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Thirty two polychlorinated biphenyl congeners (PCBs), hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) were analysed in passive sampler extracts from surface water-exposed semipermeable membrane devices (SPMDs) and in bed sediment samples from a small urban watercourse, the River Alna (Oslo, Norway). Performance reference compound-corrected data from the passive samplers deployed at three sites along the river were used to track PCB contamination in the overlying water. SPMDs were able to detect an increase in dissolved PCB concentrations at the site furthest downstream that was corroborated by bed sediment concentrations. In comparison, no major increase in concentration of HCB, PeCB or PAHs could be observed. Comparison of passive sampling-based overlying water concentrations with total concentrations measured in bed sediments supports the possibility of further PCB sources upstream of the study area. Diagnostic PAH ratios (from SPMDs) and PCB congener pattern (from sediments) were used in an attempt to identify possible contaminant sources to the Alna River. Selected PAH diagnostic ratios support a multiple emission source scenario and demonstrate the complexity of identifying specific sources of these compounds to surface waters. PCB congener patterns in sediments from all three sites tend to indicate a source of highly chlorinated PCBs (of the Archlor 1260 type) and either a source of lower chlorinated PCBs or the less-likely occurrence of dechlorination in sediment. Information collected during the present screening study also confirms the Alna River as a continuous source of PCBs to the Oslofjord.

Passive sampling devices are increasingly relied upon for monitoring non-polar organic contaminants in water. While many types of devices are available they have seldom been evaluated alongside each other. We tested six passive sampling devices namely: Chemcatcher, two modified versions of the membrane enclosed sorptive coating (MESCO I (m) and MESCO II), silicone rod and strip and semipermeable membrane device (SPMD). Samplers spiked with a range of performance reference compounds (PRCs) were exposed (5 days) in a continuous flow-through tank using Meuse river water fortified with fluctuating concentrations (20-700 ng L(-1)) of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, hexachlorobenzene and p,p'-DDE. Dissipation rates of PRCs appeared to provide reliable information on exchange kinetics even under these short-term exposure conditions. They accounted for differences between masses of contaminants accumulated by replicate samplers, indicating that the variability between replicates was in part due to differences in water turbulences and hence boundary layer thickness. In this system, resistances in the membrane and boundary layers are likely to be in the same order of magnitude for PRCs. Sampler performance was evaluated by comparing masses accumulated in the devices only for analytes for which uptake was linear (integrative) and limited by transport across the boundary layer. Consistent data were obtained across the range of samplers despite their different configurations, and the analysis being conducted in three separate laboratories. The pattern in analyte masses accumulated by Chemcatcher and MESCO II data could be explained by the extraction and analysis being conducted only on the receiving phase of the samplers and a significant impact of the lag-phase prior to obtaining a steady flux of contaminants across the polyethylene membranes.

This work aimed to evaluate whether the performance of passive sampling devices in measuring time-weighted average (TWA) concentrations supports their application in regulatory monitoring of trace metals in surface waters, such as for the European Union's Water Framework Directive (WFD). The ability of the Chemcatcher and the diffusive gradient in thin film (DGT) device sampler to provide comparable TWA concentrations of Cd, Cu, Ni, Pb and Zn was tested through consecutive and overlapping deployments (7-28 days) in the River Meuse (The Netherlands). In order to evaluate the consistency of these TWA labile metal concentrations, these were assessed against total and filtered concentrations measured at relatively high frequencies by two teams using standard monitoring procedures, and metal species predicted by equilibrium speciation modeling using Visual MINTEQ. For Cd and Zn, the concentrations obtained with filtered water samples and the passive sampling devices were generally similar. The samplers consistently underestimated filtered concentrations of Cu and Ni, in agreement with their respective predicted speciation. For Pb, a small labile fraction was mainly responsible for low sampler accumulation and hence high measurement uncertainty. While only the high frequency of spot sampling procedures enabled the observation of higher Cd concentrations during the first 14 days, consecutive DGT deployments were able to detect it and provide a reasonable estimate of ambient concentrations. The range of concentrations measured by spot and passive sampling, for exposures up to 28 days, demonstrated that both modes of monitoring were equally reliable. Passive sampling provides information that cannot be obtained by a realistic spot sampling frequency and this may impact on the ability to detect trends and assess monitoring data against environmental quality standards when concentrations fluctuate.

Biological early warning systems represent a set of tools that may be able to respond to certain chemical monitoring requirements of recent European legislation, the Water Framework Directive (WFD2000/60/EC), that aims to improve and protect water quality across Europe. In situ biomonitoring was performed along the rivers Meuse (NL), Aller (GER) and Rhine (F) within the frame of the European Union-funded Project SWIFT-WFD. Gammarus pulex was used as a test organism during the evaluation of the Multispecies Freshwater Biomonitor(R) (MFB), an online biomonitor to quantitatively record different behaviour patterns of animals. At the river Meuse G. pulex reacted to pulse exposure of either a mixture of trace metals or of several organic xenobiotics, by showing up to 20% decreased locomotory activity (already at the 1st pulse) and increased mortality (at 2nd or 3rd pulse only). G. pulex deployed within the MFB system were observed to survive well at the monitoring station on the Aller (100%) and monitoring did not result in the measurement of chemical irregularities. In contrast, deployment at the monitoring station on the Rhine river demonstrated that the test organism was able to detect chemical irregularities by up to 20% decreased locomotory activity in the animals. The MFB proved to be an alert system for water quality monitoring at sensitive sites and sites with accidental pollution.

Passive sampling devices accumulate chemicals continuously from water and can provide time weighted average (TWA) concentrations of pollutants over the exposure period. Hence, they offer a number of advantages over other conventional monitoring techniques such as spot or grab sampling. The diffusive gradient in thin film (DGT) and the Chemcatcher passive samplers can be used to provide TWA concentrations of labile metals, but the approaches to their calibration differ. DGT uses diffusion coefficients of metals in the hydrogel layer, whereas Chemcatcher uses metal specific uptake rates, with both sets of values obtained under controlled laboratory conditions with constant aqueous metal concentrations. However, little is known of how such samplers respond to fluctuating concentrations. We evaluated the responsiveness of these two passive sampling devices to rapidly changing concentrations of Cd, Cu, Ni, Pb and Zn in natural freshwater, over a relatively short deployment time. Maximum metal concentrations in water were varied between 70 and 140 microg L(-1). Experiments were carried out in a tank with a rotating carousel system and filled with Meuse river water, allowing a degree of control over experimental conditions while using natural river water. Fluctuating concentrations were obtained by stepwise addition of standard solutions of the metals. The reliability and accuracy of the TWA concentrations measured by the samplers were assessed by comparison with concentrations of the metals in spot samples of water taken regularly over the deployment period. The spot samples of water were either unfiltered (total), filtered (0.45 microm) or ultrafiltered (5 kDa). Predictive speciation modelling using the visual MINTEQ programme was also undertaken. There was reasonable agreement between the TWA concentrations of Cd and Ni obtained with Chemcatcher and DGT and the total Cd and Ni concentrations measured in repeated unfiltered spot samples. For elements (i.e. Cu, Pb, Zn) that associate to a significant degree with suspended solids, colloids or dissolved organic carbon, or form complexes with large organic ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorganic and inorganic-fulvic acid associated fractions. While Chemcatcher-based TWA concentration ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal associated with large organic ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concentration of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive.