RESUMEN
This paper outlines the background, objectives, methodology, findings, outputs and recommendations from the Direct Toxicity Assessment (DTA) Demonstration Programme. This was a trial of a suite of bioassay methods and a seven-step protocol designed to deliver water quality improvements in catchments with well-defined water quality problems, where ecotoxicity from effluents was a contributing factor. The trial was run as a collaborative venture between the environmental regulators and water and manufacturing industries in the UK and was conducted at three project sites: -a reach of the river Aire near the city of Bradford in Yorkshire; -a reach of the River Esk near the town of Langholm on the border between Scotland and England; and -the lower Tees estuary on the north-east coast of England. The outcomes of each project are summarised in this paper. The learning points delivered by the programme were used to make recommendations to the regulators on how best to use bioassays for the assessment and control of complex effluents in the UK. Guidance was provided on how to carry out the bioassays and on how to use the data generated for regulatory decision-making. The programme also demonstrated how the regulators and the regulated can successfully work together to tackle environmental issues and deliver effective and workable solutions.
Asunto(s)
Ambiente , Pruebas de Toxicidad/métodos , Contaminantes Químicos del Agua/toxicidad , Animales , Bioensayo/métodos , Medición de Riesgo , Reino Unido , Abastecimiento de Agua/normasRESUMEN
Hydrodynamic models of differing scale and complexity were used to estimate spatial patterns of effluent concentration in discharge plumes in the River Esk and the Lower Tees Estuary. The output from the Tees model was used, in conjunction with measurements of toxicity determined in short-term oyster embryo tests, to predict contours/zones of toxicity in the estuary associated with effluent discharges from four chemical processing sites. One of the discharges also combined the input from a municipal sewage treatment works. The models appeared to be effective in predicting patterns of dilution and dispersion of the effluent discharges in the respective receiving environments. Confirmation of the predictive capabilities of the Tees model was achieved by comparing predicted and measured toxicity in different regions of the plumes associated with the four discharges. Differences between predicted and measured toxicity for two of the four discharges were explicable in terms of failure to take account of the effects of real-time wind conditions when test samples were collected or overlap of adjacent discharge plumes. Suggested refinements to the models and measurement of effluent toxicity would further enhance the utility of this approach for determining the extent and significance of the effects of effluent discharges in receiving environments.
Asunto(s)
Modelos Estadísticos , Pruebas de Toxicidad/métodos , Movimientos del Agua , Contaminantes del Agua/análisis , Contaminantes del Agua/toxicidad , Animales , Monitoreo del Ambiente , Predicción , Larva/crecimiento & desarrollo , Ostreidae/crecimiento & desarrollo , Ríos , Escocia , Eliminación de Residuos LíquidosRESUMEN
The key findings to emerge from the successful Direct Toxicity Assessment Demonstration Programme are reviewed. At present, whole sample toxicity tests can identify and help control releases of complex mixtures that are likely to cause short-term toxic effects. Protection of aquatic organisms from the many hazardous chemicals that enter the environment, usually as complex mixtures, will require the introduction of new and improved techniques that are affordable and provide rapid turnaround of information. A number of bioassays were rigorously tested during the DTA programme. Further developments are suggested and other methods, including biosensors, biomarkers, and biological survey are briefly reviewed.