分层型水源水库沉积物需氧量特性

Characteristics of Sediment Oxygen Demand in a Drinking Water Reservoir

为探明分层型水源水库沉积物需氧量(SOD)特性及其影响因素,选取西安金盆水库主库区上覆水体流速较低的库心区及流速较高的入库口两处沉积物进行对比实验,估算水体不同扰动条件下沉积物需氧量,利用Biolog-Eco平板和三维荧光光谱(EMMs)技术从底栖微生物群落代谢活性和沉积物有机质两方面对取样点沉积物需氧量的差异性进行分析.结果表明,静止条件下,入库与库心沉积物在较高溶解氧时(约5 mg·L-1)的沉积物面积需氧量SOD5area分别为0.13 g·(m2·d)-1和0.36g·(m2·d)-1,库心约为入库的2.69倍.动态条件下,沉积物-水界面上覆水扰动增加使沉积物需氧量增加,沉积物耗氧动力学由一阶动力学方程逐渐向零阶动力学方程转变.入库与库心沉积物有机质含量分别为44.43 mg·g-1和45.12 mg·g-1,库心沉积物的可溶解性有机质(DOM)的总荧光强度约为入库的1.5倍.有机质含量更高的库心沉积物细菌群落代谢活性(以AWCD表征)更强,表明高含量有机质和较强细菌代谢活性是引起库心沉积物需氧量大的主要因素.将深层水库水体耗氧过程的研究结果与现有充氧曝气技术进行结合,可为提高曝气器充氧效率提供科学依据.

Depletion of dissolved oxygen（DO） in the hypolimnetic layer during stratification periods and its deleterious effects on water quality have been widely observed. However,it is still difficult to comprehend conceptually the processes of oxygen consumption at the sediment-water interface. The research presented here is,therefore,based on an areal hypolimnetic oxygen demand（AHOD） model to address three key themes related to the sediment oxygen demand（SOD） ：（1） the characteristics of sediment and its influences on SOD;（2） evaluation of SOD with different turbulence levels overlying the sediment; and（3） the influence of microbial metabolic activity on SOD. Sediment samples were collected at the entrance to and over the basin area of Jinpen Reservoir,and a sediment-water experimental chamber was designed to achieve these goals. The results showed that,under quiescent conditions,the SOD5 area（SOD at DO of 5 mg·L^-1） were 0. 13 g·（m^2·d）^-1 and 0. 36 g·（m^2·d）^-1 in the arm and basin,respectively. Under dynamic conditions,the slight mixing of the water column near the sediment induced an increase in SOD and resulted in a gradual shift from first-order to zeroorder DO uptake. The organic matter content in the reservoir arm and profundal sediment were 44. 43 mg·g-1 and 45. 12 mg·g-1,respectively. The microbial metabolic activity in the basin was stronger,and the total fluorescence intensity of the dissolved organic matter（DOM） in the profundal sediments was about 1. 5 times that in the reservoir arm. These results suggest that SOD will be higher when microbial metabolic activity is stronger and organic matter content is higher in sediments. The oxygenation aeration techniques should be designed to meet the oxygen demand of the deep reservoir to provide a theoretical basis for improving the oxygenation efficiency.