Mass Balance of PAHs at the Scale of the Seine River Basin

E Guigon,J Gasperi,D Thevenot,C Briand,R Moilleron,S Azimi,M Meybeck,V Rocher,D Gateuille,J.-M Brignon,M Blanchard,F Alliot,J.-M Mouchel,M Chevreuil,M.-J Teil

doi:10.1007/698_2019_382

Abstract

AbstractThe Seine River basin (France) is representative of the large urbanised catchments (78,650 km2) 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.

Highlights

The Seine River basin (78,650 km2), 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]
Since source types were specified, the polycyclic aromatic hydrocarbons (PAHs) emissions related to household heating, road traffic and industrial activities were estimated independently
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 yearÀ1 for all of metropolitan France

Summary

Introduction

The Seine River basin (78,650 km2), 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 m3 sÀ1); the basin is structurally vulnerable, and its river course downstream of the Paris conurbation shows heavy contamination [1]. In the European Union, water policy is based on a number of specific directives defining communitywide emission limit values and quality objectives in surface and coastal waters. The implementation of such directives requires member states to reach “good chemical” status. Based on the last report (2012, European waters – assessment of status and pressures, EEA Report), PAHs appear as a widespread cause of poor status in rivers and are identified as problematic by 11 member states

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