本文選題：重金屬 + 土壤污染�。� 參考：《西北農(nóng)林科技大學(xué)》2017年碩士論文

【摘要】：礦山開(kāi)采和選冶過(guò)程會(huì)形成露天采礦場(chǎng)、尾礦庫(kù)等廢棄場(chǎng)地,產(chǎn)生大量固體廢物。尾礦渣中的重金屬在降雨和風(fēng)蝕的作用下逐漸向周圍擴(kuò)散,破壞生態(tài)環(huán)境,對(duì)水體和土壤造成了嚴(yán)重污染。因此,對(duì)重金屬污染土壤進(jìn)行修復(fù),使其恢復(fù)植被功能至關(guān)重要。本研究以陜西省潼關(guān)縣飲用水源保護(hù)地及歷史遺留重金屬企業(yè)周邊的土壤修復(fù)示范工程為例,從土壤污染現(xiàn)狀調(diào)查、工程修復(fù)技術(shù)的篩選、修復(fù)效果評(píng)價(jià)以及修復(fù)后土壤農(nóng)業(yè)生產(chǎn)安全性評(píng)價(jià)等角度進(jìn)行了系統(tǒng)分析,科學(xué)評(píng)估了客土法,石灰、磷酸鈣、粉煤灰和Na_2S作為重金屬鈍化劑的原位穩(wěn)定化修復(fù)技術(shù)在實(shí)際重金屬污染土壤修復(fù)中的應(yīng)用潛力。研究得到的結(jié)果如下:(1)“三小”冶煉行為和鉛鋅礦的冶煉對(duì)周邊土壤造成了嚴(yán)重的污染。西街子土壤的污染源為礦渣堆,主要受Pb、Cd、Hg的污染,其濃度范圍分別為25.1～1116mg·kg~(-1),2.30～5.20mg·kg~(-1),0.15～20.0mg·kg~(-1)。鑫欣土壤的污染源為廢渣堆、堆料場(chǎng)和冶煉區(qū),主要受Zn、Cd、Pb和Hg的污染,其濃度范圍分別為89.2～742mg·kg~(-1),1.59～362mg·kg~(-1),88.4～7622mg·kg~(-1),0.21～35.0mg·kg~(-1)。(2)重金屬的濃度呈現(xiàn)出由污染源向周邊農(nóng)田土壤逐漸遞減且在污染源處向下遷移的特點(diǎn)。部分剖面土壤污染嚴(yán)重,在0～120cm范圍內(nèi)重金屬濃度全部超過(guò)土壤環(huán)境質(zhì)量二級(jí)標(biāo)準(zhǔn)。(3)西街子表層土壤的污染評(píng)價(jià)結(jié)果:內(nèi)梅羅綜合污染指數(shù)分析表明項(xiàng)目區(qū)域土壤都受到污染,97.1%的土樣受到重污染。采用潛在生態(tài)危害指數(shù)法進(jìn)行評(píng)價(jià),Cd、Hg和Pb是項(xiàng)目區(qū)域土壤重金屬污染的主要貢獻(xiàn)因子。該區(qū)域潛在生態(tài)危害指數(shù)(RI)范圍為668～10969,具有很強(qiáng)的生態(tài)危害。地積累指數(shù)法的統(tǒng)計(jì)結(jié)果表明5種重金屬污染程度由強(qiáng)到弱依次為:CdPbHgZnCu。(4)鑫欣表層土壤的污染評(píng)價(jià)結(jié)果:內(nèi)梅羅綜合污染指數(shù)分析表明土樣受到輕污染、中污染和重污染的比例分別為5.88%、35.3%和58.8%。從潛在生態(tài)危害指數(shù)(Eri)來(lái)看,Cd是潛在生態(tài)危害最嚴(yán)重的金屬元素,所有的土樣都存在極強(qiáng)的生態(tài)危害。從綜合潛在生態(tài)風(fēng)險(xiǎn)(RI)分析,該項(xiàng)目區(qū)域土壤具有很強(qiáng)的生態(tài)危害。(5)對(duì)兩個(gè)項(xiàng)目區(qū)域重污染土壤采用客土法,輕污染土壤采用原位穩(wěn)定化進(jìn)行修復(fù),修復(fù)效果顯著,土壤中重金屬的總量和有效態(tài)濃度均明顯降低。除Cd外,工程修復(fù)后的土壤中重金屬的總量均低于土壤二級(jí)標(biāo)準(zhǔn)中的限值。土壤重金屬有效態(tài)濃度與土壤pH、有機(jī)質(zhì)濃度和重金屬全量之間存在顯著的相關(guān)關(guān)系。隨著修復(fù)時(shí)間的增長(zhǎng),土壤有效態(tài)的濃度有增加趨勢(shì)。(6)西街子修復(fù)后的土壤上主要種植玉米、花生、四季豆和毛豆,鑫欣修復(fù)后的土壤上主要種植玉米和芝麻,對(duì)農(nóng)作物的重金屬污染評(píng)價(jià)發(fā)現(xiàn):部分農(nóng)作物中Cd、Pb和Hg的累積量高于國(guó)家食品安全標(biāo)準(zhǔn)中規(guī)定的限值,因此修復(fù)后土壤上種植的農(nóng)作物不能進(jìn)入市場(chǎng)流通,需要統(tǒng)一進(jìn)行處理。(7)為了探索最適宜的種植模式,在西街子修復(fù)后第二年的土壤上嘗試種植一些常見(jiàn)蔬菜,發(fā)現(xiàn)不同蔬菜對(duì)重金屬的富集能力有差異,具體表現(xiàn)為:葉菜類蔬菜非葉菜類蔬菜。(8)并非所有農(nóng)作物可食部分中重金屬的濃度與土壤中重金屬全量、有效態(tài)濃度之間都存在顯著相關(guān)性。Cd、Pb和Hg在作物中轉(zhuǎn)移系數(shù)(TF)值很小,說(shuō)明重金屬在修復(fù)后的土壤-作物系統(tǒng)中遷移量較小。玉米各重金屬元素的轉(zhuǎn)移系數(shù)(TF)均最高,因此繼續(xù)大面積種植存在一定的風(fēng)險(xiǎn)。(9)在重金屬污染修復(fù)后的土壤上不建議立刻進(jìn)行糧食生產(chǎn),應(yīng)改變?cè)猩a(chǎn)模式同時(shí)持續(xù)監(jiān)測(cè),在確保糧食安全后再進(jìn)行生產(chǎn)。
[Abstract]:Mining and smelting process will form open pit, tailings and other waste sites, producing a large amount of solid waste. Heavy metals in the tailings slag gradually spread to the surrounding area under the action of rainfall and wind erosion, destroying the ecological environment and causing serious pollution to the water and soil. Therefore, the heavy metal contaminated soil is restored to restore the vegetation. This study takes the example of the demonstration project of soil remediation around the drinking water source in Tongguan County of Shaanxi and the surrounding heavy metal enterprises left over by history, and systematically analyzes the status of soil pollution, the screening of Engineering remediation technology, the evaluation of restoration effect and the safety evaluation of soil agricultural production after restoration. The application potential of soil method, lime, calcium phosphate, fly ash and Na_2S as heavy metal passivating agent in situ remediation technology in the remediation of heavy metal contaminated soil was evaluated. The results were as follows: (1) "three small" smelting behavior and lead-zinc smelting have caused serious pollution to the surrounding soil. The source is slag pile, which is mainly contaminated by Pb, Cd and Hg, and its concentration ranges from 25.1 to 1116mg. Kg~ (-1), 2.30 to 5.20mg. Kg~ (-1), 0.15 to 20.0mg. Kg~ (-1). The pollution sources of Xinxin soil are waste residue, heap yard and smelting area. The concentration range is 89.2 ~ 1.59. 