本文關(guān)鍵詞：外源砷在土壤中的老化及其對土壤微生物影響的機(jī)理研究　出處：《中國農(nóng)業(yè)大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 砷 老化 半機(jī)理模型 細(xì)菌 古菌

【摘要】：砷是自然界中普遍存在的有毒類金屬元素,也是我國土壤中含量超標(biāo)較嚴(yán)重的有毒元素之一。外源砷進(jìn)入土壤后會隨著與土壤膠體相互作用時間的延長出現(xiàn)有效性或毒性降低的現(xiàn)象,即發(fā)生老化過程,但目前對外源砷在土壤中的老化過程、影響因素、老化機(jī)理及老化過程中土壤微生物群落變化等方面的研究較少。本研究選取了紅壤區(qū)幾種母質(zhì)發(fā)育的土壤和不同區(qū)域典型土壤,通過外源添加砷酸鈉溶液(五價砷)室內(nèi)模擬培養(yǎng)試驗,系統(tǒng)研究了外源砷進(jìn)入土壤后有效態(tài)砷及各結(jié)合態(tài)砷含量隨老化時間的變化特征,并分析了影響砷老化進(jìn)程的關(guān)鍵因子。以此為基礎(chǔ),初步構(gòu)建了外源砷在土壤中老化的半機(jī)理模型,并利用野外采集的砷污染土壤進(jìn)行了驗證,明確了外源砷老化過程中起主導(dǎo)作用的老化機(jī)理。同時,應(yīng)用高通量測序技術(shù)系統(tǒng)研究了上述土壤中理化性質(zhì)差異較大的兩種土壤中(黃壤和紫色砂頁巖發(fā)育的土壤)細(xì)菌和古菌群落隨砷老化時間的變化,初步探討了土壤中細(xì)菌和古菌在砷脅迫下的群落適應(yīng)機(jī)制。本研究結(jié)果,可為正確評價外源砷進(jìn)入土壤后對生態(tài)系統(tǒng)的風(fēng)險及砷污染農(nóng)田安全利用等提供理論支撐。主要研究結(jié)果如下：1.通過對外源砷在紅壤區(qū)幾種母質(zhì)發(fā)育土壤中老化過程的研究發(fā)現(xiàn),培養(yǎng)期間紫色砂頁巖發(fā)育的土壤(RS2)中砷的有效性顯著高于其它母質(zhì)發(fā)育的土壤。該結(jié)果意味著在湖南等砷污染較嚴(yán)重的亞熱帶地區(qū),該母質(zhì)發(fā)育土壤中砷對農(nóng)田生態(tài)系統(tǒng)的危害和風(fēng)險均較高。2.對外源砷在不同區(qū)域典型土壤中老化過程的研究發(fā)現(xiàn),外源砷進(jìn)入潮土(FS)和灌漠土(IDS1)后,其有效性始終較高(11.64-71.16%)且老化過程達(dá)到近似平衡的時間較長；而在黃壤(YS)和紅壤(RS1)中則有效性較低(0.74-31%),老化達(dá)到近似平衡的時間較短,表明外源砷在不同類型土壤中的老化過程存在差異。逐步回歸結(jié)果表明,土壤黏粒含量是決定外源砷老化達(dá)到近似平衡所需時間的關(guān)鍵因子。外源砷在不同類型土壤中老化達(dá)到近似平衡的時間排序為：褐土(CS)潮土(FS)灌漠土(IDS1)棕壤(BNS2)紅壤(RS1)紫色土(PS)黃壤(YS)磚紅壤(LS1)。3.準(zhǔn)二級動力學(xué)方程能較好地擬合外源砷在土壤中有效性的變化過程(R2=0.939-0.999,P0.01)。土壤pH值和鐵、鋁、錳等氧化物的含量是影響外源砷有效性、控制砷老化速率以及老化達(dá)到平衡時土壤有效砷含量的關(guān)鍵因素。進(jìn)一步分析發(fā)現(xiàn),富含鐵鋁氧化物的紅壤中鋁氧化物對老化進(jìn)程的影響要高于鐵氧化物,可能是由于鋁氧化物與砷結(jié)合可以形成結(jié)構(gòu)更為穩(wěn)定的雙齒雙核配合物。4.砷與土壤結(jié)合形態(tài)的改變直接影響其在土壤中的有效性。研究表明,非專性吸附態(tài)砷(F1)和專性吸附態(tài)砷(F2)是構(gòu)成土壤中有效態(tài)砷的主要組成部分。隨外源砷老化時間的延長,進(jìn)入土壤中的砷最終向弱結(jié)晶度的鐵鋁水合氧化物結(jié)合態(tài)砷(F3)、結(jié)合度好鐵鋁水合氧化物結(jié)合態(tài)砷(F4)和殘渣態(tài)砷(F5)轉(zhuǎn)化。5.結(jié)合外源砷在土壤中表面沉淀／成核、微孔擴(kuò)散和有機(jī)質(zhì)包裹等老化過程以及土壤性質(zhì)的共同影響,首次構(gòu)建了外源砷在土壤中老化的半機(jī)理模型。明確了表面沉淀/成核在外源砷老化過程中起主導(dǎo)作用,確定了不同環(huán)境條件下H2AsO4-和HAsO42-兩種離子對表面沉淀／成核作用的相對重要性。6.外源砷脅迫不同時期對黃壤(YS)和紫色砂頁巖發(fā)育的土壤(RS2)中細(xì)菌和古菌群落產(chǎn)生的影響不同。細(xì)菌中放線菌門(Actinobacteria)、變形菌門(Proteobacteria)和綠彎菌門(Chloroflexi)等相對豐度較高的優(yōu)勢種群受到砷脅迫后群落豐度變化顯著,但其在兩種土壤中的變化規(guī)律明顯不同；而古菌中的優(yōu)勢種群表現(xiàn)出較高的耐砷性和穩(wěn)定性,表明土壤中的細(xì)菌和古菌在砷脅迫下可能具有不同的群落適應(yīng)機(jī)制。
[Abstract]:Arsenic is a toxic metal elements exist in nature, is also our country one of the toxic elements in the soil content exceed the standard seriously. Exogenous arsenic in soil with prolonged effectiveness in reducing toxicity or phenomena and soil colloid interaction time, the aging process, but the external source of arsenic in soil the aging process, influence factors, and the aging mechanism in the process of soil microbial community changes and other aspects of the research. This study selected several soils in red soil area of soil in different regions and typical soil by adding sodium arsenate (arsenic) indoor simulation experiment system to study the effects of arsenic in soil available the combination of arsenic and arsenic content changes with aging time, and analyzes the key factors affecting the arsenic aging process. On this basis, initially built in exogenous arsenic Half the soil aging mechanism model, and verified by the field collection of arsenic contaminated soil, the exogenous arsenic aging mechanism in the process of leading role. At the same time, the application of high-throughput sequencing technology system to study the soil physicochemical properties between two kinds of soil (yellow soil and purple sand shale development soil) bacteria and archaea in the aging changes with time as, discussed in the community under arsenic stress of bacteria and archaea in soil adaptation mechanisms. The results of this study can be used to evaluate exogenous arsenic in soil to provide theoretical support for the correct and safe use of agricultural risk of arsenic pollution on the ecological system of the main research. The results are