沉积物疏浚中气泡防淤帘对污染物扩散控制效果的研究

Controlling effects of air bubble screen for contaminant dispersion during sediment dredging

采用模拟试验,研究了气泡防淤帘对SS、有机质及营养元素等溶解性污染物的扩散控制效果。结果表明,气泡防淤帘技术可以有效控制非溶解性和溶解性污染物的扩散,疏浚区SS、CODCr、TN、TP向空白区的扩散通量分别降低了94%,90%,71%和73%,其作用主要是通过在疏浚区和空白区形成循环流,控制大部分污染物在各自区域内的循环迁移来实现的;气泡防淤帘技术对非溶解性污染物SS的控制效果要优于溶解性物质;由于溶解氧的增加可以削减水体的CODCr总量,故在溶解性物质中该技术对CODCr的控制效果最好;气泡防淤帘并不能削减TN和TP的扩散总量,但可以降低扩散速率,有利于疏浚水体对扩散营养物质的消纳。

The controlling effects of air bubble screen to soluble contaminant dispersion such as SS, organic matters and nutrient elements were investigated by a simulation test. The results showed that the dispersion of both insoluble and soluble contaminants could be controlled effectively by air bubble screen. Diffusion flux of SS, CODcr, TN and TP from the dredging area to blank area were decreased 94%, 90%, 71% and 73% respectively. The realization of controlling effects was mainly depended on the circulation flow induced by air bubble screen. Because of the circulation flow, most contaminants in the dredging area were restricted in such area and only a little contaminant migrated from the dredging area to blank area. Also, the results showed that air bubble screen was a better controlling effect on insoluble contaminants dispersion compared with soluble contaminants. For all the soluble contaminants, the method was the best controlling effect to CODcr because of the increasing of dissolved oxygen could reduce the total amonts of CODcr. Though air bubble screen could not reduce the total dispersion amount of TN and TP during the sediment dredging, dispersion velocities were decreased, and it was helpful to the removing of contaminants in dredging waters.