發(fā)布時(shí)間：2018-01-12 19:05

  本文關(guān)鍵詞：腐殖酸活性組分含量和比例對紫色潮土中鉛的形態(tài)轉(zhuǎn)化及生物有效性的影響　出處：《西南大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鉛 紫色潮土 腐殖酸 形態(tài) 生物有效性

【摘要】：鉛是對人體健康危害較大的重金屬元素,尤其對兒童的身體發(fā)育和神經(jīng)系統(tǒng)影響顯著。土壤鉛的環(huán)境危害作用不僅與其總鉛含量有關(guān),更大程度上取決于其在土壤中的賦存形態(tài)及分布狀況。腐殖酸廣泛分布于自然環(huán)境中,因其復(fù)雜的結(jié)構(gòu)和較高的反應(yīng)活性而在影響土壤重金屬形態(tài)與生物活性的眾多因素中扮演著特殊而又十分重要的角色,施用含腐殖酸類物質(zhì)的有機(jī)物料常作為土壤重金屬污染修復(fù)措施之一,但有機(jī)物料(如腐殖酸、有機(jī)肥等)中活性組分組成因其物料來源、腐熟化條件的不同而異,施用含腐殖質(zhì)物質(zhì)等有機(jī)物料對土壤重金屬的活性調(diào)控效果常不一致。有機(jī)物料組成復(fù)雜,其對重金屬活性的影響方向和程度是其各種組分綜合作用的結(jié)果。腐殖酸是有機(jī)物料的主要活性組分,包括胡敏酸(HA)和富里酸(FA),兩者均可與土壤重金屬發(fā)生絡(luò)合(螯合)作用,但高分子量的胡敏酸在土壤中移動(dòng)性差,與土壤礦物結(jié)合緊密,而FA等低分子組分則能保持較高的移動(dòng)性和生物活性,因此,兩者在有機(jī)物料中含量和比例可能是決定其最終效應(yīng)的重要原因。同時(shí),污染土壤中的鉛可通過直接暴露對人群健康產(chǎn)生危害,而降低土壤中重金屬植物有效性的措施,能否同時(shí)降低人體直接接觸土壤的健康風(fēng)險(xiǎn)還有待考究。為此,本研究通過室內(nèi)模擬實(shí)驗(yàn),探討腐殖酸的兩大活性組分含量和比例對鉛在土壤中的吸附解吸特性、形態(tài)轉(zhuǎn)化和化學(xué)可提取性的影響,并結(jié)合體外胃腸模擬試驗(yàn)方法研究測定不同腐殖酸狀態(tài)土壤中鉛的生物有效性,闡明不同種類和比例的腐殖酸影響下土壤鉛生物有效性與其吸附解吸和形態(tài)轉(zhuǎn)化之間的關(guān)系,為深入了解腐殖酸環(huán)境化學(xué)行為及利用含腐殖酸有機(jī)物料修復(fù)土壤鉛污染提供科學(xué)依據(jù)。主要研究結(jié)果如下:腐殖酸(HAs)對土壤鉛的吸附解吸特性的影響受其種類、含量和比例的制約。HA能有效促進(jìn)土壤鉛的吸附,顯著增加土壤鉛的平衡吸附量和吸附速率常數(shù),而FA和HA/FA為5/5的HAs則顯著降低了土壤鉛的吸附能力,平衡吸附量未達(dá)到對照(CK)的50%,土壤鉛吸附速率常數(shù)較CK分別降低了18.92%、29.12%。供試土壤對鉛具有強(qiáng)力吸附能力,添加外源鉛濃度最高為1500mg·L-1時(shí),CK及HA處理土壤還未達(dá)到飽和吸附,而FA及HA/FA為5/5的HAs處理土壤鉛均達(dá)吸附平衡狀態(tài),最大吸附量分布在21.44~36.52 mg·g-1,且隨著FA含量或HA/FA比值的增加,土壤鉛的吸附能力均有所提升。鉛在所有腐殖酸處理后的紫色潮土中的解吸率均不超過15%,但與CK相比,HA處理土壤所吸附的鉛難以解吸,而FA處理土壤則降低了鉛的吸附強(qiáng)度,解吸率較CK增加了1.60~14.12個(gè)百分點(diǎn)。在等量HAs(1%C)條件下,當(dāng)HA/FA≥7/3時(shí)HAs能降低鉛的解吸率,而當(dāng)HA/FA≤5/5時(shí)HAs對土壤鉛的解吸能力顯著增加,促進(jìn)了土壤鉛的解吸,增加了土壤鉛釋放的環(huán)境風(fēng)險(xiǎn)。不同活性組分含量及比例的腐殖酸對土壤鉛形態(tài)分配的作用方向和影響程度差異較大。外源鉛進(jìn)入土壤后,隨培養(yǎng)時(shí)間的延長,添加HA的土壤交換態(tài)鉛的降低速率高于FA。轉(zhuǎn)化達(dá)平衡后,HA添加量為0.5%C、1%C、3%C、5%C的土壤碳酸鹽結(jié)合態(tài)鉛百分含量較CK分別降低了5.79、9.95、15.79、20.37個(gè)百分點(diǎn),不同F(xiàn)A添加量的土壤交換態(tài)和碳酸鹽結(jié)合態(tài)鉛百分含量較CK分別增加了3.31~17.01和0.07~10.03個(gè)百分點(diǎn)。在相同HAs(1%C)用量水平下,HAs對于土壤鉛的鈍化或活化作用受HA/FA比的制約,當(dāng)HA/FA比≥7/3時(shí),土壤有效態(tài)鉛含量均低于CK,而當(dāng)HA/FA比≤5/5時(shí),其對鉛的表觀效應(yīng)與FA相似,增加了土壤鉛的有效性。HA主要通過促進(jìn)碳酸鹽結(jié)合態(tài)鉛向鐵錳氧化態(tài)、有機(jī)結(jié)合態(tài)和殘?jiān)鼞B(tài)鉛的轉(zhuǎn)化而對土壤中鉛具有鈍化作用,FA則通過降低鐵錳氧化態(tài)、有機(jī)結(jié)合態(tài)和殘?jiān)鼞B(tài)鉛的分配比例,大幅增加交換態(tài)和碳酸鹽結(jié)合態(tài)鉛的分配比例而活化土壤中的鉛,且他們的鈍化或活化作用隨著HAs用量的增加而逐漸增強(qiáng)。HAs對土壤鉛化學(xué)提取有效性的影響與鉛的賦存形態(tài)具有密切聯(lián)系,回歸分析表明,紫色潮土化學(xué)可提取態(tài)有效鉛含量以交換態(tài)鉛和碳酸鹽結(jié)合態(tài)鉛對其貢獻(xiàn)最大。通過鉛的抑制或活化百分率可知,HA對土壤鉛的鈍化作用與其用量呈顯著正相關(guān)關(guān)系:y1=5.12 x+8.31(P0.05,n=4);FA對土壤鉛的活化作用存在臨界點(diǎn),當(dāng)FA用量≥1%C時(shí),土壤鉛活化百分率急劇增加10.01%,出現(xiàn)明顯上升拐點(diǎn),土壤鉛的生物有效性和毒性顯著增加。不同HAs處理土壤的鉛在胃階段的生物可給性均遠(yuǎn)遠(yuǎn)高于腸階段的生物可給性,而HAs不同活性組分含量及比例對鉛的生物可給性的影響較大。PBET方法中,不同碳含量HA處理土壤鉛在胃腸階段的生物可給性均低于CK,降幅分別為0.36%~1.54%、0.99%~3.85%,而不同F(xiàn)A碳含量影響下的土壤鉛在胃階段的生物可給性較CK明顯增加,且增幅為2.20%~6.02%,當(dāng)FA≥1%C時(shí)的土壤鉛在腸階段的生物可給性顯著增加,較CK增加了5.01%~12.87%,且胃腸階段的生物可給性均與FA碳含量呈正相關(guān)關(guān)系。在等量HAs(1%C)條件下,當(dāng)HA/FA≥7/3時(shí)鉛在胃腸階段的生物可給性均低于CK,HA/FA≤5/5時(shí)均高于CK。