Deposition of heavy metals to the Convention Waters of the Oslo and Paris Commissions

The deposition of heavy metals (arsenic, cadmium, copper, chromium, nickel, lead and zinc) on the Convention Waters of the Oslo and Paris Commissions (OSPARCOM) were calculated using an emission based modelling approach. Emis sions were taken from the UN-ECE/OSPARCOM/HELCOM Emission Inventory of Heav y Metals and Persistent Organic Pollutants. The atmospheric transport model EUTREND was used to calculate the transport and deposition of heavy metals on the convention waters. Results were obtained for the regions Greater No rth Sea, Celtic Sea, Bay of Biscay and Iberian Coast and for parts of the r egions Arctic Waters and Wider Atlantic. The contributions of five major so urce categories to the deposition were calculated. The contribution of OSPA RCOM countries to the deposition on the Convention Waters as well as the co ntribution of the non-OSPARCOM countries as a whole were calculated. Measur ed air concentrations were underestimated by the calculations by a factor o f 2-4 for arsenic, cadmium, copper, chromium and zinc. For lead and nickel the comparison was close to the 1:1 line. The underestimation is most likel y due to an underestimation of the emissions. A comparison between the inpu t of heavy metals by atmospheric deposition and riverine input around the N orth Sea as well as a comparison with other studies on the atmospheric inpu t to the North Sea estimated from measurements and modelling are presented.