3.01 – Sum Parameters: Potential and Limitations

Sum parameters are reasonable tools for a gross assessment of water quality. Their values are well suited for material balances and for decision on the necessity of single-component analysis, for example, for forensic purposes. Some sum parameters have made their way even into legislative water-quality control. One of the most prominent sum parameters is the organic carbon (OC) which reflects nearly all organic water constituents. Other parameters focus on specific properties like the dissolved state (DOC<0.45 μm), chemical or biochemical oxidizability (COD, BOC), UV or visible light absorbance (SAK), or the amount of on activated carbon adsorbable organically bound halogens (AOX). This chapter deals with the analytical processes which often lead to operationally defined results. Therefore, the powers and limitations of the application of the parameters are highlighted, and surrogate parameters as well as pitfalls are discussed. The limited information which has to be accepted for sum parameters is often supplemented by an advanced way of determination which includes separation and fractionation, multi-dimensional detection, or parameter ratios. In addition to the classical and broadly used sum parameters, examples for emerging ones are presented. They include characterization and quantification of specific families of compounds, nanomaterials and colloids, spectroscopic properties, and of specific bioeffects. A view on the developing role of sum parameters in water-quality assessment is given.