The impact of heavy metals on lowland rivers and the implications for man and the environment.

Increased public awareness of river water quality problems has led to concern over the continued discharge of low-level contaminants in sewage treatment work (STW) final effluents. This paper discusses the source and nature of heavy metals during sewage treatment processes and examines their behaviour and fate in the aquatic environment. The influences of physico-chemical parameters and chemical speciation on metal mobility during sewage treatment and in receiving waters have been assessed. The importance of metal speciation with regard to aquatic toxicology is discussed and the effectiveness of current legislation in controlling the release of heavy metals to lowland river systems has been reviewed.