溶解氧对水质变化和沉积物吸磷过程的影响

通过室内模拟实验,研究有光和黑暗条件下,富氧和缺氧环境对东太湖沉积物吸收磷酸盐过程的影响.研究结果表明沉积物能够吸收上覆水中高质量浓度的磷酸盐,但吸收量和吸收速度随环境条件的不同而不同;缺氧环境上覆水中的pH高于或略高于相同光照条件下的富氧环境;实验开始的前20d,富氧环境有利于沉积物吸附上覆水中的磷酸盐,并快速达到吸附平衡,缺氧环境则相反;实验开始20d后,有光缺氧组上覆水中磷酸盐质量浓度开始迅速下降,且明显低于其他实验条件;富氧环境沉积物中总磷的增加量高于缺氧环境,其含量顺序为无光富氧＞有光富氧＞有光缺氧＞无光缺氧;溶解氧对沉积物中铁结合态磷和钙结合态磷含量的影响较大,对有机磷含量的影响不大.

Effects of Dissolved Oxygen on the Changes of Overlying Water Quality and the Uptake of Phosphate by Sediment

Effects of aerobic and anoxic environment on the changes of the overlying water quality and the phosphate uptake by sediments with the presence and absence of light in East Taihu Lake were investigated. The results show:the sediments can uptake phosphate from the overlying water with high mass concentration, but the rate and quantity of uptake were different in different conditions; pH of the overlying water in the anoxic environment was higher or a little higher than that in the aerobic environment with the same light condition. During the first 20 days of the experiment, aerobic environment is benefit to the phosphate uptake in sediment, which caused the rapid decrease in phosphate concentration in the overlying water and adsorption equilibrium. After 20 days, the phosphate concentrations in the overlying water in light and anoxic environment decrease rapidly, and they were much lower than those in other experimental conditions. The increased concentrations of total phosphorus in the experimental sediment under the aerobic environment were higher than those under the anoxic environment,with the order of contents:aerobic with no light>aerobic with light>anoxic with light>anoxic without light.Dissolved oxygen concentration had significant effect on the Fe bound phosphate and Ca bound phosphate,and had little effect on the organic phosphate.