3.1. Contribution of processes to the impact categories
Life cycle impact assessment has been performed for both compared systems. In a global overview we have taken a census of 148 processes contributing to the different impacts associated to the
studied system.
The contribution analysis of TR and CR are reported in Figs. 2 and 3, respectively. At first glance, it appears that infrastructure,diesel, transportation, electricity and the hatchery are secondary to the diet process and the farming process. The PG process contributes to all impacts categories. Its relative contribution is well pronounced in the case of GWP, AP, EU and WD reaching around 25%. Remarkably, diet process contributes to all impacts except WD. The latter item was found to be responsible for 88% and 72% of the SU associated with TR and CR, respectively. Figs. 2 and 3
also show that GWP, AP and EU are influenced by the contribution of all processes contrary to others impact categories only influenced by three or two processes.
3.1.1. Environmental impact comparison
3.1.1.1. Eutrophication potential (EP). For EP, farming process and PG are dominating due to direct emissions of nitrogen and phosphorous to water (Fig. 4). Yet, the diet is responsible for just 10 kg PO4-eq per 1000 kg of produced fish mainly due to feed loss and non-digested pellets. In a comparative view, CR presents