Particle-Dissolved Phase Partition of Polychlorinated Biphenyls in High Altitude Alpine Lakes

Abstract

We investigated whether polychlorinated biphenyls (PCBs) partitioning between the dissolved and particulate phases in two high altitude alpine lakes was determined by the quantity, size structure, or composition of suspended particles. Within- and between-lakes differences in water-particulate phase partition coefficient (Kp) were not related to total suspended matter, phytoplankton biomass, or taxonomic composition. Yet, a seasonal relationship between Kp and Kow was detected for both lakes, revealing equilibrium of PCBs partition when lakes were ice covered. On the contrary, PCBs partitioning between particles and water appeared kinetically limited during the open water season. Partition is therefore mainly governed by thermodynamic laws during the ice-covered period, while none of the tested physical or biological parameters seemed to explain the distribution of these particle-reactive contaminants in the open water period. PCBs were always mainly associated with particulate matter, but partitioning within different particulate size-fractions varied between seasons and between years during open water periods. When ice cover is absent, PCBs were mainly adsorbed on microplankton, the largest phytoplanktonic size fraction, which is the least likely to get grazed by pelagic microconsumers.

Storm impacts on alpine lakes: Antecedent weather conditions matter more than the event intensity

“…The area surrounding the lake is covered by an alpine lawn and used as pasture for sheep during the summer, while the upper watershed is bare rock (Fouinat et al, 2017). The lake is oligotrophic, with total phosphorous concentrations <5 μgP/L and dissolved organic carbon concentrations <1 mg/L (Nellier, Perga, Cottin, Fanget, & Naffrechoux, 2015). The Secchi depth is typically >7 m in the early ice-free season, which allows 1% of the sunlight to reach the hypolimnion.…”

Bioconcentration may be favoured over biomagnification for fish PCB contamination in high altitude lakes

“…These lakes are oligotrophic (total phosphorus [P] concentrations <5 μg L −1 ). In 2012 and 2013, phytoplankton biomass (as C) in Lake Muzelle ranged between 0.15 and 95 μg L −1 over all seasons and were always higher than in Lake Plan Vianney (0.05-6 μg L −1 ; Nellier et al 2015b). The zooplankton densities are low in Lake Muzelle (<25 ind.…”

“…comm.). The concentration and distribution of PCBs in the waters of these lakes have been previously reported (Nellier et al 2015a(Nellier et al , 2015b.…”

“…The aim of this study was to investigate the relative role of biomagnification and bioconcentration on the individual, seasonal, and between-site variability in fish PCB contamination for 2 alpine, high altitude lakes, chosen because they are subjected to similar PCB inputs, solely from atmospheric deposition (180 ng m −2 yr −1 ; Nellier et al 2015a). PCB partitioning between the dissolved and particulate phases differs between the lakes during some seasons, however, potentially affecting the bioconcentration potential (Nellier et al 2015b). Both lakes host only salmonid fish (Salvelinus sp.).…”

“…Both lakes host only salmonid fish (Salvelinus sp.). Despite their comparable oligotrophic status, their phytoplankton and zooplankton community structures and biomasses are very different (Nellier et al 2015b). These differences are expected to be responsible for observed differences in fish growth (Y.M.…”