Mercury in terrestrial mosses in the vicinity of tne Norgips plant at Tørkop

Abstract

The Norgips plasterboard plant at Tørkop in Vestfold County, Norway, are now using industrial gypsum as a raw material in their production. This is a by-product from the cleaning of flue-gases from coal power plants. Industrial gypsum contains, in general, less heavy metals than the before used natural occurring gypsum, with the exception of a higher content of mercury (Hg). The production at the plant has increased the recent years. The atmospheric emission of mercury from the plant is now 15 kg per year, which is 2% of the annual man-made atmospheric emissions in Norway. To reveal the extent of Hg pollutions from the plant, Hg concentrations in terrestrial mosses were examined at 15 locations in the vicinity of Tørkop. Elevated Hg concentrations were found in mosses from the immediate area of the plant. This may be attributed to depositions of dust from raw materials and depositions of reactive gas-phase mercury from the production. However, this needs be verified with more specialized surveys. There could not be established any systematic concentration gradient outside the immediate area. Mercury released through the heating process exists most likely as gaseous mercury. This phase is more mobile and has a different transport and deposition pattern than particle bound mercury in the dust originating from the raw materials.