【作者】 刘佩；

【导师】 赵仕林；

【作者基本信息】 四川师范大学 ， 环境科学， 2008， 硕士

【摘要】 随着稀土在农业和材料工业上的广泛应用,导致越来越多的稀土元素进入到土壤和水体生态环境之中,而对于稀土元素对环境的影响,已有的工作对稀土农用技术、稀土生理生态效应及其对环境的影响等方面的研究较为活跃,但如何科学合理地使用稀土,充分发挥其生理生态效应,尽可能降低其对环境和人类造成的负面影响方面的系统性研究,工作仍十分薄弱,关于稀土导致水体富营养化的问题和对水体的复合污染效应,稀土与藻类光合作用的关系,尚未见国内外文献报道。根据理论稀土既然能有效促进农作物的生长,从而推测大量的稀土元素进入到水体环境中,对于水生植物的生长也应该有促进作用,这个作用将直接影响到水体富营养化程度。本着理论联系实际的原则和在前期工作的基础上,本论文通过实验室方法模拟了静态的水体环境,以EDTA试剂作为有机配体,在静态供试水体中分别添加了的不同浓度的络合态单一稀土和混合稀土,定期测定水体中N、P、DO、COD含量及藻类叶绿素a水平、藻类光合速率等表征,研究了络合态稀土对富营养化水体中浮萍藻类增长的影响。结果表明,在本实验中,添加较低浓度的络合态单一稀土和混合稀土(0.15mg/L～0.50mg/L)能显著促进红浮萍生长和实验水体的富营养化,但随着浓度的进一步升高(1.0mg/L),则对红浮萍生长和实验水体的富营养化有轻微的抑制作用。同时把实验水体中的络合态稀土和无机稀土离子进行了比较分析,证明了在相同的中低浓度条件下,添加EDTA配合的络合态稀土对水体富营养化的促进作用要大于无机稀土离子,而在较高浓度,对富营养化的抑制作用要低于无机稀土离子。同时随着四川省稀土工业的发展和稀土微肥的广泛施用,越来越多的稀土进入到四川省各大水系之中。三峡水库和长江上游的水电开发,也使得水体富营养化的发生机率大大增加。因此本论文对四川省外源性稀土和N、P进入各大水系的情况的进行了调查,初步测定了四川省境内各大水系的可溶性稀土和N、P含量,调查发现四川稀土矿区河流溶解态稀土含量要高于施用稀土微肥农业区河流的溶解态稀土含量,含量介于10.5～173.6μg/L(夏季)和37.6～287.3μg/L(冬季)之间;N、P含量则介于2.730～9.380mg/L、0.135～0.328mg/L(夏季)和3.673～14.347mg/L、0.026～0.118mg/L(冬季)之间,分别都已进入能促使藻类生长和促进水体富营养化的值域区间,由此可能带来四川主要河流水体富营养化发生机率的提高,对四川境内梯级水电站和长江三峡水库的运作安全带来巨大的潜在威胁。更多还原

【Abstract】 With rare earth trace fertilizer in agriculture broad applications, a growing number of rare earth elements into the agriculture and water ecosystems, Ree after entry to the impact of the work has been rare earth agro-technology, and rare earth biological and ecological effects of the environmental impact study in a more active, but how scientific and rational use of rare earth, give full play to their physiological ecological effects on the environment and minimize its negative effects of human systematic study very weak, only little information is vague on a number of studies into the rare earth trace fertilizer soil after crops internal systems and the distribution of agricultural ecosystems.Due to a large number of rare earth elements enter the water environment, in accordance with the theory of speculation that it can promote the growth of crops, so the elements also have the same effect on the growth of the algae ,which should be a catalyst of the eutrophication problem, In the principle of linking theory with reality, in the preparatory work on the basis of this paper, EDTA as an organic ligand ,a water environment was static simulated in laboratory, in which different concentrations of rare earth complex state single and mixed rare earth were added ,and the N, P, DO, COD content and chlorophyll-a levels of algae, algae photosynthetic rate method were analyzed regularly to study the effect of the complex rare earth elements on the growth of algae and duckweed in eutrophic water .The results showed that the addition of low concentrations of rare earth complex state single and mixed rare earth (0.15 mg / L, 0.25mg / L, 0.50mg / L) can significantly promote the growth of red duckweed and the eutrophication of the water , and with the further increase the concentration (1.0 mg / L), there is a slight inhibition to to red duckweed growth and eutrophication of water. At the same time, a comparative analysis between the complex state of rare earth elements and rare earth elements Inorganic ions proved that in low concentration, the complex state rare earth with EDTA has the greater promotion effect on the eutrophication of the water that the rare earth inorganic ions , and in higher concentrations, the inhibition is not obvious.At the same time, with the development of a wide range of rare earth fertilizer application and the improvement of the rare earth industry in Sichuan Province, more and more rare earth enter the major river systems of the Sichuan. Therefore the condition of exogenous rare earth entering the major river systems in Sichuan were studied in this paper. the soluble rare earth content of Sichuan Province of the major river systems was tested and the result showed that soluble rare earth content of rare-earth mining area rivers in Sichuan is higher than that of application of rare earth agricultural fertilizer rivers, the content lies between 10.5-173.6μg/L (summer) and 37.6-287.3μg/L (winter),which was able to promote the growth of algae and the eutrophication of the water. Because of the upper reaches where Sichuan regions is, the eutrophication potential hazards of Three Gorges Reservoir should not be ignored.更多还原