【作者】 童昌华；

【导师】 杨肖娥； 濮培民；

【作者基本信息】 浙江大学 ， 植物营养学， 2004， 硕士

【摘要】 水体污染已成为全球水资源短缺的一个重要因素。水体富营养化是水体污染中的最为普遍的现象，也是国内外水环境污染治理难题。水体富营养化发生机理和修复原理及技术的研究是国内外土壤植物营养、环境生态学科研究的前沿和热点。在富营养化水体修复的各种手段中，植物修复(生物修复的一种)是一种耗能低、效果好的新技术，已经引起国内外学术界的高度重视。本研究通过野外考察与调查研究，分析了太湖流域中莫干湖水库水体富营养化发生的主要原因，并提出综合治理的对策和方法。采用人工模拟自然的方法，比较研究了水葫芦(Eichhornnia crassipes)金鱼藻(Ceratophyllum demersum L.)、狐尾藻(Myriophyllum verticillatum L.)、微齿(禾叶)眼子菜(Potamogeton maackianus A．Bennett)、马来眼子菜(Potamgeton malaianus Miq.)、苦草(Vallisneria spiralis L.))等水生植物对富营养化水体修复作用的差异及机理。重点研究了低温条件下水生植物净化富营养化水体的效果：营养元素在土壤-植物-水系统中的变化和转移；水生植物在控制湖泊底泥营养盐释放中的作用；水生植物在低温或高温季节的生存问题和季节性变化；植物修复体系建立的相关技术等。取得的主要研究结果和结论包括： 1．通过对莫干湖流域野外调查与分析研究，明确了导致莫干湖水库水体富营养化的主要原因，其中农业非点源污染、水库流域工业污染和生活污染是引起水库富营养化的关键因素。工业污染可以采取调整结构、转移污染工厂等措施来解决，而生活污染和农业非点源污染则必须依靠生态工程技术的方法来治理。生态工程包括复合生态体系的建立、退耕还林、河道生态系统的恢复、物理生态工程等。物理生态工程在流域的应用以在丰水期的效果最好，两个观测点的总氮、总磷含量都显著低于上一年。入湖口六洞桥和莫干湖库区2003年4月的总氮含量分别为2002年4月的86.8％和48.9％，总磷含量分别为上年的31.8％和53.3％。这与流域的水环境有关，枯水期由于河道缺水，生态环境恶劣，不利于物理生态工程的发挥。 2．低温季节6种水生植物对总氮(TN)、硝态氮都有一定的去除效果，但植物种类之间差异较大。硝态氮的去除效果比总氮更好，而氨态氮的去除效果又不如硝态氮和总氮，30天时不同处理之间分别为对照的30.1％-86.9％。水生植物在短期内能有效降低富营养化水体中COD的含量，处理10天后分别只有对照的17.6％-32.3％，但在整个过程中与对照没有明显差别，表明水生植物在低温季节对降低COD的作用不明显。水生植物还能有效提高水体的透明度，改善水体观感效果。说明在冬季利用水生植物净化富营养化水体也能起到较好作用，关键是要筛选有效的植物。本研究表明，狐尾藻、微齿眼子菜和金鱼藻在冬季能生长，可以作为富营养化水体修复的优选植物。 3.水生植物能有效抑制底泥中氮的释放。在富营养化水体中，由于底泥中氮的释放，使水中的总氮(TN)浓度不断上升，尽管底泥物理隔离(包被)能暂时减缓底泥中氮的释放，但在20天后仍然达到了释放高峰，甚至高于底泥裸露处理。底泥隔离处理的水中硝态氮含量大大高于底泥裸露处理。但是无论是污水底泥还是清水底泥，种养水生植物对氮的释放的具有明显抑制作用;而沉水植物狐尾藻的效果则明显大于漂浮植物凤眼莲。这些结果表明，单靠物理措施(薄膜包被)并不能有效控制底泥氮等向水中释放，而水生植物尤其是沉水植物能有效吸收和控制底泥营养盐的释放，降低水中营养盐浓度。 4.水生植物不仅能很好地控制水中的氮、磷等营养，还能影响底泥中的其他营养元素，包括一些重金属元素，从而改善水质。研究结果表明，4种水生植物对底泥中4种重金属(Cd、Cu、Ni、Pb)的作用都表现出相同的趋势，即狐尾藻处理的底泥中4种重金属的含量均高于对照，金鱼藻、微齿眼子菜2种处理的底泥中4种重金属含量均低于对照，而凤眼莲的处理则与对照没有显著差异。水生植物由于吸收了重金属元素而使体内的含量增加，其中对锅和铅的吸收较明显。除了狐尾藻茎叶部以外，其他部位的铜和镍的含量都高于修复之前的含量。表明水生植物对这些重金属具有较好的吸收作用。因此，利用水生植物吸收、转化污染水体中的营养盐以及有毒重金属具有较大的优势。 5.用水生植物净化富营养化水体，其净化效果受许多因素的影响，如水生植物的用量、组合，水生植物种类之间如何搭配，群落之间的相互影响，以及一些物理措施对底泥的影响。以狐尾藻为例，虽然狐尾藻对污染水体有明显的修复效果，但是随着植物用量的增加，修复效果并不是不断提高的，而且用量过多，还会导致自身所产生的污染。一般以覆盖水体表面而不能重叠为合适。同时，不同的植物种群对水体的影响也存在差异，在考虑植物之间搭配时，应从自然群落的角度着手。水花生(Alternantheraphiloxeroides)是狐尾藻种群中的常见的挺水(或漂浮)植物，因此将这2种植物组合在一起可以起到互补的作用。水生植物一方面对水体的营养有吸收效果，同时对藻类的生长起到抑制作用。但水生植物过多，会引起水体中有机物增多，特别是在低温换季过程中，植物?更多还原

