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Effect of temperature on phosphorus sorption to sediments from shallow eutrophic lakes
- Huang, Lidong, Fu, Lili, Jin, Chongwei, Gielen, Gerty, Lin, Xianyong, Wang, Hailong, Zhang, Yongsong
- Ecological engineering 2011 v.37 no.10 pp. 1515-1522
- activation energy, aluminum, desorption, eutrophication, fractionation, heat, iron, lakes, models, phosphorus, sediments, sorption isotherms, temperature
- 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 6.37kJmol⁻¹ for Mei sediments and 8.67kJmol⁻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.