富营养化水体中水生植物氮代谢酶特性与不同形态氮去除的关系

Relationship Between Characteristics of Nitrogen Metabolism Enzymes of Aquatic Plants and NitrogenRemoval of Different Forms from Eutrophic Water Bodies

通过先对水芹[Oenanthe javanica(Bl.)DC]和豆瓣菜(Nasturtium officinalcR.BR.)吸收不同氮形态的动力学进行了研究,然后通过室内静态模拟试验,利用植物浮床系统研究了富营养化水体中两种水生植物氮代谢酶特性与水体中不同形态氮去除的关系,为进一步明确它们对水体中不同氮形态的去除机理及针对不同营养特征的富营养化水体的生态修复工程的植物选取提供科学的理论基础。结果表明,水芹对NH4+吸收的最大速率(Vmax)和米氏常数(Km)均明显大于对NO3-吸收的Vmax和Km值,而豆瓣菜对NH4+吸收的Vmax大于对NO3-吸收的Vmax,但吸收的Km值却明显小于对NO3-吸收的Km值。而且,水芹对低浓度的铵态氮(NH4-N)和硝态氮(NO3-N)的吸收能力较豆瓣菜要强。富营养化水体浮床生态修复中,单作或混作水芹的GS活性与水体中TN、NH4-N去除存在极显著的相关性(r>0.97),且混作水芹体内的GS活性还与水体中NO2-N去除存在显著的相关性。单作或混作豆瓣菜的GS活性与水体中TN、NH4-N去除存在显著的相关性(r>0.91),且混作豆瓣菜的GS活性与水体中NO2-N去除也存在显著的相关性。单作或混作两种水生植物的GOGAT和NR活性虽与水体中TN、NH4-N、NO3-N、NO2-N去除呈指数衰减变化趋势,但无明显的相关性。

In this paper the absorption kinetics of different nitrogen forms by water celery and watercress were studied, and the relationship between characteristics of nitrogen metabolism enzymes of two aquatic plants and nitrogen removal of different forms from eutrophic water was examined using floating bed plant system under indoor static simulation experimental condition. The purposes of this study were to provide scientific foundation for the removal mechanism of different nitrogen forms from water and selection of plant species for ecological restoration of eutrophic water bodies. The results showed that the Vmax and Km values of NH^＋4 absorption were significantly greater than those of NO; absorption for water celery, whereas the Km value of NH^＋4 absorption was obviously smaller than that of NO^-3 absorption for watercress despite of the Vmax value of NH^＋4 absorption was greater than that of NO; absorption. In addition, more NH4-N and NO3-N were uptaken by water celery than by watercress when grown at low concentrations. Significant correlation （r〉 0.97 ）between GS activity of water celery and removal of TIN and NH4-N from eutrophic water was noted when monocuhured or mixcuhured with watercress on floating bed system, and the GS activity of the mixcultured water celery was also significantly correlated with NO2-N removal from eutropic water bodies. Significant correlation （r〉 0.91 ）between GS activity of watercress and the removal of TN and NH4-N was observed when it was monocuhured and/or mixcultured with water celery, and the GS activity of the mixtured watercress was also significantly correlated with NO2-N removal from eutrophic water. The activities of GOGAT and NR of two aquatic plants, whether monocultured and/or mixcultured, decreased exponentially with the removal of TN, NH4-N, NO3-N and NO2-N, but no significant correlations were noted.