Compounds of certain metals are known to be capable of complexing phosphate ions, thereby removing them from solution. The application of this principle to the control of phosphorus levels in eutrophic lakes has been subjected to laboratory investigation in the present study. Salts of lanthanum, zirconium, and aluminum were found to effectively remove phosphorus from laboratory growth medium and natural pond water, with resulting depression of algal production. Toxicity to fishes and aquatic invertebrates was minimal, but the tests demonstrated that some components of metals salts may have adverse effects. The stability and duration of phosphorus inactivation is being studied in laboratory-scale water-sediment systems, under aerobic and anaerobic conditions. These experiments are expected to elucidate the effect of inactivant-phosphate precipitates on sediment-water phosphorus interchange. Preliminary results indicate that zirconium precipitates phosphorus from the water and holds it at low levels.

"October 1974." "ROAP 21 AIY, Task 36, Program Element 1BA031." Includes bibliographical references (pages 115-118).

"The Federal Water Pollution Control Act Amendments of 1972, PL 92-500, include the requirement that the Administrator of the United States Environmental Protection Agency issue such information on methods, processes, and procedures as may be appropriate to restore and enhance the quality of the nation's publicly owned lakes [Subsection 304(i)]. The concept of in-lake nutrient inactivation, wherein a complexing additive to the lake, is a promising restorative technique that has received limited attention in the United States and Europe. The present study is designed to more thoroughly evaluate this concept at the laboratory and pilot field scale levels, using a variety of potential inactivant materials over a range of simulated and actual operational conditions, to determine its value and potential as a practical tool in lake management."--Page ii Introduction -- Summary -- Conclusions -- Recommendations -- Efficiency of inactivant materials -- Toxicity and environmental effects -- Stability and duration of effectiveness -- Availability and costs of inactivants -- References.