凤眼莲根系分泌氧和有机碳规律及其对水体氮转化影响的研究

Oxygen and Organic Carbon Releases from Roots of Eichhornia Crassipes and Their Influence on Transformation of Nitrogen in Water

通过模拟实验,研究凤眼莲不同苗龄根系分泌氧及有机碳的规律,在此基础上分析凤眼莲根系分泌氧和有机碳对富营养化水体溶解氧、有机碳及无机氮(NH+4和NO-3)转化的影响。研究结果表明凤眼莲根系具有较强的泌氧及分泌有机碳的能力,小、中、大三个苗龄凤眼莲根系泌氧速率分别达56.19、93.15、106.32μmolO2·h-1,根系分泌有机碳的速率分别达0.25、0.60、0.92 mg·L-1·h-1。不同苗龄凤眼莲根系泌氧及有机碳的速率随苗龄的增加显著升高,而其相对应的单位根系泌氧和有机碳的能力随苗龄的增加呈降低趋势。水体中无机氮的去除率随着凤眼莲苗龄的增加而增加,这除了与凤眼莲的吸收作用有关外,还因为其泌氧和分泌有机碳的总量增加加强了硝化和硝化-反硝化过程的潜力,从而高效并快速地净化水体中外源氮负荷。

In a simulation experiment, releases of oxygen and organic carbon from roots of E. crassipes were studied at different seedling stages. The concentrations of dissolved oxygen（DO）, total organic carbon（TOC）, NH ＋4 and NO -3 in eutrophic water were monitored. The plants exhibited high capability to release oxygen and organic carbon. The rate of oxygen release from roots was as high as 56.19、93.15 and 106.32 μmol O2·h-1 and that of organic carbon release as high as 0.25、0.60 and 0.92 mg C·L-1·h-1 at seedling age 1, 2 and 3, respectively, both increasing significantly with age of E. crassipes seedling. However, this order was reversed when the rates were based on the fresh weight of the roots. The removal rates of dissolved inorganic nitrogen from eutrophic water increased with E. crassipes seedling stages. Nitro-gen removal from water by E. crassipes was mainly due to nitrogen uptake and assimilation by the plant, and enhanced nitrification and ni-trification-denitrification from increased oxygen and organic carbon in water. Hence, E. crassipes made great contribution to efficient and fast removal of the loaded nitrogen in eutrophic waters.