本文關(guān)鍵詞：硫酸鹽還原菌（SRB）對長江口典型植被根系重金屬的固定及其生物有效性研究　出處：《華東師范大學》2017年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 金屬 呰草 蘆葦 互花米草 根系沉積物 SRB 納米銀 生物有效性

【摘要】：通常認為,潮灘濕地是河口系統(tǒng)中金屬沉降的一個重要"匯"。河口地區(qū)經(jīng)濟發(fā)達,工業(yè)活動密集,承接有大量的城市污水處理廠排水和工業(yè)廢水等,進入環(huán)境的金屬最后也將匯集到河口環(huán)境中。潮汐作用下,大量金屬進入潮灘濕地環(huán)境。隨著植物生長,金屬富集、轉(zhuǎn)移至植物地上及地下組織。金屬在水相、沉積物及植物的再分配現(xiàn)象,是生物地球化學以及生態(tài)自我修復(fù)的一個重要方面。本文在調(diào)查了 13種金屬濃度在潮灘環(huán)境中時間、空間、物種以及組織間的分布基礎(chǔ)上,結(jié)合不同形態(tài)硫、硫酸鹽還原菌(SRB)在植物根系土及表層沉積物中的分布及其時間、空間分布差異,通過相關(guān)性分析研究了天然環(huán)境下植物根系土中SRB對金屬的固定作用及生物有效性。最后,結(jié)合室內(nèi)短期暴露控制實驗,以硝酸銀、納米銀為例,揭示在SRB的參與下,潮灘植被叇草根部對金屬銀的固定及生物有效性。本文通過對長江口 8個采樣點位植物根系土中金屬濃度分析,發(fā)現(xiàn)植物根系沉積物環(huán)境中1月份總的金屬平均含量最低,4月份最高,金屬Fe、Ti、Mn濃度水平均居于主導,比其它金屬元素含量高2-3個數(shù)量級,金屬Cd含量最低;總體來說,污水處理廠出水口附近的采樣點吳淞口、石洞口以及垃圾填埋場下游廢水排放口附近的采樣點朝陽,金屬含量最高;種間差異表現(xiàn)為,叇草根系沉積物中重金屬的平均含量最低,Cu在蘆葦根系沉積物濃度最高,其它12種重金屬則在互花米草根系沉積物種累積最多;除金屬錳外,植物組織中金屬含量分布為:根莖葉。1月、4月植物不同組織根、莖、葉中累積金屬的濃度水平,均高于7月、10月�？傮w來說,叇草、蘆葦不同組織中金屬元素在石洞口、吳淞口累積較多,互花米草不同組織中金屬含量則是在吳淞口、東海農(nóng)場較高。掃描電鏡表征植物組織中顆粒形態(tài)、大小,結(jié)果顯示三種植物不同組織中吸附的顆粒多種多樣,尺寸、形態(tài)不一,有圓形、四邊形、長條形,顆粒多以多個元素組成的團聚體的形式出現(xiàn),這也說明納米金屬顆粒廣泛存在于河口植被環(huán)境。本文通過對8個采樣點位植物根系沉積物、表層沉積物中不同形態(tài)硫分析,發(fā)現(xiàn)叇草.根系沉積物環(huán)境.中不同形態(tài)硫含量分布為.SO42S酸可揮發(fā)性硫。(AVS);根系沉積物環(huán)境中SRB的豐度分布為根系沉積物表層沉積物;時間分布上,4月份SRB的豐度、不同形態(tài)硫濃度水平均為最高;空間上看,污染較為嚴重的樣點如吳淞口、朝陽農(nóng)場等,其濃度水平相對高于其它點。通過對天然環(huán)境下叇草根系土中重金屬與SRB豐度相關(guān)性分析,結(jié)果表明以APS-a為靶標基因定量SRB豐度時,除Fe外,其余12種重金屬均與SRB豐度顯著相關(guān),以APS-b為靶標基因定量SRB豐度時,只有元素Mn、Pb與SRB豐度顯著相關(guān),這表明SRB在某種程度上可以有效的去除根系沉積物環(huán)境中的金屬。也存在一些樣點如瀏河口、七丫口,SRB豐度越高,SO42-含量越低,這很有可能就是SRB將硫酸鹽還原表現(xiàn)出來的結(jié)果。掃描電鏡表征結(jié)果顯示,因SRB的參與AgN03處理組營養(yǎng)液中形成了金屬硫化物顆粒,顆粒尺寸大小也是隨暴露濃度的升高而增大。不論是Ag+暴露組,還是Ag NPs暴露組,SRB參與均使得營養(yǎng)液中殘留的Ag含量低于其對照組。四個不同實驗暴露處理組,植物組織根、莖中均累積了大量的銀離子,且植物組織中累積的Ag濃度均隨著時間的推移、暴露濃度的增加而增加,其中Ag+處理實驗組,植物組織中累積Ag的濃度水平最高。對Ag+處理組而言,SRB的參與使得植物根、莖中累積的Ag低于其對照組;對AgNPs暴露實驗組而言,SRB的參與使得植物根、莖中累積的Ag高于其對照組。然而,實驗結(jié)果表明SRB的參與否,對叇草組織中Ag的傳輸因子并沒有表現(xiàn)出顯著影響,總體上來說,除Ag+與SRB暴露組外,其余3個暴露實驗組,不同暴露時間的TF值隨著暴露濃度的增加而降低。掃描電鏡表征說明暴露后叇草根、莖中均附著Ag顆粒,但叇草莖的頂端卻沒有發(fā)現(xiàn)顆粒,這可能是因為短期極性暴露,銀顆粒向上傳輸較慢。酶消解暴露后叇草組織,經(jīng)SP-ICP-MS分析,結(jié)果表明植物組織中累積了大量的AgNPs,且顆粒尺寸小于60nm,這與SEM表征結(jié)果一致。綜上所述,就室內(nèi)暴露試驗而言,SRB的參與的確對Ag+暴露實驗組植物根系環(huán)境中的Ag起到了固定作用,而AgNPs實驗組中SRB并沒有對Ag表現(xiàn)出顯著固定作用,這可能與實驗周期、顆粒尺寸大小、根系分泌物等均有關(guān)聯(lián),關(guān)于這點仍需日后繼續(xù)探討。
[Abstract]:Generally, the intertidal wetland is the settlement of metal estuarine systems an important sink. Estuary area developed economy, intensive industrial activities, to undertake a large number of city wastewater and industrial wastewater into the environment, finally will also converge to the metal in estuarine environment. Under the effect of tide, a large number of metal into the tide the beach wetland environment. With the growth of plants, metal enrichment plants transferred to the ground and underground organization. Metal in water, sediments and redistribution of plants, biological geochemistry and ecological restoration is an important