IV-559 



within their cell structure, the presence of these metals in small 

 concentrations can have deleterious effects. 



Aquatic life forms require trace amounts of some minerals and 

 vitamins for growth and reproduction. Elimination of such materials 

 from the environment or their reduction below minimum levels can 

 limit the growth and reproduction of some biota. Conversely, an 

 oversupply of all necessary trace m ineral salts and vitamins can 

 stimulate growth; providing satisfactory conditions of temperature, 

 salinity, and dissolved oxygen also exist. An oversupply of inorganic 

 nutrient salts, such as those of nitrogen and phosphorus, may be 

 associated with drastic shifts in the composition of the aquatic 

 community. 



One of the many unfavorable effects of municipal and some industrial 

 wastes is the contamination of the receiving environment with bacteria, 

 viruses and other organisms of public health significance. Pathogenic 

 organisms , especially those from the intestines of warm blooded 

 animals frequently persist for sufficient periods of time and distance 

 to pose a threat to the health and well-being of unsuspecting water 

 users. Secondary chances of exposure to these organisms exist through 

 the contamination of shellfish which can be harvested for food. 



Among the waste products that are frequently introduced into the 

 estuarine environment are some directly toxic to marine organisms. 



