Environmental Engineering Reference
In-Depth Information
CHAPTER SIX
Ecological monitoring and assessment
of pollution in rivers
J. IWAN JONES, JOHN DAVY-BOWKER,
JOHN F. MURPHY AND JAMES L. PRETTY
Introduction
Many organisms respond to pollution in a predictable way, and it has long been
realised that the biota can be used to determine the extent of pollution at a site,
a technique termed biomonitoring. Much of the science of biomonitoring
developed in aquatic systems, driven by concerns about the impact of industrial
and domestic pollution on potable water resources. Over the past century,
aquatic biomonitoring has travelled a long way from the early methodologies,
and much about the pitfalls and benefits of using biota to assess pollution or
other stressors has been discovered. Here we describe the history of biomonitor-
ing and how our understanding has developed, with particular focus on
RIVPACS (River InVertebrate Prediction And Classification System). This system
marked a major advance in biomonitoring techniques, introducing the refer-
ence condition approach, where the physical and geographical characteristics
of the river were taken into account when determining what taxa would be
expected to be present if the site were not polluted. Assessment of a site was
then based on a comparison of the observed community and derived scores, to
that expected if the site were not polluted. RIVPACS was also the first biomoni-
toring tool to incorporate a measure of uncertainty; any assessment is based on
spatially and temporally variable samples and it is necessary to calculate the
confidence associated with the quality class derived using these samples.
We are now in an era where the Water Framework Directive places a legal
obligation on European nations to use the biota to assess the ecological quality
of their rivers, lakes, coastal and transitional (brackish) water bodies. This
legislation marks a move away from assessing the influence of a single pressure
(organic pollution) on the water body, and now elements of the biota, other
than just macroinvertebrates, are used to assess a wide range of pressures
on ecological quality (e.g., acidification, low flows, hydromorphology, heavy
