Direct Toxicity Assessment and Mapping
Expanding on the Environment Agency’s current plans to regulate surface water toxicity through Direct Toxicity Assessment, this project aims to:
All data collection will be quality controlled and all aspects of the project will be quality assured within a Quality Management System.
There are three phases to the project. The main objective of Phase 1 is to compile an extensive database on groundwater toxicity in the London Borough of Hounslow. Existing information indicates that groundwater in certain areas contains high concentrations of contaminants, particularly metals and polyaromatic hydrocarbons. However, the toxicological significance of the contaminant mixtures remains unknown. Groundwater samples will be taken from the network of over 600 boreholes which have already be drilled in the Borough and at Heathrow Airport, and from 50 boreholes which will be drilled as part of this project.
In Phase 2, novel sublethal ecotoxicity tests will be used alongside standard suite tests to investigate the effect of groundwater samples on biomakers in Daphnia. This will allow the measurement of much lower levels of toxic effect than possible in Phase 1 and hence, refine the map of the spatial distribution of pollution near hotspots. It will also help to identify some of the major classes of chemicals that may be responsible for this pollution.
Once repeatable measurements of lethal or sublethal toxicity have been found through time at particular sampling sites, chemical fractionation techniques and toxicity testing (known as TIE) will be used in Phase 3 to help identify still further the toxic components of the ground water samples. TIE is a technique only recently introduced in Europe and consists of the manipulation of environmental samples to identify the physical and chemical nature of the substances causing toxic effects.
October 1998 Three years
University of London
University of Reading
The outputs of the project will include user-friendly manuals, generic monitoring strategies and peer-reviewed scientific papers.
Hounslow Borough Council
Further information is available from the following contacts:
Lead Researcher: Prof J Mather
Research Assistant: Dr R Dewhurst
URGENT Programme Manager: Graham Leeks