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HP9 Environmental Assessment, Environmental Toxicology
D137-140
1:20 PM - 5:20 PM, Thursday

() integrating ecotoxicology and analytical chemistry for the assessment of water quality.

Mankasingh, U1, Worsfold, P1, Galloway, T2, Depledge, M3, 1 School of Earth, Ocean and Environmental Sciences, Plymouth Environmental Research Centre, University of Plymouth, Plymouth, Devon, England, UK2 School of Biological Sciences, University of Plymouth, Plymouth, Devon, England, UK3 Environment Agency, Bristol, Avon, England, UK

ABSTRACT- The EU Water Framework Directive aims to maintain and improve the quality of aquatic ecosystems by using an integrated approach to the protection, improvement and sustainable use of the water environment. Nitrate and nitrite concentrations in natural waters have maximum admissible concentrations set by the EU for surface waters intended for abstraction for drinking water (11.3 mg L-1 NO3-N) and for the protection of course freshwater fish (9 g L-1 NO2-N) respectively. However, in cases of extreme pollution, concentrations may be as high as 1 mg L-1 NO2-N in waters strongly influenced by industrial effluent, or 200 mg L-1 NO3-N in sewage polluted waters.
Therefore, the acute toxicity of nitrite and nitrate to the freshwater mussel, Anodonta cygnea, was determined. The LC50 values for 96 h exposure to nitrite are 222 mg L-1 NO2-N in static tests. Studies also indicated that 96 hour LC50 values were in excess of 1500 mg L-1 NO3-N for this species. Subsequently, neutral red retention assay was used to monitor immune function and cell viability of Anodonta cygnea when exposed to sub-lethal concentrations of nitrite. Cardiac activity was also be monitored during these exposures, using a computer-aided physiological monitoring system (CAPMON) based on photodiode detection. For the analytical chemistry studies, a submersible flow injection analyser with spectrophometric detection has been developed for the in situ monitoring of nitrate/nitrite in natural waters. It has been configured to operate over a linear range of 2.8 - 100 g L-1 or 85 - 2000 g L-1 with a 10 mm path length flow cell. Freshwater leaving the Tamar River catchment in SW England has been monitored every two weeks and concentrations ranged from 10 - 30 g L-1 NO2-N and 2 - 6 mg L-1 NO3-N respectively between May 2004 and May 2004. These concentrations agree with less frequent historical data collected for the site between 1974 and 1997. The chemical monitoring data will be integrated with ecotoxicological results to allow the assessment of surface water quality based on the chemical and biological objectives of the Water Framework Directive.

Key words: Anodonta cygnea, nitrite, environmental assessment, ecotoxicology


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