Fig. 3. Hydrochemistry variations in the Thur River and its tributaries measured at the sampling stations in summer SC1 and spring SC2. Concentrations of NO3-N (±0.1 mg N/
l), Cl (±0.2 mg/l), Ca2+ (±1.7 mg/l), K+ (±0.3 mg/l), Na2+ (±0.8 mg/l), TP (±3 lg P/l) are illustrated. The hotspots of hydrochemistry variations are identified at the junctions of
the tributaries Necker (N), Sitter (S) and Murg (M) joining the Thur River.