Constructed wetlands as nitrogen sinks in southern Sweden:: An empirical analysis of cost determinants

Determinants of wetland construction costs are studied by an analysis of detailed data on wetland construction projects for attaining nitrogen reduction in two drainage basins in the agricultural district of southwest Scania, the southernmost part of Sweden. Cost equations are estimated. and they illustrate the importance of considering excavation efforts for obtaining more accurate construction-cost forecasts. The sensitivity of underlying assumptions about a cost estimate is analysed, and a comparison with an earlier effort to estimate a cost equation for constructed wetlands in Sweden is carried out. Cost-estimate implications, in terms of average cost per kilogram (kg) of reduced nitrogen, are also shown. For example, a base case that involves an average total cost of USD 2150 ha(-1) per year and a rule of thumb of a nitrogen reduction of 1000 kg-N ha(-1) per year imply a cost of USD 2.15 kg(-1) of reduced nitrogen. (C) 2002 Elsevier Science B.V. All rights reserved.