Application of a New Integrated Concept to Assess the Effects of Organic Contamination in Surface Waters.

The new BMBF (Ministry for Education and Research) research project "Application of a new integrated concept to assess the effects of organic contamination in surface waters" started October 1998. In the project we cooperate with the Lehrstuhl für Botanik, Technische Universität München (Prof. Dr. B. Hock), WFM Wasserforschung Mainz (Dr. U. Obst), and Staatliches Institut für Gesundheit und Umwelt des Saarlandes (Dr. R. Kirn). The purpose of the project is to develop a concept for a more detailed description and evaluation of the organic contamination of different surface waters. Type and degree of the contamination as well as its effects on aquatic organisms are to be characterized. Recommendations for future wastewater treatment measures based on the developed concept are to be given, aiming at the reduction of the organic pollution of natural waters.
Natural waters (surface and ground water) are raw water sources for drinking water as well as recipients of wastewater treatment plants effluents. The organic contamination is an important chemical link between both types of use. Protection of the water quality must be one of the main goals of environmental and technical strategies since the use of natural waters is inseparably related to human life all over the world.
For the evaluation of the organic pollution of surface waters different models have been used, for example the Saprobiensystem, the establishment of water quality classes (Gewässergüteklassen), or the Basler Model. Biological, toxicological and chemical-physical tests and parameters have been used to characterize the water quality. Biological and toxicological tests (e.g. tests with Daphnia magna, Ames test) often investigate the effects of individual compounds on organims. Contrarily, for the description of the chemical composition of natural waters analytical determination of individual substances is performed, but is often very time-consuming and labor-intensive. Considering the great variety of organic compounds in natural systems, the analysis of individual compounds will never comprise every compound that could possibly be present. Therefore sum parameters like the dissolved organic carbon (DOC), the spectral absorption coefficient (A(254 nm), SAK), or adsorbable organic halogens (AOX) are often used to describe the quality of surface waters. It has often been stated that a solid "link" between biological and chemical methods of analysis was missing. This is especially the case when only sum parameters are determined for a particular water sample, but no analysis of individual substances is done. The chemical analysis then does not allow an unambiguous assignment of adverse effects seen in biological tests to individual compounds that may be present in the sample. Consequently, for the evaluation of the effects of water components on organisms as well as for predictions regarding the fate of organic pollutants during water treatment a more detailed description of the organic load of natural waters is needed.
The sum parameter DOC is a common parameter for the characterization of the organic load, and together with humic substances it has been one of the main research topics at our department for several years. In our part of the project fractionation of the DOC into different molecular weight classes using size exclusion chromatography (SEC) in preparative scale is going to be done. Through this approach the analytical gap between sum parameteres and individual compounds will be reduced. Chemical and physical standard parameters of the fractions obtained after SEC are going to be determined, and various biological tests are going to be performed. Biological tests include methods for the determination of degradation and biotransformation mechanisms as well as adverse effects. Enzyme tests are going to be undertaken for the investigation of inhibition and toxic effects, using enzymes present in natural waters. Our research group is dealing mainly with the preparation and chemical-physical characterization of the DOC fractions. The research groups in Muenchen, Mainz and Saarbruecken are working on the development of biological test systems.