黄菖蒲和狭叶香蒲根系对氮磷的吸收动力学

采用改进的常规耗竭法，研究了黄菖蒲（Iris pseudacorus L.）和狭叶香蒲（Typha angustifolia L.）根系对NH₄⁺、NO₃^-和H₂PO₄^-的吸收特征及差异。结果表明，这2种植物根系对NH₄⁺、NO₃^-和H₂PO₄^-的吸收动力学特征均可采用Michaelis-Menten方程描述。2种植物根系对NH₄⁺、NO₃^-和H₂PO₄^-的亲和力（Km）和最大吸收速率（Vmax）有显著差异。吸收H₂PO₄^-时，黄菖蒲根系具有较高的Vmax值和较低的Km值，说明黄菖蒲具有嗜磷特性，并能够适应广范围浓度的H₂PO₄^-环境，适宜用于污染水体磷的去除；吸收NO₃^-时，狭叶香蒲根系具有较高的Vmax值和较低的Km值，表明狭叶香蒲可用于广范围浓度NO₃^-污染的水体修复；吸收NH₄⁺时，黄菖蒲根系具有较低的Vmax值和Km值，而狭叶香蒲根系具有较高的Vmax值和Km值，说明黄菖蒲适宜用于NH₄⁺污染较轻水体的修复，而在NH₄⁺污染较重水体中宜选用狭叶香蒲作为先锋植物。

Kinetics of nitrogen and phosphorus uptake by root system of Iris pseudacorus L. and Typha angustifolia L.

The NH₄⁺, NO₃^- and H₂PO₄^- uptake kinetics of root system of Iris pseudacorus L. and Typha angustifolia L. were investigated by using the modified depletion method. Results showed that the NH₄⁺, NO₃^- and H₂PO₄^- uptake kinetics of the two plants' root system could be expressed with the Michaelis-Menten equation. The Michaelis-Menten constant (Km) and the maximum uptake rate (Vmax) was significantly different between the two plants' root systems. The root system of Iris pseudacorus L. had higher Vmax and lower Km for H₂PO₄^- than that of Typha angustifolia L.' root system, which suggested that Iris pseudacorus L. had the capability to adapt to a various concentrations of H₂PO₄^- environment and made it a better candidate for removing phosphorus in polluted water. In addition, Typha angustifolia L.' root system had higher Vmax and lower Km for NO₃^- than that of Iris pseudacorus L.' root system, which indicated that Typha angustifolia L. was suitable for treatment of all levels of NO₃^- polluted water. The values of V_max and Km for NH₄⁺ of Iris pseudacorus L.' root system were lower than that of Typha angustifolia L.' root system, which showed that Iris pseudacorus L. was applicable to repair the less contaminated water by NH₄⁺ and Typha angustifolia L. should be selected for NH₄⁺ seriously polluted water bodies.