Construction of wetlands in the agricultural landscape may reduce nitrogen and phosphorus transfer to streams, thereby reducing the eutrophication of lakes and seas. The agriculturalstream Lillån, a tributary to stream Sagån, ends up in Lake Mälaren and is transporting large amounts of these plant nutrients. The aim of this study was to estimate how hypothetical wetlands of different size and location may reduce nitrogen and phosphorus load from stream Lillån. Estimated nutrient retention in several small wetlands was compared to retention in a single large wetland based on existing data from the agricultural stream and from a nearby smaller stream. Retention in the stream was suggested to decrease along with the nutrient concentration in the water.

Nutrient enrichment is the main cause of the increasing eutrophication process in the Baltic Sea during last century. A prerequisite counteract this process the load of nutrients to the Sea must be investigated. The large contribution of nutrients to the Sea is caused by emission from the rivers within the drainage basin. For the total emission of nutrient into the Sea the retention process in the rivers has big influence. This process in the river system has been assumed as a not important part of the nutrient cycle.

The objective of this thesis is to explore opportunities to enhance the phosphorus use efficiencyof inorganic fertilizers in crop production, with techniques available today and in thefuture. Phosphorus is a finite resource of declining quality; therefore a phosphorus use efficiencyin crop production of only 15-30 % is unacceptable. The main reason for low efficiencyis the retention by Ca and Mg in calcareous soils and Fe and Al in non-calcareoussoils. Due to the low mobility of phosphorus, plant uptake is mainly dependent on root growthrather than diffusion. Therefore, measurements need to be taken that benefit contact betweenroot and fertilizer, before fertilizer phosphorus becomes unavailable to the plant.

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.

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.

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.

It is important to construct or recreate different types of wetlands and study their retention of nutrients, since knowledge of their effectiveness in this matter is poor. In 2003 a wetland was constructed on an old meadow on the western shore of Lake Bornsjön in central Sweden. The main purpose of the wetland was to reduce the amount of phosphorus entering the lake, which is the back-up water supply for Stockholm when the city cannot obtain water from Lake Mälaren. Large areas around Lake Bornsjön consist of agricultural land and the nutrient concentrations in the inflows to the lake are usually relatively high (approx. 1 mg/l total nitrogen and 0.05-0.1 mg/l total phosphorus).

Environmental subsidies are used as incitements to farmers for development of sustainable land use. In 2014, applications for funding constructed wetlands were not available. This paper examines the environmental consequences of this lack of funding in one intensively cultivated region Skåne län, southern Sweden.A review of wetland applications between year 2007-2013 show that the average rate of applications has been 31 projects per year with a wetland size of 4,48 ± 1,61ha per project (mean±95% CI). Based on interviews, the result suggests that the lack of funding in one year leads to between 102 and 140 ha of constructed wetlands that is not built. This correspond to a total loss of increased nitrogen retention capacity between 6,0 and 91,7 tons/year and a loss of increased Phosphorus retention capacity between 0,17and 2,1 tons/year in the drainage basins of Skåne.Further the interviews show that continuity of environmental regulations and funding is important for the farmers? interest in environmental measures.It is concluded that the total loss of increased retention capacity is small compared to the annual transport of nitrogen and phosphorus in the drainage basins.

Eutrophication is a major problem in the Baltic Sea, as a result of increased loading of nitrogen and phosphorus. In the coastal parts of Östergötland the soil largely consists of clay and contains high levels of phosphorus bound to clay particles. Erosion of the soil in agricultural areas makes the water turbid and transports phosphorus to the Baltic Sea. The aim of this project was to examine the relationship between phosphorus and turbidity in the coastal streams of Östergötland. The aim was also to evaluate the possibility to use turbidity as a surrogate measure for phosphorus.

During the nineties, ecological handling of urban storm water became very popular in Sweden. Together with Chalmers University of Technology and two Swedish communities, DHI Water and Environment has been doing research of storm water ponds and constructed wetlands. This thesis work is a part of that research project. The work has been applied at the Bäckaslöv storm water treatment plant in Växjö, Sweden. The plant consists of one storm water pond and a downstream constructed wetland.

Hammarby Sjöstad is a new district of southern Stockholm built with focus on reduced environmental impact by recirculation of materials and sustainability. The environmental goals aim to cut the water consumption by half and a separate storm water treatment. Thus, the wastewater will be more concentrated and will originate from the households only. The Sjöstad project includes the idea of a local treatment plant for the household wastewater. To evaluate this possibility, Sjöstadsverket, an experimental treatment plant was constructed.

Eutrophication is a major problem in the Baltic Sea, as a result of increased loading of nitrogen and phosphorus. In the coastal parts of Östergötland the soil largely consists of clay and contains high levels of phosphorus bound to clay particles. Erosion of the soil in agricultural areas makes the water turbid and transports phosphorus to the Baltic Sea. The aim of this project was to examine the relationship between phosphorus and turbidity in the coastal streams of Östergötland. The aim was also to evaluate the possibility to use turbidity as a surrogate measure for phosphorus.

This work is a part of the project ?Våtmarker i odlingslandskapet ? uppföljning av miljömålen? (Wetlands in arable land ? following-up of the environmental goals). The main objective with this project is to study nitrogen and Phosphorus retention in a constructed wetland by using mass balance calculations. Continuous measurements of nutrients and water flow through the inlet and the outlet of the wetland are made. However, substantial amounts of nitrogen and phosphorus were assumed to reach the wetland with a drain-pipe transporting wastewater from nearby houses (10 persons).

The short term effect of phosphorus in sewage sludge was investigated to establish howmuch of this a farmer can grant him- or herself, if using sewage sludge as a phosphorusfertilizer. Possible differences in plant availability between sludge phosphorus precipitatedby iron, aluminum or calcium integrations were studied in a sandy soil at two pH levels.The sludges were analyzed using pot and incubation trials. As the intention was to investigategrowth limitation due to phosphorus deficiency, a soil with low phosphorus supplywas chosen as well as a low phosphorus application rate. Sludge corresponding to 12kg phosphorus per hectare was applied. Treatments fertilized by sludge were compared totreatments where 0, 6 and 12 kg phosphorus per hectare from mineral fertilizer was applied.Every treatment was replicated six times.

An excessive input of nutrients to lakes and other water bodies has created a problem with eutrophication in Sweden. Untreated, or partially treated, domestic sewage is a major source for discharge of phosphorus (P), which is the nutrient most frequently responsible for eutrophication of most fresh waters and the Baltic Sea. The waste water can be cleaned by filter materials, which have a high P-retention ability and which after saturation may be used as fertilizers. Four potentially suitable filter materials were tested in batch- and column experiments in this study. In the batch experiments, the following materials were shaken with waste water in time series ranging from 5 seconds to 60 minutes: coarse (1-4 mm) and fine (0-2 mm) Polonite® (heated bedrock from Poland); Filtralite® (light expanded clay aggregates with limestone added before burning); water cooled blast furnace slag (BF-slag) and BF-slag mixed with 10% burned limestone.