Ian Allan

Calibration and use of the polar organic chemical integrative sampler—a critical review

The implementation of strict environmental quality standards for polar organic priority pollutants poses a challenge for monitoring programs. The polar organic chemical integrative sampler (POCIS) may help to address the challenge of measuring low and fluctuating trace concentrations of such organic contaminants, offering significant advantages over traditional sampling. In the present review, the authors evaluate POCIS calibration methods and factors affecting sampling rates together with reported environmental applications. Over 300 compounds have been shown to accumulate in POCIS, including pesticides, pharmaceuticals, hormones, and industrial chemicals. Polar organic chemical integrative sampler extracts have been used for both chemical and biological analyses. Several different calibration methods have been described, which makes it difficult to directly compare sampling rates. In addition, despite the fact that some attempts to correlate sampling rates with the properties of target compounds such as log K(OW) have been met with varying success, an overall model that can predict uptake is lacking. Furthermore, temperature, water flow rates, salinity, pH, and fouling have all been shown to affect uptake; however, there is currently no robust method available for adjusting for these differences. Overall, POCIS has been applied to a wide range of sampling environments and scenarios and has been proven to be a useful screening tool. However, based on the existing literature, a more mechanistic approach is required to increase understanding and thus improve the quantitative nature of the measurements.

Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations

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 Unions Water Framework Directive.

Passive Sampling in Regulatory Chemical Monitoring of Nonpolar Organic Compounds in the Aquatic Environment

We reviewed compliance monitoring requirements in the European Union, the United States, and the Oslo-Paris Convention for the protection of the marine environment of the North-East Atlantic, and evaluated if these are met by passive sampling methods for nonpolar compounds. The strengths and shortcomings of passive sampling are assessed for water, sediments, and biota. Passive water sampling is a suitable technique for measuring concentrations of freely dissolved compounds. This method yields results that are incompatible with the EUs quality standard definition in terms of total concentrations in water, but this definition has little scientific basis. Insufficient quality control is a present weakness of passive sampling in water. Laboratory performance studies and the development of standardized methods are needed to improve data quality and to encourage the use of passive sampling by commercial laboratories and monitoring agencies. Successful prediction of bioaccumulation based on passive sampling is well documented for organisms at the lower trophic levels, but requires more research for higher levels. Despite the existence of several knowledge gaps, passive sampling presently is the best available technology for chemical monitoring of nonpolar organic compounds. Key issues to be addressed by scientists and environmental managers are outlined.

Effect of sampler material on the uptake of PAHs into passive sampling devices

Increasing demand for simple and reliable passive samplers for monitoring hydrophobic organic contaminants in water has led to increased frequency of use of single-phase polymeric sampling devices. In this study, we evaluate the effect of sampler material on the passive sampling of polycyclic aromatic hydrocarbons (PAHs) in two Norwegian rivers. Low density polyethylene membranes (LDPE), silicone strips and semipermeable membrane devices (SPMDs) with the exact same surface area and conformation were exposed in the Drammen River for overlapping exposures of 24 and 51 d, under identical hydrodynamic conditions. Dissipation rates of performance reference compounds (PRCs) spiked in all samplers were consistent and demonstrated no significant differences in sampler-water analyte exchange kinetics between the two exposures. The transition to fully boundary layer-controlled uptake shown by PRC dissipation rates was confirmed by investigating PAH masses absorbed by the samplers. Masses of analytes with log K(ow)>4.5 absorbed into the samplers were similar and independent of the sampler material used, generally indicating for these compounds that the boundary layer dominated the resistance to mass transfer. The very low variability in analyte masses absorbed across sampler types observed here indicates that much of the overall variability in dissolved contaminant concentrations seen in passive sampler intercomparison studies is likely the result of the uncertainty associated with sampler-water partition coefficients and PRC dissipation rates. PRC dissipation rates and ratios of masses absorbed over 51 and 24 d for these compounds demonstrated integrative sampling over 51 d and no major effects of biofouling on sampling. The equivalence of data obtained using silicone strips and SPMDs supports the use of single-phase polymeric passive sampling devices.

Passive sampling for target and nontarget analyses of moderately polar and nonpolar substances in water.

The applicability of silicone rubber and low-density polyethylene (LDPE) as passive sampling materials for target and nontarget analyses of moderately polar and nonpolar substances was assessed through a field deployment of samplers along a small, polluted stream in Oslo, Norway. Silicone and LDPE samplers of identical surface area (but different volumes) were deployed at 6 sites in the River Alna for 49 d. Quantitative target analysis by gas chromatography-mass spectrometry (quadrupole, single-ion monitoring mode) demonstrated that masses of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine compounds absorbed in the 2 polymeric materials were consistent with the current understanding of the control and mode of accumulation in these sampler materials. Some deviation was observed for decabromodiphenyl ether (BDE-209) and may be linked to the large molecular size of this substance, resulting in lower diffusivity in the LDPE. Target and nontarget analyses with gas chromatography coupled to high resolution time-of-flight mass spectrometry allowed the identification of a wide range of chemicals, including organophosphate compounds (OPCs) and musk compounds (galaxolide and tonalid). Semiquantitative analysis revealed enhanced quantities of the OPCs in silicone material, indicating some limitation in the absorption and diffusion of these substances in LDPE. Overall, silicone allows nontarget screening analysis for compounds with a wider range of log octanol-water partition coefficient values than what can be achieved with LDPE.

