光照和黑暗条件下苦草(Vallisneria natans)和穗花狐尾藻(Myriophyllum spicatum)对铵态氮的吸收

Uptake of ammonium by Vallisneria natans and Myriophyllum spicatum under light and dark regimes

在室内模拟实验中,研究了光照(50μmol/(m2.s))和黑暗条件下苦草(Vallisneria natans)和穗花狐尾藻(Myrio-phyllum spicatum)对铵态氮(NH4+-N)的吸收速率与去除效果.结果表明,随着外源铵态氮浓度(0,0.01,0.1,1和10 mg/LNH4+-N)的增加,苦草和穗花狐尾藻对铵态氮的吸收速率都是先增加后又逐渐降低,在外源铵态氮浓度为1 mg/L时吸收速率达到最大.同种植物在光照条件下对铵态氮的吸收率不低于黑暗条件下的吸收率;相同光强条件下穗花狐尾藻对铵态氮的吸收率不低于苦草的吸收率.在黑暗条件下,在外源铵态氮浓度为1 mg/L时,穗花狐尾藻对铵的吸收速率是苦草的2.42倍;在光照条件下,在外源铵态氮浓度为1和10 mg/L时,穗花狐尾藻对铵态氮的吸收速率分别是苦草的2.47和1.79倍.因此,在富营养湖泊治理过程中,在沉水植物可耐受铵态氮浓度范围内,可以优先考虑把穗花狐尾藻作为植物修复的先锋物种.

The uptakes and removal effects of ammonium nitrogen （ NH4＋ -N） by Vallisneria natans and Myriophyllum spicatum un- der light （ 50 I.Lmol/（ m2 ~ s） ） and dark regimes were investigated in a laboratory experiment, with external NH -N concentrations at 0, 0.01,0.1, 1 and l0 mg/L. The results showed that the absorption rates of NH4＋ -N by V. natans and M. spicatum increased with external NH4＋ -N concentrations and peaked at 1 mg/L, and then decreased at 10 mg/L. The absorption rates of NH4＋ -N by the same plant species in the light condition was not less than those in the dark condition. The absorption rate of NH4＋ -N by M. spicatum was not less than that by V. natans in the same light regime. Under dark regimes, with external NH4＋ -N concentrations at 1 mg/L, the absorption rates of NH4＋ -N by M. spicatum was 2.42-fold higher than that of V. natans. Under light regimes, with external NH4＋ -N concentrations at 1 and 10 mg/L, the absorption rates of NH4＋ -N by M. spicatum was 2.47-fold and 1.79-fold higher than that of V. natans, respectively. Therefore, at a certain range of NH4＋ -N concentrations that macrophytes can tolerate, M. spicatum should be considered as the pioneer species for the restoration of macrophytes in eutrophic lakes.