A nutrient balance study showed a big difference between estimated emissions into the surface waters of the Danube Basin and the measured loads that enter the Danube Delta and the Black Sea. That means the emission estimations are wrong, the measured loads are wrong or retention and losses of nutrients in the hydrosphere are of decisive importance. An interpretation of water quality monitoring of the Danube at Vienna from about 400 days and the comparison of emissions from It (sub-) catchment areas of Austrian Danube tributaries and measured loads in these rivers, underline the importance of retention and losses of nutrients in the hydrosphere and increase the understanding of the relevant processes, even a lot of questions remain, and quantification of some processes on regional scale is not possible yet. Nevertheless, as an overall summary it can be concluded, that a high average area specific surface water runoff assists transport of nutrients in the hydrosphere. Respectively the importance of retention and losses increases with decreasing area specific runoff. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.
