This paper presents primary research results on nutrient emissions, resulting water quality and ecological impacts of the Kharaa river basin (Mongolia) during a three-year water resource management study. Based on surveillance data from Mongolian environmental authorities and a complementary own monitoring scheme we calculated nutrient emissions on a sub-basin scale. Additionally, the ecological situation of fish fauna, macroinvertebrates and their habitats were investigated on selected river sections in order to link anthropogenic pressures, nutrient status and ecological impact. was estimated. Main contributors are urban settlements with a high proportion of households without connection to wastewater treatment plants and, to a lesser extent, agricultural land-use. These nutrient levels have a significant eutrophication potential in the Kharaa River and we observed functional shifts of the macroinvertebrates and fish fauna, while the drinking water abstraction through bank filtration showed no significant alteration of raw water quality. DedicationHORST BEHRENDT developed the conceptual nutrient emission model MONERIS, which was designed for the river systems in Central Europe (see VENOHR et al. 2011 With the publication of this study we present the results of his modelling approach and the implications for an innovative water quality assessment in data-scarce regions.

MONERIS is a semi-empirical, conceptual model, which has gained international acceptance as a robust meso-to macro scale model for nutrient emissions. MONERIS is used to calculate nitrogen (N) and phosphorus (P) emissions into surface waters, in-stream retention, and resulting loads, on a river catchment scale. This paper provides the first (i) comprehensive overview of the model structure (both the original elements and the new additions), (ii) depiction of the algorithms used for all pathways, and for retention in surface waters, and (iii) illustration of the monthly disaggregation of emissions and the implementation of measures. The model can be used for different climatic conditions, long term historical studies, and for future development scenarios. The minimum validated spatial resolution is 50 km 2 , with a temporal resolution of yearly or monthly time steps. The model considers seven emission pathways (atmospheric deposition on surface waters, overland flow, erosion, tile drainage, groundwater, emissions from sealed urban areas, and point sources), and six emission sources (natural background, fertilizer application, nitrogen atmospheric deposition on arable land and other areas, urban sources, and point sources); and these are calculated separately for different land-uses. The pathway and source-related approach is a prerequisite for the implementation of measures to reduce non-point and point-source emissions. Therefore, we have modified MONERIS by the addition of a "management alternative" tool which can identify the potential effectiveness of nutrient reduction measures. MON-ERIS is an appropriate tool for addressing the scientific and political aspects of river basin management in support of a good surface water quality.

Eutrophication management is still one of the major challenges in the Baltic Sea region. Intense transformation processes in several Baltic Sea states have led to drastic changes in e.g., landuse and thereby nutrient emissions and water quality. Several future development directions are possible. The Oder catchment -lagoon -coastal water system serves as a pilot study area, since it has a major influence on the nutrient loads into the Baltic Sea and about 90% of the catchment is located in Poland, a state with transitional economy. Different scenarios for landuse changes in the Oder catchment are developed and their consequences on nutrient emissions simulated. Next to politically induced changes of agricultural landuse in general, specific aspects such as cultivation of energy maize and increased animal stocks are considered. Nitrogen emissions are likely to increase due to agricultural landuse changes whereas phosphorus emissions will not change or even decrease according to the application of the EC-Urban Waste Water Treatment Directive. Resulting nitrogen loads to the Oder Lagoon could increase up to 23%, phosphorus loads could decrease by 11% compared to 2005. These trends may lead to higher nitrogen availability compared to phosphorus at least in the Oder lagoon. Interannual differences in discharge also have profound effects on nutrient emissions. A good status of the Oder river basin -lagoon -coastal sea system according to EC-Directives is not very likely to be achieved under the investigated circumstances.

Climate change effects on freshwater biogeochemistry and riverine loads of biogenic elements to the Baltic Sea are not straight forward and are difficult to distinguish from other human drivers such as atmospheric deposition, forest and wetland management, eutrophication and hydrological alterations. Eutrophication is by far the most well-known factor affecting the biogeochemistry of the receiving waters in the various sub-basins of the Baltic Sea. However, the present literature review reveals that climate change is a compounding factor for all major drivers of freshwater biogeochemistry discussed here, although evidence is still often based on short-term and/or small-scale studies.

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