| Constructed wetland water treatment system has been widly used for purification of organic substance, nitrogen, phosphorus and other pollutants in eutrophic water in recent years. In this study, one-year-old and two-year-old seedlings of Pterocarya stenoptera and Salix babylonica were chosen to be wetland plants in simulated constructed wetlands,whose purification ability of TN and TP in eutrophic water was investigated. The concentration of TN and TP in eutrophic water was 2.0 and 0.4 mg/L,20.0 and 8.0 mg/L,40.0 and 15.0 mg/L,80.0 and 25.0mg/L respectively. The two wetland plants'corresponding growing and physiological characteristic were also investigated. The main results were described as follows:1. In the two stages, the TN, TP removal rates of Pterocarya stenoptera wetland, Salix babylonica wetland and blank wetland showed a sequence of Salix babylonica wetland >Pterocarya stenoptera wetland>blank wetland. In the autumn-winter stage, the average TN, TP removal rate of Pterocarya stenoptera wetland, Salix babylonica wetland and blank wetland was 9.72%,16.06%,4.43% and 22.72%,30.25%,16.73% separately, while in the summer-autumn stage, the TN, TP average removal rate of Pterocarya stenoptera wetland, Salix babylonica wetland and blank wetland was 53.50%,61.73%,23.84% and 51.59%,57.47%,34.01% separately.2. In the two stages, the stem height and base diameter of Pterocarya stenoptera and Salix babylonica in each group had risen comparing to the initial stages.In the autumn-winter stage the leaf numbers firstly increased and then decreased, while in the summer-autumn stage the leaf numbers was growing continuously in groupC2-C4. The growing condition of Pterocarya stenoptera and Salix babylonica was above "comparatively good" in the middle of the autumn-winter stage and after the middle of the summer-autumn stage. There were positive correlations between the stem height and the concentration of eutrophic water, the leaf numbers and the concentration of eutrophic water, the growing condition score and the concentration of eutrophic water for Pterocarya stenoptera in the two stages and for Salix babylonica in the summer-autumn stage. There were significant correlation between the stem hight and base diameter, the leaf numbers and growing condition of the two plants in autumn-winter test. There were also significant correlation among the morphology indexes of the two plants.3. In the summer-autumn stage, the concentration of chlorophyl(a+b) in the leaves of Pterocarya stenoptera and Salix babylonica firstly decreased and then increased and then decreased, while the concentration of MDA and soluble protein firstly increased and then decreased, the POD activities increased significantly over moderate degree of eutrophic water. The concentration of chlorophyl(a+b) and POD activities was increasing along with the eutrophication degree of the eutrophicated water, whereas the relation between the content of soluble protein and the concentration of eutrophic water, the relation between the concentration of MDA in Pterocarya stenoptera's leaves and the concentration of eutrophic water were not obvious. There were significant negative correlations between POD activities and MDA concentration in Pterocarya stenoptera's leaves, and there were very significant correlations between soluble protein concentration and MDA concentration in Salix babylonica's leaves.4. In the two stages, the total biomass of Pterocarya stenoptera and Salix babylonica was 1.64～5.15 times as much as that in the initial stages, relative growth rate was 0.0083-0.0187d-1. By the end of the two stages A/U of Pterocarya stenoptera and Salix babylonica was 2.81-3.74 and 1.55～4.10. In the autumn-winter stage, the total biomass, relative growth rate and A/U of Pterocarya stenoptera was biggest in groupC2, while the total biomass and relative growth rate of Salix babylonica was biggest in groupCl, the A/U of Salix babylonica was biggest in groupC4. In the summer-autumn stage, the total biomass and relative growth rate of Pterocarya stenoptera and Salix babylonica was biggest in groupC3, while the A/U was biggest in groupC4.5. By the end of the autumn-winter stage, the concentration of TN, TP in various part of Pterocarya stenoptera has not changed, and the concentration of TN, TP in various part of Salix babylonica showed a sequence of:roots>stems>leaves. The content of TN, TP in the stem was biggest in various part of Pterocarya stenoptera and Salix babylonica. By the end of the summer-autumn stage, the concentration of TN, TP in various part of Pterocarya stenoptera and Salix babylonica showed a sequence of:leaves>roots>stems. In the two stages, the concentration of TN, TP in various part of Pterocarya stenoptera was lower than that in Salix babylonica, whereas the content of TN, TP in various part of Pterocarya stenoptera was higher than that in Salix babylonica. In the two stages, the TN, TP concentration and content in various part of Pterocarya stenoptera and Salix babylonica in each group increased along with the concentration of eutrophic water.6. By the end of autumn-winter stage, the percentage of TN and TP uptake amount of Pterocarya stenoptera, Salix babylonica in total removal amount of constructed wetland in groupC2-C4 was 52.47%-71.98%,33.51%-49.11% and 17.57%～25.22%,6.20%～14.72%, and their relations with concentration of the eutrophic water was not obvious. By the end of summer-autumn stage, the percentage of TN and TP uptake amount of Pterocarya stenoptera, Salix babylonica in total removal amount of constructed wetland of groupC2-C4 was 30.39%～84.75%,23.05%～95.41% and 16.74%～70.26%,24.30%～58.20%, and they had negative correlations with concentration of the eutrophic water.In the two stages, the percentage of TN, TP uptake amount of Pterocarya stenoptera in total removal amount of constructed wetland was 1.47～2.92 times as much as that of Salix babylonica. |
PDF Full Text Request