FUNKTION OCH STABILITET I SÖTVATTENSMODELLEKOSYSTEM / Function and Stability of Freshwater Model Ecosystems
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 […]
KVÄVE OCH FOSFOR SOM BIOMASSABEGRÄNSANDE ÄMNEN I HAVET / Nitrogen and Phosphorus as Growth Limiting Substances in the Sea
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 […]
KVÄVE ELLER FOSFOR – VAD ÄR BEGRÄNSANDE NÄRSALT I KUSTOMRÅDEN? EXEMPEL FRÅN NORSKA FJORDAR / Nitrogen or Phosphorus – what is Limiting Nutrient in Coastal Areas? Examples from Norwegian Fjords
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 […]
NITRIFICATION WITH IMMERSION PERCOLATING FILTERS – Wider uses for new technologies even in large sewage works
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 […]
KVÄVEREDUKTION I ETT BASSÄNGREAKTORSYSTEM / Nitrogen Removal in a Suspended Growth System
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 […]
FIXED ENDPOINT TITRATION OF ALKALINITY IN ACID PRECIPITATION RESEARCH
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 […]
ORSAKER TILL AVRINNINGSÖKNING EFTER KALAVVERKNING / Cause to Run-off Increase after Clear-cutting
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 […]
KONSEKVENSER AV HAVSYTANS HÖJNING FÖR SKÅNES KUSTOMRÅDEN / Effects of Sea Level Rise on Scanian Coast Reaches
Today there is a serious concern about the consequences of a global climate change. One possible effect of this change is a considerable rise of the sea level. According to several prognoses it may be expected that the sea level rise by the year 2100 may lie between 0.9 and 1.7 m with a preferred […]
DAGS FÖR NYA PERSPEKTIV PÅ DRICKSVATTENKLORERING OCH RISKER? / Time for New Perspectives on the Risks of Drinking Water Chlorination?
The past decade’s chemical, toxicological and epidemiological research on by-products of drinking water chlorination has been reviewed. A large number of by-products has been identified and tested in different bioassays, and, recently, considerable progress has been made in the identification of Ames mutagenic byproducts. Still, there is little hope that the present uncertainty of chemical-toxicological […]
HETEROTROPHIC MICROORGANISMS IN DISTRIBUTION SYSTEMS FOR DRINKING WATER
Raw water, treated water and distributed water from three water works in the vicinity of Oslo, Norway, were investigated for content of heterotrophic, aerobic microorganisms and total count of bacteria. The treatment was different in the three water works, but they all got raw water from the hypolimnion of stratified lakes. The total counts were […]