In industrialized countries, the assessment of water quality in rivers has shifted in recent years from nutrients and industrial contaminants to micropollutants, such as pharmaceuticals, daily-care products, various additives, etc., which are introduced via sewage treatment plants into the rivers at concentrations typically in the nanogram-per-liter range. Persistent organic pollutants, typically sorbed to suspended matter, also prevail at low concentration levels in rivers, either as legacy compounds or from atmospheric input. Because the input into streams is temporally quite variable and transport processes vary with discharge, thorough understanding of micropollutant dynamics require mechanistic numerical models of flow, solute transport, sediment transport, water-sediment partitioning, and degradation processes.
Within WESS, several tributaries to River Neckar have been monitored for micropollutants over the last years, among them the rivers Steinlach and Ammer in the direct vicinity of Tübingen, both of which receive water from seawage treatment plants. In addition, discharge, major ions, DOC, turbidity, and electrical conductivity were monitored. The monitored substances include pharmaceuticals (e.g., carbamazepine, diclofenac), pesticides (e.g., mecoprop, DEET), flame retardants (e.g., TCPP, TDCPP), and fragrants (e.g., OTNE, HHCB). Lagrangian sampling techniques were used in conjunction with natural and artificial tracer studies, to eliminate effects of physical transport on the change of observed concentrations.
