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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 marine water ) 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 marine water) to DGTs (EQS DGT ), in the context of the WFD. Moreover, due to the large number of sampling sites, it could also be used for other types of research, such as those dealing with metal speciation or the determination of baseline levels., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

This study investigates the relationships among Ni, Cd and Pb's different chemical forms determined by different methodologies in coastal and transitional waters across a broad geographical scale. Concentrations were measured in spot samples and through passive sampling (DGT). High variability of metal concentrations was found among sampling sites and methodologies due to natural water fluctuations rather than to a given metal or method. Total dissolved metal concentrations in spot samples were lower than the EQS-WFD values. The labile fractions of Cd and Pb, measured in spot samples by Anodic Stripping Voltammetry and by DGT-ICPMS, were highly correlated. Similar labilities were found for Cd, while for Pb, the ASV labile fraction was ≈50% lower. These results reflect the pool of mobile and labile species available towards each technique kinetic window, and they seem not to be affected by discrete sampling flaws., (Crown Copyright © 2022. Published by Elsevier Ltd. All rights reserved.)