Boliden – Diffuse emissions from unloading of zinc concentrate (Boliden)

Diffuse emissions from the unloading of zinc (Zn) concentrate in Odda, Western Norway have been quantified using an inverse modelling approach.

Eleven deposition samplers were strategically placed around the plant with sampling period of six months, approximately one month exposure time. Metal content of deposited material in the samplers were analyzed by mass spectrometry.

The gaussian deposition model CONDEP, driven by wind data measured on site, was applied to estimate emissions of cadmium (Cd), lead (Pb), mercury (Hg), nickel (Ni), zinc (Zn), arsenic (As) and copper (Cu). These emission estimates were then used to calculate deposition onto water surfaces.

The emission rate of Zn was estimated to be 19 (between 7 and 36) g per ton unloaded mass, equivalent to 214 (150‑300) kg per 30 days. Of the total mass emitted, 40% (27-45%) were estimated deposited onto water, equivalent to 89 (40‑140) kg per 30 days.