The MONITOOL Project is based upon Directive 2013/39/EU [1] with regards to priority metals in the field of water policy, including cadmium, nickel, and lead. Existing Environmental Quality Standards for these methods only include biota sampling, and therefore new in situ solution sampling methodologies are a priority. The MONITOOL Project aims to define suitable EQS to allow for the use of Diffusive Gradient in Thin film (DGT) passive sampling devices [2] for the monitoring of these priority metals in a regulatory context. DGT devices are composed of an ion-exchange resin, separated from solution by a diffusive ion-permeable gel layer. Their design allows for the continuous accumulation of metals in situ, and subsequent quantitation via methods such as ICP-MS. While many of the chemical aspects of the devices have been well studied [3], effects of environmental physicochemical parameters on the functionality of the devices has not been examined in detail. Five-day deployments of DGT devices, alongside spot sampling and physicochemical parameter measurement, will be conducted in both wet and dry seasons in coastal and transitional waters of the North Atlantic coast, including locations in Ireland such as Cobh, Dun Laoghaire and the Alexandra Basin. The data collected from these sampling campaigns will inform potential future EQS adaptations.