Liu Bo, Han Rui-Ming, Wang Wen-Lin, Yao Hong, Zhou Feng
School of Geography Science, Nantong University, Nantong, 226007, China.
School of Environment, Nanjing Normal University, Nanjing, 210023, China.
Environ Sci Pollut Res Int. 2017 Apr;24(10):9481-9494. doi: 10.1007/s11356-017-8631-3. Epub 2017 Feb 24.
To reveal the detailed vertical oxygen distribution at the sediment-water interface (SWI) and its relation with the oxygen consumption processes during and after aeration of polluted urban rivers, experimental systems constructed with collected sediment and in situ overlying water from a polluted urban river were aerated above or beneath the sediment-water interface 12 h a day for 15 days and left nonaerated for the following 10 days. The results showed that aeration of water or sediment both increased dissolved oxygen (DO) concentrations in the SWI, characterized by shifts in a "decrease-increase-decrease" manner during around 3 h for the aeration of water treatment (AW) and 6 h for the aeration of sediment treatment (AS). The oxygen penetration depth for AS experiments was between 0.66 and 4.16 mm with an average of 1.79 mm, significantly higher than that for AW experiments; however, the oxygen dissipation constant (mm) measuring the decay rate of DO near the SWI was greater for the AW experiments than the AS experiments. During the 10-day nonaeration period, the accumulation of nitrate in both the overlying water and sediment was greatly increased concomitantly with the higher oxygenation in AS experiments. From the nitrogen removal viewpoint, these results suggest that the SWI needs moderate oxygenation which enables nitrate and nitrite to be removed by denitrification rather than to be totally nitrified and accumulate as would result from the conventional practice by singly elevating DO concentrations.
为揭示污染城市河流曝气期间及曝气后沉积物 - 水界面（SWI）详细的垂直氧分布及其与氧消耗过程的关系，利用采集的沉积物和某污染城市河流的原位上覆水构建实验系统，每天在沉积物 - 水界面上方或下方曝气12小时，持续15天，随后10天不曝气。结果表明，对水或沉积物进行曝气均会增加SWI中的溶解氧（DO）浓度，水处理曝气（AW）在约3小时内、沉积物处理曝气（AS）在约6小时内呈现出“先降低 - 再升高 - 再降低”的变化特征。AS实验的氧穿透深度在0.66至4.16毫米之间，平均为1.79毫米，显著高于AW实验；然而，测量SWI附近DO衰减率的氧消散常数（毫米），AW实验大于AS实验。在10天的不曝气期间，AS实验中较高的氧合作用使得上覆水和沉积物中硝酸盐的积累大幅增加。从氮去除的角度来看，这些结果表明SWI需要适度的氧合作用，以便通过反硝化作用去除硝酸盐和亚硝酸盐，而不是像单纯提高DO浓度的传统做法那样将其完全硝化并积累。
