FIGURES 



Section Page 



1 Processes of mineralization in solutions with triethyl 



stannic chloride 3 



1 Processes of mineralization in solutions of pryror-70 . . 7 



1 Processes of nitrification in solutions of pryror-70 ... 8 



4 Toxicity curve demonstrating lethal threshold concentra- 

 tion (LTC) •. . 38 



4 Tolerance of (A) fathead minnows ( Pimephales promelas ) and 

 (B) goldfish ( Carassius au^atus) to hydrogen sulfide at 

 different temperatures 41 



4 Tolerance of bluegills (Lepomis macr ochirus) to molecular 



cyanide (HCN) at various temperatures 42 



7 Platform from which oyster trays are suspended 70 



7 Oyster tray /I 



7 The structure of a natural diatom community /3 



7 The structure of a diatom community under the effects of 



pollution high in nutrients /5 



7 The structure of a diatom community under the effects of 



toxic conditions 76 



7 Invertebrate sampler 78 



9 The relationship between mean total nitrogen concentration 



in streams and land use in the Eastern United States ... 93 



9 The relationship between mean total phosphorus concentra- 

 tions in streams and land use in the Eastern United 

 States 93 



vn 