SBET方法中,HA均降低了鉛的生物可給性,降低幅度與HA添加量呈正相關(guān)關(guān)系,FA均增加了鉛的生物可給性,當(dāng)FA≥1%C時(shí)增幅更加明顯。HAs對土壤鉛的生物可給性與鉛的賦存形態(tài)呈顯著相關(guān)性(P0.01),PBET(y1)和SBET(y2)兩種方法在胃階段的鉛生物可給性受交換態(tài)(x1)、碳酸鹽結(jié)合態(tài)(x2)、鐵錳氧化態(tài)(x3)和有機(jī)結(jié)合態(tài)鉛(x4)的影響,關(guān)系式分別為y1=-7.827+0.968x1+1.001x2+0.574x3+0.764x4(R2=0.996),y2=-1.439+1.287x1+1.046x2+0.656x3+1.160x4(R2=0.994);而鉛在腸階段的生物可給性主要受交換態(tài)和碳酸鹽結(jié)合態(tài)兩種形態(tài)鉛調(diào)控(R2=0.904)。因此在選取有機(jī)肥等有機(jī)物料治理土壤鉛污染時(shí)應(yīng)考慮采用HA或HA組分占比較高的修復(fù)材料,以降低土壤活性態(tài)鉛的含量,有效抑制土壤鉛對植物或人體的毒害作用,而采用化學(xué)提取態(tài)判定鉛在人體內(nèi)部生物有效性時(shí)需考慮胃部強(qiáng)酸性的情況。
[Abstract]:Lead is a heavy metal, the harm to human health, especially the effect on the physical development and the nervous system of children. Significant environmental hazards of soil lead to not only the total lead content, to a large extent depends on the speciation in soil and distribution. Humic acid is widely distributed in the natural environment, because of the reaction the complex structure and high activity and the main influence factors of soil heavy metals and biological activity plays a special and important role in the application of organic materials containing humic acids used as one of the heavy metal contaminated soil remediation measures, but the organic materials (such as humic acid, organic fertilizer and so on) in the active component. Because of its material sources, different curing condition of rot, activity regulation effect of humic substances containing organic materials in the soil heavy metals are often inconsistent. Organic materials. The complex, its influence on the activity of heavy metal in the direction and extent of its various components. The comprehensive effect of humic acid is the main active group of organic materials, including Hu Min acid (HA) and fulvic acid (FA), both with the soil heavy metal complex (chelate), but humic acid with high molecular weight in the soil poor mobility, combined with soil minerals, FA and low molecular components can maintain mobility and high biological activity, therefore, both in the content of organic materials and the proportion may be an important cause of its final decision effect. At the same time, the pollution of lead in soil by direct exposure to cause harm to people health, and reduce the availability of heavy metal in the soil plant measures can also reduce health risks in direct contact with the human body soil remains to be determined. Therefore, this research through laboratory simulation experiment, humic acid of two active components The content and proportion of adsorption and desorption characteristics of Pb in soil, chemical speciation and extractable effects, combined with the determination of bioavailability of lead in soil of different humic acid condition in vitro gastrointestinal simulation test method, the relationship between the effect of humic acid to clarify the different types and proportion of the soil lead bioavailability and adsorption desorption and transformation, to understand the environmental