Figure 1
Nitrate and ammonium concentrations and respective water quality classes27 in the sampled catchments in Germany.
Class I: no anthropogenic pollution, Class I-II: very low pollution, Class II: moderate pollution, Class II-III: significant pollution, Class III: increased pollution, Class III-IV: high pollution, Class IV: very high pollution. Maps were generated with ArcGIS 10.0, ESRI.
