泥沙颗粒生长生物膜后起动的实验研究——Ⅰ.起动实验设计及结果分析

Experimental study of the effect of biofilm formation on sediment incipient motion: I.Design and analysis

天然水体中泥沙颗粒表面容易生长生物膜,生物膜的生长会对泥沙颗粒的运动特性产生显著影响。设计了泥沙颗粒表面生长生物膜的实验,以及生长生物膜后泥沙颗粒的起动水槽实验。在水槽观测段分别放置由去离子水浸泡和天然水培养的两种泥沙,对比观察两种泥沙起动过程的区别,分析起动流速的差异和随培养时间的变化规律。结果表明,天然富营养水体中生物膜生长繁茂,对泥沙起动特性有着显著的影响,能够增强泥沙颗粒的抗冲性,并随时间呈现出先逐步增强到一个最优值后有所削弱的钟形曲线的变化趋势,表明在研究天然河流和湖泊尤其是污染严重的水域的泥沙起动时,需要考虑到生物膜的作用。

Biofilm colonization on sediment particles can have a significant effect on particle incipient motion.A series of flume experiments was conducted on two types of sediments,one of which was immersed in deionized water,and the other was cultivated in a mixture of natural water and nutrient solution.The result shows that the two sediment types can result in a significant difference in incipient motion.The incipient velocity of cultivated sediment varies over time.Sediment cultivated in natural nutritious water has a higher stability due to the biofilm growth.The incipient velocity increases with time until reaching a critical threshold,at which the optimum condition for biological activities is obtained,and then decrease.It is indicated that the role of microbes in sediment incipient motion needs to be considered,especially in polluted water bodies.