Polymeric membrane as passive sampler : a new simple calibration protocol

International audienc

What does Semipermeable Membrane Device (SPMD) sampling mean? accuracy of time-weighted average concentration estimations of truly dissolved compounds

International audienceSPMDs1 are commonly used integrative passive samplers for hydrophobic organic compounds in water. Two major assumptions drive the interpretation of accumulated amounts of contaminants: Because of steric hindrance in the polyethylene membrane, only a fraction of dissolved organic compounds in water may be accumulated. - 1st assumption : only truly dissolved compounds are SPMD-available From the accumulated amount of a substance in SPMD, and dissipation of Performance Reference Compounds, the concentration of SPMD-available substance in water can be estimated. - 2nd assumption : the estimated SPMD-available concentration is a time-weighted average (TWA) concentration. Compiling field studies (sampling campaigns in rivers2 and wastewater treatment plants3) and using numerical simulations, we investigated the validity of these two assumption

What does Semi-Permeable membrane device (SPMD) sampling mean? an insight on the "time-weight integrative" and "SPMD-availability" hypothesis

International audienceSPMDs are commonly used integrative passive samplers for hydrophobic organic compounds [1]. Because of steric hindrance in the polyethylene membrane, only a fraction of dissolved organic compounds in water may be accumulated. It is usually assumed that only truly dissolved compounds are available to SPMD. From the accumulated amount of a substance in SPMD, and dissipation of Performance Reference Compounds, the exchange rate constant and the concentration of SPMD-available substance in water can be estimated. It is usually assumed that the SPMD-available concentration estimated from accumulation in SPMD corresponds to the time-weight average (TWA) concentration. Moreover, provided that the half-time is higher than the exposure duration, the sampling is supposed to be fully integrative. In this study, we investigate the significance of the "time-weight" integrative sampling: factors such as deployment duration, exchange rate constants, but also water concentration variations are examined. The chemical form of SPMD-available compounds is also investigated: compiling several field studies, SPMDavailable concentrations are compared to total dissolved concentrations of Polycyclic Aromatic Hydrocarbons (PAHs). Assuming that PAHs that are bond to dissolved organic matter cannot enter the membrane of SPMD, in situ partitioning coefficients KDOC are computed and compared to lab data

Polybrominated diphenyl ethers fluxes in the atmosphere of Paris city, France

No abstract availabl

Polycyclic aromatic hydrocarbon sampling in wastewaters using semipermeable membrane devices: Accuracy of time-weighted average concentration estimations of truly dissolved compounds

International audienceSemipermeable membrane devices (SPMDs) previously spiked with performance reference compounds were exposed in wastewater. After 6 days of exposure, 13 polycyclic aromatic hydrocarbons (PAHs) were quantified in SPMDs. Exchange rate constants and time-weighted average (TWA) concentrations of SPMD-available PAHs in water were calculated. The bias of using SPMDs to estimate an actual TWA concentration if the concentration in water fluctuates, as can be expected in wastewater, was studied with numerical simulations. The bias increased with the exchange rate constant. However, most exchange rate constants evaluated in SPMDs exposed in wastewater were small enough for SPMDs to estimate a TWA concentration of PAHs even when the water concentration varied. TWA-SPMD-available concentrations were always below total dissolved (operationally defined as 0.7 lm) concentrations, indicating that part of the dissolved PAHs was not available for sampling. In situ partitioning coefficients KDOC were computed and found to be slightly higher than data from the literature. This confirms that only truly dissolved PAHs should be sampled by SPMDs in wastewater