Effects of the reduction of cement plant pollution on the foliar and bark chemical composition of Scots pine

The impact of dust emissions from the cement plant of Kunda, north-eastern Estonia, was studied by analysing Scots pine needles and bark. Element concentrations of needles were measured by atomic absorption spectrometry. A scanning electron microscope with an energy dispersive X-ray microanalyzer was used to study dust deposition on the surface of needles and bark. A thick cement dust layer covered plant surfaces, increasing the content of several elements of unwashed needles tenfold as compared with unpolluted sites. The distribution pattern of manganese was totally different to other elements, showing the highest concentrations at the remotest sample sites. Near the plant, pine needles suffered a serious deficiency of Mn. This was due to the unavailability of Mn caused by the alkalising of soil as an impact of dust pollutants. The renovation programme was aimed to reduce dust emissions by 97% over five years. Dust pollutants on pine needles and bark decreased remarkably. However, considerable dust deposition could be observed two years after the renovation. This was caused by the still continuing dust emissions (over 1000 tonnes y–1) and by re-emissions of very large dust masses formerly deposited. The results gave indirect evidence that the recovery of the soil was slow.