Assessing variability in the ratio of metal concentrations measured by DGT-type passive samplers and spot sampling in European seawaters

José Germán Rodríguez*, Isabelle Amouroux , María Jesús Belzunce-Segarra, Philippe Bersuder, Thi Bolam, Miguel Caetano, Inês Carvalho, Margarida Correia dos Santos, Gary Fones, Jean-Louis Gonzalez, Stephane Guesdon, Joana Larreta, Barbara Marras, Brendan McHugh, Florence Menet-Nédélec, Iratxe Menchaca, Vanessa Millán Gabet , Natalia Montero, Martin Nolan, Fiona ReganCraig D. Robinson, Nuno Rosa, Marta Rodrigo Sanz, Marco Schintu, Blánaid White, Hao Zhang

*Corresponding author for this work

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The current study evaluates the effect of seawater physico-chemical characteristics on the relationship between the concentration of metals measured by Diffusive Gradients in Thin films (DGT) passive samplers (i.e., DGT-labile concentration) and the concentrations measured in discrete water samples. Accordingly, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to measure the total dissolved metal concentrations in the discrete water samples and the labile metal concentrations obtained by DGT samplers; additionally, lead and cadmium conditional labile fractions were determined by Anodic Stripping Voltammetry (ASV) and total dissolved nickel was measured by Cathodic Stripping Voltammetry (CSV). It can be concluded that, in general, the median ratios of DGT/ICP and DGT/ASV(CSV) were lower than 1, except for Ni (median ratio close to 1) and Zn (higher than 1). This indicates the importance of speciation and time-integrated concentrations measured using passive sampling techniques, which is in line with the WFD suggestions for improving the chemical assessment of waterbodies. It is the variability in metal content in waters rather than environmental conditions to which the variability of the ratios can be attributed. The ratios were not significantly affected by the temperature, salinity, pH, oxygen, DOC or SPM, giving a great confidence for all the techniques used. Within a regulatory context such as the EU Water Framework Directive this is a great advantage, since the simplicity of not needing to use corrections to minimize the effects of environmental variables could help in implementing DGTs within monitoring networks.
Original languageEnglish
Article number147001
Number of pages9
JournalScience of the Total Environment
Early online date9 Apr 2021
Publication statusPublished - 20 Aug 2021


  • EU Water Framework Directive
  • Diffusive Gradients in thin-films (DGT)
  • Passive samplers


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