芦苇、香蒲和藨草3种挺水植物的养分吸收动力学研究

Abstract

The emergent plants may differ in their capacity to assimilate nutrients from eutrophic water bodies,so the utilization of suitable emergent plants is the key part for successful restoration of shallow eutrophic lakes. This research applied the depletion method after plants were grown for 4 weeks in 1 /8 Hoagland nutrient solution to study the kinetics of uptake of nutrient( H2PO-4,NH+ 4,NO-3) by the three emergent aquatic plants Phragmites australis,Typha orientalis and Scirpus triqueter dominated in the littoral zones of Wuliangsuhai Lake( 40°36'—41°03'N,108°43'— 108°57'E),a shallow eutrophic lake located in Urat Front Banner of Bayannaoer city,Inner Mongolia. The maximum uptake rate( Imax), Michaelis-Menten constant( Km),and Minimum equilibrium concentration( Cmin) were estimated by the ion consumption dynamics equation. The Imaxfor H2PO-4of Phragmites australis,Typha orientalis,and Scirpus triqueter are 0.3895 μmol g-1( dry weight,DW) h-1,0.3053 μmol g-1DW h-1,and 0.6330 μmol g-1DW h-1,While the Kmfor H2PO-4are 0. 0637 mmol / L,0.0645 mmol / L,and 0.0702 mmol / L,respectively. Results indicated that the Scirpus triqueter has a significantly higher uptake rate of H2PO-4than Phragmites australis and Typha orientalis,but no differences have been found in the adaptation( tolerance) of the three species to low H2PO-4concentrations. The Imaxfor NH+ 4of Phragmites australis,Typha orientalis,and Scirpus triqueter are 8.995 μmol g-1DW h-1,5.584 μmol g-1DW h-1,and 13.819 μmol g-1DW h-1,While the Kmfor NH+ 4are 1. 882 mmol / L,1. 787 mmol / L,and 1. 874 mmol / L,respectively. The Imaxfor NO-3of Phragmites australis,Typha orientalis,and Scirpus triqueter are 3.374 μmol g-1DW h-1,2.544 μmol g-1DW h-1,and 10.146 μmol g-1 DW h-1,While the Kmfor NO-3are 0.924 mmol / L,0.884 mmol / L,and 0.847 mmol / L,respectively. Results indicated that Scirpus triqueter had also highest uptake rates of NH+ 4and NO-3,was tolerant to low NO-3concentrations but did not adapt to( tolerate) low NH+ 4concentrations. By contrast,Typha orientalis dislayed the strongest affinity to NH+ 4and the highest uptake at low NH+ 4concentrations,which the Cminis 1.724 mmol / L lower than Phragmites australis( 1.865 mmol / L) and Scirpus triqueter( 1.833 mmol / L). Overall the three emergent plants showed higher uptake capacity for NH+ 4than for NO-3. Nutrient uptake characteristics of the emergent plants are species-specific and influenced by the structure of roots. Outcomes of this research suggest that Scirpus triqueter suits best as pioneering species for ecological restoration of water bodies with high NH+ 4and NO-3concentrations,while Typha orientalis suits well for stabilizing improved water quality conditions.