as follows: 1. through the foreign source of arsenic in several soils on red soil aging process in soil found during the cultivation of Purple Sandy Shale soil (RS2) is effective in significantly high arsenic In other soils soil. This result means that the arsenic pollution is more serious in Hunan and other subtropical regions, the development of parent materials of arsenic in soil on farmland ecosystem hazard and risk of.2. were higher in different regions of typical exogenous arsenic in soil aging process found that exogenous arsenic into soil (FS) and irrigated desert soil (IDS1), has high effectiveness (11.64-71.16%) and the aging process to approximate balance of a longer time; and (YS) in the Yellow Soil and red soil (RS1) in lower effectiveness (0.74-31%), aging reached approximate balance for a short time, indicate the presence of exogenous arsenic in aging process in different types of soil differences. Stepwise regression results showed that the soil clay content is the key factor to determine the exogenous arsenic aging time required to approximate balance. Exogenous arsenic aging reached equilibrium time was approximate sorting in different types of soils: Cinnamon ( CS) (FS) soil irrigated desert soil (IDS1) (BNS2) red brown purple soil (RS1) (PS) (YS) yellow latosol (LS1).3. quasi two order kinetic equation can better fit the exogenous arsenic in soil changes in the effectiveness of the process (R2=0.939-0.999, P0.01). The pH value of soil and iron, aluminum, manganese oxide content is the effect of exogenous arsenic effectively, control the rate of aging and aging arsenic balance available arsenic content of soil factors. Further analysis showed that the red soil is rich in iron and aluminum oxides and aluminum oxides in the influence of the aging process is higher than that of iron oxide, aluminum oxide and arsenic may be due to the structure can combine to form more stable complexes with bidentate binuclear.4. arsenic combined with the soil morphological changes directly affect its effectiveness in the soil. The study shows that the non specifically adsorbed arsenic (F1) and specifically adsorbed arsenic (F2) constitute a major group of Available Arsenic in soil Part. With the prolonging of aging time of exogenous arsenic in soil, arsenic in iron and aluminum oxides to weak crystallinity bound arsenic (F3), the combination of good iron hydrated aluminum oxide bound arsenic (F4) and residual arsenic (F5) combined with exogenous.5. transformation of arsenic in soil and surface precipitation the nucleation, micropore diffusion and organic package aging process as well as the influence of soil properties, first constructed a semi mechanistic model exogenous arsenic in soil aging. The surface precipitation / nucleation plays a dominant role in exogenous arsenic during aging process were determined under different environmental conditions of H2AsO4- and HAsO42- two kinds of ions on the relative the importance of.6. exogenous arsenic surface precipitation / nucleation stress at different stages on yellow soil (YS) and the development of purple sand shale soil (RS2) effect in bacteria and archaea in different bacteria. Actinobacteria (Actinobacteria), Proteobacteria ( Proteobacteria) and Chloroflexi (Chloroflexi) dominant species relative abundance affected by changes in abundance after arsenic stress significantly, but in the two kinds of soil changes were significantly different; and the advantages of the archaeal populations showed arsenic tolerance and high stability, showed that the bacteria in soil and archaea in may under arsenic stress have different mechanisms to adapt to the community.

【學(xué)位授予單位】：中國農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S151.9

【引證文獻(xiàn)】

相關(guān)期刊論文 前1條

1 高雪;曾希柏;白玲玉;尼瑪扎西;蘇世鳴;王亞男;吳翠霞;;有機(jī)酸對As(Ⅴ)在土壤中老化的影響[J];農(nóng)業(yè)環(huán)境科學(xué)學(xué)報;2017年08期

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本文編號：1377587