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| Nutrient Removals from Eutrophic Water by Eichhornia Crassipes at Different Growth Stages |
| Received:June 27, 2014 |
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| KeyWord:nitrogen;phosphorus;water hyacinth;eutrophication |
| Author Name | Affiliation | E-mail | | GAO Yan | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | MA Tao | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | ZHANG Zhen-hua | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | ZHANG Li | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | WANG Yan | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | | | YAN Shao-hua | Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China | shyan@jaas.ac.cn |
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| Abstract: |
| The capability of floating macrophyte, water hyacinth(Eichhornia crassipes), to clean up eutrophic water has been widely recognized, but there is still lack of information on the effect of E. crassipes at different growth stages on nutrient removal from eutrophic water with various concentrations of nitrogen(N) and phosphorous(P). A series of simulated experiments were conducted comparing the efficiency of N and P removals from eutrophic water by E. crassipes at different growth stages. The proportion of N accumulated by E. crassipes to the total dissolved nitrogen(TDN) removal from the water declined as the initial concentrations of N in the water increased. However, E. crassipes at different growth stages showed different efficiencies of TDN removal from the water with the various concentrations of N and P. In water with relatively low concentrations of N and P, the effects of E. crassipes on the removals of TDN and total dissolved phosphorous(TDP) were not significantly different among the different growth stages; whereas in water with relatively high concentrations of N(TDN ~7 mg·L-1 or ~13 mg·L-1), the efficiency of TDN removal from the water at the initial phase of the experiments was significantly higher at the early stage of plant growth than the middle and late growth stages, but became closer among the different growth stages as the experiments progressed. In water with TDN levels of ~7 mg·L-1, the proportion of plant N accumulation to N removals from water was in order of the late growth stageE. crassipes significantly reduced the contents of N and P in sediments. The amount of P assimilated by E. crassipes exceeded the amount of P removed from the water. The contribution of plant assimilation to the removals of TDP was not significantly different among the different stages of plant growth. These results showed that nitrogen assimilation by E. crassipes at the early growth stage contributed greatly to N removals from water; while N removal via the root biological processes was small, and E. crassipes not only removed P from the water, but also assimilated P released from the sediments. |
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