Anthony Gravell

Measurement of environmental pollutants using passive sampling devices – an updated commentary on the current state of the art

The following provides a short overview of the important topics arising from the 6(th) International Passive Sampling Workshop and Symposium (IPSW 2013) held in Bordeaux, France between 26 and 29(th) June, 2013. Most of the discussions focussed on monitoring non-polar and polar organic pollutants in water with less coverage on air (probably already seen as a mature technology for this medium) and sediments. The use of passive sampling devices within regulatory water monitoring programmes was also a major theme of the Workshop.

An improved method for measuring metaldehyde in surface water using liquid chromatography tandem mass spectrometry

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In Situ Calibration of a New Chemcatcher Configuration for the Determination of Polar Organic Micropollutants in Wastewater Effluent

Passive sampling is proposed as an alternative to traditional grab- and composite-sampling modes. Investigated here is a novel passive sampler configuration, the Chemcatcher containing an Atlantic HLB disk covered by a 0.2 μm poly(ether sulfone) membrane, for monitoring polar organic micropollutants (personal care products, pharmaceuticals, and illicit drugs) in wastewater effluent. In situ calibration showed linear uptake for the majority of detected micropollutants over 9 days of deployment. Sampling rates (RS) were determined for 59 compounds and were generally in the range of 0.01-0.10 L day(-1). The Chemcatcher was also suitable for collecting chiral micropollutants and maintaining their enantiomeric distribution during deployment. This is essential for their future use in developing more accurate environmental risk assessments at the enantiomeric level. Application of calibration data in a subsequent monitoring study showed that the concentration estimated for 92% of micropollutants was within a factor of 2 of the known concentration. However, their application in a legislative context will require further understanding of the properties and mechanisms controlling micropollutant uptake to improve the accuracy of reported concentrations.

A simple, low cost GC/MS method for the sub-nanogram per litre measurement of organotins in coastal water

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Review of the molluscicide metaldehyde in the environment

Metaldehyde is the active ingredient in most slug pellets used to protect crops. This molluscicide is considered an emerging pollutant and is frequently detected in surface water bodies above the EU statutory drinking water limit of 0.1 μg L−1 for a pesticide. This presents a challenge for providers of drinking water. Understanding the sources, transport and environmental fate of this compound is therefore important. This critical review discusses these aspects including monitoring and analytical techniques used for the detection of metaldehyde in environmental matrices. Novel techniques used for the removal of metaldehyde from drinking water are presented together with potential catchment management strategies and initiatives useful for the mitigation of this molluscicide in the environment.

NORMAN interlaboratory study (ILS) on passive sampling of emerging pollutants

Passive samplers can play a valuable role in monitoring water quality within a legislative framework such as the European Union’s Water Framework Directive (WFD). The time-integrated data from these devices can be used to complement chemical monitoring of priority and emerging contaminants which are difficult to analyse by spot or bottle sampling methods, and to improve risk assessment of chemical pollution. In order to increase the acceptance of passive sampling technology amongst end users and to gain further information about the robustness of the calibration and analytical steps, several inter-laboratory field studies have recently been performed in Europe. An inter-laboratory study on the use of passive samplers for the monitoring of emerging pollutants was organised in 2011 by the NORMAN association together with the European DG Joint Research Centre to support the Common Implementation Strategy of the WFD. Thirty academic, commercial and regulatory laboratories participated in the passive sampler comparison exercise and each was allowed to select their own sampler design. All the different devices were exposed at a single sampling site to treated waste water from a large municipal treatment plant. In addition, the organisers deployed in parallel for each target analyte class multiple samplers of a single type which were subsequently distributed to the participants for analysis. This allowed an evaluation of the contribution of the different analytical laboratory procedures to the data variability. The results obtained allow an evaluation of the potential of different passive sampling methods for monitoring selected emerging organic contaminants (pharmaceuticals, polar pesticides, steroid hormones, fluorinated surfactants, triclosan, bisphenol A and brominated flame retardants). The results will be used to inform EU Member States about the potential application of passive sampling methods for monitoring organic chemicals within the framework of the WFD.

Calibration and field evaluation of the Chemcatcher® passive sampler for monitoring metaldehyde in surface water

Metaldehyde is a potent molluscicide. It is the active ingredient in most slug pellets used for crop protection. This polar compound is considered an emerging pollutant. Due to its environmental mobility, metaldehyde is frequently detected at impacted riverine sites, often at concentrations above the EU Drinking Water Directive limit of 0.1µgL-1 for an individual pesticide. This presents a problem when such waters are abstracted for use in the production of potable water supplies, as this chemical is difficult to remove using conventional treatment processes. Understanding the sources, transport and fate of this pollutant in river catchments is therefore important. We developed a new variant of the Chemcatcher® passive sampler for monitoring metaldehyde comprising a Horizon Atlantic™ HLB-L disk as the receiving phase overlaid with a polyethersulphone membrane. The sampler uptake rate (Rs) was measured in semi-static laboratory (Rs = 15.7mLday-1) and in-field (Rs = 17.8mLday-1) calibration experiments. Uptake of metaldehyde was linear over a two-week period, with no measurable lag phase. Field trials (five consecutive 14day periods) using the Chemcatcher® were undertaken in eastern England at three riverine sites (4th September-12th November 2015) known to be impacted by the seasonal agricultural use of metaldehyde. Spot samples of water were collected regularly during the deployments, with concentrations of metaldehyde varying widely (~ 0.03-2.90µgL-1) and often exceeding the regulatory limit. Time weighted average concentrations obtained using the Chemcatcher® increased over the duration of the trial corresponding to increasing stochastic inputs of metaldehyde into the catchment. Monitoring data obtained from these devices gives complementary information to that obtained by the use of infrequent spot sampling procedures. This information can be used to develop risk assessments and catchment management plans and to assess the effectiveness of any mitigation and remediation strategies.