【Abstract】 Water pollution is a main factor causing short water supply, and water eutrophication is a worldwide phenomenon, become the most difficulty in environmental remediation for water pollution. Understanding the mechanisms of eutrophication of water body and develop feasible remediation technology is the frontier and hot research field in plant nutrition and environmental ecology. As a new, cheap and ecological sound technology, phytoremediation of eutrophicated water system attract many scientists all over the world . The objectives of this study were : to analyze the factors causing eutrophication in Mu Ge Hu resevoir of Thai Lake catchment, investigate on the strategies for controlling and remediating water eutrophication in Mu Ge Hu resevoir, compare the effectiveness of different aquatic plant species on remediating eutrofication water body under simulated conditions. The aquatic plants species used included: Eichhornnia crassipes, Ceratophyllum demersum L., Myriophyllum verticillatum L, Potamogeton maackianus A.Bennett, Potamgeton malaianus Miq., Vallisneria spiralis L The major comparisons and observations made were: 1) The efficiency of growing aquatic plants on decontaminating the eutrophicated in low temperature season; 2) The changes and transfer of nutrients in the soil-plant-water system; 3) Effects of growing aquatic plants on the regulation of nutrient release from the lake sediment; 4) The seasonal change of aquatic plants in low or high temperature season; 5) The key techniques for phytoremediation on the eutrophicated water sysytem. The main results obtained are summarized as follows:1. By survey and investigation on the causes of eutrophication in Mu Ge Hu reservoir, it was found that the degradation of eco-system of the catchment was the main cause of eutrophication in the rswervoir. The major factors causing eutrophication of Mu Ge Hu Reservoir included N and P non-point pollution from agricultural practices, industry pollution and daily life pollution. The industry pollution may be controlled by changing their structureand move out the pollution township-industries. The pollution caused by daily life and agriculture must be controlled by ecological engineering technology, including setting up the healthy eco-system, recovering the forest and the river eco-system, as well as introducing physical-ecological engineering on the water system. It was observed that the best time for the physical-ecological engineering to apply in the catchment was during the abundant water period. After application of physical-ecological engineering, the contents of nitrogen and phosphorus at the 2 stations were lower than that before application. The content of total nitrogen in the entrance and the center of the reservoir decreased to 86.3 % and 48.9% , and the phosphorus content decreased to 31.8%t and 53.5 % of that before application, separately.2. In low temperature season, all the 6 aquatic plant species showed effective ability in decreasing total nitrogen, nitrate nitrogen and phosphorus in the eutrophicated water body. Different plant species had different effectiveness. The values of COD decreased in short period (10 days) but recovered afterwards. Growing aquatic plants in the eutrophicated water body increased water transparency and improved the water quality in the low temperature season. These results indicated that aquatic plants can decontaminate the polluted water. Selecting suitable plant species is critical. In this ’study, Myriophyllum verticillatum L. ,Potamogeton maackianus A.Bennett ,Ceratophyllum demersum L.) can survive in winter, which could be firstly chosen for phytoremediation engineering.3. The aquatic plants could also control nitrogen release from the sediment. In the polluted water system, the nitrogen release from the sediment could resulted in the increase of total nitrogen in water body. Sediment rapped by plastic sheet could stop nitrogen release in short period, but could not in longer time period, and N release peaked after the sediment was covered for 20 days. Either with更多还原