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In recent decades, extensive monitoring programmes have been conducted at the national, international, and project levels with the objective of expanding our understanding of the contamination of surface waters with micropollutants, which are often referred to as hazardous substances (HS). It has been demonstrated that HS enter surface waters via a number of pathways, including groundwater, atmospheric deposition, soil erosion, and urban systems. Given the ever-growing list of substances and the high resource demand associated with laboratory analysis, it is common practice to quantify the listed pathways based on emission factors derived from temporally and spatially constrained monitoring programmes. The derivation calculations are subject to high uncertainties, and substantial knowledge gaps remain regarding the relative importance of the unique pathways, territories, and periods. This publication presents a monitoring method designed to quantify the unique emission pathways of HS in large geographical areas characterized by differences in land use, population, and economic development. The method will be tested for a wide range of HS (ubiquitous organic and inorganic pollutants, pesticides, pharmaceuticals) throughout small sub-catchments located on tributaries. The results of the test application demonstrate a high diversity of both emission loads and instream concentrations throughout different regions for numerous substances. Riverine concentrations are found to be highly dependent on the flow status. Soil concentration levels of polycyclic aromatic hydrocarbons (PAH) and perfluoroalkyl substances (PFAS) are found to be in proportion, whereas that of potentially toxic elements (PTE) in a reverse relationship with economic development. In many instances, concentration levels are also contingent upon land use. The findings of this study reinforce the necessity for the implementation of harmonised and concerted HS monitoring programmes, which should encompass a diverse range of substances, emission sources, pathways and geographical areas. This is essential for the reliable development of emission factors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Riverine floods cause increasingly severe damages to human settlements and infrastructure. Ecosystems have a natural capacity to decrease both severity and frequency of floods. Natural flood regulation processes along freshwaters can be attributed to two different mechanisms: flood prevention that takes place in the whole catchment and flood mitigation once the water has accumulated in the stream. These flood regulating mechanisms are not consistently recognized in major ecosystem service (ES) classifications. For a balanced landscape management, it is important to assess the ES flood regulation so that it can account for the different processes at the relevant sites. We reviewed literature, classified them according to these mechanisms, and analysed the influencing ecosystem characteristics. For prevention, vegetation biomass and forest extent were predominant, while for mitigation, the available space for water was decisive. We add some aspects on assessing flood regulation as ES, and suggest also to include flood hazard into calculations., (© 2022. The Author(s).)

There is general agreement among scientists that global temperatures are rising and will continue to increase in the future. It is also agreed that human activities are the most important causes of these climatic variations, and that water resources are already suffering and will continue to be greatly impaired as a consequence of these changes. In particular, it is probable that areas with limited water resources will expand and that an increase of global water demand will occur, estimated to be around 35-60% by 2025 as a consequence of population growth and the competing needs of water uses. This will cause a growing imbalance between water demand (including the needs of nature) and supply. This urgency demands that climate change impacts on water be evaluated in different sectors using a cross-cutting approach (Contestabile in Nat Clim Chang 3:11-12, 2013). These issues were examined by the EU FP7-funded Co-ordination and support action "ClimateWater" (bridging the gap between adaptation strategies of climate change impacts and European water policies). The project studied adaptation strategies to minimize the water-related consequences of climate change and assessed how these strategies should be taken into consideration by European policies. This article emphasizes that knowledge gaps still exist about the direct effects of climate change on water bodies and their indirect impacts on production areas that employ large amounts of water (e.g., agriculture). Some sectors, such as ecohydrology and alternative sewage treatment technologies, could represent a powerful tool to mitigate climate change impacts. Research needs in these still novel fields are summarized.