Field Evaluation and in Situ Stress Testing of the Organic-Diffusive Gradients in Thin-Films Passive Sampler

Abstract

The organic-diffusive gradients in thin-films (o-DGT) technique has emerged as a promising aquatic passive sampler that addresses many of the challenges associated with current sampling tools used for measurement of polar organic contaminants. This study represents the first comprehensive field evaluation of the o-DGT in natural surface waters, across a wide suite of polar pharmaceuticals and pesticides. We explore the utility and limitations of o-DGT as a quantitative measurement tool compared to grab sampling and the polar organic chemical integrative sampler (POCIS) across four connected agricultural and wastewater-influenced freshwater systems spanning 600 km from the U.S. border to northern Manitoba, Canada. Overall, the suite of analytes detected with o-DGT and POCIS was similar. Concentrations in water estimated using o-DGT were greater than concentrations estimated from POCIS in 71 of 80 paired observations, and on average, the estimates from o-DGT were 2.3-fold greater than estimates from POCIS. Grab sample concentrations suggested that the systematic underestimation with POCIS were largely a result of sampling rate variation related to flow rate and boundary-layer effects, an issue reported consistently in the POCIS literature. These comprehensive measurements in an agriculturally influenced fast-flowing river, longterm sampling (>40 days) in a large dilute lake system, deployments in wastewaters, and under ice at near-freezing temperatures represent effective stress testing of o-DGT under representative and challenging conditions. Overall, its strong performance and improved accuracy over POCIS supports its use as a robust, quantitative, and sensitive measurement tool for polar organic chemicals in aquatic systems.

Fungal bioremediation of soil co-contaminated with petroleum hydrocarbons and toxic metals

“…This could provide scientific explanations for fungal responses to multiple contaminants at the molecular level (Aydin et al 2017 ; Wang et al 2017 ). Further, to obtain high-resolution spatial distribution characteristics of toxic metals and reveal interface reaction processes of soil-metals-fungal interactions, new methods such as gradient diffusion film technology (DGT) combined with laser ablation-inductively coupled plasma mass spectrometry could be applied to analyze dynamic changes in toxic metal speciation at soil-microbe interfaces (Challis et al 2018 ; Feng et al 2016 ; Koppel et al 2020 ; Wang et al 2018 ). Such approaches will further clarify fungal transformation mechanisms in soil contaminated with petroleum hydrocarbons and toxic metals and may contribute to more effective strategies for fungal bioremediation.…”

Trends in the use of passive sampling for monitoring polar pesticides in water

“…One solution to protect the hydrogel layers during deployments is the inclusion of a protective filter or membrane. A range of membranes (cellulose acetate, cellulose ester, Nylon and PES) has been evaluated and were found to suppress uptake [80,81]. Commenting on use of protective membranes, Guibal et al [70] proposed two points to consider before use: "1: target analytes and their potential interaction with the membrane (several compounds are often targeted and there is no "universally" inert membrane).…”

Development and Application of the Diffusive Gradients in Thin-Films Technique for Measuring Psychiatric Pharmaceuticals in Natural Waters

“…In contrast, the diffusive gradients in thin films (DGT) technique contains a well-defined diffusive layer which controls the uptake of analytes and reduces the effect of the DBL on the measurement. 20 DGT provides in situ sampling of trace chemicals in water without field calibration. 21 The principle of DGT is based Invented in the 1990s for work on heavy metals and nutrients, DGT has been developed over recent years for many classes of trace organic contaminants, including antibiotics, 22 pesticides, 23 herbicides, 24 bisphenols (BPs), 25 perfluoroalkyl substances (PFASs), 26 organophosphorus flame retardants (OPFRs), 16 and pharmaceuticals and personal care products (PPCPs).…”