本文選題：砷　切入點(diǎn)：腐殖酸　出處：《西南大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：砷(As)作為一種典型的類重金屬污染物,其污染狀況日趨嚴(yán)重,As污染及其治理問題已經(jīng)受到廣泛關(guān)注。土壤As的環(huán)境危害不僅與其總量有關(guān),更與其在土壤中的形態(tài)分布密切相關(guān)。腐殖酸(HAs)是有機(jī)肥及土壤有機(jī)質(zhì)的主要成分,其中的胡敏酸(HA)和富里酸(FA)是影響土壤重金屬形態(tài)和活性的關(guān)鍵活性組分,它們可通過復(fù)雜機(jī)制對(duì)土壤As的吸附解吸和形態(tài)轉(zhuǎn)化產(chǎn)生影響,進(jìn)而影響土壤As的生物有效性。土壤重金屬不僅可以通過食物鏈產(chǎn)生危害,還可以通過直接暴露的方式對(duì)人體產(chǎn)生直接危害。本研究通過室內(nèi)模擬實(shí)驗(yàn),從腐殖酸影響土壤As的環(huán)境行為(吸附解吸、形態(tài)轉(zhuǎn)化)著手,探討了腐殖酸活性組分含量和比例(HA/FA比)對(duì)陰離子形態(tài)的As在土壤中生物有效性(植物有效性和動(dòng)物生物可給性)的影響,揭示土壤As生物有效性與As賦存形態(tài)的關(guān)系,為土壤As生物活性調(diào)控及含腐殖酸類有機(jī)物在As污染土壤修復(fù)中的應(yīng)用提供科學(xué)依據(jù)。主要研究結(jié)果如下:腐殖酸對(duì)土壤As的吸附-解吸的影響與其種類、含量和活性組分比例具有密切聯(lián)系。Langmuir方程能很好地?cái)M合HAs影響下土壤對(duì)As的等溫吸附,擬合相關(guān)系數(shù)(R2)在0.971~0.996之間。HAs兩種活性組分中,HA能促進(jìn)土壤對(duì)As的吸附,增加土壤As的最大吸附量,且隨著HA添加量的增加,最大吸附量逐漸增大,當(dāng)HA添加量最高(5%C)時(shí),最大吸附量為2162.29 mg·kg-1,是對(duì)照組(1052.95 mg·kg-1)的2倍;FA則能抑制土壤對(duì)As的吸附,降低土壤As的最大吸附量,FA添加量為5%C時(shí)最低,比對(duì)照降低了31.59%。等碳量HAs(1%)條件下,當(dāng)HA/FA比≥5/5時(shí)增加了土壤As的吸附,HA/FA比≤3/7時(shí)降低了土壤As的吸附。同時(shí)HA處理土壤所吸附的As較對(duì)照更難以解吸,且隨著HA添加量的增加,解吸率逐漸減小;而FA促進(jìn)了土壤As的解吸,增加了土壤As的環(huán)境風(fēng)險(xiǎn);當(dāng)HAs中HA/FA比≤5/5時(shí)促進(jìn)呢土壤As的解吸,而HA/FA比≥7/3時(shí)則對(duì)As的固持作用增強(qiáng),土壤As的解吸率降低。從土壤砷的吸附固定和解吸釋放的角度看,HA增加了土壤對(duì)砷的吸附同時(shí)抑制了土壤砷的釋放,有利于降低土壤砷的危害,而FA則抑制了土壤砷的吸附且促進(jìn)了土壤砷的解吸,增加了土壤砷的環(huán)境危害風(fēng)險(xiǎn)。外源As進(jìn)入土壤后迅速向各形態(tài)轉(zhuǎn)化分配,以前15天內(nèi)轉(zhuǎn)化最為劇烈,30天后基本趨于平衡并穩(wěn)定在一定水平。FA促進(jìn)交換態(tài)砷(Ex-As)和鈣型砷(Ca-As)向鐵型砷(Fe-As)、鋁型砷(Al-As)及殘?jiān)鼞B(tài)砷(Res-As)轉(zhuǎn)化,而HA促進(jìn)了外源As由Ex-As、Ca-As、Al-As向Fe-As和Res-As轉(zhuǎn)化。外源As在土壤中的形態(tài)分配與腐殖酸活性組分的含量、比例和外源As添加量有關(guān)。FA和添加量≤1%C的HA增加了Ex-As的分配比例,FA添加量為1%C時(shí)Ex-As占比最高為6.29%,HA添加量≥3%C時(shí)則顯著降低了Ex-As的分配比例,5%C時(shí)Ex-As所占比例最低為1.20%;FA顯著促進(jìn)了土壤As由Al-As和Fe-As向Res-As轉(zhuǎn)化,且隨用量的增加作用增強(qiáng),而HA這種作用強(qiáng)度較弱。等量(1%C)條件下,當(dāng)HA/FA比為3/7時(shí),HAs顯著增加了Ex-As的分配比例,當(dāng)HA/FA比為7/3時(shí),Ex-As的比例最低為1.99%,不同HA/FA比的HAs均降低了Al-As和Fe-As的分配比例,顯著增加了Res-As的比例,HA/FA比為3/7時(shí)Al-As和Fe-As的分配比例最低分別為21.97%和42.73%,Res-As的比例最高為24.51%。腐殖酸通過影響土壤中As的形態(tài)分配進(jìn)而影響As的植物有效性和生物可給性。不同F(xiàn)A含量對(duì)土壤As的植物有效性影響不同,FA含量較低(≤3%C)時(shí)能增加土壤植物有效性As含量,FA含量較高(5%C)時(shí)則能夠降低土壤有效性As的含量。HA能夠顯著降低土壤中As的植物有效性,且HA含量越高對(duì)土壤As的植物有效性的抑制效果越好。在等碳量(1%)情況下,不同HA/FA比的HAs均提高了土壤植物有效性As含量,隨著HA/FA比的增加,土壤植物有效性As含量逐漸降低。多元回歸分析表明,土壤中Ex-As和Ca-As對(duì)土壤As的植物有效性具有顯著影響,單位Ex-As對(duì)植物有效性As的貢獻(xiàn)比Ca-As大。FA增加了土壤As在胃和小腸階段的生物可給性,隨著FA添加量的增加土壤As胃階段的生物可給性先增加后逐漸降低,在添加量為1%C時(shí)達(dá)到最高,小腸階段的生物可給性逐漸增加。