons year
À1 (Σ16). At the same time, industries emitted E6 ¼ 130 kg year
À1
(Σ16). As for all fluxes that were not supported by environmental data, the quality
grade was set at 0. In particular, although the source inventory was quite exhaustive,
the emission coefficients used to quantify the emissions could hardly be confirmed.
Therefore, the value of the estimated flux is provided as a rough estimate. However,
the order of magnitude was in agreement with a study reported by the French Center
for Atmospheric Pollution Study (CITEPA) that estimated the emissions of eight
PAHs (FLH, BaA, BaP, BbF, BkF, BghiP, IcdP and DahA) at 72 tons year
À1 for all
of metropolitan France (a sevenfold higher population).
3.1.2 Atmospheric Deposition
To quantify the atmospheric fallout over the Paris conurbation, PAH contents
were taken from four studies gathering 95 bulk deposition samples collected
between 2002 and 2014 [6, 20–22]. The seasonality in the atmospheric fallout
was instigated, and the concentrations of PAHs in the bulk deposition displayed
significant monthly changes (Kruskal-Wallis test, p-value < 0.05). The rise was
related to household heating during winter leading to significantly higher PAH
emissions. The annual deposition was consequently estimated as the sum over the
cold and the warm periods of the rainwater volumes over 4-day periods multiplied
by random concentration values drawn in the corresponding database. The 4-day
period was chosen to ensure a drawn probability for each sample of approximately
one out of the number of samples in the database (n ¼ 95). Following this method,
the atmospheric deposition totalled F12 ¼ 290 Æ 70 kg year
À1 (Σ15). This fallout
flux (160 g km
À2 year
À1 ) was lower than previously reported values within the
range 208–234 g km
À2 year
À1 [12, 23] measured over urban areas across the Seine
River basin from 1999 to 2002. These results suggest a decrease in the atmospheric
deposition over the past few decades, in agreement with the overall reduction of
about 44% in PAH emissions reported by the CITEPA between 2000 and 2014.
Because the database gathered a large number of samples representative in time
and space of the PAH atmospheric deposition in the Seine River basin, the flux
estimation was awarded the quality grade of 4.
170
D. Gateuille et al.
Urban and industrial PAH emissions to the atmosphere were estimated based on the
INERIS (French National Institute for Environmental Technology and Hazards)
database. A recurrent spatial inventory of atmospheric pollutant emissions including
PAHs has been made since 2003 by the INERIS. It includes emissions from
all reported sources, whether anthropogenic or natural. Since source types were
specified, the PAH emissions related to household heating, road traffic and industrial
activities were estimated independently. Thus, household heating and road
traffic, respectively, amounted to E5a ¼ 11 tons year
À1 (Σ16, naphthalene included)
and E5b ¼ 4 tons year
À1 (Σ16) of PAHs, leading to total urban emissions of
E5 ¼ 15 tons year
À1 (Σ16). At the same time, industries emitted E6 ¼ 130 kg year
À1
(Σ16). As for all fluxes that were not supported by environmental data, the quality
grade was set at 0. In particular, although the source inventory was quite exhaustive,
the emission coefficients used to quantify the emissions could hardly be confirmed.
Therefore, the value of the estimated flux is provided as a rough estimate. However,
the order of magnitude was in agreement with a study reported by the French Center
for Atmospheric Pollution Study (CITEPA) that estimated the emissions of eight
PAHs (FLH, BaA, BaP, BbF, BkF, BghiP, IcdP and DahA) at 72 tons year
À1 for all
of metropolitan France (a sevenfold higher population).
3.1.2 Atmospheric Deposition
To quantify the atmospheric fallout over the Paris conurbation, PAH contents
were taken from four studies gathering 95 bulk deposition samples collected
between 2002 and 2014 [6, 20–22]. The seasonality in the atmospheric fallout
was instigated, and the concentrations of PAHs in the bulk deposition displayed
significant monthly changes (Kruskal-Wallis test, p-value < 0.05). The rise was
related to household heating during winter leading to significantly higher PAH
emissions. The annual deposition was consequently estimated as the sum over the
cold and the warm periods of the rainwater volumes over 4-day periods multiplied
by random concentration values drawn in the corresponding database. The 4-day
period was chosen to ensure a drawn probability for each sample of approximately
one out of the number of samples in the database (n ¼ 95). Following this method,
the atmospheric deposition totalled F12 ¼ 290 Æ 70 kg year
À1 (Σ15). This fallout
flux (160 g km
À2 year
À1 ) was lower than previously reported values within the
range 208–234 g km
À2 year
À1 [12, 23] measured over urban areas across the Seine
River basin from 1999 to 2002. These results suggest a decrease in the atmospheric
deposition over the past few decades, in agreement with the overall reduction of
about 44% in PAH emissions reported by the CITEPA between 2000 and 2014.
Because the database gathered a large number of samples representative in time
and space of the PAH atmospheric deposition in the Seine River basin, the flux
estimation was awarded the quality grade of 4.
170
D. Gateuille et al.