【作者】 唐超；

【导师】 李辉信；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 硕士

【摘要】 近年来,蚓粪和水溶性有机物(DOM)在污染土壤上的应用得到了较多关注。一方面,蚓粪在促进作物生长、抑制病原菌活性、改善土壤肥力和促进重金属向地上部迁移等方面具有重要作用；另一方面,DOM是陆地生态系统中最为活跃的有机碳库,也是土壤圈层与相关圈层进行物质与能量交换的重要表现形式,它是土壤中有机和无机污染物的载体、重金属的有机配体,对受重金属污染土壤的修复起重要作用。为探索蚓粪DOM在生态系统中的作用,验证蚓粪DOM与提高重金属污染土壤植物修复效率的关联,促进植物吸收重金属的机理,本文设置了一系列的水培试验,以蚓粪(赤子爱胜蚓作用过的牛粪)和牛粪提取的DOM为添加物,主要研究：(1)蚓粪DOM对黑麦草生长的影响；(2)蚓粪DOM对黑麦草吸收重金属Cu的影响；(3)黑麦草对络合Cu的吸收效果。主要结果如下：1、蚓粪DOM对黑麦草生长的影响研究表明：两种DOM均显著增加了黑麦草地上部和地下部的生物量以及根系的长度、表面积、体积和根尖数(P<0.05,下同)；且对根系的促进作用显著大于茎叶；各项指标都以添加20 g蚓粪DOM的处理为最大,这说明来自蚓粪的DOM对植物的影响显著优于牛粪DOM,并且高浓度的DOM效果显著优于低浓度的DOM。2、蚓粪DOM对黑麦草吸收重金属Cu的影响对植株进行不同Cu浓度处理,Cu的浓度梯度为0、5、10 mg／L。结果表明：随着Cu浓度的增加,黑麦草地上部、地下部干重逐渐下降,两种DOM在5、10 mg／L Cu2+浓度处理下,均显著增加了黑麦草地上部、地下部的生物量,但加DOM的各处理间无显著差异；随着Cu浓度的增加,黑麦草根系的长度、表面积、体积、根尖数也逐渐下降,5、10 mg／L的Cu2+浓度处理下,两种DOM也促进了根系的长度、表面积、体积、根尖数的增长,高浓度的蚓粪DOM(20E)效果尤为显著；两种DOM都降低了黑麦草地下部Cu浓度,促进了Cu从地下部向地上部运输,显著增加了地上部Cu积累量,在5、10 mg／L的Cu2+浓度处理下,添加高浓度蚓粪DOM(20E),地上部Cu积累量均达最大值,说明来自蚓粪的DOM对植物的影响优于牛粪DOM,并且高浓度的DOM效果优于低浓度的DOM。3、黑麦草对络合Cu的吸收效果设置水培试验,添加不同比例的络合Cu处理,结果表明：未加Cu处理的地上部、地下部生物量显著高于加Cu的各处理,Cu2+与络合Cu相比,Cu2+对植株生物量的抑制作用更明显；添加Cu抑制了黑麦草根系的生长,加入络合Cu比例越高,对黑麦草根系的长度、表面积、体积、根尖数的影响越小,如处理D的根系各项指标显著高于A、B、C；络合Cu与Cu2+相比,黑麦草更容易吸收Cu2+,如A、B、C处理地下部Cu浓度显著高于D、E、F,络合Cu在植株体内更容易被运输,加Cu各处理地上部Cu积累量没有显著差异。上述三项结果表明,蚓粪DOM促进了植物的生长,降低了植株对Cu的吸收,促进了Cu从植株地下部向地上部的运输,植株更容易吸收Cu2+,络合Cu在植株体内更容易被运输。更多还原

【Abstract】 Recently, many researches have been focused on the effects of earthworm casts and Dissolved Organic Matter (DOM) on the phytoremediation of heavy metal contaminated soil. One hand, earthworm casts have an unignored function in the soil-plant ecosystem, such as promote the growth of plant, restrain the pathogen of soil, improve the soil nutrition, accelerate the translocation of heavy metal from roots to shoots of plant; on the other hand, DOM, an important active organic carbon pool in terrestrial ecosystem, and the manifestation of exchange material and energy between pedosphere and other sphere. DOM is the organic and inorganic pollutants’carrier in soils, and heavy metals’organic ligand. It plays a vital role in the rehabilitation of heavy metals’pollution.We had designed a series of hydroponics experiments to study the effects of DOM extracted from earthworm (Eisenia foetida) casts in the ecosystem, and the potential role in modifying the efficiency of phytoremediation. Mainly focused on:(1) Effects of DOM extracted from earthworm casts on the ryegrass growth;(2) Effects of DOM extracted from earthworm casts on the absorption of heavy metal by ryegrass; (3) the effect of absorption of complexation-Cu by ryegrass. Results shows:1 Effects of DOM extracted from earthworm casts on the ryegrass growthThe results show that DOM extracted from earthworm casts significantly increased the biomass of shoots and roots of ryegrass, and length, surface area, volume, and number of tips of the root system (P<0.05); the growth of the root was promoted more significantly than the shoot; each indicator reached the maximum quantity under the treatment of 20 g earthworm casts DOM, which explained that the earthworm casts DOM significantly promote the ryegrass growth than cattle manure DOM. In addition, the high concentration of DOM had better effects on the ryegrass growth than the low concentration of DOM. Overall, it could be inferred that the earthworm casts DOM significantly promote the growth of plants.2 Effects of DOM extracted from earthworm casts on the absorption of heavy metal by ryegrass This study based on an artificial copper with 3 pollution level-0,5,10 mg/L.Results show that the biomass of shoots and roots of ryegrass, and the length, surface area, volume, and number of tips of the root system reduced under the increasing of copper concentration; DOM extracted from earthworm casts and cattle manure significantly increased biomass of shoots and roots under the treatments of 5,10mg/L copper concentration(P<0.05),but there is no significant difference between them; the treatment of 20g earthworm casts DOM has the best effects; DOM reduced the copper concentration in root, earthworm casts DOM promoted the copper transportation from root to shoot, significantly increased the copper accumulation of shoots, and the indicator reached the maximum quantity under the treatment of 20 g earthworm casts DOM, which explained that the earthworm casts DOM had better effects than cattle manure DOM. In addition, the high concentration of DOM had better effects than the low concentration of DOM.3 The effect of the absorption of complexation-Cu by ryegrassThis study under hydroponics condition based on different proportion of the complexation-copper.Results shows that Cu inhibit the growth of ryegrass, for example the treatment of F significantly increased the biomass of roots and shoots of ryegrass(P<0.05); Cu2+has the worse effects on the growth of ryegrass than complexation-Cu, the high proportion of complexation-Cu has the less harmful on length, surface area, volume, and number of tips of the root system, for example the indictor of root system, treatment of D significantly higher than the A,B,C; ryegrass absorbed more Cu2+ than Complexation-Cu, for example the Cu concentration of root, treatment of A,B,C significantly higher than D,E,F; furthermore, Complexation-Cu transportation easier than Cu2+, the high proportion of complexation-Cu has the less harmful to plants.更多还原