Jesper Knutsson

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.

Performance optimisation of a passive sampler for monitoring hydrophobic organic pollutants in water

The performance of an integrative passive sampler that consists of a C18 Empore disk sorbent receiving phase fitted with low density polyethylene membrane was optimised for the measurement of time-weighted average concentrations of hydrophobic micropollutants in water. A substantial improvement of sampling characteristics including the rate of sampling and the sampling precision was achieved by decreasing the internal sampler resistance to mass transfer of hydrophobic organic chemicals. This was achieved by adding a small volume of n-octanol, a solvent with high permeability (solubility [times] diffusivity) for target analytes, to the interstial space between the receiving sorbent phase and the polyethylene diffusion-limiting membrane.

Blast-Furnace Sludge as Sorbent Material for Multi-Metal Contaminated Water

Alternative and waste product materials are much in demand for use as sorbent material for contaminated water due to lower costs as well as the sustainability aspects of recycling industrial waste products. In this project batch tests were carried out to evaluate the capacity of blast-furnace sludge to remove Cd, Cr, Cs, Cu, Mo, Ni, Pb, Sn, V and Zn in multi-metal solutions. The sorption tests were conducted on different metal concentrations and pH values. Old sludge deposited at a landfill was also tested, using real leachate from the landfill area spiked with the multi-metal solutions. The data were evaluated by means of calculations of removal/sorption capacities, construction of Freundlich adsorption isotherms and speciation of the metal forms with CHEAQS software. The mineral composition of the sludge was determined qualitatively using XRD. At pH 7 – 9, the sludge had a high removal capacity for the majority of the specific metals in the multi solutions. The capacity of the old sludge with multi metals in real leachate was lower. The isotherms reveal that sorption could be the main mechanism for the removal of Cd, Cu, Mo, Ni and Pb. At pH < 7 there is a risk of leaching of V and Cs, and at pH 5.6 the capacity to remove all metals was low; Zn, Cs and Pb could be leached. The sludge was composed of different iron hydr/oxides, carbonates and silicates, and the active surfaces of the iron hydr/oxides may explain the good sorption capacity for metals. The carbonates endowed the material with a high buffer capacity and the risk of a decrease of pH in water in contact with the material is low.

Speciation analysis of thallium in water samples after separation/preconcentration with the Empore™ chelating disk

A simple, reliable and novel solid phase extraction procedure using the Empore™ chelating disk has been developed for determination of Tl(I) and Tl(III) in environmental water samples by electrothermal atomic absorption spectrometry (ETAAS). The influence of humic acids on separation/preconcentration of thallium species with the Empore™ chelating disk is investigated. The preconcentration factor and detection limit are 500 and 5 ng L−1, respectively. The recoveries are in the range 93–103% for mineral, pond, sea, snowmelt, waste waters at 28–500 ng L−1 Tl and in the range 82–112% for river waters at 18–28 ng L−1 Tl.

Estimation of measurement uncertainties for the DGT passive sampler used for determination of copper in water

Diffusion-based passive samplers are increasingly used for water quality monitoring. While the overall method robustness and reproducibility for passive samplers in water are widely reported, there has been a lack of a detailed description of uncertainty sources. In this paper an uncertainty budget for the determination of fully labile Cu in water using a DGT passive sampler is presented. Uncertainty from the estimation of effective cross-sectional diffusion area and the instrumental determination of accumulated mass of analyte are the most significant sources of uncertainty, while uncertainties from contamination and the estimation of diffusion coefficient are negligible. The results presented highlight issues with passive samplers which are important to address if overall method uncertainty is to be reduced and effective strategies to reduce overall method uncertainty are presented.

Evaluation of a passive sampler for the speciation of metals in urban runoff water

Metals in urban runoff water need to be monitored in order to estimate fluxes and assess their impact on the aquatic environment. Passive sampling is a useful and reliable emerging tool for measuring time averaged concentrations of metals in water bodies. This paper describes the deployment of a passive sampler to measure Cu, Ni and Zn in an urban runoff water treatment facility. The concentrations derived from the passive samplers are compared to concentrations obtained from an automated water sampler which provides pooled spot water samples and to model predictions from the visualMINTEQ computer speciation code. Results show that visualMINTEQ predictions partly describe the metal speciation in non-equilibrium systems. In addition we conclude that passive samplers are useful for monitoring and characterization of metal speciation under chemodynamic conditions.

FoodWatch and Food Resource Flows

Food consumption represents a significant environmental impact, and in terms of climate impact, food consumption ranks among the top three contributing sectors. By changing dietary choices and reducing food waste, significant reductions in food-derived GHG emissions can be achieved. However, food consumption behavior depends on several interrelated factors, some of which have proved difficult to influence. Further research and new approaches in data collection and intervention design are needed to identify effective strategies. Here, a web-based tool for collecting highly disaggregated data on household food consumption and food waste behavior, called Food Watch, is presented. I present the results of an early version field trial, with detailed analysis of food waste categories and a discussion about intervention and feedback design. A roadmap for future research and development of the Food Watch application is also presented.

Designed to support or impede energy conservation? How design characteristics influence people's energy use

This paper explores how the design of domestic appliances influences people’s energy use during everyday activities. Drawing on findings from an interview study with 81 informants, a variety of design characteristics were uncovered, which set preconditions for use that in different ways impede or support energy conservation. The identified characteristics did not only concern appliances’ operative functions but also their interactive and communicative functions as well as people’s underlying motives for using specific appliances. Addressing the full range of characteristics during the development of new appliances will highlight a variety of design opportunities and increase the possibilities for developing appliances that support people to go about their everyday activities in less energy-reliant ways.

THE HABITATION LAB AS A PLATFORM FOR SUSTAINABLE INNOVATIONS IN THE BUILT ENVIRONMENT: A CASE STUDY

Household consumption is the ultimate driver for all production in our economies, and a significant part is direct consumption that takes place within physical boundaries of the household, which we call the home. Important consumption categories include utilities like water, electricity, heating and cooling, but also the food we eat and the clothes we wear. To facilitate sustainable innovation in the built environment, reducing innovation cost and product time to market a co-creation open innovation approach is proposed, which is expected to lower thresholds for new innovation project for all actors, and in particular small to medium enterprises (SMEs). In the Habitation Lab academia, public bodies, industry and users come together to form a quadruple helix of innovation. The open innovation process involves multiple stakeholders, and end users take on the role not only as test subjects, but also as active contributors and co-creators of new products and services. A newly built Habitation Lab in Gothenburg, Sweden, containing 29 apartments, a co-creation studio and 2,000 sensors is presented as a case study.