Characterization factors for inland water eutrophication at the damage level in life cycle impact assessment
Purpose Life Cycle Impact Assessment methodology is still lacking a procedure that relates phosphorus emission to ecological damage in freshwater ecosystems. The aim of this study is to apply new insights in the characterization of aqueous eutrophication at the end-point level. Characterization factors for freshwater eutrophication in European waters caused by emissions of phosphorus to agricultural soils and freshwater were developed. The characterization factors are representative for emissions to the 101 most important European river catchments west of the Ural Mountains. Methods We combined site-generic fate factors of total phosphorus, calculated by means of the integrated assessment model CARMEN, with damage factors based on a concentration–response relationship between the concentration of total phosphorus and occurrence of macrofauna species in freshwaters. Environmental fate processes, such as surface run off, groundwater drainage, and hydrological freshwater residence times, are included in the fate factor which relates emission of phosphorus from wastewater treatment plants and due to agricultural supply of manure and fertilizer, to concentrations in freshwater. Results and discussion The product of fate factor and damage factor constitutes the characterization factor at the endpoint level with the following results: 1.1·103, 1.2·103, and 2.1·104 disappeared fraction of species·m3·day/kg phosphorus emission for manure, fertilizer, and sewage treatment plants, respectively. Normalization factors are based on the emission of total phosphorus in Europe resulting in 60.1 disappeared fraction of species·m3/person with a relative contribution of 16% by manure application, 18% by fertilizer application, and 66% by sewage treatment plant emissions. Conclusions From intervention (P emission) to ecological damage of inland waters, most relevant site-specific processes are included to derive a characterization factor at the damage level. Although the characterisation factor for P due to agricultural application is a factor of 20 lower compared to emissions to freshwater, the nutrient enrichment of European freshwaters is still for one third attributed to agricultural application of phosphorus.