發(fā)布時間：2018-03-17 06:15

  本文選題：地下水　切入點：大同盆地　出處：《中國地質(zhì)大學》2016年博士論文　論文類型：學位論文

【摘要】：與世界其它地區(qū)眾多研究相似,多種因素導致了中國北部大同盆地高砷地下水的形成。干旱,單一依靠地下水,地下水水流緩慢(長滯留時間)和封閉的系統(tǒng)等條件,導致大同盆地地下水通過蒸發(fā)濃縮作用、水位波動效應,水巖相互作用和沖刷洗脫砷等方式保持較高濃度的砷。高砷地下水嚴重威脅人類健康,亟需對地下水中多因素活化砷的機制進行調(diào)查,為高砷地下水的修復提供科學依據(jù)和理論支持。相比基于反向模擬和水流模型對大同盆地高砷地下水進行的眾多研究,基于反應運移模型開展研究將是未來研究的熱點。強還原環(huán)境中高砷地下水模擬需要對反應進行精細刻畫,反應運移模型在此類模擬中的應用研究更為重要。本研究的目的如下：(1)解釋和揭示可能影響試驗場水化學分布的因子；(2)評估沉積物地球化學特征和地下水補給對砷遷移轉(zhuǎn)化的影響；(3)基于反應運移模型模擬離子交換、礦物溶解/沉淀以及本身條件對砷在時間尺度和空間尺度遷移的影響；(4)解釋影響地下水中砷遷移富集的機制。研究基于大同盆地中心試驗場數(shù)據(jù)對水流路徑(一維)變化和二維空間分布的影響因素進行了分析。本研究的主要研究對象是埋深約20m厚度約1m的淺層含水層地下水。通過野外試驗場現(xiàn)場測定的參數(shù)以及室內(nèi)水化學和沉積物分析數(shù)據(jù)對地下水水化學特征和砷的分布進行了分析,以闡明導致地下水砷活化的潛在機制。在此基礎(chǔ)上,本文通過TOUGHREACT和PHT3D建立了兩個反應運移模型以分析和識別大同盆地地下水砷富集的主控因素。本文3-5章對結(jié)果進行了分析,并得到以下主要結(jié)論：(1)試驗場水化學數(shù)據(jù)和沉積物地球化學數(shù)據(jù)在室內(nèi)分析完成,試驗場地下水化學類型主要為Na-HCO3,地下水中砷濃度最高為2627.1μg L-1,沉積物中砷的最高濃度為26.21mg kg-1。結(jié)果表明高濃度HCO3、高pH以及強還原環(huán)境有助于增強地下水中砷的活性。此外,Fe(Ⅱ)/Fe(Ⅲ)以及SO4/HS循環(huán)可以解釋由沉積物中有機質(zhì)降解作為電子供體而產(chǎn)生的As(Ⅲ)。然而,通過S04還原形成硫化物抑制地下水中砷的活性雖微不足道,但是仍有可能。基于非反應運移模擬(MODFLOW/MT3DMS)的砷形態(tài)分布說明,相比強還原環(huán)境,在溫和的還原條件下As(V)是主要的形態(tài),而且伴生Fe(Ⅲ)和Al。(2)基于TOUGHREACT的一維水流路徑模型表明主要水化學組分、pH變化以及離子交換對砷的富集有顯著影響。從模型可知Fe(Ⅲ)、 As(Ⅴ)和S04的還原影響砷的分布。此外,從模型推斷砷從鐵錳氫氧化去/氧化物表面解吸是大同盆地還原條件下砷富集的重要機制。模擬結(jié)果進一步顯示硅酸鹽風化產(chǎn)生大量的Na進入含水層,并通過影響沉積物的穩(wěn)定性促進了砷的富集。(3)基于PHT3D對試驗場砷和其他共存元素的分布進行了模擬和預測。模型顯示,在考慮地下水空間演化的基礎(chǔ)上,氧化敏感元素的分布與弱還原到強還原條件的演化保持一致的。模型結(jié)果有力支持了第三章的結(jié)論即砷的分布受到Mn、Fe氧化物/氫氧化物的影響,Mn、 Fe氧化物/氫氧化物是研究區(qū)砷的主要載體。此外,模擬的分布結(jié)果強調(diào)了除表面絡合反應外,pH/pe分區(qū)和離子交換對As(Ⅲ)/As(V)濃度變化的影響的重要性。研究的創(chuàng)新點在于,基于針對大同盆地建立的自定義數(shù)據(jù)庫應用反應運移模型對厭氧條件下偏堿性地下水中砷遷移進行了分析。首先,TOUGHREACT數(shù)據(jù)庫極其缺乏,尤其是針對于還原性含水層,本研究建立為TOUGHREACT建立了適用還原含水層的數(shù)據(jù)庫。其次,兩個模型作為首次針對大同盆地高砷地下水建立的反應溶質(zhì)運移模型,為進一步進行反應溶質(zhì)運移模擬奠定了基礎(chǔ)。最后,與大同盆地相比試驗場面積雖然較小,但論文研究成果通過為地下水質(zhì)量管理提供有效信息和預測地下水時空變化,有力推動了本地區(qū)的研究。
[Abstract]:Similar to other parts of the world, many studies, many factors lead to the formation of high arsenic groundwater in Datong Basin in the north of China. Drought, single rely on groundwater, groundwater flow is slow (long retention time) and the conditions of closed system, resulting in groundwater in Datong Basin by evaporation condensation, water level fluctuation, water rock interaction and scour elution arsenic and other ways to keep a higher concentration of arsenic. High arsenic groundwater is a serious threat to human health, the activation of arsenic on groundwater mechanism need many factors in the investigation, provide scientific basis and theoretical support for the repair of high arsenic groundwater. Compared to many studies of high arsenic groundwater in Datong basin simulation and reverse flow based on the model, based on research carried out reactive transport model will be the focus of future research. Strong reducing environment in simulation requires fine description of high arsenic groundwater, reactive transport Application of the model in such simulation is more important. The purpose of this study is as follows: (1) to explain and reveal the field may affect the distribution of water chemical factor; (2) assess the geochemical characteristics of sediments and groundwater recharge on the impact of migration and transformation of arsenic; (3) - migration model based on ion exchange. Mineral dissolution / precipitation and its influences on the migration of arsenic in temporal and spatial scales; (4) to explain the effects of arsenic in groundwater migration and enrichment mechanism. Research center of Datong Basin test field data based on flow path (one-dimensional) factors affecting the distribution change and the two-dimensional space are analyzed. The main research object of this research is the depth of about 20m thickness of about 1m of the shallow aquifer groundwater. Through field