Current and historical patterns of heavy metals pollution in Estonia as reflected in natural media of different ages: ICP Vegetation, ICP Forests and ICP Integrated Monitoring data

Comparing the studied media, three types of HM retention patterns were detected: (1) for Cu, Ni, Cr (2) for Cd, Pb, (3) for Zn. The mean current level of HM deposition in Estonia is low comparison to previous decades, especially the 1980s. The effect of the previously significantly higher exposure of HM emissions and deposition is preserved in older part of soil organics (OF), where the highest stocks and concentrations of HMs (with the exception of Zn) are currently found. The HM proportions in fly ash of oil shale and in OF layer of soil were very similar with regards to Ni and Cr-indicating their origin from the oil shale industry in the N-E region. According to spatial distribution analysis, the greatest accumulated storages of Ni and Cr in OF layer of coniferous forest soils are characteristic to S-W Estonia.