Phragmites australis and Typha orientalis in removal of pollutantin Taihu Lake, China
TIAN Ziqiang , ZHENG Binghui , LIU Meizhen , ZHANG Zhenyu
DOI:
Received March 26, 2008,Revised October 20, 2008, Accepted , Available online
Volume 21,2009,Pages 440-446
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Two plant populations of Phragmites australis and Typha orientalis grown in gravel and sediment substrate were studied to assess
their capabilities for purifying polluted water in Taihu Lake, China. The substrate displayed most significant e ects on the suspended
matter (P < 0.01), with the reduction of 76%–87% and 52%–63% for P. australis, and 83%–86% and 45%-62% for T. orientalis in
gravel substrate and sediment substrate, respectively. Both species and substrates significantly decreased the N and P concentrations of
water body (P < 0.01). P. australis showed higher total N and P concentrations in tissues than T. orientalis and had a greater potential
to remove nutrients from the lake. Phosphate was easily to concentrate in the belowground tissues, while nitrate concentration was
higher in leaf and stalk. Therefore, harvesting the aboveground tissues could take most of nitrate out of the sediment. The saturate
photosynthetic rate (Asat) of P. australis was higher than that of T. orientalis when grown in sediment substrate. But instance water-usee
ciency (WUEi) (A/E) and intrinsic water use e ciency (A/gs) showed the maximum values of two species grown in river water.With
significant di erence in gs, however, intercellular CO2 concentration (Ci) had no obvious di erence in two species which indicated that
high Asat value of P. australis might result from the increased carboxylation capacity of the mesophyll, because of the central role of N
in photosynthetic enzymes. Our findings suggest that the plants could absorb most of nitrogen in polluted water, while gravel displayed
a high capacity for absorbing the suspended matters and phosphate salts. Therefore, biological and physiological pathways for pollutant
removal should be integrated.
