臺灣博碩士論文加值系統

砷對生物具有致癌力，故土壤與河水砷污染是當前全球關注的議題，若能了解河川環境因子對於砷的濃度、可溶性與物種轉變的直接或間接性影響，將有助於對於河川流域中的砷移動與分佈進行管理。本研究將以台中烏溪流域為試驗地點，試驗分為二大部份，第一部分為烏溪流域環境因子對於底泥與河水砷之分布影響，配合主成分分析 (principal components analysis, PCA)、皮爾森相關係數 (Pearson product-moment correlation coefficient, Pearson’s)分析並藉由X光吸收光譜 (X-ray absorption spectroscopy, XAS) 配合線性組合擬合(Linear combination fitting, LCF)進行底泥砷的物種鑑定。結果顯示，河川底泥中砷的累積與底泥中無定形鐵(氫)氧化礦物的分佈呈高度正相關性，且在河床廣而水流平緩的下游以及水流量較少的旱季時，底泥中砷累積程度也越高，而在中科放流口(採樣點S5)與其下游之W5採樣點處發現，底泥砷濃度高於品質指標下限 (11 mg kg-1)，其中水中可溶性砷的濃度也較高。物種分析結果表示烏溪底泥中的鐵(氫)氧化礦物雖然能夠固定砷於底泥中，但卻是以不穩定之吸附態為主 (49.3-91.8%)，容易因環境的變動而造成砷的釋出。第二部分為兩種孵育試驗，藉由調整環境因子來探討砷的溶出情形，第一孵育試驗為調整不同pH值 (5.5, 7.5, 9.5) 與碳源濃度 (0 mM, 3 mM, 6 mM)，觀察孵育期間鐵與砷的溶出濃度變化，結果顯示底泥中砷的溶出主要受固定載體如鐵(氫)氧化物型態變化而影響其釋出，且越高濃度碳源 (Glucose 6 mM) 處理條件下對於砷與鐵在孵育期間的溶出變化更為顯著。藉由線性關係分析可知在烏溪流域環境pH值範圍中 (pH 5.5-7.5)，砷的溶出濃度在鐵溶出的影響下其與Eh值之間有高的指數負相關性 (R2 = 0.86-0.97) ，藉此試驗可知環境因子pH與Eh值為影響底泥中鐵的溶出進而導致砷的釋出的重要因子。第二孵育試驗為在厭氧條件下以四種硫酸根與無定形鐵莫耳比例 (SO42-/Fe=0, 0.3, 1, 3) 的添加孵育試驗，以探討對底泥中砷與鐵溶出的影響以及砷物種轉變情形，研究結果顯示，SO42-/Fe=0.3與1的處理在13-21天時可能因有限的HS-反應使得砷從固相中的釋出更為顯著，而在SO42-/Fe=3的處理下，生成的硫化鐵 (FeS/FeS2) 與針鐵礦或磁鐵礦可能吸附或共沉澱懸浮液中的砷，使砷的溶出有抑制情形，但藉由XANES-LCF分析底泥砷物種轉變結果得知，SO42-/Fe=3的處理在孵育16-18天期間由於硫化砷的轉變，底泥As(III) 濃度卻是高於其他三者處理的任何孵育階段，且至孵育終點41天時As(III)比起原始底泥 (Initial)上升了8.3%。且另外藉由序列萃取 (Sequential Extraction Procedure, SEP) 鑑定砷物種轉變結果，相關性結果顯示，SEP與XANES-LCF兩種鑑定方法在無定形鐵鋁(氫)氧化物與硫化物上的砷濃度皆有良好的線性關係 (R2=0.78、0.74)。

