The discharge of nutrients to freshwater systems may cause
eutrophication and, subsequently, various impacts to ecosystems. The ‘Freshwater eutrophication’ impact
category includes the impacts in the area of protection ‘Ecosystem quality’ caused by the emission of
phosphorus (P) into the freshwater and into the soil compartment.
We propose a method to assess the eutrophication impact of P emissions to freshwater as species richness
decrease caused by P emissions to freshwater (namely, the decrease in fish species richness following
the emission of P to freshwater).
The model consists of two parts. The first part represents the transport of P once it is emitted to
freshwater. The emission of P must be defined by the user (unit: mg·day-1) and the P
transport depends upon the fraction of P emitted to soil that reaches the freshwater compartment and the
rate by which P is removed from a given freshwater type once it has been introduced to the freshwater
compartment. This rate is determined by water advection, water use, and retention. The second part
represents the decrease in fish species richness resulting from the increase in the concentration of
concentration of P in the freshwater. This decrease is constant (since it is determined with linear
effect factors) and it is dependent upon region and by the type, discharge, and volume of freshwater.
The time horizon for this impact category is not relevant since it is assumed that the impact occurs at
the moment of emission of P to soil or freshwater bodies.
The spatial resolution of the model is per freshwater ecoregion of the world (FEOW). The coverage of the
model is global.
Characterisation factors are provided for emissions to freshwater, emissions to soil, as well as