8 8.4 ~ 7622mg / kg~ (-1), 0.21 to 35.0mg. Kg~ (-1). (2) the concentration of heavy metals is gradually decreasing from the pollution source to the surrounding farmland and moving downward in the source of pollution. The soil pollution is serious in some sections, and the concentration of heavy metals in the range of 0 to 120cm is more than the standard of the soil environmental quality two. (3) the surface soil of the West Street subsoil The results of pollution assessment: the analysis of Nemero's comprehensive pollution index indicates that the soil in the project area is polluted and 97.1% of the soil samples are heavily polluted. The potential ecological hazard index method is used to evaluate the soil heavy metal pollution in the project area. Cd, Hg and Pb are the main contributors to the soil heavy metal pollution in the project area. The area of the potential ecological hazard index (RI) in this region is 668~10969. The statistical results of the land accumulation index method showed that the pollution degree of 5 kinds of heavy metals from strong to weak was in turn: CdPbHgZnCu. (4) Xinxin surface soil pollution evaluation result: the Nemero comprehensive pollution index analysis showed that the soil samples were exposed to light pollution, the proportion of medium pollution and heavy pollution were 5.88%, 35.3% and 58.8%. from potential birth, respectively. The state hazard index (Eri) shows that Cd is the most serious metal element of potential ecological hazards, and all soil samples have very strong ecological hazards. From the comprehensive potential ecological risk (RI) analysis, the soil of this project has a strong ecological hazard. (5) the soil method is used for the heavy polluted soil in the two projects, and the soil in the light polluted soil is stabilized in situ. In addition to Cd, the total amount of heavy metals in soil after engineering repair is lower than that in the two level of soil. There is a significant correlation between the effective concentration of soil heavy metals and soil pH, the concentration of organic matter and the total heavy metal content. The concentration of soil effective state increased. (6) corn, peanuts, four season beans and peas were mainly planted on the soil after the restoration of West Street. The main planting corn and sesame on the soil after Xinxin restoration showed that the accumulation of Cd, Pb and Hg in some crops was higher than that of national food. The limit set in the safety standard, therefore, the crops planted on the soil after repair can not enter the market circulation and need to be treated in a unified way. (7) in order to explore the most suitable planting pattern, we try to plant some common vegetables on the soil of second years after the restoration of West Street, and find that the enrichment ability of different vegetables on heavy metals is different. The leaf vegetables are not leafy vegetables. (8) there is a significant correlation between the concentration of heavy metals in the edible parts of the crops and the total heavy metals in the soil, and the significant correlation between the effective concentrations and the.Cd. The transfer coefficient (TF) of the Pb and Hg in the crops is small, indicating that the heavy metal has a small migration in the soil crop system after the restoration. The transfer coefficient (TF) of each heavy metal element is the highest, so there is a certain risk for continuing large area planting. (9) it is not recommended to carry out grain production immediately after the remediation of heavy metal pollution. It should change the original production mode and keep monitoring at the same time, and then make production after the food security is ensured.

【學(xué)位授予單位】：西北農(nóng)林科技大學(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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