三峡库区悬移质泥沙对磷污染物的吸附解吸特性

ADSORPTION AND DESORPTION OF PHOSPHORUS ON SUSPENDED PARTICLES IN THE THREE GORGES AREA

就三峡库区悬移质泥沙对磷污染物的吸附解吸特性从野外同步监测和室内试验研究两个方面展开研究。选取长江干流、嘉陵江和乌江共7个监测断面于2002年和2003进行野外同步监测,测试结果表明:水中的悬移质泥沙对水中各种覆存形态的磷污染物浓度具有显著影响,单位重量泥沙对磷的吸附量与水体总泥沙含量、泥沙粒径有密切关系。采集寸滩断面泥沙对磷酸盐吸附解吸特性进行室内试验研究,并根据Langmuir吸附动力学方程对吸附解吸过程进行了拟合,发现吸附速率常数k随着泥沙粒径的增加而呈递增变化,而磷酸盐初始浓度对k值的影响并不明显,同时,磷酸盐解吸量随着泥沙浓度的增加和粒径的增加呈递减变化,k值随着泥沙粒径的增加而呈递增变化,泥沙浓度对k值的影响不明显。

The adsorption and desorption behavior of phosphorus on particles in the Three Gorges Area was siudied by synchronous monitoring and laboratory experiments. Monitoring experiment revealed a close relationship between phosphorus concentration and particle content. Laboratory experiments were carried out in isothermal adsorption equilibrium and kinetics by mixture particles, the size of which was classified by D1≤0. 020 mm and D2≤0. 008 mm. The isothermal adsorption equilibrium experiments showed that the particle size has great effect on adsorption amount, with the adsorption amount increasing with the decrease of particle size. The data from kinetics experiment fitted by the second-order kinetics equation showed that the kinetics coefficient was affected by particle size, particle content and phosphate concentration. Under the condition of the same particle content and initial phosphate concentration, the kinetics coefficient was greater on thinner particles. Adsorption and desorption experiments were carried out by using particles from Cuntan cross-section. The adsorption experiment data can well be fitted by Langmuir kinetics equation, with rate coefficient k being greater on the coarser particles, and initial phosphate concentration having no obvious effect on, rate coefficient k. The desorption experimental data fitted by Langmuir kinetics equations showed that the phosphate desorption amount decreased with the increase of particle concentration and particle size, and rate coefficient k decreased with the increase of particles size. There was no obvious effect of particle size on coefficient k.