test field parameters and the determination of indoor water chemistry and sediment data analysis on groundwater chemical characteristics and arsenic The distribution is analyzed, in order to elucidate the potential mechanism resulting in groundwater arsenic activation. On this basis, this paper established two reactive transport model by TOUGHREACT and PHT3D to analyze and identify the Datong basin groundwater arsenic enrichment controlling factors. The 3-5 chapter analyses the results, and get the following conclusions: (1 complete the analysis field test) of hydrochemical data and sediment geochemical data in the indoor test site, chemical types of groundwater are mainly Na-HCO3, the highest arsenic concentration of 2627.1 g L-1 in groundwater, the highest concentration of arsenic in the sediments of 26.21mg kg-1. results showed that the high concentration of HCO3, high pH and strong reducing environment is helpful to the enhancement of arsenic in groundwater activity. In addition, Fe (II) /Fe (III) and SO4/HS cycle can be explained by the degradation of organic matter in sediments as the electron donor and As (III). However, through the reduction of S04 sulfide formation Inhibition of arsenic in groundwater activity is not worth mentioning, but there are still possible. The simulation of non reactive transport (MODFLOW/MT3DMS) based on the arsenic distribution, compared with the strong reducing environment, reduction in mild conditions (As V) is the main form, and the associated Fe (III) and Al. (2) one-dimensional flow path model TOUGHREACT that the main chemical components of water based on the change of pH and ion exchange on arsenic enrichment have significant effects. From the model shows that Fe (III), As (V) and S04 reduction effect of arsenic distribution. In addition, inferred from the model of arsenic from oxidation of iron and manganese oxide / hydrogen to surface desorption is an important mechanism of arsenic enrichment the Datong Basin reducing conditions. The simulation results further showed that silicate weathering produced large amounts of Na into the aquifer, and the effects of sediment stability and promote the accumulation of arsenic. (3) the test field of arsenic and its distribution he coexisting elements based on PHT3D The simulation and prediction. The model shows that considering the groundwater spatial evolution, the evolution of the distribution of oxidation sensitive elements and weak reducing to strong reducing conditions consistent. Model results support the conclusion of the third chapter is the arsenic distribution by Mn, Fe oxide / hydroxide effect, Mn, Fe oxide the study area is the main carrier of hydroxide / arsenic. In addition, the distribution of the simulation that in addition to surface complexation reactions, pH/pe partition and ion exchange of As (III) /As (V). The effects of concentration of the importance of innovation, custom database application model for reactive transport for the Datong Basin Analysis of anaerobic alkaline arsenic in groundwater migration based on TOUGHREACT database. First of all, extremely deficient, especially for the reduction of the aquifer, this study established TOUGHREACT is established with reduction Water database. Secondly, two for the first time as model reaction solute transport model of high arsenic groundwater in Datong Basin, laid the foundation for further simulation of reaction solute transport at last, compared with the field test of Datong Basin area is small, but to provide effective information and prediction of temporal and spatial variation of groundwater for groundwater quality management through the research results that has promoted the research in the area.

【學位授予單位】：中國地質(zhì)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：P641.3
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本文編號：1623508