Calibration and application of the Chemcatcher® passive sampler for monitoring acidic herbicides in the River Exe, UK catchment

Abstract

Acidic herbicides are used to control broad-leaved weeds. They are stable, water-soluble, and with low binding to soil are found frequently in surface waters, often at concentrations above the EU Drinking Water Directive limit of 0.10 μg L−1. This presents a problem when such waters are abstracted for potable supplies. Understanding their sources, transport and fate in river catchments is important. We developed a new Chemcatcher® passive sampler, comprising a 3M Empore™ anion-exchange disk overlaid with a polyethersulphone membrane, for monitoring acidic herbicides (2,4-D, dicamba, dichlorprop, fluroxypyr, MCPA, MCPB, mecoprop, tricolpyr). Sampler uptake rates (Rs = 0.044–0.113 L day−1) were measured in the laboratory. Two field trials using the Chemcatcher® were undertaken in the River Exe catchment, UK. Time-weighted average (TWA) concentrations of the herbicides obtained using the Chemcatcher® were compared with concentrations measured in spot samples of water. The two techniques gave complimentary monitoring data, with the samplers being able to measure stochastic inputs of MCPA and mecoprop occurring in field trial 1. Chemcatcher® detected a large input of MCPA not found by spot sampling during field trial 2. Devices also detected other pesticides and pharmaceuticals with acidic properties. Information obtained using the Chemcatcher® can be used to develop improved risk assessments and catchment management plans and to assess the effectiveness of any mitigation and remediation strategies.Electronic supplementary materialThe online version of this article (10.1007/s11356-018-2556-3) contains supplementary material, which is available to authorized users.

Comparison of different monitoring methods for the measurement of metaldehyde in surface waters

“…The reason for this anomaly is unknown; however, a possible cause is that the PES membranes either moved within the PTFE sampler body during their preparation or storage or were damaged during this deployment. These issues would lead to a greater sequestration of metaldehyde similar to that observed previously for acidic herbicides (Townsend et al 2018 ). There was good agreement in the TWA concentration obtained with each of the duplicate samplers for all of the trial periods, showing the reproducibility of the device.…”

“…These devices have been introduced as a method for providing more representative (e.g. time-weighted average [TWA]) concentrations of pollutants in water (Townsend et al 2018 ; Castle et al 2018a ). Passive samplers offer many advantages including low-cost, are non-mechanical, requiring no external energy source and can be deployed in a wide range of different field situations.…”

Use of the Chemcatcher® passive sampler and time-of-flight mass spectrometry to screen for emerging pollutants in rivers in Gauteng Province of South Africa

“…The use of another type of receiving phase in the Chemcatcher® (e.g. ion-exchange sorbents) could be used to overcome this issue (Townsend et al 2018 ). Methanol is a suitable extraction solvent and can recover ~ 100% of the sorbed analytes (Petrie et al 2016 ; Castle et al 2018a , b ).…”

Detection of pharmaceuticals in wastewater effluents—a comparison of the performance of Chemcatcher® and polar organic compound integrative sampler

“…Most routine monitoring procedures rely on the infrequent (typically monthly) collection of low-volume (~1 L) spot (bottle or grab) samples of water. This approach has a number of shortcomings when the concentration of substances is known to fluctuate widely or there are stochastic inputs of pollutants over time (Castle et al 2018a;Castle et al 2019;Townsend et al 2018). In order to overcome some of these difficulties, alternative monitoring strategies, such as the use of passive sampling devices has been proposed (Vrana et al 2005).…”

“…In the qualitative mode, they can be used simply to screen for the presence or absence of pollutants (Rimayi et al 2019). In the quantitative mode, they can yield time-weighted average (TWA) (Castle et al 2018a;Castle et al 2019;Townsend et al 2018) or equilibrium concentrations (Vrana et al 2005). To achieve this, the compound-specific sampler uptake rate (R s , mL day −1 ), diffusion coefficient or the sample/water partition coefficient (K sw ) needs to be determined previously in either the laboratory or in situ in the field (Booij et al 2007;Castle et al 2018b;Petrie et al 2016).…”