Answer:

Explanation:

For monitoring heavy metal pollution of streams in urban and industrial AREAS residue analyses were undertaken in different aquatic invertebrates with SPECIAL regard to the freshwater molluscs Bithynia tentaculata, Physa acuta, Radix peregra and Dreissena polymorpha to define the heavy metal residues in shell and soft body parts in natural populations.

To control the distribution and dynamics of the heavy metals, the accumulation and elimination behaviour is determined after experimental contamination tests with cadmium, lead and zinc and their complexes for synergisms on standardized populations under laboratory conditions.

Due to a strong accumulation of these organisms they appear to be well suited for monitoring programs. Experimental studies SHOW, that zinc and lead absorbed with the food accumulate in the haemolymph, the food muscle and the protein gland. The different rates of accumulation depend however among others on the different PHYSIOLOGICAL variables as well as on population specific strategies. Furthermore, different mechanisms result in a rivalry among the heavy metals for uptake.