Cost-effective nutrient abatement in the Baltic Sea

laskettaessa. Tarkempaan lopputulokseen päästäisiin nämä riippuvuudet huomioivilla osittais-tai kokonaistasapainomallilla. The Baltic Sea is threatened by numerous environmental problems, with eutrophication being the most visible to the public due to increased cyanobacterial blooms and decreased sight depth. It is a problem which is too widespread to be solved by unilateral actions and therefore requires international cooperation. However, in actions against eutrophication public resources could easily be wasted on inefficient policies, and thus the development of an efficient abatement strategy is essential. The aim of this thesis is to propose a cost-efficient allocation of a common fund in the Baltic Sea such that the overall damage from eutrophication can be minimized in twelve years. It presents a dynamic model for simulating the movements of nutrients in the Baltic Sea and in its catchment area with four abatement measures as control variables: reduction of nitrogen and phosphorus fertilizers, wetland construction and reduction of cattle. The model is used to solve a cost-effective set of measures by means of dynamic optimization. The reliability of the model results is assessed and proven adequate by validation. According to the results, it is possible to reduce the eutrophication damage index by 14-27 % in twelve years by an efficient allocation of funding of EUR 20 billion. The significance of international cooperation is obvious, owing to the fact that in total 58 % of the fund is used in Poland and only 13 % in countries with high GDP per capita, Sweden, Finland, Germany and Denmark. The most efficient way for load reduction in all countries is a considerable reduction in inorganic phosphorus fertilizers. The results point out two separable efficient abatement strategies: construction of wetlands and reducing leaching at the source. The former seems to be cost-effective in countries with high GDP per capita, and the latter is suggested for Poland and the Baltic States. Furthermore, the results emphasize the role of phosphorus loads, which are reduced by 27 % while nitrogen loads are reduced only by 17 %. This is due to both the lower cost of phosphorus-related measures, and reduced nitrogen fixation in the sea. The thesis also points out the importance of interdependencies between economic sectors. A partial or a general equilibrium model should be used for more accurate result. Acknowledgement This thesis was conducted at the MTT Agrifood Research Finland as a part of a PROBAPS-project. I would like to thank my instructor, …