Longitudinal profile of the genotoxic potential of the River Danube on erythrocytes of wild common bleak (Alburnus alburnus) assessed using the comet and micronucleus assay.

The Joint Danube Survey 3 (JDS3; the biggest river expedition in 2013) had offered the unique opportunity for a large-scale monitoring approach for biomarker response in feral fish collected along a Danube stretch from Kehlheim (DE) to Sulina (RO). The advantage of genotoxicity as a marker for pollution exposure in fish is the early detection of possible long-term effects such as cancer. Therefore, genotoxicity was in the focus of the biomarker investigations in fish during the expedition. Blood samples of common bleak (Alburnus alburnus) for the investigation of the micronucleus frequency and comet tail intensity of fragmented DNA material in erythrocytes were collected at 18 and 12 sampling sites, respectively. For 9 sampling sites same samples were used to compare the in-situ data for the comparable genotoxic endpoint in the micronucleus (MN) and comet assay (CM). The data of both in-situ assays showed a significant correlation, indicating the strength and comparability of the data sets. Significant variation in DNA damage in fish along the longitudinal profile of the Danube was demonstrated for both assays compared to reference sites. The results suggest that DNA damage in erythrocytes of fish was mainly affected by wastewater of highly populated regions. No linkage between the results and the general health/dietary status of the fish were revealed, whereas correlation with some genotoxicity drivers in the water phase, suspended particulate matter and sediments could be demonstrated.

Challenges of river basin management: Current status of, and prospects for, the River Danube from a river engineering perspective.

In the Danube River Basin multiple pressures affect the river system as a consequence of river engineering works, altering both the river hydrodynamics and morphodynamics. The main objective of this paper is to identify the effects of hydropower development, flood protection and engineering works for navigation on the Danube and to examine specific impacts of these developments on sediment transport and river morphology. Whereas impoundments are characterised by deposition and an excess of sediment with remobilisation of fine sediments during severe floods, the remaining five free flowing sections of the Danube are experiencing river bed erosion of the order of several centimetres per year. Besides the effect of interruption of the sediment continuum, river bed degradation is caused by an increase in the sediment transport capacity following an increase in slope, a reduction of river bed width due to canalisation, prohibition of bank erosion by riprap or regressive erosion following base level lowering by flood protection measures and sediment dredging. As a consequence, the groundwater table is lowered, side-arms are disconnected, instream structures are lost and habitat quality deteriorates affecting the ecological status of valuable floodplains. The lack of sediments, together with cutting off meanders, leads also to erosion of the bed of main arms in the Danube Delta and coastal erosion. This paper details the causes and effects of river engineering measures and hydromorphological changes for the Danube. It highlights the importance of adopting a basin-wide holistic approach to river management and demonstrates that past management in the basin has been characterised by a lack of integration. To-date insufficient attention has been paid to the wide-ranging impacts of river engineering works throughout the basin: from the basin headwaters to the Danube Delta, on the Black Sea coast. This highlights the importance of new initiatives that seek to advance knowledge exchange and knowledge transfer within the basin to reach the goal of integrated basin management.

Assessment of the genotoxic potential along the Danube River by application of the comet assay on haemocytes of freshwater mussels: The Joint Danube Survey 3.

In this study we assessed the level of genotoxic pollution along the Danube River by measuring the level of DNA damage in the haemocytes of freshwater mussels of Unio sp. (Unio pictorum/Unio tumidus) and Sinanodonta woodiana. The comet assay was used for the assessment of DNA damage. The research was performed on 34 out of 68 sites analysed within the Joint Danube Survey 3 - the world's biggest river research expedition of its kind in 2013. During research, 2285 river kilometres were covered with an average distance of 68 km between the sites. The complex data set on concentrations of various substances present in water, suspended particulate matter and sediment on investigated sites gave the opportunity to identify the groups of xenobiotics which mostly affect the studied biomarker - DNA damage. The highest levels of DNA damage were recorded in the section VI (Panonnian Plain), which is under the impact of untreated wastewater discharges. Both positive and negative influences of the large tributaries on the level of genotoxicity in the Danube River were evident. Significant correlation in response was detected between the studied species of freshwater mussels. The level of DNA damage in mussels correlated with concentrations of compounds from the group of hazardous priority substances (polycyclic aromatic hydrocarbons), persistent organic pollutants (dioxins) and emerging pollutants (Oxazepam, Chloridazon-desphenyl).

The SOLUTIONS project: challenges and responses for present and future emerging pollutants in land and water resources management.

SOLUTIONS (2013 to 2018) is a European Union Seventh Framework Programme Project (EU-FP7). The project aims to deliver a conceptual framework to support the evidence-based development of environmental policies with regard to water quality. SOLUTIONS will develop the tools for the identification, prioritisation and assessment of those water contaminants that may pose a risk to ecosystems and human health. To this end, a new generation of chemical and effect-based monitoring tools is developed and integrated with a full set of exposure, effect and risk assessment models. SOLUTIONS attempts to address legacy, present and future contamination by integrating monitoring and modelling based approaches with scenarios on future developments in society, economy and technology and thus in contamination. The project follows a solutions-oriented approach by addressing major problems of water and chemicals management and by assessing abatement options. SOLUTIONS takes advantage of the access to the infrastructure necessary to investigate the large basins of the Danube and Rhine as well as relevant Mediterranean basins as case studies, and puts major efforts on stakeholder dialogue and support. Particularly, the EU Water Framework Directive (WFD) Common Implementation Strategy (CIS) working groups, International River Commissions, and water works associations are directly supported with consistent guidance for the early detection, identification, prioritisation, and abatement of chemicals in the water cycle. SOLUTIONS will give a specific emphasis on concepts and tools for the impact and risk assessment of complex mixtures of emerging pollutants, their metabolites and transformation products. Analytical and effect-based screening tools will be applied together with ecological assessment tools for the identification of toxicants and their impacts. The SOLUTIONS approach is expected to provide transparent and evidence-based candidates or River Basin Specific Pollutants in the case study basins and to assist future review of priority pollutants under the WFD as well as potential abatement options.

Statistical analysis of trends in organic pollution and pollution by nutrients at selected Danube river stations.

The paper describes an application of a statistical analysis for estimating long-term trends in pollutant concentrations of selected pollutants in the Danube river. The results show the changes of concentrations of NH(4)(+)-N, NO(3)(-)-N, PO(4)(3-)-P, total P, BOD(5) and COD(Cr) in a ten year period with the aim to find how the concentrations vary in the whole stretch of this river. The study was based on the data collected in the frame of Transnational Monitoring Network of the ICPDR. To obtain plausible results we have chosen statistical methods, such as tests based on the Spearman correlation coefficient and median regression, which are not sensitive to departures from normality as high skewness or outliers.