Purification Of Eutrophic Water Body By Greenery Vegetable Cultivated On Floating-beds

As planting stuff on floating-beds, greenery vegetable Lactuca and Amaranthus were studied about their growth in the eutrophic water and the effect of absorbing nutrient from it in this experiment. At the same time the POD and NR in vegetables as well as the relation between APA and the reducing rate of nutrition in water. Meanwhile the nitrate, nitrite and heavy metal contents of vegetable were examined for the purpose of vegetable according with the eating standard. It indicates as follows:1 .The results indicated that the removal rate of TN,NH₄⁺-N, NO₃^--N,TP and PO₄^3--P respectively reached 75.9%,89.6%,77.3%,68.9% and 75.0% by lactuca, and the removal rate of TN,NH₄⁺-N,NO₃^--N,TP and PO₄^3--P respectively reached 70.5%,91.7%,76.6%,73.8% and 71.4% by amaranthus, Lactuca and Amaranthus not only can remarkably improve the quality of water, but also have no enrichment, so they accord with the eating standard.2. The change of NR and POD of the vegetables, the growth of vegetables in planting time on water and the change of reducing rate to water are identical. In the early stage of vegetables growth increase fast, which absorbs a lot of the nutrition and enzyme active increases gradually. But from the 21st day on, the growing rate of vegetables and the absorbing rate to nutrition become slower and slower and enzyme active has a tendency of drop. This may indicate that with the increase of enzyme active of vegetables, its growth metabolize also increases which will lead to the improvement of absorbing speed to diversified nutrition and indirectly improve the purifying effect of water quality.3. APA in water and vegetables can improve the conversion from organic P to inorganic P, and then improve the reducing rate of to water.4. Though vegetables absorb nutrient from eutrophic water, its nitrate, nitrite and heavy metal contents haven't overstep standard, according with the eating standard.