title: How do PDMS-coated stir bars used as passive samplers integrate concentration peaks of pesticides in freshwater?
abstract: Passive samplers are theoretically capable of integrating variations of concentrations of micropollutants in freshwater and providing accurate average values. However, this property is rarely verified and quantified experimentally. In this study, we investigated, in controlled conditions, how the polydimethylsiloxane-coated stir bars (passive Twisters) can integrate fluctuating concentrations of 20 moderately hydrophilic to hydrophobic pesticides (2.18 < Log Kow< 5.51). In the first two experiments, we studied the pesticide accumulation in the passive Twisters during high concentration peaks of various durations in tap water. We then followed their elimination from the passive Twisters placed in non-contaminated water (experiment no. 1) or in water spiked at low concentrations (experiment no. 2) for 1 week. In the third experiment, we assessed the accuracy of the time-weighted average concentrations (TWAC) obtained from the passive Twisters exposed for 4 days to several concentration variation scenarios. We observed little to no elimination of hydrophobic pesticides from the passive Twisters placed in non-contaminated water and additional accumulation when placed in water spiked at low concentrations. Moreover, passive Twisters allowed determining accurate TWAC (accuracy, determined by TWAC-average measured concentrations ratios, ranged from 82 to 127 %) for the pesticides with Log Kowhigher than 4.2. In contrast, fast and large elimination was observed for the pesticides with Log Kowlower than 4.2 and poorer TWAC accuracy (ranging from 32 to 123 %) was obtained.
authors.affiliation: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 rue de la Doua, CS 70077, 69626, Villeurbanne Cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Assoumani
authors.affiliation: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 rue de la Doua, CS 70077, 69626, Villeurbanne Cedex, France. christelle.margoum@irstea.fr.
authors.forename: C
authors.initials: C
authors.lastname: Margoum
authors.affiliation: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 rue de la Doua, CS 70077, 69626, Villeurbanne Cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Lombard
authors.affiliation: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 rue de la Doua, CS 70077, 69626, Villeurbanne Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Guillemain
authors.affiliation: Irstea, UR MALY, Centre de Lyon-Villeurbanne, 5 rue de la Doua, CS 70077, 69626, Villeurbanne Cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Coquery
mesh_terms: D004129:Dimethylpolysiloxanes / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008962:Models, Theoretical; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry; D013048:Specimen Handling; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D004129:Dimethylpolysiloxanes; D010575:Pesticides; D014874:Water Pollutants, Chemical; C013830:baysilon
keywords: Passive SBSE; Passive sampling; Time-weighted average concentrations (TWAC); Variations of concentrations