The Phosphate Content of Fresh and Salt Waters in its Relationship to the growth of the Algal Plankton

Abstract

On account of the minute quantities in which they are present and of the fact that they are considered of secondary importance as indicating sewage contamination, phosphates are not usually estimated in analyses of natural waters. The tediousness of the determination also militated against it in the past. As a result, of the numerous analyses recorded by Clarke (1920), but few mention phosphates. C. H. Stone's analysis of the Mississippi in 1905, carried out upon a sample above Carrolton, Louisiana, shows 0.27 per cent of phosphate (PO 4 ) with a total salinity of 146 parts per million, or 0.39 mgrm. PO 4 per litre, corresponding to 0.29 mgrm. P 2 O 5 .