chemical behavior of humic acid and provide scientific basis for the utilization of humic acid containing organic materials to repair the soil lead pollution. The main results are as follows: humic acid (HAs) effect on adsorption and desorption of lead in soil by their types, restricting the content and proportion of.HA can effectively promote the adsorption of Pb in soil the significant increase in adsorption capacity and adsorption rate constants of lead in soil, while FA and HA/FA 5/5 HAs significantly reduced the adsorption capacity of lead in soil, the equilibrium adsorption amount has not reached Control (CK) 50%, soil Pb adsorption rate constant CK decreased 18.92%, 29.12%. soil has strong adsorption ability of Pb, Pb added the highest concentration of 1500mg, L-1, CK and HA in soil has not yet reached the saturation adsorption, while the FA and HA/FA 5/5 HAs of soil lead as the adsorption equilibrium, the maximum adsorption capacity distribution in 21.44~36.52 mg g-1, and with the increase of FA content or HA/FA ratio, soil Pb adsorption capacity increased. Desorption of lead in all humic acid treated in purple soil were less than 15%, but compared with the CK, HA adsorption in soils the lead desorption, and FA soil decreased the adsorption strength of lead, the desorption rate increased by 1.60~14.12 percentage points higher than CK. In the same amount of HAs (1%C) conditions, when HA/FA is larger than 7/3 HAs can reduce the lead desorption rate, desorption capacity when HA/FA = 5/5 HAs on soil lead Increased significantly, promote the desorption of lead in soil, increase the environmental risk of soil Pb release. Different active component content and the ratio of humic acid on soil Pb speciation distribution influence direction and degree of difference. Pb in soil, with prolonged incubation time, add HA of soil exchangeable lead reduce the conversion rate is higher than the FA. reached equilibrium after HA was added to 0.5%C, 1%C, 3%C, 5%C soil carbonate bound Pb content compared with CK were decreased by 5.79,9.95,15.79,20.37 percentage points, different FA contents of soil exchangeable and carbonate bound Pb content of CK were increased 3.31~17.01 and 0.07~10.03 percentage points HAs (1%C). At the same dosage level, HAs for passivation of lead in soil or activation by HA/FA than the control, when the HA/FA ratio is greater than or equal to 7/3, the lead content of soil is lower than that of CK, while HA/ FA is less than 5/5, the To lead the apparent effect similar to FA,.HA increase the effectiveness of lead in soil mainly through promoting carbonates lead to iron and manganese oxides, conversion of organic bound and residual lead and passivation effect of lead in soil by reducing FA, Fe Mn oxide, organic bound and distribution proportion the residual lead, a substantial increase in the exchangeable and carbonate distribution proportion of Pb and Pb in soil activation, and their activation or inactivation increased with the amount of HAs increased.HAs on lead extraction chemical soil influencing the