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22대 대한민국 국회 국회정보길라잡이 국회의원검색
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Title Page

ABSTRACT

국문 초록

Contents

1. General Introduction 18

1.1. Ice Chemical Reactions 18

1.2. Cryogenic Geochemical Reactions 22

1.3. Research Topics 23

1.4. References 26

2. Chemical Weathering of Granite in Ice and Its Implication for Weathering in Polar Regions 30

2.1. Introduction 30

2.2. Materials and Methods 32

2.2.1. Materials 32

2.2.2. Pretreatment and Batch Experiments 32

2.2.3. Chemical and Optical Analysis 33

2.3. Results 36

2.3.1. Filtrate Analysis 36

2.3.2. XRD Analysis and Amorphous Silica Formation 39

2.3.3. Optical Images of Ice Grain Boundaries 42

2.4. Discussion 43

2.4.1. The Mechanism behind the Dissolution of Granite in Ice 43

2.4.2. Silica Polymerization in Ice and Its Implication for Polar Regions 45

2.5. Conclusions 48

2.6. References 49

3. Cryogenic Iron-Phosphate Formation as a Sink for Bioavailable Iron and Phosphorus 53

3.1. Introduction 53

3.2. Materials and Methods 55

3.2.1. Materials 55

3.2.2. Experimental Design 56

3.2.3. Chemical and Microscopic Analysis 57

3.3. Results and Discussion 58

3.3.1. Accelerated Removal of Phosphate and Ferrous in Ice 58

3.3.2. Observations of the Solid Particles Formed during the Freezing Process 62

3.3.3. Identification of Amorphous Ferric Phosphate 64

3.3.4. Mechanism of Enhanced Removal of P and Fe Reactions in Ice 67

3.4. Implications 69

3.5. References 71

4. Frozen Clay Minerals as a Potential Source of Bioavailable Iron and Magnetite 79

4.1. Introduction 79

4.2. Materials and Methods 82

4.2.1. Materials 82

4.2.2. Batch Experiment 83

4.2.3. Chemical Analysis and Microscopic Analyses 84

4.2.4. Electron Microscopy Analyses 85

4.3. Results and Discussion 86

4.3.1. Enhanced Reductive Dissolution of Fe(III) from Nontronite in Ice 86

4.3.2. Mechanisms of the Reductive Dissolution and Freeze Concentration Effect 90

4.3.3. Accelerated Transformations of Iodine Species in Ice 93

4.3.4. Irreversibility of Reactive Iodine Species Generated from Iodide 94

4.3.5. Abiotic Formation of Magnetite in Ice 97

4.4. Environmental Implications 101

4.5. References 103

5. Conclusions 114

List of Tables

Table 2-1. Chemical composition of granite powder used in this study analyzed by X-ray fluorescence spectroscopy. 35

Table 2-2. Averaged dissolved cation concentrations after 29-day batch experiment analyzed by ion chromatography. 38

List of Figures

Figure 1-1. Scheme of acceleration mechanism in ice. A single crystal of ice (I), concentrated phase (C), solution enclosed within the ice grain boundaries (S), and... 21

Figure 1-2. Changes in the distribution of hexavalent chromium concentration of a frozen solution containing hexavalent chromium and iodide. 21

Figure 2-1. Pretreatments and batch experiments of the bulk type of granite. (a) Bulk rock sample, (b) diamond blade, (c) small rock chips sliced with (b), (d) ring... 35

Figure 2-2. Chemical composition changes of filtrate after a batch experiment with a pH 3 solution and DW. (a) [Na⁺], (b) [K⁺], (c) [Mg²⁺], and (d) [Ca²⁺]. 37

Figure 2-3. Chemical composition changes of filtrate after batch experiment with pH 2 solution and DW. (a) [Na⁺], (b) [K⁺], (c) [Mg²⁺], and (d) [Ca²⁺]. 38

Figure 2-4. XRD patterns for a fresh granite sample and filtered solid material after the 29-day batch experiment under different conditions; quartz (Q),... 40

Figure 2-5. SiO₂ concentration analysis of filtrate after a batch experiment with a pH 2 solution. 41

Figure 2-6. Representative optical images of (a) pH 3 solution and (b) the mixture of PH 3 solution and granite powder frozen to -20 ℃ on the Linkam stage with... 41

Figure 2-7. Scheme of dissolution of granite in ice. 41

Figure 3-1. Time profiles of dissolved P, Fe(II), and total Fe concentrations in aqueous and ice samples after filtering. Experimental conditions were as described... 60

Figure 3-2. Time profiles of dissolved Fe(II) and total Fe concentrations in aqueous and ice samples after filtering. The circle, triangle, inverted triangle, square, and diamond shapes... 61

Figure 3-3. UV/Vis full spectra of unfiltered samples after reaction time. (a) aqueous samples, (b) ice samples after thawing. The peaks at around 210 and 310 nm indicate the... 61

