Costs of nutrient reductions to the Baltic Sea

Gren, Ing-Marie; Jonzon, Ylva; Lindqvist, Martin

Costs of nutrient reductions to the Baltic Sea

2008

Gren, Ing-Marie | Jonzon, Ylva | Lindqvist, Martin

This paper presents calculations of costs for measures reducing nitrogen and/or phosphorous loads to the Baltic Sea and minimum cost solutions for different nutrient reduction target formulations. In total, 14 measures are included for nitrogen (N) reductions and 12 for phosphorous (P) reduction, out of which six measures affect both nutrients. Calculations show that land use measures provide low cost measures for N reductions and P free detergents and improved sewage cleaning for P reductions. Two types of targets are chosen for calculation of minimum cost solutions: overall reductions of nutrient to the Baltic Sea and reductions to specific basins. Three different assumptions on adjustments among basins to exogenous load changes are made for basin specific targets; no adjustment, partial first-order adjustment, and total steady state adjustment. For a given nutrient reduction in percent, both estimated total cost and cost effective allocation of reduction in loads to different basins vary considerably depending on target setting. However, costs of different measures, and thereby estimated minimum cost solutions are sensitive to parameter values on leaching, retention, and abatement cost and capacity. Sensitivity analyses show that minimum costs of nitrogen reductions are mainly affected by changes in assumed abatement capacity of land use measures, and costs of phosphorus reductions are sensitive to cleaning cost at sewage treatment plants.

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