Study On The Phosphate Adsorption Of The Different Particle Size Fractions In The Sediments From The Baotou Section Of The Yellow River

Adsorption of phosphate (PO4-P) by sediments taken from Baotou section of the the Yellow River was studied in a laboratory. The studies of adsorption kinetics, isotherm curves of phosphate on different particle size fractions and effects of environmental factors on phosphate adsorption were carried out. And the transformation of species of phosphorus after adsorption was studied for the first time. We reached the conclusion as follows:1. The phosphate mostly transformed into exchangeable form of sediments after adsorption.2. The illite and chlorite were the important minerals which adsorbed phosphate in the sediments of Baotou section of the the Yellow River, and calcium carbonate (calcite) impacted pH and the concentration of Ca²⁺ and further influenced the adsorption of phosphate. 3. The risk assessment of the release of phosphate was carried out, and the impacts of tributaries' input and seasons were discussed.4. The study indicated that the process of phosphorus adsorption onto sediments mainly occurred within 0-8 h, and then reached a dynamic equilibrium. This experimental finding had shown maximum adsorption rates occurred within 0-30min, and the adsorption capacities accounted 47 %—82 % for maximum adsorption capacities. And there were notable differences among different particle size fractions.5. The results of study indicated that Elovich is the optimal equation to the adsorption of phosphate in the sediments of Baotou section of the the Yellow River, and Langmuir model and Freundlich model were suggested as the appropriate types for the sediments.