Figure 3-4. X-ray diffraction (XRD) pattern of freeze-dried solid particles with a characteristic amorphous peak. 63

Figure 3-5. Representative transmission electron microscopy (TEM) image of the collected from solid particles and corresponding energy-dispersive X-ray... 63

Figure 3-6. Selected area diffraction (SAED) patterns of (a) single globule and (b) agglomerated globules of freeze-dried solid particles. 64

Figure 3-7. Raman spectrum of the centrifuged and freeze-dried solid particles. Mono-chromatic irradiation at 532 nm was used to analyze the composition of the... 66

Figure 3-8. ATR-FTIR spectrum of freeze-dried solid particles. The sample surface was in contact with a Ge tip ATR accessory to obtain the spectrum. 66

Figure 4-1. Time profiles of dissolved Fe concentrations in aqueous and ice samples with or without iodide. Filled markers represent the data of frozen samples... 88

Figure 4-2. The transformations of iodine species. (a) I¯ concentrations of aqueous and ice samples measured using IC system (b) UV/Vis spectra of I¯ in aqueous and ice... 89

Figure 4-3. Optical image of concentrated NAu-2 particles at the ice grain boundaries. Experimental condition: [NAu-2]＝0.2 g L¯¹, [DW]＝10 mL, freezing rate: -2 ℃ min¯¹,... 89

Figure 4-4. UV/Vis spectra of iodine species of the ice sample taken after 24h of reaction and filtered. (a)UV/Vis spectradenoting I¯ around 226 nm and (b)UV/Vis... 96

Figure 4-5. Images of the thawed and filtered 24h ice sample (before and after 24 h) left to be evaporated at room temperature. Experimental conditions: [NAu-2]＝... 96

Figure 4-6. TEM images of NAu-2 with the corresponding SAED patterns. (a) TEM image of initial NAu-2 and (b) NAu-2 after 24 h of freezing. 99

Figure 4-7. TEM images of NAu-2 and magnetite. (a) NAu-2 after 24 h of freezing (b) nanoparticulate magnetite (c) corresponding SAED pattern and (d)... 99

Figure 4-8. X-ray diffraction profiles of initial NAu-2 and NAu-2 after 12 and 24 h of freezing. 100

Figure 4-9. Scheme of the freezing induced reductive dissolution of clay mineral and transformation of iodine species, and magnetite formation 100

초록보기

 최근 연구에서는 얼음이 극지방의 대기, 토양, 해양 등에서 일어나는 화학 반응에 대해 중요한 역할을 하는 것이 알려졌음에도 불구하고, 지화학적 반응에 대한 얼음의 영향 연구는 거의 이루어지고 있지 않다. 이 연구에서는 자연환경에서 지화학 반응에 대한 동결의 영향과 그에 따른 생물의 필수 영양분의 이용 가능성을 연구하였다. 첫 번째로, 산성 조건에서 동결했을 때 화강암의 용출 반응을 연구했다. 이 연구에서는 어는 점 이하의 낮은 온도에도 불구하고 분쇄한 화강암으로부터 상당한 양의 양이온이 녹아나오며 화강암의 결정형이 감소하는 것을 확인하였다. 또한 동결 과정 중에 무정형의 실리카가 형성되는 것이 관찰되었다. 이러한 반응은 준액체층에 농축되어 농도가 높아진 화강암 파우더, 수소이온, 용존 실리카에 기인하는 것으로 확인되었다. 두 번째로, 동결 과정에서 일어나는 인산염과 2가철 이온의 생물 이용가능성 변화를 연구하였다. 이 연구에서는 동결 과정에서 2가철의 3가철로의 산화가 가속화되며 철인산염 고체가 형성되어, 철과 인의 이동성이 감소하는 것으로 확인되었다. 세 번째로, 철을 포함하는 점토 광물의 동결 용출 반응을 연구하였다. 아이오딘화물이 공존할 때 아이오딘화물이 전자 공여체로 작용하면서 점토 광물로부터 생물이 이용 가능한 형태의 철이 용출되는 것으로 확인되었다. 이와 동시에 동결 반응에서는 아이오딘화물이 트라이아이오다이드 또는 아이오딘분자로 변화했고, 동결 반응 후 자철석의 생성이 관찰되었다. 이 연구 결과에서는 자연 환경에서 동결 반응이 양분의 생물 이용 가능성, 생물 이용 가능한 철의 용출, 아이오딘 활성종의 생성에 중요한 역할을 하는 것을 확인하였다. 또한 동결 과정이 자연 환경에서 양분의 공급원이 되는 동시에, 동결 과정에서 용출된 양분을 다른 고체 형태로 변화시키며 동결 과정이 하나의 저장소로 작용할 수 있다는 것을 보여준다.

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