TEOTIL Metals: Development report - 2021

The model TEOTIL has been widely used in Norway for simulating nutrient fluxes at national scale. This report describes extending TEOTIL to incorporate metals. A review of metal behaviours is presented and the requirements and constraints for extending TEOTIL described. Key datasets for the metals of interest are identified and statistical analyses undertaken to explore relevant relationships. A new model is constructed using metal concentrations from the 2019 “1000 Lakes” survey to represent spatial variability, and regionally aggregated data from Elveovervåkingsprogrammet to infer temporal patterns. Performance of the model is evaluated by comparison to observed datasets and shown to be better than the current method used to estimate metal fluxes for annual reporting to the OSPAR Commission.