COPRECIPITATION OF PHOSPHATE WITH CALCITE IN THE PRESENCE OF PHOTOSYNTHESIZING GREEN-ALGAE

The results of phosphate coprecipitation on calcite, occurring in a so lution of calcium bicarbonate, in the presence of photosynthesizing al gae are presented. The precipitation experiments were carried out at 2 0 degrees C in an illuminated culture apparatus with continuous record ings of pH and conductivity. The alga used in the experiment was the u nicellular green alga Chlorococcum sp. The results are analysed using chemical kinetic models and are compared to phosphate coprecipitation occurring in abiotic conditions. The calculated values of the maximum surface density of coprecipitated phosphate are in good agreement with those from abiotic conditions, which indicates that the same mechanis m is in operation. (C) 1997 Elsevier Science Ltd.