aspect. This paper investigated 13 kinds of metal concentrations in the tidal environment in time and space distribution. Based on the species and between organizations, with different forms of sulfur, sulfate reducing bacteria (SRB) distribution and time in root soil and sediments in plants, the differences of spatial distribution, based on correlation analysis study Plant root soil natural environment in SRB of metal fixation and biological effectiveness. Finally, combined with the indoor exposure control experiment, using silver nitrate, silver nanoparticles were revealed in a SRB, the grass root of beach vegetation cloudy sky silver fixing and biological effectiveness. This article through to the Yangtze River in 8 sampling points of metal concentration of plant roots in soil analysis, found in January in the total sediment environment of plant roots average metal content was the lowest, the highest in April, Ti, metal Fe, Mn concentration levels were dominant, than other metal elements with high content of 2-3 orders of magnitude, the metal content of Cd was the lowest; overall, factory outlet near the sampling point of Wusong sewage treatment, landfill and Shidongkou Wastewater Discharge downstream near the mouth of the sampling point in Chaoyang, the highest content of metal; interspecific differences, the average content of root system in cloudy sky of heavy metals in the sediments Low Cu was the highest in the reed root sediment concentration, the other 12 kinds of heavy metals in Spartina alterniflora sediments accumulated most species; except manganese metal, metal content in plant tissue distribution: the rhizome and leaf of.1 month, April plants in different tissues of root, stem, leaf metal accumulation concentration level, higher than in July. October. Overall, cloudy sky grass, reed of different metal elements in the stone cave, Wusong accumulated more metal content of different tissues in Spartina alterniflora is in Wusongkou, Donghai farm is higher. The particle morphology, scanning electron microscopy in plant tissues showed a variety of particle size, adsorption in different tissues of three species of plants in the various dimensions form a circle, square, rectangular, appeared in aggregates of many elements of the form, which also shows that the nano metal particles exist widely in estuarine vegetation environment. Based on the 8 sampling points Plant root sediment, analysis of different forms of sulfur in the surface sediments, found the cloudy sky grass. Root sediment. The sulfur content of different forms of distribution in the volatile sulfur acid..SO42S (AVS); abundance distribution of root sediment SRB for root surface sediment sediment; time distribution, abundance of different forms of SRB in April. Sulfur concentrations were the highest; the space, the more serious pollution samples such as Wu, Chaoyang farm, its concentration level is relatively higher than other points. Through the analysis of the correlation