The anti-epileptic drug carbamazepine was used as marker species in wastewater to identify and quantify sewer exfiltration. In several studies carbamazepine turned out to be hardly removed in wastewater treatment and not or just slightly attenuated during bank infiltration. Concentrations in wastewater are generally 1000 times higher than the limit of quantification. In contrast to many other marker species a "young" drug as carbamazepine is discharged to the environment only by wastewater. The results from this study carried out in Linz, Austria indicate an average exfiltration rate, expressed as percentage of the dry weather flow that is lost on the city-wide scale, of 1%. This rate is lower than sewage losses reported in most other studies which attempted to quantify exfiltration on the basis of groundwater pollution. However, it was also possible to identify one area with significant higher sewage losses.

Nutrient emissions by point and diffuse sources were estimated for 388 sub-catchments of the Danube river basin for the period 1998-2000 by means of the Model MONERIS. For nitrogen total emissions of 684 kt/a N were estimated for the Danube basin. 80% of these emissions were caused by diffuse sources (mainly groundwater, urban areas and tile drainage). For phosphorus the emission was 57 kt/a P, with a contribution of diffuse sources to this sum of 58%. The comparison of calculated and observed loads shows that the mean deviation for the investigated sub-catchments of the Danube river basin is 20% for dissolved inorganic nitrogen and 34% for phosphorus. The spatial resolution of the emission calculations allows the identification of regional hot spots and the derivation of specific regional measures to reduce the emissions into the Danube and consequently into the Western Black Sea.

In this paper, results from rivers of different sizes in Romania, Hungary and Austria are presented. The paper shows the dynamics of extreme events and their contribution to the total P and suspended solids transported in these rivers. Special attention is paid to the influence of the size of the catchment and the event probability on the relative contribution of a single event to the total loads transported in the river. Further, the development of phosphorus loads along the Danube River at a flood event is shown. From the results it can be concluded that there is no immediate influence of high flow and flood events in upstream parts of the Basin on the transport of phosphorus from the catchment to the receiving Sea. Particle-bound phosphorus is mobilised from the catchment (through erosion) and the river bottom to a high extent at high flow events and transported at peak discharges to downstream, where retention by sedimentation of particles takes place. On the one hand this retention is a transport to flooded areas. In this case it can be considered as more or less long term retention. On the other hand sedimentation takes place in the riverbed, in case the tractive effort of the river is reduced. In this second case the P-pool in the sediments of the sedimentation area will be increased. If anaerobic conditions in the sediment appear, part of the phosphorus will be transformed to soluble ortho-phosphate and will continuously contribute to the phosphorus transport to the receiving sea. Part of the P-retained in the river sediment will be mobilised by resuspension at the next biggest high flow event. Altogether, these alternating processes of suspension, transport, export to flooded areas or sedimentation in the river bed with partly solution and partly resuspension at the next event decrease the share of the phosphorus transport during high flow events on the total loads transported in the more downstream parts of a catchments as compared to the more upstream parts. In the year of occurrence of an extreme flood event the P-transport of this year is dominated by the flood event. As an average over many years the contribution of high flow events to the total P-transport still may be between 7 and 20% in smaller catchments (around 1,000 km2). In a big catchment (e.g. river Danube) much smaller contributions of flood events on the total P-transport can be expected as an average over many years.

Integrated presentation of total emissions on catchment scale is prerequisite for many tasks in integrated management of point and diffuse sources of pollution. This paper will focus on emissions of nutrients from municipal point sources. Based on calculations of discharges of N, P from households into wastewater and on the detailed evaluation of data from 76 municipal wastewater treatments plants, this paper presents ranges of specific loads of inhabitants and population equivalents in the raw wastewater. In addition data of these treatment plants have been evaluated in respect of the treatment efficiency for nitrogen and phosphorus (average reduction rates) dependent on the design characteristic (with or without nitrification, denitrification or enhanced phosphorus removal). The results of the investigation show that the specific N and P loads from households in Austria lie within the range 1.6-2.0 g P/(inhabitant.d) and 11- 13 g N/(inhabitant.d). The specific contribution of industries to municipal wastewater varies between 0.3 and 2.0 gP/(pe.d) and 0 and 13 g N/(pe.d) with average values of 1.3 g P/(pe.d) and 6.5 g N/(population equivalent (pe)/d). As average values for municipal wastewater (contributions from household and industry) this leads to specific influent loads of 1.5 g P/(pe.d) and 8.8 g N/(pe.d). Average treatment efficiencies of treatment plants are for instance 50% nitrogen removal in treatment plants with nitrification and 80% in treatment plants with nitrification/denitrification. For phosphorus a removal of about 85% can be expected where the treatment plant was designed for enhanced phosphorus removal. Finally a method for load estimations based on standard values as mentioned above was tested for the estimation of emission from municipal point sources of selected regions.

Monitoring of carbamazepine concentrations in wastewater and groundwater enables us to identify and quantify sewer exfiltration. The antiepileptic drug carbamazepine is hardly removed in wastewater treatment plants and not or just slightly attenuated during bank infiltration and subsoil flow. Concentrations in wastewater are generally 1000 times higher than the limit of quantification. In contrast to . many other wastewater tracers carbamazepine is discharged to the environment only via domestic wastewater. The results from this study carried out in Linz, Austria indicate an average exfiltration rate of 1%, expressed as percentage of the dry weather flow that is lost to the groundwater on the city-wide scale. This rate is lower than sewage losses reported in most other studies which attempted to quantify exfiltration on the basis of groundwater pollution. However, it was also possible to identify one area with significantly higher sewage losses. This method seems to be very suitable for the verification of leakage models used to assess sewer exfiltration on a regional scale.