Environmental Engineering Reference
In-Depth Information
metals). As the Water Framework Directive requires member states to achieve
'Good' ecological status by 2015, techniques are now urgently required that
can predict the consequences and cost-effectiveness of potentially difficult and
expensive catchment management measures. There is now an unprecedented
drive by water managers and freshwater biologists to develop the wide range of
biomonitoring tools needed to predict and support the return of ecological
integrity to European waters after decades of industrial, agricultural and
domestic impacts; and this against an uncertain background of global change.
Early biomonitoring techniques
Historically the link between water and the development of industry has always
been strong. Water has been used as a power source, for transport, in process-
ing and as a conduit for waste. As a consequence, industry and associated urban
areas developed along waterways, with profound consequences for rivers:
historically pollution of rivers has been chronic in many industrial areas. How-
ever, the strong link between industrial development and the development of
urban areas to house the workforce, coupled with a common usage of waterways
for waste disposal, has always made it difficult to determine the source of
pollution, industrial or urban, impacting upon waterways. Initial concerns were
for public health and the security of potable water supplies; increasingly regular
outbreaks of cholera and other waterborne diseases occurred in the expanding
cities, more likely a consequence of domestic sewage rather than industrial
pollution. These public health concerns led to the implementation of combined
sewerage systems in several developing industrial cities, with the aim of remov-
ing waste, both industrial and urban, to a safe distance from water supplies.
It wasn't until late in the nineteenth century that the impact of pollution on
the biological community of freshwaters was first noted, but again organic
pollution and public health were paramount in these observations.
Concern over the purity of potable water supplies and safety of fish for human
consumption led to the development of simple environmental monitoring
systems to determine the extent of organic pollution, based on the protozoan
fauna (Cohn
1853
; Mez
1898
). Later workers noted the impact of gross (organic)
pollution on a wider range of organisms. In particular, the 'saprobic system' was
proposed by Kolkwitz and Marsson (
1902
,
1908
,
1909
) to estimate the extent of
organic pollution, particularly from urban sewage, on streams and rivers using
benthic invertebrates, microbes and plants. In this system saprobity is defined as
the sum total of all those metabolic processes within the bioactivity of a body of
water which are the antithesis of primary production. Four conditions of saprob-
ity were defined, using either chemical or biological methods, namely,
Polysaprobic (p) Reduction processes predominate
Alpha-mesosaprobic (ยด) Reduction processes diminish and
