The Baltic Sea, due to its special conditions, is a unique and vulnerable marine environment. There are many pressures that have an impact on the sea and one of the major problems is the extensive flow of nutrients from land. The most visible effect of the supply of nutrients is the annual algal blooms. One of the main sources of Nitrogen and phosphorus supply is agriculture. Nutrient losses from arable land have been increasing as agricultural production has intensified. At the end of the twentieth century an increased awareness of these problems led to the formation of organizations such as HELCOM and Baltic 21.

Two ecological models of Nitrogen processes in treatment wetlands have been evaluated and compared. These models have been implemented, simulated, and visualized in the Modelica language. The differences and similarities between the Modelica modeling environment used in this thesis and other environments or tools for ecological modeling have been evaluated. The modeling tools evaluated are PowerSim, Simile, Stella, the MathModelica Model Editor, and WEST. The evaluation and the analysis have been performed using McCall?s factors for software quality (McCall et al, 1977), a correlation analysis and the Constant Comparative Method (Glaser&Strauss, 1999).

One of the environmental problems today in seas, lakes and streams is eutrophication. This is often caused by nutrients such as phosphorus (P) and Nitrogen (N) that leak from agricultural areas. A measure to partly prevent the nutrient discharge is to construct or restore wetlands.In order to control the efficiency of nutrient reduction of existing wetlands in the county, the administrative board in Västra Götaland wants to find different criterias for reference wetlands. These reference wetlands should represent other wetlands and be used in future evaluations of reduction of nutrients and design of constructed wetlands. According to the administrative board in Västra Götaland the reference wetlands should have a catchment area of about 50 hectare consisting of at least 70 % arable land, to represent wetlands created to remove nutrients.

The impact of the distribution in the soil volume of two farm manures on the net mineralization and immobilization processes of Nitrogen were studied in an incubation experiment. Cattle slurry and broiler litter were placed in the soil with three procedures for incorporation including placement on top of the soil (TOP), in the middle of the soil (MID) and mixed homogenously with the soil (MIX). During the two weeks of incubation, few significant differences in net mineralization were seen between TOP, MID and MIX. However, there was a tendency that MIX led to a larger net immobilization of N than placement at one point (TOP and MID). This is also the result in the literature.

In Halland, agriculture is the major source of eutrophication of water. In the study, synoptic sampling were performed in the three watercourses Nyrebäcken, Skintan and Vinån all located in the county of Halland. Sampling occurred during the period February to May on three occasions with different flow rates: high, low and base flow. Samples were taken in the mainstream and tributaries with intention to show how big the impact of eutrophication it is in the water and  to assess the impact of the tributariesThe results show that all watercourses are affected by eutrophication. Nyrebäcken has the highest concentrations of Nitrogen and phosphorus in the mainstream, then Skintan and last Vinån.

Emission of Nitrogen oxides as well as carbon monoxides is an inevitable result of combustion. A Swedish law "Law of environmental fee for emissions of Nitrogen oxides as a result of energy production" (lagen om miljöavgift på utsläpp av kväveoxider vid energiproduktion (SFS 1990:613)) controls the emission of NOx from energy production by a system of fees. The system has resulted in a strong approach toward less emissions of NOx among the energy production plants. High emission levels, today exceeding 52 mg/MJsupplied fuel, leads to costs for energy production companies. This paper examines possibilities to reduce the emissions of NOx by optimization of the SNCR-technique in a biofuel fired heat and power plant.

An increasing demand for wood products in China has resulted in large areas invested in fast-growing tree plantations of eucalyptus. Eucalyptus plantations are often associated with an intensive management including fertilization. By understanding the effects of fertilization and where in the ecosystem nutrients are accumulated a more sustainable forest management could be achieved. In this study, a nutrient budget including all biomass and soil components was created for Eucalyptus urophylla. The examined nutrients were Nitrogen, phosphorus and potassium.

