1st October 1997 - 30th September 2001
Control of point source pollution and increasing curtailment of combined sewer overflows (CSOs) has propelled non-point source pollution to the forefront of concern for those involved with managing in situ river water quality. Concurrently, there is increasing Government and public pressure for much higher grades of river water and a concomitant increase in ecological integrity, particularly within urban environments. Macroinvertebrates are recognised as excellent biomonitors and their existence is vital for ecological integrity. The ability to recognise and forecast changes in macroinvertebrate assemblages as they respond to changing water quality factors is fundamental in enabling freshwater managers to prioritise appropriate actions.
Contaminants of major concern include heavy metals and hydrocarbons, because of their persistence and known toxicities even at low concentrations. These contaminants derive primarily from vehicles and the urban infrastructure itself. Contaminants bond to particulate matter which is transported to and within streams during storm events where they may exert a deleterious impact on the biota. The general rise in water quality standards has eliminated the most serious sources of toxic contamination. The current focus is upon contaminants which may be non-toxic but are nevertheless damaging to certain organisms. It is a matter of correcting and maintaining a balance in levels because contaminants such as certain metals are required in small amounts as essential micronutrients.
At present there is a paucity of research examining the deleterious impacts of PAHs on freshwater ecosystems. Current research within the School of Geography is focusing on PAH concentrations in surface runoff derived from urban areas within west Yorkshire. Data for the 16 USEPA PAHs will complement data concerning heavy metal concentrations in surface runoff to significantly improve our understanding of the impacts surface runoff imposes upon freshwater ecosystems. At present data for certain heavy metals and PAHs has been collected from single locations approximately 25m downstream of the discharge outlets draining different landuse covers during spring and autumn. Using Canonical Correspondence Analysis and Monte Carlo simulations those contaminants which exert the greatest influence on macroinvertebrates can be identified and incorporated into a model capable of predicting macroinvertebrate assemblages within urban watercouses. Such a model will be a useful tool for both freshwater managers and local authorities assessing the impacts of development proposals.
Future research will examine distance decay relationships of PAHs downstream from discharge outlets to provide a more ‘complete’ model capable of predicting biological water quality at any point along a watercourse. Being a new area of research, scope exists for future grant applications to examine such relationships and to undertake research on a greater number of streams throughout the country to produce a model which is applicable nationwide.