Air-pollutant dispersal patterns and vegetation damage in the vicinity of three aluminium smelters in Norway.

Dispersal patterns for fluoride and damage to vegetation was studied near three aluminium smelters in Norway. Leaf samples from three broad-leaved species (Betula pubescens Ehrh., Salix caprea L. and Sorbus aucuparia L.) were collected and leaf injury and the plants overall vitality were evaluated systematically in areas with different distance and direction from the emission sources. Both dispersal patterns and the distribution of damages were mainly determined by the predominant wind direction in the growing season and partly by topography. Damage was restricted to the areas closest to the smelters, within 2 km from the emission sources. Even with the average F- emission as low as 7.1 kg h-1, serious damage to vegetation was observed in built-up areas within 1 km south of the smelter in Mosjøen. Regression analysis showed a correlation between leaf injury and fluoride content in leaves within a locality, but great variation between localities. Leaf injury appeared at concentrations as low as 30 mg kg-1 in some species. An average leaf injury of 1 (scale 0-9) appeared at approximately 100 mg kg-1 in the vicinity of the northernmost smelter, Mosjøen, compared to approximately 150 and 300 mg kg-1 at Husnes and Ovre Ardal, respectively. Fluoride uptake and leaf injury differed among species. Approximately 100 species, mostly woody plants were evaluated for leaf injury and overall vitality. Conifers such as Pinus sylvestris L. and Picea omorika (Pan_) Purk. were sensitive. Except for Populus tremula L., most broad-leaved indigenous species were less sensitive. Species composition in natural areas as well as vegetation use in gardens were affected by pollution. In old gardens at the polluted site Ovre Ardal both the number of plant species and the area used for edible plants was lower compared to old gardens in an unpolluted nearby community. In newer gardens the use of both ornamentals and edible plants was more similar.