不同湿地植物土壤氮、磷去除能力比较

Comparison on purification capacity of soil nitrogen and phosphorus in different wetland plants

湿地植物是湿地的重要组成部分,也是决定湿地降解污染物、发挥净化功能的决定性因素之一。选取黄花鸢尾、睡莲和芦苇作为研究对象,采用野外氮、磷控制试验对植物吸收和去除土壤氮、磷能力进行了比较研究。结果表明:不同湿地植物的净增生物量差异较大,变化范围在12.81～119.43 g.m-2之间,其中黄花鸢尾净增生物量最大,芦苇最小;3种湿地植物地上部分植株氮、磷吸收率差异明显,对氮、磷的吸收贡献率分别在23.96%～41.86%和2.18%～12.73%之间,其中睡莲的氮、磷吸收贡献率最大;3种湿地植物土壤氮、磷去除率也有明显的差异,分别在12.20%～45.28%和33.3%～52.56%之间,土壤氮的去除率由高到低依次是黄花鸢尾、睡莲、芦苇,土壤磷的去除率依次是黄花鸢尾、芦苇、睡莲,3种湿地植物对土壤磷的去除效果要优于对土壤氮的去除效果。对土壤氮、磷去除率与湿地植物净增生物量、植株氮、磷含量、植物氮、磷吸收率的相关分析表明,湿地植物的净增生物量是决定湿地植物土壤氮、磷净化能力的一个重要因素。因此,在选择利用湿地植物的净化功能时,应优先考虑去除率高的植物种,从通过收割植物去除氮、磷的角度看,植物地上部分植株氮、磷含量越高越有利于通过收割植物去除氮、磷,可以大大提高净化效果,以达到净化的目的。本研究为进一步揭示湿地植物对过剩营养物质的净化机理奠定基础,为湿地生态恢复植物筛选工程提供科学依据,对湿地保护与恢复具有重要的指导意义。

Wetland plants are very important component of wetlands; these plants are necessary for the degradation of pollutants and water/soil purification. In this paper, three aquatic plants （i.e. lris wilsonii, Nymphaea tetragona, and Phragmites australiss） were chosen to compare the diversity on nutrition absorption and soil nitrogen and phosphorus purification capacity based on field control test. The results showed that net accumulated biomass varied intensively among different wetland plants, which ranged from 12.81 to 119.43g·m-2, with the highest biomass of Iris wilsonii and lowest of Phragmites australiss. Besides, the absorption rate of nitrogen and phosphorus in the above vegetations changed from 23.96%-41.86% and 2.18%-12.73% respectively with the highest uptake ratio of Nymphaea tetragona. Furthermore, obvious discrepancy （i.e. 12.20%-45.28% and 33.30%-52.56% respectively） was calculated in soil nitrogen and phosphorus decomposition ratio under different wetland plants. Consequently Iris wilsonii was having the highest calculated decomposition ratio of soil nitrogen and phosphorus. Similarly Phragmites australiss was having the lowest decomposition ratio of soil nitrogen, whereas Nymphaea tetragona was found lowest in the decomposition ratio of soil phosphorus. Overall, the removal of soil phosphorus from three plants was found superior to that of soil nitrogen. Therefore, species with higher removal ratio would be considered superior in the use of purification capacity. In addition, the higher percent of nitrogen and phosphorus in the ground surface plants seemed better for removing them when reaping, which was beneficial for purification to some extent. Moreover, it is useful to reveal the purification mechanism of surplus nutrient from wetland plants, and provide scientific reference for wetland restoration and plant screening projects, which is also significant for wetland protection and restoration.