Chemical monitoring activity under the Water Framework Directive – Analytical challenges and solutions

Abstract

In December 2000, the European Water Framework Directive (WFD) came into force and became part of UK law in December 2003. The underpinning basis of WFD was ecology driven, with the key mandated objective to provide for the planning and delivery of a better aquatic environment. The Directive aimed to help protect and further enhance the quality of surface freshwater (including lakes, streams and rivers), groundwater, estuaries and coastal waters across all member states. The main goals of statutory monitoring under the Water Framework Directive (WFD) are to protect the quality of all water bodies at the river basin level across Europe and to ascertain the magnitude and impact of pollution. Ensuring compliance with the WFD provisions is currently based on chemical analysis of ‘spot’ or ‘grab’ samples taken at a defined frequency. Chemical monitoring under the WFD focuses primarily on the measurement of the concentrations of the priority substances (33 priority substances and 8 other pollutants) in surface waters against environmental quality standards. There is also a requirement to undertake investigative monitoring in order to identify unknown non-target pollutants in water bodies where poor ecology exists or which have been identified through risk assessments. For investigations within the WFD, the current practice of taking grab or spot samples of water followed by their laboratory analysis may not always provide a useful indication of the environmental status of a water course. Alternative monitoring methods are therefore needed in order to detect potential impacts that may not be found through conventional sampling strategies. Passive sampling is such a technique, where pollutants are sequestered by a device over extended periods of time; typically 2-4 weeks. This approach increases the likelihood of capturing different pollution events, whether they are point or diffuse. The technique measures the toxicologically relevant fraction of contaminant mixtures and can also indirectly lower analytical detection limits.