A survey on trace organic chemicals in a German water protection area and the proposal of relevant indicators for anthropogenic influences.

A comprehensive monitoring programme of trace organic chemicals (TOrC) was conducted for a German water protection area in karstic ground. The aim of this survey was to detect the potential anthropogenic influences of point sources such as wastewater treatment plants and diffuse pollution such as runoff water from roads on the raw water used for drinking water treatment. The programme comprised seven sampling campaigns within 2 years each with up to 20 sampling sites. In total, the programme included 84 anthropogenic compounds from pharmaceuticals, iodinated X-ray contrast media, sweeteners, industrial chemicals (benzotriazoles, melamines and benzothiazoles) and pesticide metabolites. Cyclamate occurred with the highest median concentration of 44 μg l-1 in untreated wastewater and acesulfame occurred with a concentration of 20 μg l-1 in treated wastewater. In runoff water from roads, the most relevant compounds were tolyltriazole with 2.3 μg l-1 and the desphenyl-chloridazon with 1.2 μg l-1. In the stream waters, the highest median concentrations were found for melamine and acesulfame both at 0.61 μg l-1. High elimination during conventional wastewater treatment was observed for 5 out of 49 compounds. These are acetyl-sulfamethoxazole, aciclovir, cyclamate, ibuprofen and saccharin. Based on the survey results, we propose a set of nine compounds to be used as indicators for wastewater, untreated wastewater and runoff water from roads for an efficient surveillance. The indicators are intended to detect anthropogenic influences in surface, ground and drinking water.