Authors:
Sarah Hale | Norwegian Geotechnical Institute | Norway
Hans Peter Arp | Norwegian Geotechnical Institute | Norway
Nicolas Morin | Norwegian Geotechnicsl Institue | Norway
PhD Gudny Okkenhaug | Norwegian Geotechnical Institute | Norway
Gijs Breedveld | Norwegian Geotechnical Institute | Norway
Mona Hansen | Norwegian Geotechnical Institute | Norway
Espen Eek | Norwegian Geotechnical Institute | Norway
Paul Cappelen | Norwegian Geotechnical Institute | Norway
Gerard Cornelissen | Norwegian Geotechnical Institute | Norway
Amy Oen | Norwegian Geotechnical Institute | Norway
The introduction of pollutants in to the environment around us is a constant threat. Often the concentrations of such pollutants are very low and their detection is challenging. Passive samplers provide a simple and robust monitoring tool used in order to monitor the transport and fate of organic and inorganic pollutants in the water phase. The principle of passive sampling is based on the free flow of pollutant molecules from the sampled medium to a sampling device as a result of a difference in pollutant chemical potential in the two media.
Environmental compliance with existing and new legislation is necessary in order to maintain and improve the quality of the environment. With an ever increasing number of pollutants requiring monitoring, and more stringent environmental quality standards being put in to place, there is a need for a low cost yet reliable method for measuring contaminants at trace levels.
Passive samplers have a very important role to play in the monitoring of the fate and transport of pollutants in the real world. Some key applications will be illustrated through the use of real field examples that are grouped according to:
• Pollutant source identification
• Tracking the fate and transport of pollutants in water (ground, surface and fjord), sediment and air
• Pollutant monitoring in combination with complimentary methods
• Risk assessment
The examples that will be discussed in which passive samplers have been used to monitor diverse pollutants include:
• Within the research project WASTEFFECT funded by the Norwegian research council a robust waste emission and exposure model for waste regulators and companies to anticipate and reduce risks from emerging contaminants is being developed. Passive sampling strategies have been developed in order to determine the concentration of brominated flame retardants (BFRs), bisphenol A (BPA) the endocrine disrupting compound, and antimony (Sb), a toxic metalloid in various waste streams. Diffusive Gradients in Thin-films (DGT) devices have been used in order to measure the freely dissolved concentration of Sb. BFRs and BPA have been measured in the water phase and in the air phase with the use of several different types of passive sampler membrane materials. Freely dissolved concentrations of BFRs and BPA have been determined with the use of polydimethylsiloxane and polyoxymethylene (POM) respectively, and air concentrations of contaminants have been sampled with the use of XAD beads, a type of polystyrene copolymer resin.
• The Impact of Climate Change on the Quality of Urban and Coastal Waters - Diffuse Pollution (diPol) project aimed to identify impacts and suggest measures to reduce adverse consequences of climatic changes impacting the quality of urban and coastal waters. The concentrations of PAHs and PCBs in the inner Oslo fjord were measured using total water sampling (taking a grab water sample and extracting it with solvent) and with polyoxymethlene passive samplers. By following concentrations over time, temporal and spatial patterns could be identified.
• A landfill used between 1953 and 1965 for industrial waste from a Hydro power plant containing PAHs, heavy metals, oil and tar provided a field case study for the comparison of passive sampling methods and total water sampling. Passive samplers made of polyoxymethylene to sample organic compounds and DGT devices to sample metals were placed upstream, just outside and downstream the landfill in order to track changes in concentration spatially. All of the passive samplers displayed similar concentrations showing no evidence of increasing concentrations just outside the landfill compared to upstream the site. Although the total water concentrations were higher than the freely dissolved concentrations, the passive sampler results allowed the conclusion to be drawn that pollutants were not being released from the landfill in its current state
In addition a focus on the use of passive samplers in risk assessment will be discussed. Passive samplers can be used in order to determine how strongly pollutants are bound to contaminated soil or sediment, which is a pivotal piece of information when the risk such pollutants pose via leaching and spreading to the surrounding environment needs to be considered. By carrying out a simple laboratory experiment in which passive samplers are exposed to the contaminated soil or sediment, the soil or sediment – water partitioning coefficient value (Kd) can be determined. Indeed, in the model developed by Miljødirektoratet to assess contaminant spreading and the negative effect it could have on the environment, the use of site specific input model parameters are encouraged. In this context, the determination of the soil or sediment-water partitioning coefficient for a particular pollutant can be used and reduce the inherent conservatism in the model. Several examples will be given to highlight the vital nature of the information obtained via the use of passive sampling.