【作者】 欧阳坤；

【导师】 廖柏寒；

【作者基本信息】 中南林业科技大学 ， 环境科学， 2007， 硕士

【摘要】 为了探索沉水植物逆境生理及其净化能力,本文以沉水植物轮叶黑藻(Hydrilla varticillata)、穗花狐尾藻(Myriophyllum spicatum L.)和金鱼藻(Ceratophyllaceae)为材料,研究了不同水质条件下沉水植物的净化作用及其生理生化反应,表面活性剂LAS对沉水植物生长的影响及生理生化反应,沉水植物的光合作用对光照强度以及DIC/pH的响应。为探索湖泊富营养化进程中水生植被退化与恢复机理,提供了研究资料,具有一定的参考价值。主要结论如下：(1)轮叶黑藻对生活污水具有一定的净化和适应能力,但对水质不同的污水其处理能力不一样,对居民楼废水其中CODcr和总氮的去除率分别为81.51%和71.36%,在污染水体的影响下轮叶黑藻的SOD和CAT活性变化均经历了先升高后降低的过程,分别在第3天和第10天达到最大值,而后急剧下降。说明过高的CODcr或氨氮浓度对轮叶黑藻是一种逆境胁迫,可抑制其生长甚至导致植物死亡。轮叶黑藻对污水中污染物质虽有一定耐性,但其耐性会随时间的延长而变弱。(2)阴离子表面活性剂LAS对沉水植物轮叶黑藻和穗花狐尾藻的损伤程度与浓度有关。在实验浓度范围内LAS<1 mg·L-1时,对穗花狐尾藻和轮叶黑藻的生理活动影响不大；当LAS为(1.0-5.0 mg·L-1)时,LAS开始抑制生长,影响了植物正常生理活动。当LAS超过5.0 mg·L-1时,轮叶黑藻保护酶防御系统崩溃,植物死亡,而在LAS大于20 mg·L-1时穗花狐尾藻也会出现这个现象。结果表明,轮叶黑藻和穗花狐尾藻对LAS具有一定的耐性,穗花狐尾藻对LAS浓度的耐受性要强于轮叶黑藻。(3)LAS对沉水植物穗花狐尾藻和轮叶黑藻的损伤程度与胁迫时间有关。穗花狐尾藻(LAS<10.0 mg·L-1时)和轮叶黑藻(LAS<1.0 mg·L-1时),SOD、CAT和POD活性在前48th h没有明显变化；随后穗花狐尾藻的上述指标在72th h急剧增加,而轮叶黑藻则在96th h急剧增加。这表明,该条件下在对应时间点LAS开始抑制这两种沉水植物的生长,影响了植物正常生长。穗花狐尾藻对LAS胁迫时间的耐受性要强于轮叶黑藻,在LAS浓度较高水域进行沉水植被恢复时穗花狐尾藻是首选。(4)显微观察显示,轮叶黑藻在LAS为5.0 mg·L-1时,叶绿体形状不规则且聚集成团；10.0 mg·L-1时叶绿体逐渐分解减少,叶片大面积脱绿,呈细胞壁分离,胞质环流停止,气道消失；20.0 mg·L-1时细胞壁分离,叶片脱绿死亡。轮叶黑藻在为5.0mg·L-1的LAS胁迫10小时后光合作用速率仅为对照的58%,对氮、磷营养盐的吸收速率仅为对照的61%。结果表明,LAS通过穿透细胞壁,使蛋白质变性,胞质环流停止,损伤叶绿体、气道等的正常活动,从而使沉水植物的光合作用和氮、磷代谢受阻,这是导致轮叶黑藻等沉水植物衰弱死亡的主要原因之一(5)本次的实验结果表明,LAS达到5.0 mg·L-1以上时,才会对沉水植物轮叶黑藻产生明显的胁迫效应和生理损伤。而目前中国富营养化湖泊均未达到该水平,这说明LAS不是引起富营养化水体中沉水植被退化的主要因素,而可能只是影响高等水生植物生长和演替的间接性因素。(6)通过研究轮叶黑藻、穗花狐尾藻和金鱼藻光合作用对光照强度的响应,比较了它们的光合能力及光合特征。从三种沉水植物光补偿点、光饱和点及强光下光合作用受抑制的表现特点来看,不同光照强度下供试材料的光合速率高低排列各不相同。当光照强度在10-890μmol.m-2.s-1之间时,光合作用速率金鱼藻>轮叶黑藻>穗花狐尾藻,轮叶黑藻和金鱼藻对光的需求最高。三种沉水植物的光合作用都表现出强光抑制现象,结果显示在不同深度的水层,有不同的竞争优势种,轮叶黑藻和金鱼藻在上层有较强的竞争能力；穗花狐尾藻对光的需求最低,在水深水域有更强的适应性。(7)通过研究在不同pH值和不同浓度溶解性无机碳(DIC)下轮叶黑藻、穗花狐尾藻和金鱼藻光合作用特征,发现DIC/pH对三种沉水植物的影响有所不同。三种沉水植物,当环境中pH值从9降低到6时,对外源无机碳的表观光合作用亲合力都降低；同时发现穗花狐尾藻比轮叶黑藻和金鱼藻对pH值变化的耐受力更高；但当DIC浓度达到饱和时,金鱼藻的最大光合作用速率要远远大于穗花狐尾藻和轮叶黑藻的最大光合作用速率。这一个特性为在富营养治理中及其沉水植被恢复中的植物的选择上提供了参考。更多还原

