本文選題：水稻　切入點：氣態(tài)單質(zhì)汞　出處：《華東師范大學》2017年碩士論文

【摘要】：濕地是汞的重要富集場所,其還原性底質(zhì)會促進氣態(tài)單質(zhì)汞的產(chǎn)生。本研究以水稻這一典型的濕地植物為例,研究其根系及通氣組織是否也能成為根際氣態(tài)汞向大氣運輸?shù)耐ǖ?并探究其機制和影響因素。論文通過設(shè)計密閉分室培養(yǎng)裝置將水稻根部與地上部分隔開,對水稻根部進行汞蒸氣暴露,并通過氣體吸收劑吸收由葉片揮發(fā)出的氣態(tài)汞。論文還通過鐵膜誘導和營養(yǎng)元素脅迫培養(yǎng)方法,研究闡明鐵膜對汞揮發(fā)的調(diào)控作用和機理,及營養(yǎng)元素缺乏對水稻吸收和揮發(fā)氣態(tài)單質(zhì)汞的影響。研究結(jié)果表明:(1)水稻可以從根系吸收氣態(tài)單質(zhì)汞并向地上組織遷移,其中根系的汞含量與水稻根孔隙度呈顯著負相關(guān),并呈二次擬合(R=0.8309,P0.01);而水稻地上部汞遷移量與水稻根表面積和根體積均呈線性正相關(guān)(R=0.896,P0.01;R=0.871,P0.01)。研究還發(fā)現(xiàn)由根系吸收的汞最終可通過水稻葉片揮發(fā)進入大氣,葉片汞的揮發(fā)量隨著葉片面積的增加呈線性增加(R=0.897,P0.01),單位葉面積汞揮發(fā)量與水稻蒸騰作用強度呈線性顯著正相關(guān)(R=0.73,P0.01)。(2)不同基因型之間,根表鐵膜的生成量具有顯著性差異(P0.05),在同樣的培養(yǎng)條件下,秈稻的根系鐵膜生成量明顯高于粳稻。水稻根表鐵膜可吸附氣態(tài)單質(zhì)汞。秈稻根表鐵膜對氣態(tài)單質(zhì)汞的吸附量均明顯高于粳稻(P0.05),其吸附量與水稻的根表鐵膜生成量呈顯著正相關(guān)(R=0.701,P0.01)。水稻根表鐵膜可顯著減少水稻根系對氣態(tài)單質(zhì)汞的吸收,并降低水稻地上部汞的遷移和水稻葉片汞的揮發(fā)。(3)在氮、磷營養(yǎng)缺乏脅迫下,水稻生長受到不同的影響。其中缺氮處理抑制了水稻根與葉的生長。與正常組進行對比,我們發(fā)現(xiàn)氮脅迫的三種水稻的根表面積、根長、根體積和根干重均有下降,而水稻的根孔隙度則顯著增加(P0.05),且其葉面積和地上部干重也隨著氮濃度的降低而減少。我們發(fā)現(xiàn)氮脅迫降低了水稻對氣態(tài)單質(zhì)汞的吸收、轉(zhuǎn)運和揮發(fā)。與之相反,缺磷則促進了水稻根和葉的生長,且磷脅迫使水稻根系汞含量和地上部汞轉(zhuǎn)運量先降低后增加。在磷脅迫的條件下,三種基因型水稻葉片的汞揮發(fā)量略有差異。水稻Ⅱ優(yōu)1259和武運粳21號隨著磷濃度的降低,葉片汞揮發(fā)量也隨之減少,且與對照組呈顯著性差異(P0.05),而粳稻屜優(yōu)267水稻葉片汞揮發(fā)量只是略微減少,并不與對照組呈顯著性差異(P0.05)。以上研究結(jié)果證明了水稻根系不僅能吸收氣態(tài)單質(zhì)汞,并且能將汞從根部轉(zhuǎn)運到地上部,再通過葉片的氣孔釋放到空氣中。研究結(jié)果為進一步揭示濕地生態(tài)系統(tǒng)中汞的遷移及調(diào)控機理提供了科學依據(jù)。
[Abstract]:Wetland is an important enrichment site of mercury, and its reductive sediment can promote the production of gaseous elemental mercury.In this study, rice, a typical wetland plant, was used as an example to study whether the root system and aerated tissue could also be used as a pathway for the transport of gaseous mercury to the atmosphere, and to explore its mechanism and influencing factors.In this paper, a closed chamber culture device was designed to separate the roots of rice from the aboveground parts, and to expose the roots to mercury vapor, and to absorb the gaseous mercury volatilized from the leaves by gas absorbent.The regulation and mechanism of Fe film on mercury volatilization and the effect of nutrient element deficiency on the absorption and volatilization of elemental mercury in rice were also studied by the methods of iron film induction and nutrient element stress culture.The results showed that rice could absorb gaseous elemental mercury from the root system and migrate to the aboveground tissue, and the root mercury content was negatively correlated with the root porosity.There was a linear positive correlation between the aboveground mercury transport and root surface area and root volume.The study also found that mercury absorbed by the root system can eventually volatilize into the atmosphere through rice leaves.The leaf mercury volatilization increased linearly with the increase of leaf area. There was a significant linear correlation between the Hg volatilization per leaf area and the transpiration intensity of rice.There was significant difference in the amount of iron film produced in root surface. Under the same culture conditions, the iron film production in the root of indica rice was significantly higher than that in japonica rice.Rice root surface iron film can adsorb gaseous elemental mercury.The adsorption capacity of gas elemental mercury in indica rice root surface iron film was significantly higher than that in japonica rice (P0.05A), and there was a significant positive correlation between the adsorption amount and the root surface iron film formation.Iron film on the root surface of rice could significantly reduce the absorption of gaseous elemental mercury by the root system, and decrease the migration of mercury in the aboveground part of rice and the volatilization of mercury in the leaves of rice.) under the stress of nitrogen and phosphorus deficiency, the growth of rice was affected by different factors.Nitrogen deficiency inhibited the growth of rice roots and leaves.Compared with the normal group, we found that the root surface area, root length, root volume and root dry weight of the three kinds of rice under nitrogen stress decreased.The root porosity of rice increased significantly, and the leaf area and dry weight of shoot decreased with the decrease of nitrogen concentration.We found that nitrogen stress reduced the absorption, transport and volatilization of gaseous elemental mercury in rice.On the contrary, P deficiency promoted the growth of roots and leaves of rice, and phosphorus stress decreased the content of mercury in root and then increased the amount of mercury transport in shoot.Under phosphorus stress, there was a slight difference in mercury volatilization in leaves of three genotypes of rice.With the decrease of phosphorus concentration in rice 鈪，

本文編號：1725390