Passive sampling as an alternative strategy to monitor metals and PAHs trends at an upstream and rural catchment: a French case study

Abstract

AbstractThe study presents an alternative strategy to conventional spot sampling for monitoring metals and polycyclic aromatic hydrocarbons (PAHs) at an upstream, rural and karstic catchment in the north eastern part of France, in order to get insight into their spatial and temporal variability. Passive samplers, as diffusive gradients in thin films (DGT) and semipermeable membrane device (SPMD), are monthly deployed from August 2012 to March 2016 at five of the catchment monitoring stations located on the Saulx and Ornain Rivers. An improvement of the frequency of quantification (by a factor 2 to 8, depending on the targeted compound) is observed allowing us to better identify spatial and temporal variability. For instance, the upstream monitoring station on the Saulx River is characterized by high concentrations of Ni and Mn whereas the upstream monitoring station on the Ornain River is enriched in Cu and Zn. Furthermore, five metals (Al, Fe, Mn, Ni, Zn) and three PAHs (fluoranthene, pyrene and chrysene) show significant variations with water levels when grouped in three categories (low, medium and high water levels) in relation with hydrological and climatic patterns. This study leads to a more accurate assessment of the background pollution in metals and PAHs within surface waters than when based on spot sampling data.