氮周期供给时潜流带沉积物硝化、反硝化动力学

Kinetics of Nitrification and Denitrification in Hyporheic Zone Sediment with Periodical Supply of Nitrogen

河流潜流带最显著的特征是河水和地下水周期性交替导致的水化学成分的动态变化,且周期间的间隔长短不一;潜流带是脱氮热区,其硝化和反硝化微生物对这种周期性变化的响应规律决定着潜流带脱氮效率.据此,时间间隔不同多次供给不同氮素、DO等,研究多周期内硝化、反硝化动力学规律.第1周期的硝化、反硝化速率较慢,有明显迟滞期;后续的第2和第3周期,无论底物投加间隔时间长短,硝化和反硝化未观察到明显迟滞期,反应速率均加快,且功能菌数量增加,但是功能菌数量和间隔时间成反比.硝态氮起始浓度会明显影响亚硝态氮动力学过程.硝化和反硝化菌数量增加及长时间维持高反应活性,是潜流带高效脱氮机制之一.

The most significant feature of the river hyporheic zone is the dynamic change of water chemical composition caused by the periodical alternation of river water and groundwater,and the interval between periods is different.The hyporheic zone is a denitrification hot zone,and the response law of nitrification and denitrifying microorganisms to this periodical change determines the nitrogen removal efficiency of the hyporheic zone.According to this,different nitrogen,DO,etc.were supplied multiple times at different intervals to study the kinetics of nitrification and denitrification in multiple cycles.The nitrification and denitrification rates in the first cycle were slow,and there was an obvious hysteresis period.In the subsequent second and third cycles,regardless of the length of substrate dosing interval,no significant hysteresis period was observed for nitrification and denitrification,the reaction rate was accelerated,and the number of functional bacteria increased,but the number of functional bacteria was inversely proportional to the interval time.The initial concentration of nitrate nitrogen significantly affects the nitrous nitrogen kinetic process.The increase in the number of nitrifying and denitrifying bacteria and the maintenance of high reactivity for a long time are one of the efficient nitrogen removal mechanisms in the hyporheic zone.