Abstract The Seine River basin (France) is representative of the large urbanised
catchments (78,650 km
2 ) located in Northwestern Europe. As such, it is highly
impacted by anthropogenic activities and their associated emissions of pollutants
such as polycyclic aromatic hydrocarbons (PAHs). These compounds, originating
from household heating and road traffic, are responsible for serious environmental
issues across the basin. This study aims at establishing and using mass balance
analyses of PAHs at the Seine River basin scale as an efficient tool for understanding
PAH pathways in the environment. A dual-scale approach (urban vs. rural areas) was
used successfully, and mass balances provided useful knowledge on the environmental fate of PAHs. In urban areas, runoff and domestic and industrial discharges
contributed similarly to the PAH supply to the sewer system. During the wastewater
treatment process, PAHs were mainly eliminated through sludge removal. At the
basin scale, substantial amounts of PAHs were quantified in soils, and the limited
annual inputs and outputs through atmospheric deposition and soil erosion, respectively, suggest that these compounds have long residence times within the basin.
While wastewater and runoff discharges from urban areas account for a substantial
part of PAH urban fluxes to the Seine River, soil erosion seems to be the predominant contributor at the basin scale. Overall, the PAH flux at the basin outlet was
greater than supplies, suggesting that the Seine River system may currently be
undergoing a decontamination phase.
Keywords eLTER, Environmental fluxes, Mass balance, PIREN-Seine, Pollutant
fate, Polycyclic aromatic hydrocarbons, Seine River basin, Urban fluxes, Zone
Atelier Seine
1 Introduction
The Seine River basin (78,650 km
2
), located in Northwestern France, has been
studied since 1990 within the PIREN-Seine programme and can be considered as
representative of river basins exposed to the impacts of intense human activity [1, 2].
This basin accommodates a combination of strong human pressures (17 million
people, with approximately 10 million aggregated within the Paris conurbation; 30%
of French industrial and agricultural production) with very limited dilution by the
Seine River, due to its low flow (median flow, 300 m
3 s
À1 ); the basin therefore is
structurally vulnerable, and its river course downstream of the Paris conurbation
shows heavy contamination [1]. Similarly to other river basins in Europe, the SeineNormandie Water Agency reported that more than 50% of waterbodies were in poor
chemical status, mostly due to polycyclic aromatic hydrocarbons (PAHs).
PAHs are a group of widespread organic compounds. Due to their high toxicity
and their known carcinogenic properties for animals and humans [3], they constitute
an environmental threat. Besides natural sources, PAHs are mainly emitted by
anthropogenic activities such as combustion of fuels, coal and biomass or the use
of bitumen- and petroleum-containing products [4] or by domestic sources such as
tobacco smoke and cooking [5]. In Europe, PAHs (nine congeners) were included
164
D. Gateuille et al.
catchments (78,650 km
2 ) located in Northwestern Europe. As such, it is highly
impacted by anthropogenic activities and their associated emissions of pollutants
such as polycyclic aromatic hydrocarbons (PAHs). These compounds, originating
from household heating and road traffic, are responsible for serious environmental
issues across the basin. This study aims at establishing and using mass balance
analyses of PAHs at the Seine River basin scale as an efficient tool for understanding
PAH pathways in the environment. A dual-scale approach (urban vs. rural areas) was
used successfully, and mass balances provided useful knowledge on the environmental fate of PAHs. In urban areas, runoff and domestic and industrial discharges
contributed similarly to the PAH supply to the sewer system. During the wastewater
treatment process, PAHs were mainly eliminated through sludge removal. At the
basin scale, substantial amounts of PAHs were quantified in soils, and the limited
annual inputs and outputs through atmospheric deposition and soil erosion, respectively, suggest that these compounds have long residence times within the basin.
While wastewater and runoff discharges from urban areas account for a substantial
part of PAH urban fluxes to the Seine River, soil erosion seems to be the predominant contributor at the basin scale. Overall, the PAH flux at the basin outlet was
greater than supplies, suggesting that the Seine River system may currently be
undergoing a decontamination phase.
Keywords eLTER, Environmental fluxes, Mass balance, PIREN-Seine, Pollutant
fate, Polycyclic aromatic hydrocarbons, Seine River basin, Urban fluxes, Zone
Atelier Seine
1 Introduction
The Seine River basin (78,650 km
2
), located in Northwestern France, has been
studied since 1990 within the PIREN-Seine programme and can be considered as
representative of river basins exposed to the impacts of intense human activity [1, 2].
This basin accommodates a combination of strong human pressures (17 million
people, with approximately 10 million aggregated within the Paris conurbation; 30%
of French industrial and agricultural production) with very limited dilution by the
Seine River, due to its low flow (median flow, 300 m
3 s
À1 ); the basin therefore is
structurally vulnerable, and its river course downstream of the Paris conurbation
shows heavy contamination [1]. Similarly to other river basins in Europe, the SeineNormandie Water Agency reported that more than 50% of waterbodies were in poor
chemical status, mostly due to polycyclic aromatic hydrocarbons (PAHs).
PAHs are a group of widespread organic compounds. Due to their high toxicity
and their known carcinogenic properties for animals and humans [3], they constitute
an environmental threat. Besides natural sources, PAHs are mainly emitted by
anthropogenic activities such as combustion of fuels, coal and biomass or the use
of bitumen- and petroleum-containing products [4] or by domestic sources such as
tobacco smoke and cooking [5]. In Europe, PAHs (nine congeners) were included
164
D. Gateuille et al.