validity and lead deposit form has close connection with the regression analysis showed that the purple soil chemical extractable Pb content in effective exchangeable Pb and carbonate bound Pb. The greatest contribution to lead through inhibition or activation of the percentage, HA passivation effect on soil Pb and its amount was positive shut off Department: y1=5.12 x+8.31 (P0.05, n=4); the role of FA on the activation of soil lead the existence of critical point, when the content of FA is not less than 1%C, the percentage of activated soil lead a sharp increase in 10.01%, significantly increased the inflection point, the bioavailability and toxicity of lead in soil increased significantly. HAs treatment in different biological soil lead in the stomach of the to the stage are far higher than the intestinal bioavailability, and HAs of different active component content and the ratio of the bioaccessibility of Pb is greatly influenced by the.PBET method, different carbon content in the HA soil lead in the GI phase bioaccessibility were lower than CK, the reduction rate of 0.36%~1.54% and 0.99%~3.85%, respectively. The biological effects of different carbon content of Pb in soil FA under the stage to stomach than CK increased significantly, and the increase of 2.20%~6.02%, when the biological soil lead FA is not less than 1%C in the intestinal phase availability increased significantly, increased by 5.01%~12.87% compared with CK, and gastrointestinal stage Bioaccessibility and FA carbon content were positively correlated. In the same amount of HAs (1%C) conditions, when HA/FA is not less than 7/3 in the stage of gastrointestinal lead bioaccessibility were lower than that of CK method was higher than that of CK.SBET HA/FA is less than or equal to 5/5, HA decreased the bioaccessibility of Pb, and decreased the amount of HA was positively correlated, FA increased the bioaccessibility of Pb, when FA is not less than 1%C was more obvious in.HAs on soil lead bioavailability and speciation of Pb was significantly correlated (P0.01), PBET (Y1) and SBET (Y2) lead bio two methods in gastric stage the availability of exchangeable, carbonate bound (x1) (x2), Fe Mn oxide (x3) and organic bound Pb (x4) effect relationship were y1=-7.827+0.968x1+1.001x2+0.574x3+0.764x4 (R2=0.996), y2=-1.439+1.287x1+1.046x2+0.656x3+1.160x4 (R2=0.994); and the biological lead in the intestinal phase is mainly affected by the availability of exchangeable And carbonate bound two forms of lead control (R2=0.904). So in the selection of organic fertilizer and other organic material treatment of lead contaminated soil should be considered when using HA or HA components for repair materials relatively high, in order to reduce the content of soil active Pb, effectively inhibit soil Pb toxicity to plants or human body, and the judge should consider the state chemical extraction lead strong acid in the stomach inside the human body bioavailability.

【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X53

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