The behavior of dissolved ( < 0.45 gm) inorganic compounds during infiltration of river water into the adjacent aquifer (unconsolidated glacio-fluvial sediments) was investigated at the Glatt River, Switzerland, field site. The water was sampled in the river and from wells at distances of 2.5, 5, 13, and 110 m along an estimated groundwater flow line. Sodium, K, Ca, Mg, Sr, Cr, Cu, Zn, Cd, Pb, C1-, NO 3 -, 8 0 4 2 -, and P043-were measured using AAS, NAA, and ion chromatography. Groundwater concentrations of these species are mainly determined by the concentrations in the river. However, the concentrations of NO 3-, (PO43-), Cr, Cu, Zn, Cd, and Pb are also subject to seasonal variations in the near infiltration field (<--5 m). These variations are probably triggered by temperature dependent biological processes which influence parameters such as pH, redox potential and complexing agents. The redox potential controls the chemical behavior of Mn, which influences the solubility of heavy metal compounds. The extent of inorganic pollution in the investigated system is still much below drinking water standards, but for Cd, reaches the toxicity limit for aquatic organisms.