【摘要】：土壤砷污染是全球尤其是東南亞和中國非常突出且亟需解決的環(huán)境問題。自從砷超富集植物——蜈蚣草(Pteris vittata L.)發(fā)現(xiàn)以來,一直是國內(nèi)外學(xué)者研究的熱點(diǎn)。深入理解蜈蚣草體內(nèi)砷代謝和富集機(jī)制是有效利用植物修復(fù)技術(shù)治理砷污染土壤的關(guān)鍵。在長期的自然進(jìn)化過程中,蜈蚣草逐漸分化出不同生態(tài)型,已有研究結(jié)果顯示:不同生態(tài)型蜈蚣草在砷吸收、富集方面存在顯著差異。然而,不同生態(tài)型蜈蚣草砷吸收差異特征及其機(jī)理尚不清楚。本文通過野外調(diào)查、室內(nèi)植物水培、土培和人工模擬等方法從吸收動(dòng)力學(xué)、根系分泌物和砷酸還原酶3個(gè)方面探究不同生態(tài)型蜈蚣草砷吸收差異機(jī)理,初步得出如下結(jié)論:(1)在磷處理?xiàng)l件下,污染生態(tài)型及非污染生態(tài)型蜈蚣草根系對As(V)的吸收均符合米氏吸收方程。在磷處理?xiàng)l件下,非污染生態(tài)型具有較低的Km值,對As(V)的親和力較污染生態(tài)型強(qiáng),其α值(α=Vmax/Km,反映根系對離子的實(shí)際吸收能力,α值越大,吸收能力越強(qiáng),反之則越弱)也高于污染生態(tài)型。隨著磷濃度升高,污染生態(tài)型和非污染生態(tài)型對As(V)的親和力均減小,實(shí)際As(V)吸收速率降低。(2)As(III)處理下,無論是污染生態(tài)型還是非污染生態(tài)型蜈蚣草對砷的吸收效率均比As(V)處理時(shí)高,但是砷從根部向地上部轉(zhuǎn)移的能力弱于As(V)處理。(3)不同砷形態(tài)[As(V)和As(III)]對蜈蚣草根系分泌物的數(shù)量和種類無顯著性影響。4種生態(tài)型蜈蚣草根系分泌的有機(jī)酸中主要以草酸為主,非污染生態(tài)型與污染生態(tài)型相比分泌更多的草酸。(4)非污染生態(tài)型蜈蚣草根系分泌物對土壤砷的活化能力優(yōu)于污染生態(tài)型,室內(nèi)模擬實(shí)驗(yàn)進(jìn)一步表明:根系分泌物中的草酸對土壤砷的活化發(fā)揮顯著作用。(5)不同生態(tài)型蜈蚣草地上部中砷形態(tài)分布存在明顯差異:非污染生態(tài)型地上部As(III)的濃度顯著高于污染生態(tài)型,其地上部中As(III)所占的比例也明顯高于污染生態(tài)型。(6)不同生態(tài)型蜈蚣草之間根系砷酸還原酶活性存在顯著差異,非污染生態(tài)型與污染生態(tài)型相比具有更高的的砷酸還原酶活性。
[Abstract]:Arsenic pollution in soil is an important environmental problem in the world, especially in Southeast Asia and China. Since the arsenic Super-enrichment Plant, Pteris vittata (Pteris vittata L.) Since its discovery, scholars at home and abroad have been the focus of research. Understanding the mechanism of arsenic metabolism and enrichment in Pteris vittata is the key to effectively use phytoremediation technology to control arsenic contaminated soil. In the long-term natural evolution process, Pteris vittata gradually differentiated into different ecotypes. The results showed that there were significant differences in arsenic absorption and enrichment between different ecotypes of Pteris vittata. However, the characteristics and mechanism of arsenic absorption in different ecotypes of Pteris vittata are unclear. In this paper, through field investigation, indoor plant hydroculture, soil culture and artificial simulation, the mechanism of arsenic absorption in different ecotypes of Pteris vittata was explored from three aspects: absorption kinetics, root exudates and arsenate reductase. The main conclusions are as follows: (1) under phosphorus treatment, the absorption of As (V) by the roots of Pteris vittata (Pteris vittata) was in accordance with the Michelson equation. Under phosphorus treatment, the non-polluted ecotypes have lower Km value and stronger affinity to As (V) than polluted ecotypes. The 偽 value (偽 = Vmax/Km,) reflects the actual absorption ability of the roots, and the higher the 偽 value, the stronger the absorption ability. On the contrary, the weaker) is also higher than the pollution ecotype. With the increase of phosphorus concentration, the affinity of polluted ecotypes and non-polluted ecotypes to As (V) decreased, and the actual As (V) absorption rate decreased. (2) under the treatment of) As (III), The arsenic absorption efficiency of Pteris vittata, whether polluted ecotype or non-polluted ecotype, was higher than that of As (V) treatment. However, the ability of arsenic transfer from root to shoot was weaker than that of As (V) treatment. (3) different forms of arsenic [As (V) and As (III)] had no significant effect on the number and species of root exudates of Pteris vittata. Oxalic acid was the main organic acid secreted by the roots of four ecotypes of Pteris vittata. Compared with the polluted ecotypes, the non-polluted ecotypes secreted more oxalic acid. (4) the root exudates of Pteris vittata, a non-polluted ecotype, could activate arsenic in soil more effectively than the polluted ecotypes. The results of laboratory simulation further showed that oxalic acid in root exudates played a significant role in the activation of arsenic in soil. (5) there were significant differences in the distribution of arsenic forms in the upper part of different ecotypes of centipede grassland: the above ground As (III) of non-polluted ecotypes. The concentration was significantly higher than the pollution ecotype, The percentage of As (III) in shoot was also significantly higher than that in polluted ecotype. (6) there were significant differences in arsenate reductase activity among different ecotypes of Pteris vittata, and non-polluted ecotypes had higher arsenate reductase activity than polluted ecotypes.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X173;X53

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