Comparative investigation on physiological responses of Pontederia cordata and purifying efficiencies of heavily polluted river water under continuous aeration in different seasons.

With field test,Pontederia cordata was hydroponic cultivated in 6 purifying-tanks(aeration and no aeration) with same planting density of 10,to investigate physiological characteristics(POD and CAT of roots tissues,Chl and SP of leaves) of the plant and main physical and chemical characteristics of the corresponding effluents in various seasons(spring,summer and autumn) . Lengths of roots,stems and leaves,tillers and roots densities,nitrogen(N) and phosphorus(P) accumulations and the biomass et al. of the plant′s biological indexes were analyzed. Comparative investigation on physiological responses of P. cordata and purifying efficiencies of heavily polluted river water under continuous aeration in various seasons was conducted. Results showed aeration affected physiological characteristics of the plant. Roots,stems and leaves lengths of the plant at the aeration were shorter than the lengths at the no aeration,respectively. Chla,Chlb and SP contents of the leaves at the aeration were lower than the contents at the no aeration,respectively. However,POD and CAT activities of roots tissues at the aeration exceeded the activities under the no aeration. N and P accumulations and the biomass of the plant were lower at the aeration than the plant at the no aeration. Tillers and roots densities in aeration purifying-tanks were more than the no aeration purifyingtanks. TN and NH4+-N removals of the effluents at the aeration exceeded the removals at the no aeration,while TP and soluble P removals were lower than the removals at the no aeration. Effects of aeration on physiological characteristics of the plant were obviously correlated with the growing of the plant. The effects became less in spring and summer,while the water qualities differences between two type purifying-tanks were great. However,the effects were obvious in autumn,while the water qualities variations between two type purifying-tanks became less.