As a result of changes in hydrology, the former mesotrophic, shallow lake Naardermeer, has been eutrophicated during the last decades. To compensate for shortage of water, eutrophicated water with different chemical characteristics has been supplied. In order to determine the effects of alkalinity, acidity and external sulphate and phosphorus load on eutrophication processes, developments in water chemistry have been studied in enclosures. A decrease of the phosphorus load of the lake did not improve water quality on the short term. This observation was confirmed by this enclosure experiment. Reduction of alkalinity did improve water quality, particularly by reductions of turbidity and chlorophyll-a content. The significant increase in sulphate load in the water layer led to deterioriation of the water quality and an increased biomass of sessile algae by internal eutrophication, probably as a result of increased sulphate reduction in the sediment. Therefore, it seems that lowering of sulphate concentrations in the inlet water after the removal of phosphorus is necessary to improve the water chemistry. The best option, however, is to restore the former hydrological conditions after which the system will be fed only by seepage of groundwater poor in nutrients and sulphate.

The bioaccumulation and toxicity of zinc in Spirogyra fluviatilis Hilse, from two populations in the River Seyhan, Adana, Turkey, were examined in laboratory flowing-water channels. Plants were subjected to zinc concentrations ranging from 0 to 4.0 mg L⁻¹ at current velocities of 25–35 cm s⁻¹ for up to 3 h. There was little difference in zinc bioaccumulation between Spirogyra from the site showing mild organic pollution and that from the site subjected to considerable inputs from urban and motorway runoff. Uptake of zinc increased with increasing concentration in the test solution and was linear and proportional up to 0.5 mg L⁻¹. Cellular damage was evident in Spirogyra subjected to 0.5 mg L⁻¹ zinc, and increased with increasing zinc concentration.

The absorption of atmospheric radionuclides by soybean plants was experimentally studied using a radioactive multitracer consisting of radionuclides of Sc, Mn, Co, As, Se, Rb, Sr, Y, Eu, Gd, Yb, Hf, Re, and Ir. The soybean plants were cultivated in soil under no-rain conditions in a box containing air in which multitracer-absorbed cellulose particles were dispersed. The soil was covered with plastic film. After about one-month cultivation, the plants were harvested and washed with dilute HCl solution. The leaves, stems, and beans were subjected to γ-ray measurement. The radionuclides of As, Se, and Re were accumulated in the leaves, and those of Co, Se, and Rb were accumulated in the beans. Among them Se was accumulated to a large extent in the leaves and in the beans. Small amounts of the radionuclides of Co, Se, Rb and Re were found in the roots. Little absorption of these radionuclides into the soil occurred. These results indicate that various radionuclides in the atmosphere were absorbed through the soybean leaves and then transported to the seeds. These findings must be taken into consideration for a complete understanding of the system of uptake of radionuclides by the soybean plant.