between soil heavy metals and SRB abundance in the natural environment under cloudy sky roots, the results showed that the APS-a target gene quantitative SRB abundance, except Fe the rest, 12 kinds of heavy metals were significantly related with the abundance of SRB, with APS-b as the target gene quantitative SRB abundance, only the elements of Mn, Pb was significantly correlated with the abundance of SRB, suggesting that SRB can be effectively removed in some extent Root sediments of metal in the environment. There are some samples such as Liuhekou, seven Yakou, SRB abundance is higher, the lower the content of SO42-, it is likely that the SRB will show the sulfate reduction results. SEM results show that by participating in the SRB AgN03 group in nutrient solution to form a metal sulfide particle size, but also with the exposure concentration increased. Either Ag+ or Ag exposure group, NPs exposure group, SRB were involved in the Ag content of the residual in the nutrient solution is lower than the control group. Four different experimental exposure group, the tissue of root, stem had accumulated a lot of silver ion the concentration of Ag, and accumulated in plant tissues were with the passage of time, the exposure concentration increased, the treatment of Ag+ experimental group, plant tissue accumulated in the concentration level of Ag. The highest Ag+ treatment group, SRB in the roots and stems The cumulative Ag less than that of the control group; the experimental group exposed to AgNPs, SRB the roots and stems of the accumulation of Ag is higher than that of the control group. However, the experimental results show that SRB is involved in not on the transmission factor of Ag and cloudy sky grass tissue showed no significant effect on the whole, in addition to Ag+ and SRB exposure group, the remaining 3 exposure to the experimental group, different exposure time TF values decreased with increasing exposure concentration. Scanning electron microscopy shows that after exposure to cloudy sky roots, Ag particles were attached to the stem, but the top of the cloudy sky grass stems but did not find the particles, this may be because the polarity of short-term exposure the silver particles to transmit the cloudy sky slowly. Grass tissue enzyme digestion after exposure by SP-ICP-MS analysis, the results showed that plant tissue accumulated a large amount of AgNPs, and the particle size is less than 60NM, which is consistent with the SEM results. In summary, indoor exposure test, the participation of SRB Indeed to Ag+ exposure in experimental group of plant root Ag in the environment play a fixed role, while AgNPs and SRB in the experimental group showed no significant fixed effects on Ag, which may be related to the period of the experiment, particle size, root exudates were associated, on this day to still need.

【學位授予單位】：華東師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X17

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