【Abstract】 This dissertation studied the decontamination abilities, the physiological and biochemical reactions of Hydrilla varticillata, Myriophyllum spicatum L, and Ceratophyllaceae under different water conditions, effects of LAS on their growth, physiological and biochemical reactions, photosynthesis responding to pH and DIC. It explored not only the stress physiology and the decontamination abilities of submerged aquatic plants, but also the degeneration and restoration mechanism of aquatic macrophytes, which had the important scientific significance. Major conclusions were described as follows:1. The results showed that Hydrilla verticillata could clear sewage effectively, and the removal rates for CODcr and TN were 81.51% and 71.36% respectively. It also indicated that Hydrilla verticillata had the abilities of decontaminating and the adaptation to sewage, but they were varied when were planted into different laboratory conditions. When Hydrilla verticillata was put into wastewater, the changes of SOD activities and CAT activities had a similar trend that declined after increasing, and the highest activities appeared at the 3rd day and the 10th day. The result showed that high COD and excessive concentration of NH4+-N would stress the growth of Hydrilla verticillata and led it to death, and that Hydrilla verticillata could resist and adapt to sewage to a certain extent. However, its endurance ability would gradually become weakened at high concentrations of sewage, eventually resulted in death.2. Damage degree of Myriophyllum spicatum L and Hydrilla verticillata was directly responded to concentrations of LAS. There was little changes of SOD, CAT and POD in the range of experimental LAS concentrations (0-0.5 mg-L"1), which indicated that no apparent effects took place in physiological activities of these aquatic plants. When concentrations of LAS were between 1.0 and 5.0 mg-L-1, activities of SOD, CAT and POD increased, Myriophyllum spicatum L. suffered apparent effects. When LAS was higher than 5.0 mg-L-1, SOD defensing system collapsed, and made macrophytes to death. For Hydrilla verticillata, however, this situation happened when LAS was higher than 20.0 mg-L-1, which indicated that both Myriophyllum spicatum L and Hydrilla verticillata could resist and adapt to sewage, but the latter was more sensitive than the former. 3. The damage degree of Myriophyllum spicatum L and Hydrilla verticillata was directly related to the contacting time of LAS. When concentration of LAS was below 10.0 mg-L-1 for Myriophyllum spicatum L., and below 1.0 mg-L-1 for Hydrilla varticillata, no apparent effects took place on the physiological activities of SOD, CAT and POD in the first 48 h, but it sharply increased at the 72th h to Myriophyllum spicatum L. and at the 96th h to Hydrilla varticillata, which indicated that the tolerance of Myriophyllum spicatum L was higher than that of Hydrilla varticillata, and Myriophyllum spicatum L should be the pioneer species to the restoration of submerged macrophytes for the urban sewage treatment.4. The microscopic observation showed that in LAS polluted environment, chloroplasts of Hydrilla varticillata deformed and assembled when LAS was 5.0 mg-L-1; and when LAS was 10.0 mg-L"1, chloroplasts disintegrated gradually, a lot of leaves lost their color, the cell walls were separated from the others, the circular movement of the plasma stopped, and gas passages disappeared. In LAS (5.0 mg-L-1) polluted environment for ten hours, the photosynthetic rate of Hydrilla varticillata was only 58% of the control group, the rates of uptake N and P was 61% of the control group. The resuls showed that due to LAS penetrated the cell wall of the plants, the protein changed properties, the chloroplasts stopped circular movement, photosynthesis of Hydrilla varticillata and metabolism of nitrogen and phosphorus was inhibited. This was one of main causes of aquatic vegetation degeneration.5. The result also showed that obvious stress and physiological damage of Hydrilla varticillata appeared when concentration of LAS was higher than 5.0 mg-L"1. In China, however, LAS in eutrophication lakes did not reached this level, which indicatd that LAS was not an important role in degradation of aquatic macrophytes caused by eutrophication, but might be an indirect factor that affecting growth and evolution of plants in water environment.6. Through investigating variations of photosynthesis and respiration of the submerged plants including Hydrilla varticillata, Myriophyllum spicatum L. and Ceratophyllacea, this paper compared photosynthetic productivity and photosynthetic characteristics. Different ranks of photosynthetic productivity were observed for different plants at different light intensity. At the light intensity of 10-890μmol-m-1·s-1, the photosynthetic rate of Ceratophyllaceae was the highest, followed by Hydrilla varticillata and Myriophyllum spicatum L. Photosynthesis of 3 submerged plants was inhibited by high-light. Hydrilla varticillata and Ceratophyllaceae adapted to high-light, and were dominant species in surface water layer. Myriophyllum spicatum L had the lowest light requirement and could adapte to a deep water layer.7. The effects of pH and DIC (dissolved inorganic carbon) on photosynthesis of Hydrilla varticillata, Myriophyllum spicatum L and Ceratophyllaceae were investigated. The results showed that photosynthesis of these three plants was different for various pH and DIC conditions. A lower affinity to carbon was observed as pH decresed from 9.0 to 6.0, and Myriophyllum spicatum L was adaptable to extensive pH ranges. When the concentration of DIC reached the saturated level, the highest photosynthesis rate for Ceratophyllaceae was much greater than those for Hydrilla varticillata and Myriophyllum spicatum L.更多还原