Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4390273 | Ecological Engineering | 2011 | 8 Pages |
The availability of phosphorus (P) in lakes is dependent on the sorption characteristics of the underlying sediments. Temperature is a crucial factor affecting the P sorption in sediments. The objective of this study was to evaluate the effect of temperature on sorption of P by sediments from two eutrophic lakes. The study was carried out using short-term batch experiments at 4, 20 and 30 °C. Phosphorus sorption kinetics, isotherms, fractionation and desorption were investigated. The P sorption was dependent on sediment type and temperature (p < 0.001). The Mei sediments showed a higher sorption rate and sorption capacity than Hua sediments. The P sorption kinetics were best described by a pseudo second order model (R2 > 0.97). Activation energies derived from the kinetics rate constant indicated that P sorption onto the two sediments was controlled by a diffusion process. For both sediments, Freundlich model fit the P sorption isotherms well and the calculated apparent sorption heat was 6.37 kJ mol−1 for Mei sediments and 8.67 kJ mol−1 for Hua sediments. This indicated that P sorption onto both sediments was endothermic. Adding P significantly increased the soluble and loosely bound P (S/L–P), aluminum-bound P (Al–P) and iron-bound P (Fe–P) (p < 0.05). The amount of Al–P and Fe–P was markedly higher at 30 °C than at 4 °C (p < 0.05). Subsequent P desorption indicated that adsorbed P was highly labile, in particular for Hua sediment. The degree of P mobility that occurred during sediment sorption was inversely related to the temperature at the time of sorption. A significant relationship (R2 = 0.978) between phosphorus sorption maximum and oxalate-extractable Fe and Al at different temperatures reflects that the amorphous contents of Fe and Al are responsible for the temperature effect on P sorption.