Gypsum treatment as a restoration method for sediments of eutrophied lakes – experiments from southern Finland

The internal load of phosphorus can be treated with chemicals improving a sediment's phosphorus binding capacity. Gypsum (CaSO₄?2H₂O) is a novel material to be applied for this purpose. In the hypereutrophic Lake Enäjärvi, southern Finland, sediments were treated with gypsum in test basins. The basins were isolated from open water to create artificial anoxia, which allowed the effects of the treatment on the internal load to be measured. The results indicate that gypsum treatment decreases the sediment's release of nutrients under anoxic conditions. This was demonstrated as less increased total-P and total-N concentrations and decreased chlorophyll-a concentrations in the water column of treated basins as compared with the control basins. Because the gypsum treatment prevents internal load, it has potential in lake restoration in cases where the internal load of phosphorus is accelerated by anoxic conditions at the sediment/water interface.     

Development of human ecology in Lapland,Finland, after World War II Die Landesentwicklung in Finnisch-Lappland seit dem II. Weltkrieg Développement écologique de la Laponie Finlandaise après 1945

Everywhere in the industrially advanced world, a fundamental feature of the population trend has been a movement from the countryside into towns and from sparsely settled regions into previously densely inhabited areas and cities. In Finland a region that is being deserted is the province of Lapland. The development of its economic life after World War II has been studied. This war cut short the vigorous growth experienced by the province in the previous decades, but its aftermath inaugurated a period of reconstruction and state-supported measures that for a short time enlivened economic activity there and brought about optimism as to future prospects. The short-sightedness of the developmental measures and, to some extent, the lack of planning behind them have later become evident; the promising rise of economic activity has now halted or turned downward in nearly every field of endeavor.