Integrative samplers for the monitoring of PCBs in the dissolved phase of aquatic media: the ECLIPSE project
Résumé
Various integrative samplers, at different stages of development, are now available to estimate time-weighted average (TWA) concentrations of freely dissolved hydrophobic contaminants in aquatic environments. The ECLIPSE project (2009-2011, coord. C Miège, Irstea) involves 5 laboratories and aims to calibrate and compare 5 different integrative samplers for the monitoring of indicator and dioxin-like PCB in water: semi-permeable membrane device (SPMD, studied by Irstea), low-density polyethylene strip (LDPE, Ifremer), silicone rubber (SRPS, Deltares), Chemcatcher® (BRGM) and ontinuous-flow integrative sampler (CFIS, LABAQUA). The first step of the project was the simultaneous calibration of these samplers under laboratory conditions. During summer 2009, samplers were exposed under constant agitation and temperature in a stainless steel tank filled with 200 L of PCB contaminated water. A constant PCB concentration of about 1 ng/L was achieved by immersing a large amount of silicone rubber sheets [Rusina 2010] spiked with indicator and dioxin-like PCB. Prior to deployment, samplers were spiked with Performance Reference Compounds (PRC) and exposure durations ranged from 1 day to 3 months. After exposure, processing and analysis, samplers were compared in terms of sampling rate, linear uptake phase duration, repeatability and accuracy of calculated TWA concentration. The second step of the ECLIPSE project was the deployment and comparison of these samplers in real aquatic environments. In summer and autumn 2010, and in spring 2011, three field campaigns were carried out along the Rhône River and near the lake Le Bourget (France), known to be contaminated by PCB. Using appropriate cages, canisters and holders, studied samplers were exposed simultaneously at an approximate depth of 1 m during 1, 2, 3 and 4 weeks with duplicates and/or triplicates. These field campaigns allowed to compare in-situ ease of use and robustness of the five integrative samplers in addition to repeatability of sampling and TWA concentration estimate.