Toward a holistic and risk‐based management of european river basins

Abstract

The European Union Water Framework Directive (WFD) requires a good chemical and ecological status of European surface waters by 2015. Integrated, risk-based management of river basins is presumed to be an appropriate approach to achieve that goal. The approach of focusing on distinct hazardous substances in surface waters together with investment in best available technology for treatment of industrial and domestic effluents was successful in significantly reducing excessive contamination of several European river basins. The use of the concept of chemical status in the WFD is based on this experience and focuses on chemicals for which there is a general agreement that they should be phased out. However, the chemical status, based primarily on a list of 33 priority substances and 8 priority hazardous substances, considers only a small portion of possible toxicants and does not address all causes of ecotoxicological stress in general. Recommendations for further development of this concept are 1) to focus on river basin-specific toxicants, 2) to regularly update priority lists with a focus on emerging toxicants, 3) to consider state-of-the-art mixture toxicity concepts and bioavailability to link chemical and ecological status, and 4) to add a short list of priority effects and to develop environmental quality standards for these effects. The ecological status reflected by ecological quality ratios is a leading principle of the WFD. While on the European scale the improvement of hydromorphological conditions and control of eutrophication are crucial to achieve a good ecological status, on a local and regional scale managers have to deal with multiple pressures. On this scale, toxic pollution may play an important role. Strategic research is necessary 1) to identify dominant pressures, 2) to predict multistressor effects, 3) to develop stressor- and type-specific metrics of pressures, and 4) to better understand the ecology of recovery. The concept of reference conditions to define the ecological status is hard to apply and tends to ignore the fact that ecosystems can be highly dynamic. A better understanding of ecosystem responses to changes as well as early warning systems and concepts sensitive to various stressors to discriminate disturbances from natural variation are required. Because ecosystems are closely interconnected, an integrated monitoring, diagnosis, and stressors-based management of the whole water, sediment, groundwater, soil, and air system is required considering land use and the interaction with a changing climate. Extending this holistic approach beyond a consideration of existing pressures by anticipating on future ones to use and protect the aquatic environment in a sustainable way is one of the big challenges.

Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale

“…New frontiers in pollution prevention, such as designing chemicals according to the principles of green chemistry and substitution of hazardous chemicals preferably by nonchemical solutions, closed cycles of chemicals, specific treatment of unavoidable effluents at the source, innovative take-back systems from consumers, as well as new approaches in communication and education, should be promoted (5,39). Furthermore, considering that ∼100,000 organic chemicals are currently in daily use and may enter freshwater ecosystems via different routes (5), the success of mitigation measures obviously cannot be based on chemical monitoring of a limited set of target chemicals only, but requires a smart combination of stressor-specific indices, effect-based monitoring tools, and chemical screening (40). Holistic basin-scale assessments (e.g., European Water Framework Directive; ref.…”

Integrated Risk Assessments for the Management of Contaminated Sediments in Estuaries and Coastal Systems

“…Due to the nonspecific nature of some biomarkers, the authors argued that laboratory studies may induce stress and that there would be artifacts in the biomarker assessments ex situ. In Europe, some scien tists are developing assays focusing on effect-type-oriented approaches including cytotoxicity, neurotoxicity, mutagenicity, and estrogenic or photosynthesis-inhibiting potencies, all of which may have ecological impacts not generally detected in standard assessments for acute and chronic toxicity (Brack et al, 2009). The focus was on metals, PAHs, and PCBs.…”

Assessing cumulative effects of multiple activities in New England watersheds

“…A number of approaches and case studies have appeared using different techniques for CEA; notable are a series of studies in Canadian watersheds in the last 10 years (see Dube et al 2013 for an introduction) and the approach developed for the European Union Water Framework (Brack et al 2009). Each case study presents unique solutions to the challenges of CEA through inclusion of different sources of monitoring data, uncertainty analyses and incorporation of expert judgment.…”