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Background: The European Water Framework Directive foresees the establishment of emission inventories for micropollutants (MP) to facilitate an evidence-based development of mitigation measures. Regionalized pathway analysis constitutes a moderately data-intensive approach to quantify the contribution of different pathways to the total pollution of surface waters. So far, only few European member states have created an inventory that includes diffuse pathways. The fundamental basis to enable it is an accessible, well-structured and harmonized database with data on the concentration of MPs in multiple compartments, such as soils, groundwater, atmospheric deposition and urban systems. Combined with the water and suspended substance balance in river basins, such data enables the estimation of emission loads via specific pathways. In the Danube River Basin, but in general in Europe, a public data management platform with such scope and criteria is still lacking. Results: We collected and harmonized MP measurements across multiple compartments and countries together with key metadata, harmonized and combined them into a new database. The resulting tool, available for download, facilitates the assessment of current data availability, in terms of quantity and quality. For example, while the majority of available data stems from groundwater and surface water, other highly relevant compartments are scarcely represented. By examining differences in MP concentration level across compartments, the database can lead to understand the relevance of specific emission pathways and thus to prioritize data-retrieval and calculation efforts in modelling applications. Selected examples show how to exploit the metadata associated to the measurements to extrapolate the results to regions not covered by specific monitoring programmes. For example, PFAS concentrations in treated wastewater show significant dependence on the design capacity of the treatment plant. Conclusions: This study showcases how such database can support the setup of emission inventories, guide data providers and national authorities in prioritizing the allocation of resources for new surveys and in optimizing their national data collection and management systems. The process tested showed a great need for enhanced data literacy across countries and institutions to increase data availability and quality to secure the exploitation of the full information potential generated via monitoring programmes. [ABSTRACT FROM AUTHOR]

Shallow lakes provide a multitude of ecosystem functions, but they are particularly vulnerable to natural and anthropogenic disturbances. Understanding the driving factors determining the fate and spatial distribution of nutrients and pollutants in such systems is fundamental to assess the impact of ongoing or future external pressures endangering their ecological integrity. This study investigates the fate of trace contaminants transported into the large shallow Lake Neusiedl, including contaminants representative of different patterns of sources and emission pathways and of environmental behavior, namely metals, pharmaceuticals, an artificial sweetener and perfluoroalkyl substances. Further, it examines the horizontal spatial distribution of nutrients, ions and physico-chemical parameters with an unprecedented detailed focus on the internal variability within the large reed belt. As described in the past e.g. for chloride, evaporation was identified as the process leading to a substantial concentration enrichment of the industrial chemical PFOA and the sweetener acesulfame K from the tributary river into the open lake. This is particularly relevant in view of the predicted future increase of evapotranspiration due to climate change. In contrast, the observed loss of diclofenac, but also of PFOS and carbamazepine suggests that the well-mixed, humic-rich and alkaline Lake Neusiedl offers favorable conditions for the photodegradation of otherwise very persistent chemicals. Another important finding, in the context of possible modifications in lake water levels due to climate change, is the fundamental role played by the connectivity between open lake and reed belt but also by the presence and characteristics of inner water areas within the reed belt region in determining the hydrochemistry of the lake system. By revealing systematic spatial patterns and by focusing on the underlying factors and processes, the understanding offered by this study is of high value for the conservation of shallow lakes. [ABSTRACT FROM AUTHOR]