劉振宇臺灣大學:生物環境系統工程學研究所賴志傑Lai, Chih-ChiehChih-ChiehLai2010-05-052018-06-292010-05-052018-06-292008U0001-2907200812294400http://ntur.lib.ntu.edu.tw//handle/246246/181135民國40年代，台灣西南沿海地區流行一種地區性之疾病-「烏腳病」，經由學者研究引發烏腳病之原因與本地飲用含砷之深井水有關。砷為地殼中自然存在之物質，含砷之地下水，其砷之來源為地質生成與人為活動引起；而地質生成之砷釋出至地下水為本區地下水中之主要來源。為瞭解本區地下水之水質特性，本研究採用統計學上多變量分析之因子分析方式，評估嘉南地區90口地下水監測井之水質檢測資料；再由9口地質鑽探井採取462個地質岩心樣本進行總砷與總鐵分析，同時由地下水砷濃度高之區域挑選42個樣本，進行沈積物砷相別連續萃取。此外亦挑選20個與10個樣本分別使用X光螢光分析儀 (XRF)與電子能譜儀 (XPS)進行礦物主成分與表面特性之評估並使用掃瞄式電子顯微鏡觀察鐵化合物之礦物型態。因子分析結果顯示主因子一、二與三分別為鹽化因子、砷污染因子與鐵因子，其中砷污染因子之結果可觀察到砷與氧化還原電位(Eh)呈現負的相關性，即本區地下水中砷與還原環境相關。沈積物總砷與總鐵分析之結果顯示砷與鐵於泥質海相沈積地層或陸相(含河口灣)沈積地層具有中等相關性。連續萃取與電子能譜儀之結果顯示沈積物之砷於鐵相礦物含量最高，而鐵化合物主要為鐵之(氫)氧化物，其次為鐵硫化物，由XRF結果顯示岩心沈積物的主成分為矽、鋁與鐵，且由沈積物元素含量觀察可發現砷與硫呈現高度相關（r2=0.77）。由此，本研究推估地下水中含有高濃度砷之主要原因為在趨於還原環境下，鐵之(氫)氧化物會漸漸的釋出到地下水中形成二價鐵離子，而原本吸附在鐵之(氫)氧化物上之砷會一併釋出進入地下水中，因而形成含砷濃度之地下水，還原環境達鐵還原程度時亦達到硫酸根還原程度，還原釋出進入地下水中之硫離子與二價鐵離子結合形成硫鐵礦物，會再次將砷離子吸附回礦物，但本區地下水具有腐植物質可與砷進行螯合，因而將部分砷保留於水體中，而於還原條件下形成含砷之硫鐵礦物可能再經由微生物之催化，進行氧化反應再將砷釋出進入地下水中；且陰離子競爭吸附亦為砷釋出進入地下水機制之一。Blackfoot disease was caused by high arsenic concentrations in the groundwater ingested by local inhabitants in several villages in the Chianan Plain of southwestern Taiwan. Generally, arsenic is a natural occurring element found in the earth’s crust. Arsenic contamination of groundwater can occur by geogenic and human activities. Release from natural sources is the dominant cause of elevated arsenic in groundwater. A factorial analysis was employed to evaluate the principal components of the hydrochemical characteristics of 90 groundwater samples in Chianan plain. To determine the correlation between As(s) and Fe(s) in sediment, a total of 463 geological core samples from 9 drilling wells situated at Chianan plain were collected and analyzed the contents of total arsenic and iron. Meanwhile, 42 and 20 samples around high arsenic concentration groundwater were selected, respectively, for additionally sequential extraction and mineralogical characterization. Mineralogical characterization and concentrations of arsenic and iron in the sediment were analyzed using atomic absorption spectrophotometer (AAS) and mineralogical characteristics were evaluated by using X-Ray Fluorescence (XRF) and X-ray Photoelectron Spectrometer (XPS) and Scanning Electron Microscope and Energy Dispersive Spectrometer (SEM-EDS). Results of factor analysis show that hydrochemical characteristics of groundwater samples are grouped by three main factors: salinization, arsenic enrichment, iron. A moderate correlation between As(s) and Fe(s) in sediment is found. The primary and secondary minerals of iron were iron oxy-hydroxides and FeS as shown by XPS analysis. Silicon (Si), aluminum (Al) and iron (Fe) were identified as the main components in the core samples by XRF. The result of XRF revealed that the arsenic correlated well with sulfur (r2=0.77). Accordingly, we postulated that the major processes causing high arsenic levels in groundwater were mainly from reductive dissolution of As-rich Fe oxy-hydroxides and partially from competitive exchange of adsorbed and microbial-mediated oxidation of As-bearing pyrite mineral.中文摘要...........................................................................................................................ibstract...........................................................................................................................iii目錄..................................................................................................................................v目錄...........................................................................................................................viii目錄..............................................................................................................................x一章 前言.....................................................................................................................1-1 研究動機............................................................................................................11-2 研究目的............................................................................................................21-3 論文架構............................................................................................................2二章 文獻回顧.............................................................................................................4-1 砷之化學特性與分布........................................................................................4 2-1-1砷之化學特性與分布..............................................................................4-1-2全球含高砷地下水區之分布..................................................................5-1-3台灣含高砷地下水區..............................................................................82-2台灣嘉南平原水文地質中砷之研究.................................................................92-3 地質環境中砷可能釋出之機制......................................................................102-4 因子分析..........................................................................................................112-5 連續萃取..........................................................................................................12三章 材料與方法.......................................................................................................133-1 研究區域..........................................................................................................13 3-1-1 研究區域概述.......................................................................................13 3-1-2 水文地質特性.......................................................................................143-2 研究架構與方法..............................................................................................19 3-2-1 樣本採集...............................................................................................20 3-2-2 地下水水質特徵及因子分析...............................................................24 3-2-3 沈積物總砷、總鐵分析.......................................................................26 3-2-4 礦物主成分與表面化學特性分析.......................................................29 3-2-5 連續萃取方法與步驟...........................................................................32 3-2-6 地化模式模擬-PHREEQC...................................................................34四章 結果與討論.......................................................................................................354-1 地下水水質特徵..............................................................................................35 4-1-1 派博水質圖法......................................................................................35-1-2 地下水特性之因子分析......................................................................40-1-3 地下水物種砷分布探討......................................................................474-2 沈積物分析結果..............................................................................................53 4-2-1 沈積物總砷總鐵分布..........................................................................53 4-2-2 高解析電子能譜儀(HR-XPS) ............................................................62 4-2-3 X光螢光螢光分析儀(XRF) ................................................................62 4-2-4 掃瞄式電子顯微鏡暨能量分散光譜儀(SEM-EDS)….......................63 4-2-5 砷之連續萃取......................................................................................634-3 地化模式模擬結果..........................................................................................644-4 綜合討論..........................................................................................................65 4-4-1 地質環境中砷之分布探討..................................................................65 4-4-2 嘉南地區砷之可能釋出之機制..........................................................67五章 結論與建議.......................................................................................................845-1 結論..................................................................................................................845-2 建議..................................................................................................................85考文獻.........................................................................................................................86錄A 歷年因子分析之結果........................................................................................94錄B 岩心沈積物總砷總鐵分析結果........................................................................97錄C 土壤標準品介紹..............................................................................................107application/pdf5321156 bytesapplication/pdfen-US砷地下水因子分析嘉南平原X光螢光分析儀連續萃取地化模擬ArsenicGroundwaterFactor AnalysisChianan PlainX-Ray FluorescenceSequential ExtractionGeochemical Modeling[SDGs]SDG3thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/181135/1/ntu-97-R95622045-1.pdf