Heavy metals migrate in thc environment in different forms (free ions, labile inorganic and organic complexes). Most of the heavy metals create a potential threat to organisms. Their harmfulness is connected not only with biological, biochemical properties, but also depends on forms in which heavy metals appear in the environment, so-called speciation. The chemical term speciation has several meanings and can be defined as analysis, distribution, bioavailability and transformation. In the presented paper the occurrence of heavy metals and possibilities of their determination are discussed. Using anodic stripping voltammetry (DPASV) it was found that 1 gram of humic substances (HS) dissolved in surface water bound to 13.7 μg Cu/g HS and 7.1 μg Pb/g HS. Stronger complexing properties were observed for HS isolated from groundwater: 27 μg/g HS in the case of Cu and 46 μg/g HS for Pb.
Some important scientific and practically useful achievements in the scope of land improvement and shaping the agricultural environment in Poland within 1945-1996 are presented against the background of information on land improvement science progress noted from the tum of the 19th century. General trends of scientific and practical activities before 1945 and in 1945-1969 dealt with the erosion protection, drainage and river regulation. In the 60th and 70th the sprinkling irrigation, building of farm roads and rural water supply network were developed. In the '80th the microirrigations were introduced and the exploitation processes of subsurface irrigation were improved in order to limit the water and energy consumption. In the next period the attention was paid on the problems of water quality and environmental protection. The methods of sewage purification in soil-plant environment and plant consolidation of the water course bed were developed. Towards to decreasing resources of available water, every form of retentioning water, within so called small retention, are developed. Changes in land improvement service activities follow the economic changes in Poland, science progress and they are convergent with the tendency of changes in Europe.