HA對(duì)土壤As在胃和小腸階段生物可給性的作用效果與FA不同,在胃階段,PBET方法中當(dāng)HA含量1%C時(shí),能降低土壤砷的生物可給性,最低為24.78%;在小腸階段,IVG方法中HA增加了土壤砷的生物可給性,而在PBET方法中當(dāng)HA含量0.5%C能降低土壤砷的生物可給性。在等碳量(1%)條件下,不同HA/FA比的HAs均提高了土壤As的胃和小腸階段生物可給性。與植物有效性相同,對(duì)土壤As生物可給性影響顯著的是Ex-As和Ca-As。腐殖酸影響下土壤砷的生物可給性與植物有效性具有顯著相關(guān)性。在用含腐殖酸的有機(jī)物料修復(fù)As污染土壤時(shí)要充分考慮腐殖酸活性組分含量和比例,有效降低土壤Ex-As和Ca-As的含量,以降低土壤As對(duì)植物和人體健康的潛在危害。
[Abstract]:Arsenic (As) as a kind of typical heavy metal pollutants, the pollution is becoming more and more serious, As pollution problem has attracted widespread attention. Soil As environmental hazards is not only related to its amount and speciation in soil is closely related to the distribution. Humic acid (HAs) is the main component of organic fertilizer and soil organic matter Hu Min, one of the acid (HA) and fulvic acid (FA) is a key activity group influence the morphology and activity of heavy metals in the soil, they can through the complex mechanisms of adsorption and desorption and morphology of soil As transformation impact, thereby affecting the bioavailability of soil As. Soil heavy metals can not only cause harm through food the chain, also can have a direct harm to the human body by direct exposure method. This study through laboratory simulation experiment, from the environmental behavior of humic acid soil As (adsorption and desorption, transformation) to discuss humic The acid content of active component and ratio (HA/FA ratio) on the effectiveness of anion speciation of As in soil biological (plant availability and animal bioavailability) effect, to reveal the relationship between soil As bioavailability and speciation of As, to provide a scientific basis for the application of the regulation of soil biological activity and As containing humic acid type organic matter in the remediation of As contaminated soil. The main results are as follows: the effect of humic acid on adsorption and desorption of As in soil and its types, content and proportion of active components are closely related to the.Langmuir equation can well fit the adsorption isotherm of HAs under the influence of soil As, fitting correlation coefficient (R2) between 0.971~0.996.HAs two active components, HA can promote the adsorption of As in soil, increase the maximum adsorption capacity of soil As, and with the increasing amount of HA, the maximum adsorption capacity increases gradually, when the content of HA was the highest (5%C), the maximum adsorption capacity was 2162 .29 mg路kg-1,鏄鐓х粍(1052.95 mg路kg-1)鐨，

本文編號(hào)：1562871