Effects of Lanthanum modified bentonite on the water phosphorus concentration and sediment phosphorus form in a shallow eutrophic lake

分析湖泊沉积物磷形态的变化是揭示控制沉积物磷释放机理的关键.本研究分析了暨南大学南湖加镧改性膨润土前后水体磷浓度和沉积物磷形态变化，以探讨镧改性膨润土对削减水体磷浓度的效果.结果显示，镧改性膨润土添加后，上覆水磷浓度波动较大，总体呈下降趋势；至60 d时，水体总磷、颗粒态磷、总溶解磷和溶解性反应磷分别比添加前下降了45.1%、44.1%、48.2%和85.3%；沉积物中的弱结合态磷和氧化还原敏感性磷含量减少，更稳定的磷灰石结合态磷和残渣磷含量增加，而金属氧化物磷和有机磷含量变化较小.本研究表明镧改性膨润土能改变沉积物磷形态，使活性磷转化为稳定的磷形态，从而提高沉积物对磷的滞留能力、降低湖水磷含量，改善水质.;Analyzing the changes in phosphorus(P) forms of sediments is the key to understanding the mechanisms of sediment P release control. This study investigated the changes in water P concentrations and sediment P-fractions before and after the application of Lanthanum modified bentonite in South Lake in Jinan University in order to analyze the effect on water P concentrations. The results showed that the total P concentration of the lake water decreased by 45.1% after 60 days of water P concentration of the lake changed dramatically after the treatment, after 60 days of the addition of Lanthanum modified bentonite. Meanwhile, the contents of labile-P and reductant-soluble-P were reduced and that of more stable apatite-P and residual-P increased after the treatment, but metal-oxide-P and organic-P did not change. These findings indicate that lanthanum modified bentonite can change sediment P forms and reduce the contents of the potentially releasable sediment P forms which likely contribute to the reduced P concentration in the lake water and thus improve water quality.