|Other Abstract||Restoration of aquatic vegetation was one of the most important steps of ecosystem rehabilitation in polluted waterbodies. But the restoration of aquatic vegetation is difficult because the growth of the aquatic vegetation was effected by many factors, such as, water temperature, light, pH, nutrient, dissolve oxygen and environmental pollutants. Submerged macrophytes physiologically depended more on water environment than other aquatic plant, so they were more sensitive to the change of water quality. Therefore, submerged macrophyte, Hydrilla verticillata (L.f) Royle, was chosen to study its physio-ecological response to different environmental factors. Major results are as follows:
1.Under the treatments of increased NH4+-N, NO3--N, PO43--P concentrations, NH4+-N & PO43--P and NO3--N & PO43--P combination, the physiological character of the activities of POD and CAT and SOD and content of chlorophyll and biomass and productivity of H. verticillata had some relevant changes. The activities of POD and CAT had slight changes when [NH4+-N] is 1.25mg/L. The treatment of 5 mg/L [NH4+-N] partially restrained the growth of H. verticillata. The treatment of 5+0.75 mg/L [NH4+-N + PO43--P] decreased the activity of SOD, and the treatment of 20+3 mg/L [NH4+-N + PO43--P] eliminated SOD. The toxic symptoms of the plant were more serious caused by [NH4+-N & PO43--P] combination than by NH4+-N. Under the treatments of NO3--N, PO43--P and NO3--N & PO43--P combination, photosynthesis of H. verticillata was only restrained at the high concentration, indicating that the toxicities caused by these treatments were not serious.
2.The maximum tolerable concentration of SDBS and STPP of H. verticillata was 8mg/L, 256 mg/L , indicting that Sodium Dodecylbenzene-Sulfonate (SDBS) damaged SOD more than Sodium Tripo1yphosphate (STPP). POD was sensitive to STPP but CAT was insensitive. Under the combination of SDBS and STPP, the tolerable SDBS and STPP concentration of H. verticillata were 32 mg/L and 64 mg/L, respectively, indicating that STPP decreased the negative effect of SDBS in H. verticillata.
Under 16h/8h day-night cycle, the shoot lengths and the number of branches of H. verticillata increased in 2 and 8 mg/L SDBS, and the stem lengths and its biomass decreased in 32 mg/L SDBS. Under 12h/12h day-night cycle, the stem lengths and the biomass of stems and the sum of branches of H. verticillata increased in 2 mg/L SDBS, and the growths of H. verticillata were restricted in 8 and 32 mg/L SDBS. Under 8h/16h day-night cycle, all concentration of SDBS restrained the growth of the length and biomass. Also the ability of restraining function was gradually increasing with the increase of SDBS stress concentration.
3.Under full-sun, the removal effect of H. verticillata to NO3--N, NH4+-N, TP, IP, CODCr were markedly, and under 30% and 15% full-sun, the removal effects of H. verticillata for Total-N, NO2--N, BOD5 were significant. Numbers of branches and the root biomass increased with increasing light intensities, while elongation and the shoot biomass decreased.
4. The neutral water environment and the alkalescent water environment and the relative short light time all helped to the growth of H. verticillata.
When H. verticillata was dealt with the different heavy metal, the stem lengths and the biomass of stems and the sum of branches of H. verticillata had obvious increase in 50 mg/L Pb, and the growths of H. verticillata were restricted in 100 mg/L. the stem lengths and the sum of roots of H. verticillata had obvious increase in 0.5 mg/L Hg, and the growths of H. verticillata were restricted beyond 1 mg/L. H. verticillata was sensitive to the stress of Cr and the lower concentration stress, 5 mg/L, can restrict the growth.
5. The POD isoenzyme’s strip and shade of H. verticillata were changed under the different concentration of SDBS, STPP and SDBS & STPP combined and NH4+-N, NO3--N, PO43--P, NH4+-N & PO43--P combined and NO3--N & PO43--P combined in a certain extent.
6. H. verticillata had obvious sorption to pentachlorophenol (PCP) at beginning of the experiment (24h), but the ability of sorption was reducing with extend of time (96h).|