In the process of making carton boards into Skoghall Mill, are great quantities of water being contaminated. This water has to be treated before it is possible to release into the recipient, Kattfjorden. One of the contaminations that is important to extract from the wastewater, is organic carbon (measured as TOC-total organic carbon) because microbiological breakdown can lead to the bottom becomig free of oxygen.The wastewater treatment at Skoghall Mill is done through an external wastewater treatment that is located at the factory. The biological treatment (aerated lagoon) is a 140 000 m3 water pool with surface aerator, which is give oxygen to the water. In the lagoon live microorganisms who performs the biggest part of the TOC-reduction.One problem with the lagoon is that the treatment of TOC is considerably worse during wintertime than during summertime.

Couch grass (Elymus repens (L.) Gould) is a severe weed in Sweden, and since both the use of herbicides and cultivation should be decreased, it will become increasingly problematic to control couch. The present work is meant to, by literature studies and an experiment, give some answers to the question if cutting and competition can depress the growth of couch. The experiment was carried out in the growing season 2001 at Ultuna, Uppsala, in plastic boxes. The design was three-factorial randomised complete blocks. The factors were plant combination, Nitrogen level and cutting strategy.

The Swedish boreal forests are limited by Nitrogen (N) availability. While biological N2 fixation by cyanobacteria hosted by pleurocarpous feather mosses are important sources of N input to natural boreal forest ecosystems, little is known about the patterns of N2 fixation in silvicultural systems. This study investigates the biological N2 fixation rates of two boreal feather moss species (Pleurozium schreberi and Hylocomium splendens) along a chronosequence from clear-cut to mature forest, as well as the vegetation characteristics along the chronosequence. Measurements and samples were collected from 32 forest sites that were classified into four age classes (clear-cut, pre-commercially thinned, thinned and mature forest). The sites were located near the city of Arvidsjaur in northern Sweden.

The Yara N-Tester is a handheld chlorophyll meter which can be used in several different crops as an aid to determine if there is a need of complementary fertilization with Nitrogen (N) or not. If the crop requires more N the N-Tester will recommend an amount in kg per ha. The possibility to assess the need of N depends on the strong relation that exists between chlorophyll- and N-concentration in the leaves of plants. In the multiannual trial series ?Nitrogen to winter wheat at different soil conditions? measurements with the N-Tester was carried out at flag leaf emergence (GS 37). In this work the result of measurements, the NTesters ability to estimate the need of N in winter wheat, will be presented for the years 2008-2011.

High levels of ammonia in grass silage have been up for discussion by Swedish advisers. One reason is that it is more difficult for the rumen-microbes to utilise high levels of ammonia. A low level of ammonia is also good because if the cattle can use more of the protein in the silage, they don?t need so much protein concentrate. That is very good for the economy at the farm, and it is also good for the environmental problems caused by high levels of ammonia. In this project, 24 samples of silage have been taken at 20 different farms in the south west of Sweden.

This study evaluates the retention of Nitrogen and phosphorus in four newly constructed wetlands in the municipality of Falkenberg, Sweden. The four wetlands have been selected because they have been specifically constructed with the aim to reduce Nitrogen and phosphorus in farming areas. The process of selecting the specific wetlands has been done in collaboration with the county administration in Halland. Through field studies in collaboration with the landowners where the wetlands are sited, the areas that provide the wetlands with water were determined. The size of these drainage areas were determined in a GIS computer program. The type of land use within the drainage areas was also determined.

The main aim was to investigate the provenance of Viking age antler material findings of moose and red deer from Sigtuna and from three sites on the island of Gotland in the Baltic sea. This was done by analysis of the stable isotopes of carbon, Nitrogen and sulphur. Thre were never any living population of these mammals on Gotland during the Viking age.?34S-values of sulphur from this study was compared with earlier research and by studying maps of the Swedish bedrock. The ?34S-values were more like the ?34S-value for bedrock other than European granite.

This study evaluates the retention of Nitrogen and phosphorus in four newly constructed wetlands in the municipality of Falkenberg, Sweden. The four wetlands have been selected because they have been specifically constructed with the aim to reduce Nitrogen and phosphorus in farming areas. The process of selecting the specific wetlands has been done in collaboration with the county administration in Halland. Through field studies in collaboration with the landowners where the wetlands are sited, the areas that provide the wetlands with water were determined. The size of these drainage areas were determined in a GIS computer program. The type of land use within the drainage areas was also determined.