Alla artiklar

Soil acidification has not as yet been observed in upper Norrland. Possibly the investigations mostly carried out in well drained soils may not be relevant however as an early stage of surface water acidification should concern the discharge zones. In these zones the flow is channelled to restricted soil volumes both depthwise and sideways. This […]

Scandinavian freshwater acidification was observed at the end of the nineteen sixties and was thought to be a result of the observed pH-decreasing in the precipition over north-western and northern Europe (Oden and Ahl 1970). These results were obtained from the monitoring of the water quality in the Swedish rivers started in 1965 and a […]

Recent studies show that anthropogenic acid surges provide the major acidification problem for lakes and watercourses in northern Sweden. Anthropogenic acid episodes may occur in around 20-40 % of all watercourses and in around 15-30 % of all lakes. Anthropogenic acidification throughout the year is a lesser problem. Predictions for the future using mathematical models […]

In southern Sweden, changes in agricultural practices have affected the streamland interface increasing nutrient transport to the sea. Results from ongoing studies suggest that these areas surrounding Scanian streams are important in nutrient removal. In artificially induced surface runoff through a riparian buffer strip, 66 % of the PO4-P was retained during the first 8 […]

The concentration of nitrous oxide in the atmosphere increases with 0.25 % per year. Nitrous oxide degrades ozone and it also increases the green-house effect. Many biological processes can produce nitrous oxide. The three most important processes are nitrification, denitrification and dissimilatory ammonium production. These biological processes are of importance in development of systems for […]

From September 1988 up to June 1991 a full-scale experiment was conducted using a submerged macrophyte pond and a root-zone for wastewater treatment. The mean removal was 32 % and 46 % of nitrogen and 62 % and 61 % of phosphorus respectively. The major removal mechanism for N was denitrification and for P assimilation, […]

The role of wetlands, ponds and lakes in the retention of nitrogen and thus in the decrease of nitrogen transport to the sea is under discussion in Sweden. In this paper nitrogen budgets for Lake Björkaren during four years are presented. The lake is very shallow and almost covered with higher vegetation and the water […]

There are diverging opinions on nitrogen retention in wetlands. In southern Sweden, wetlands contribute to limit nitrogen leaching. In forest wetlands in central and northern Sweden there are only indications on small or no retention effects. Wetland types as well as the nitrogen load vary. Outflow of nitrogen from forested watersheds, including considerable wetland areas, […]

The creation and restoration of wetlands has been suggested as an efficient method for the reduction of the transport of nitrogen to the Swedish coastal waters. In the paper, which is written from a hydrological viewpoint, a few critical questions are identified which require further clarification. The questions concern our knowledge about retention processes, dynamics […]

There are several ways to obtain information about land use and vegetation for an area. In this project we have used satellite images to calculate statistics for the drainage area of River Fyrisån in Uppland, Sweden. A Landsat TM (Thematic mapper) image registered on the 7th of July, 1989 was used. The spectral information in […]