It
has been well established since last ten years that hydrophobic organic chemicals,
and also inorganic contaminants, that enter the aquatic environment, rapidly becomes
associated with sediments and suspended particles. The sedimentation of the latter
form one of the most important 'Sink' of pollutants from the column these ailability
of these mainly sediment sorbed chemicals to the biota is important as the sediment
reservoir may constitute a primary source of contamination for benthic organisms.
Even when the quality of the overlaying water is again improving, the polluted
sediments still act as a long-term threat to organisms exposed to it. However,
the main rout of exposure to sediment inhabiting species is the one via the (pore)
water phase. The biological community strongly influences the Physical & Chemical
environment in the sediment and this influences the bio-availability of contaminants
by several abiotic and biotic factors such as:
Primary productivity influences Ph conditions which in turn influences metal chemistry;
and
Sulphate
reduction to sulphide by bacteria facilities metal sulphide formation etc.
