Hejzlar, JosefBoers, PaulKronvang, BrianKaraer, FezaGnauck, AlbrechtHeinrich, Ralph2019-09-162019-09-162003https://dl.gi.de/handle/20.500.12116/27066A set of P and N retention data from 178 lakes and reservoirs was analysed using a simple mass balance model requiring knowledge only of water residence time, mean depth, and average mass transfer coefficients for P and N loss (vP and vN, respectively). The model for P retention was refined by categorisation of water bodies according to their input P concentration into three classes, i.e. <10, 10-35, and >35 μg l -1, with corresponding vP values of 7, 15, and 40 m yr -1, respectively. The model for N retention used only one vN value (8 m yr -1) for all water bodies. The absolute mean error of the models was within the range between 9 and 19% of the calculated retention values. The models are suggested for use in determining reference conditions of natural and artificial water bodies within the application of the EU Water Framework Directive in the Czech Republic legislation.Text/Conference Paper