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The Gran procedure described by Molv©¡rsmyr and Lund (1983) was modified and automated for the routine analysis of strong and weak acids in freshwater. The titrations are carried out by coulometric generation of hydroxide ions in the pH range 3.6-10.3. The method measures the amount of non-volatile strong and weak acids in freshwater with a […]

The Askerö fjord receives wastewater from petrochemical industries located in Stenungsund on the Swedish west coast. During the autumn of 1987 an investigation was performed where the physiological status of common mussels (Mytilus edulis) which had been caged in this area was studied. The measured physiological parameters were: feeding rate, absorption efficiency, respiration and ammonia […]

Introduction of energy forestry in Sweden is likely to occur in the beginning of the 1990’s. To describe how an intensively cultivated willow forestry might affect the water resources and what the irrigation need might be, the evaporation and water balance were simulated by a reasonably simple, yet physically realistic model. Average evaporation during the […]

Function and stability of five freshwater model ecosystems were studied during three months in 1985. Two of the models had no fish and the other three had fishpopulations of different kinds. The ecosystems intended to be models of a Lobelia/Isoetes-community in the oligotrophic lake Nedre Fryken. Most of the material for the model ecosystems was […]

The controversy whether nitrogen or phosphorus limits phytoplankton growth in Swedish coastal and sea areas has been ongoing since the early 1970’s. Today there is a consensus among scientists that nitrogen is the key factor controlling phytoplankton growth in the Baltic proper, Kattegat and Skagerrak and phosphorus in the Bothnian Bay, while the Bothnian Sea […]

The dominating role of phosphorus as limiting nutrient in fresh water is well documented, while the situation in coastal areas and the open sea is less clear. In the marine environment phosphorus (P) and nitrogen (N) availability appears to be more balanced to the nutrient requirements of algae. When nutrient limitation is discussed, it is […]

New process technologies have considerably improved the specific nitrification capacity per unit area of immersion percolating filters. The operating principle is based on strict separation of the carbon reduction and nitrification processes together with uniform substratum supplies in cascade plants. These processes lake the immersion percolating filter viable even for high capacity plants. The method […]

The intention with the trial operation at the sewage treatment plant Västra Stranden, Halmstad was to investigate what the nitrogen removal would be during summer conditions after extension of the tanks for anoxic pre-denitrification to the double. The flow to the three separate activated sludge units was distributed in such a way that two of […]

Systematic recordings of alkalinity may give early warning of change in acidification status. Fixed endpoint titration is a method well suited for routine measurements. But, standardized procedures for alkalinity titration do not take into account errors in endpoint pH caused by stirring of the samples. The magnitude of this effect depends on individual and variable […]

Earlier investigations have shown that the run-off from a forested area increases after clear-cutting. For Swedish conditions, values between 90 and 406 mm/year have been reported. On the bases of micrometeorological measurements above clearcut and forest areas and of theoretical discussions, light can be shed on the causes to the run-off increase. The present micro-meteorological […]