Arsenic (As) is carcinogenic to organisms, As pollution in soil and river has been a global problem recently. Studies have shown that under anaerobic conditions, the iron (hydrogen) oxidized minerals that adsorb or co-precipitate As in the soil will be reduced and dissolved, which will release arsenic into the liquid phase and cause harm to the ecology. Therefore, if the influence of environmental factors on the concentration, solubility and species transformation of As can be understood, it will help analyze and manage the movement and distribution of arsenic in river. This study focusing on Wuxi River in the Taichung area has two parts. The first part was the distribution of environmental factors in the Wuxi River Basin for the analysis and sampling of As, combined with principal components analysis (PCA), Pearson product-moment correlation coefficient (Pearson's) analysis, and X-ray absorption spectroscopy (XAS) technique species identification showed that the accumulation of As in river sediment was mainly affected by amorphous Fe(III) hydroxide in sediment. As and Fe was highly positively correlated with the concentration distribution in the river, and the accumulation of arsenic in the sediment (W1-6) was higher than F1-6 as the riverbed is wide and the water flow is gentle downstream and the dry season with less water flow. At the sampling point S5, the distribution of the Taichung Science Park discharge port, and the downstream W5 analysis found that the As concentration in the sediment was higher than the lower quality index (11 mg kg-1). Additionally, the concentration of soluble As in the W1-6 water was also higher than F1-6. The results showed that although the iron (hydrogen) oxidized mineral in the sediment can fix As in the sediment, it accumulated in an unstable adsorption state and was easily released due to environmental changes. The second part was the incubation experiment which the dissolution of As was investigated by adjusting the environmental factors such as pH and carbon source concentration. The first incubation experiment is to adjust the pH (5.5, 7.5, 9.5) and the carbon source concentration (0 mM, 3 mM, 6 mM) as factors in order to observe the change of the dissolution concentration of Fe and As during the incubation period. The results showed that the higher carbon source was added under the acidic condition of pH 5.5 for the reduction of soil microorganisms, the higher the concentration of As and Fe dissolved in the sediment. Therefore, if the waste water discharged from the surrounding factories, it will influence the environmental balance and the amount of arsenic released to the river will increase. The second incubation experiment was to investigate the effect of different molar ratios of sulfate and amorphous iron in the environment (SO42-/Fe=0, 0.3, 1, 3) on the dissolution of As. Previous study showed that under higher concentration of sulfate, the iron-sulfur compound formed can reduce the release of arsenic into the liquid phase. However, the results of this study showed that under the incubation environment of SO42-/Fe=3, there was indeed a significant inhibition of As dissolution compared to the lower concentration of sulfate addition. However, there was no significant inhibitory effects on the control group. The results of SEP and XAS showed that after adding sulfate to the incubation experiment, Fe(III) minerals were reduced and recombined under anaerobic conditions and further indirectly caused an increase in arsenite species and increased the potential risk of As poisoning. This research aimd to understand the influence of environmental factors on the distribution and mobility of As in rivers in order to be used as a cornerstone for As remediation in rivers.

中文摘要 i
Abstract ii
目錄 iv
圖目錄 vi
表目錄 viii
第一章 前言 1
1.1. 研究背景與動機 1
1.2. 研究目的 3
第二章 文獻回顧 4
2.1. 環境砷的來源 4
2.2. 歷史上砷中毒的案例與危害性 5
2.3. 砷的特性 5
2.4. 砷對作物的影響 8
2.5. 砷在台灣內的各項指標 8
2.6. 砷在台灣的人體規範 10
2.7. 影響砷物種形態之環境因子 11
2.7.1. 酸鹼度(pH) 11
2.7.2. 氧化還原電位(Eh) 12
2.7.3. 鐵/鋁/錳(氫)氧化物 14
2.7.4. 有機質 16
2.7.5. 微生物 16
2.7.6. 硫酸根(SO42-) 18
2.8. X光吸收光譜(XAS) 20
第三章 研究方法與設計 22
3.1. 實驗架構 22
3.2. 事業放流水採樣方法 23
3.2.1. 採樣設備與材料 24
3.2.2. 水樣採樣步驟 25
3.3. 底泥採樣方法(NIEA S104.30C) 26
3.3.1. 採樣位置選取原則 26
3.3.2. 採樣器材選取原則 26
3.3.3. 泥採樣步驟 27
3.4. 樣品保存與運送 27
3.5. 底泥與水樣基本性質分析 27
3.5.1. 樣品前處理 27
3.5.2. 水分校正 28
3.5.3. pH值測定 28
3.5.4. 氧化還原電位測定 28
3.5.5. 無定形鐵鋁測定-草酸銨萃取法 29
3.5.6. 重金屬檢測方法 29
3.6. 資料分析-主成分分析(PCA)、皮爾森相關係數(Pearson’s)30
3.7. 孵育試驗設計 30
3.7.1. 第一孵育試驗-不同pH值與碳源濃度調控之厭氧孵育砷與鐵溶出
試驗設計 30
3.7.2. 第二孵育試驗-不同鐵與硫酸根莫耳比添加之厭氧孵育砷與鐵溶
出試驗設計 33
3.7.3. 孵育期間測定、取樣與樣品保存 37
3.7.4. 孵育溶出砷與鐵濃度測定 38
第四章 結果與討論 40
4.1. 環境因子分析 40
4.1.1. 統計分析-主成分分析 (PCA) 43
4.1.2. 統計分析-皮爾森相關性係數 (Pearson’s) 46
4.1.3. 烏溪流域底泥X光吸收光譜砷物種分布 47
4.2. 第一孵育試驗-pH值與碳源濃度對厭氧孵育中砷與鐵從底泥溶出
的影響 49
4.2.1. 孵育結果之pH與Eh值 49
4.2.2. 孵育試驗之砷與鐵溶出 52
4.3. 第二孵育試驗-硫酸根與鐵莫耳比例對厭氧孵育中砷與鐵從底泥
溶出的影響 57
4.3.1. 烏溪流域水中硫酸根濃度 57
4.3.2. 孵育試驗之砷與鐵溶出 58
4.3.3. 固相底泥砷&鐵溶出以及砷物種與價態轉變分析: X光吸收光譜
(XAS) & 線性組合擬合(LCF) 62
4.3.4. X光吸收光譜與序列萃取結果比較 68
第五章 結論 71
第六章 參考文獻 73
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