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The MONITOOL project (2017-2023) was carried out to describe the relationships between total dissolved and labile metal concentrations measured in spot water samples and in concurrently deployed Diffusive Gradients in Thin-films (DGTs) passive samplers, respectively. The ultimate aim was to adapt existing marine metal Environmental Quality Standards (EQS ) for DGTs, enabling their use in the context of the European Directives (the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD)). Time-integrated metal concentrations provided by DGTs, representing several days, are an advantage compared to conventional spot sampling, especially in highly dynamic systems, such as transitional waters. Hence, the MONITOOL project aimed to provide a robust database of dissolved and labile metal concentrations in transitional and coastal waters, based upon co-deployments of DGTs and collection of spot water samples at several sampling sites (England, France, Ireland, Italy, Northern Ireland, Portugal, Scotland and Spain), followed subsequently by DGT and water metal analysis. Samplings were carried out in 2018 and 2022, following agreed protocols developed in the framework of the project. The MONITOOL dataset includes metal concentrations from DGTs, measured with Inductively Coupled Plasma Mass Spectrometry (ICP-MS: Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) and in concurrently collected spot water samples by ICP-MS (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) and Anodic/Cathodic Stripping Voltammetry (ASV/CSV: Cd, Pb, Ni). Moreover, data on seawater physical-chemical parameters (salinity, temperature, dissolved oxygen, pH, turbidity, total suspended solids, dissolved organic carbon, and total organic carbon) is provided. This database presents the results obtained using, concurrently, different forms of sampling and analytical techniques, enabling the comparison of the results obtained by these strategies and allowing the adaptation of EQS in marine water (EQS to DGTs (EQS )

In order to move forward in the acceptance of a novel contaminant monitoring technique (Diffusive Gradients in Thin-films: DGT) for assessment of marine water bodies, sensu the WFD, an Inter-Laboratories Comparison (ILC) exercise (nine Europeans laboratories) was organized in the framework of the Interreg Atlantic Area MONITOOL project, which focused on the use of the DGT technique for the measurement of WFD priority metals (Cd, Ni and Pb). Reproducible results were obtained for each metal by several laboratories, supporting the assertion that DGT analysis can be performed satisfactorily by laboratories experienced in measuring metals at trace levels in marine environments, even if they have limited practice in DGT analysis. According to the Z-score analysis, among the 9 participating laboratories, 3 had 100 % of satisfactory results for Cd, Ni, and Pb, 3 had >80 % satisfactory results and 2 had about 60 % satisfactory results. This work highlights the need to clearly describe the DGT method in order to control sources of contamination during analytical steps, in particular the resin gel retrieval and the elution steps. Such international intercomparison exercise is an important step to develop the laboratory network involved in DGT analysis and contributes to the improvement of data quality.

In order to move forward in the acceptance of a novel contaminant monitoring technique for the status assessment of marine water bodies, sensu the Water Framework Directive (WFD), an Inter-Laboratories Comparison (ILC) exercise was organized by Ifremer in the framework of the MONITOOL project - New tools for monitoring the chemical status in transitional and coastal waters under the EU WFD. This ILC focused on the use of DGT technique for the measurement of WFD priority metals (Cd, Ni and Pb). The objectives of this ILC were to test the performance of laboratories when analysing DGTs and to identify the critical handling (resin gel retrieval and elution) and analytical steps when working with DGT samplers, to establish recommendations to prevent misleading results.

Le présent document fournit des instructions pour les meilleures pratiques relatives à l’utilisation des échantillonneurs passifs à Gradient de Diffusion en couche mince (DGT) pour l’échantillonnage des eaux de transition et côtières à des fins de surveillance de la qualité de l’eau. La méthodologie définie dans ce guide a été développée par le consortium du projet Interreg MONITOOL de l’Union européenne afin d’assurer la comparabilité et la reproductibilité des données obtenues par chaque partenaire du projet dans les différentes régions. Le guide fournit des informations pratiques et détaillées sur tous les aspects à prendre en considération avant le déploiement de ces dispositifs et lors des étapes essentielles après leur déploiement, extraction et trai - tement ultérieur des échantillons pour l’analyse des métaux traces. Bien qu’il ne s’agisse pas d’un protocole standard, ces lignes directrices abordent la nécessité d’une approche commune et l’intention de promouvoir les meilleures pratiques.

This document provides guidance on best practice for the use of Diffusive Gradient in Thin films (DGT) passive samplers devices in sampling of transitional and coastal waters for water quality monitoring. The methodology1 to be addressed in this guide was developed by the consortium of the European Union’s Interreg MONITOOL Project in order to ensure comparability and reproducibility of the data obtained from each project Partner in different regions. The guide provides practical and detailed information on all the aspects to be considered before the deployment of these devices and the essential steps for their deployment, retrieval and subsequent sample processing for the analysis of trace metals. Although it is not aimed as a standard protocol, these guidelines address the need for a common approach and the intention to promote best practice.

The presence of ten metals (Cd, Ni, Pb, Cr, Cu, Zn, Al, Fe, Mn, and Co) was investigated in the final discharge of six facilities, including four wastewater treatment plants, which were continuously discharging treated wastewater to the coastal environment in Gran Canaria Island. A four-day sampling campaign was carried out at each facility in July 2020, in which both the spot samplings technique and the diffusive gradient in thin-film technique (DGT) were carried out to measure total dissolved metals and the in situ labile metal fraction, respectively. After the necessary sample preparation steps, measurements were carried out by ICP-MS for both samplings. Raw data referred to the spot total dissolved and DGT-labile metal concentrations were reported. In general, the average metal concentrations were dispersed in a broad range. As expected, the highest metal contents were found in those facilities with larger industrial contributions. The values of annual average environmental quality standards (AA-EQS) were used to assess the total dissolved metal concentrations for every metal in every final discharge. In only one of the studied facilities, some metals (Ni and Zn) exceeded these EQS within the receiving waterbody, highlighting the need for more efficient treatment targeted towards a specific discharging-water quality. In addition, the total dissolved and labile metal daily fluxes of discharge were calculated to estimate the contribution of every effluent to the receiving water bodies.