Bottom trawling resuspends sediment and releases bioavailable contaminants in a polluted fjord

Sediments are sinks for contaminants in the worlds oceans. At the same time, commercial bottom trawling is estimated to affect around 15 million km(2) of the worlds seafloor every year. However, few studies have investigated whether this disturbance remobilises sediment-associated contaminants and, if so, whether these are bioavailable to aquatic organisms. This field study in a trawled contaminated Norwegian fjord showed that a single 1.8 km long trawl pass created a 3-5 million m(3) sediment plume containing around 9 t contaminated sediment; ie. 200 g dw m(-2) trawled, equivalent to c. 10% of the annual gross sedimentation rate. Substantial amounts of PCDD/Fs and non-ortho PCBs were released from the sediments, likely causing a semi-permanent contaminated sediment suspension in the bottom waters. PCDD/Fs from the sediments were also taken up by mussels which, during one month, accumulated them to levels above the EU maximum advised concentration for human consumption.

The challenge of exposure correction for polar passive samplers--the PRC and the POCIS.

The Challenge of Exposure Correction for Polar Passive Samplers— The PRC and the POCIS Christopher Harman,* Ian John Allan, and Patrick Steven B€auerlein Norwegian Institute for Water Research (NIVA), Oslo Centre for Interdisciplinary Environmental and Social Research (CIENS), Gaustadall een 21, NO-0349, Oslo, Norway KWR Watercycle Research Institute, P.O. Box 1072, 3430 BB, Nieuwegein, The Netherlands

Blue mussels (Mytilus edulis spp.) as sentinel organisms in coastal pollution monitoring: A review

The blue mussel (Mytilus spp.) is widely used as a bioindicator for monitoring of coastal water pollution (mussel watch programs). Herein we provide a review of this study field with emphasis on: the suitability of Mytilus spp. as environmental sentinels; uptake and bioaccumulation patterns of key pollutant classes; the use of Mytilus spp. in mussel watch programs; recent trends in Norwegian mussel monitoring; environmental quality standards and background concentrations of key contaminants; pollutant effect biomarkers; confounding factors; particulate contaminants (microplastics, engineered nanomaterials); climate change; harmonization of monitoring procedures; and the use of deployed mussels (transplant caging) in pollution monitoring. Lastly, the overall state of the art of blue mussel pollution monitoring is discussed and some important issues for future research and development are highlighted.

Passive sampling methods for contaminated sediments: Risk assessment and management

This paper details how activity-based passive sampling methods (PSMs), which provide information on bioavailability in terms of freely dissolved contaminant concentrations (Cfree), can be used to better inform risk management decision making at multiple points in the process of assessing and managing contaminated sediment sites. PSMs can increase certainty in site investigation and management, because Cfree is a better predictor of bioavailability than total bulk sediment concentration (Ctotal) for 4 key endpoints included in conceptual site models (benthic organism toxicity, bioaccumulation, sediment flux, and water column exposures). The use of passive sampling devices (PSDs) presents challenges with respect to representative sampling for estimating average concentrations and other metrics relevant for exposure and risk assessment. These challenges can be addressed by designing studies that account for sources of variation associated with PSMs and considering appropriate spatial scales to meet study objectives. Possible applications of PSMs include: quantifying spatial and temporal trends in bioavailable contaminants, identifying and evaluating contaminant source contributions, calibrating site-specific models, and, improving weight-of-evidence based decision frameworks. PSM data can be used to assist in delineating sediment management zones based on likelihood of exposure effects, monitor remedy effectiveness, and, evaluate risk reduction after sediment treatment, disposal, or beneficial reuse after management actions. Examples are provided illustrating why PSMs and freely dissolved contaminant concentrations (Cfree) should be incorporated into contaminated sediment investigations and study designs to better focus on and understand contaminant bioavailability, more accurately estimate exposure to sediment-associated contaminants, and better inform risk management decisions. Research and communication needs for encouraging broader use are discussed. Integr Environ Assess Manag 2014;10:224–236.

Chapter 9 Monitoring of priority pollutants in water using chemcatcher passive sampling devices

Publisher Summary The design of Chemcatcher passive sampling device was developed to provide a single low-cost sampler body that could house a range of combinations of receiving phases and diffusion membranes as appropriate for the wide range of classes of pollutants in the aquatic environment. Two types of polymeric membranes have been tested for construction of Chemcatcher samplers; non-porous membranes including low-density polyethylene (LDPE) and microporous membranes including glass fibre, nylon, polycarbonate, polytetrafluoroethylene (PTFE), polyvinylidenedifluoride (PVDF), cellulose acetate (CA), polysulfone (PS), polyethersulfone (PES), and regenerated cellulose. To enable measurement of time-weighted average (TWA) water concentrations of a range of pollutants, the Chemcatcher sampler was calibrated in flow-through tank studies under controlled conditions of temperature and water turbulence. Concentrations of the analytes in water and the amounts accumulated in the receiving disk were measured regularly during the exposure. A Chemcatcher variant based on diffusion through a porous CA membrane to a receiving phase, where the analyte is removed by chelation in a chelating Empore TM disk has been developed for monitoring metals. Another version of Chemcatcher has been developed for the measurement of the TWA concentrations of organotin compounds in water.