Pergamon War. Sci. Tech. Vol. 33. No. 4-S. pp. 89-97. 1996. Copynght (/:) 1996 IA WQ. Published by Elsevier SCience Ltd. Printed in Great Britain. All rights reserved. PU: S0273-1223(96)00218-1 0273-1223/96 $15'00 + 0'00 REGIONAL MATERIALS ACCOUNTING OF NITROGEN IN UPPER AUSTRIA M. Zessner *, T. Kaas**, P. H. Brunner* and H. Fleckseder*** * TV Vienna. Institut for Water Quality and Wastes Management, Karlsplatz 13, A-I040 Vienna, Austria **Drogdensgade 4, 47V, DK-2300 Kopenhagen S, Denmark ***BundesministeriumjUr Land- und Forstwinschaft, IVA7, Stubenring 12, A-JOJO Vienna, Austria ABSTRACT A nitrogen balance for the region of Upper Austria is presented containing a short introduction to the method and materials used and the overall results with emphasis on the N balance for the atmosphere. agriculture and surface waters. It is shown that it was possible to obtain only with existing data an overall balance for nitrogen which takes all important nitrogen fluxes into consideration. Important results are: The biggest input of nitrogen (as NHx-N or NOX-N) into the atmosphere comes from agriculture, but also traffic and industrial processes play an important role. The N-Iosses from agriculture to the environment depend to a high extent on the rate of animal protein production. The N-input to surface waters from nonpoint source discharges is noticeably bigger than from point source discharges. Copyright © 1996 IAWQ. Published by Elsevier Science Ltd. KEYWORDS Diffuse pollution; nitrogen; materials accounting; point source pollution; regional balance; Upper Austria. INTRODUCTION In numerous reports it is estimated that the loads in nutrients - among them nitrogen - in river catchments in the developed world are increasing, sometimes even strongly increasing. For the Danube Basin, there are indications that the load of nitrogen in front of the Danube Delta augmented between 1960 and 1990 about tenfold, and the load for phosphorus about threefold (Mee, 1992). Whether these increases are real or due to sampling artefacts, remains open in regard to a non-existing integrated sampling in the 1960s. On the other hand, the change in popUlation - looked upon at first sight as the main driving force for such changes - in the Danube catchment increased by < 20% only. Assuming constant life style over time, thus the population increase alone cannot account for the increase in e.g. the nitrogen load. As a conclusion, the increase must be due to a change in lifestyle as well, in land-water interactions along the drainage network, but also with different "uses" of human excreta over time. Thus, the questions arise: Can we find a plausible method indicative with sufficient evidence what activities are causing the loss of nitrogen to the water environment? Who are the actual and primary players and who are the ones who it seems to be, but in fact are only secondary players? What are the various causes for this increase? What role can regional materials 89