環境中砷的濃度和移動主要是藉由吸附到金屬氧化物的表面，特別是鐵、鋁、錳來控制。腐植酸亦可以影響此種吸附之行為，進而增加砷之遷移率。這種形成之複合物的相互作用將影響每一個局部濃度及確定它們在天然含水層中的可用性。本研究利用各種光譜來闡明腐植酸、鐵、砷之結合性質，進而證明複合物之鍵結，以及在不同的氧化還原電位和酸鹼性條件下之鍵結變化。研究結果將可以在地下環境中的鐵、砷及腐植酸得到更好的理解，以對砷移動之動力學有更進一步的瞭解。
本研究即要探討腐植酸與砷之鍵結程度，利用X光吸收光譜EXAFS方法分析複合物鍵結之鍵長及配位數，用紅外線光譜分析鍵結之官能基變化，XPS則分析複合物之表面鍵結情形。另外，本研究也討論腐植酸-鐵-砷複合物於不同條件下之酸鹼性或氧化還原電位是否會造成鍵結上之變化。
本研究結果顯示，腐植酸與毒化物砷於鐵離子存在下形成雙齒之複合物砷酸鐵，而其鐵-砷之鍵長約為3.27~3.29 Å，配位數為2，腐植酸則憑藉著羧基與鐵離子形成鐵-氧之鍵結，鍵長約為1.98 Å，配位數為4;腐植酸中的碳亦能與鐵形成鍵結，其鍵長約3.05 Å，配位數為1;砷酸中之砷-氧鍵結其配位數為4，鍵長為1.70 Å。而腐植酸-鐵-砷複合物在極酸性環境下(pH=2)其鐵-砷之鍵結會遭受破壞，不易存在。當還原電位增加時，鐵-砷之鍵長及砷-氧之鍵長隨而減少，鐵-氧之德拜瓦勒因子(Debye-Waller factor)隨還原電位的增加而增加。然而腐植酸-鐵-砷的鍵結之氧化還原電位由+25 mV降至 -120 mV都沒有明顯的變化。
本研究成果能提供鐵、砷、腐植酸之間相互作用的重要參考基礎。此外，其也會影響到毒化物砷在土壤或水體中之移動過程，然而，腐植酸、鐵、砷的鍵結之形成將影響到毒化物砷的去除率及傳輸與生物利用等問題。由實驗室合成的腐植酸、鐵、砷複合物之鍵結，可瞭解其在自然環境中形成及分離的條件及控制因子(如酸鹼度、氧化還原電位)。

Summary
Arsenic is a widespread toxicant in the soil or aquifer in the global environment. Humic acid contains multiple functional groups capable of chelating with heavy metals. In this study, Fourier transform infrared (FTIR), X-ray photon spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to study the bonding between the groups. The degree of bonding between humic acid and arsenic was investigated in this study. The bond distance and coordination number were analyzed by XAS, the binding energy of the humic acid-iron-arsenic complex was determined by XPS, and the functional groups of humic acid were analyzed by FTIR. The results of this study provide the binding properties of iron, arsenic, humic acid interactions. In the cationic state, iron may bind with humic acid and arsenic more easily between the bonds. This information could be valuable to understand the arsenic pollution in the soil or water due to its release or mobilization. The results proved that humic acid in the presence of iron ions can form a bidentate ternary complex. The bond distance and coordination number of Fe-As are 3.27~3.29 Å and 2, respectively. The Fe-As bonds of HA-Fe-As complex were subjected to break under strongly acidic conditions (pH=2), but not significantly affected by changing oxidation-reduction potentials (25, 0, -25, -50, -120 mV)

Alberts, J. J., & Filip, Z. (1998). Metal binding in estuarine humic and fulvic acids: FTIR analysis of humic acid-metal complexes. Environmental Technology, 19(9), 923-931. doi: 10.1080/09593331908616750

Barr, T. L., Seal, S., Wozniak, K., & Klinowski, J. (1997). ESCA studies of the coordination state of aluminium in oxide environments. Journal of the Chemical Society-Faraday Transactions, 93(1), 181-186. doi: 10.1039/a604061f

Blake R.L Blake, R.E Hessevick, T Zoltai, L.W Finger.(1966). Refinement of the hematite structure. American. Mineral. 51 (1966), pp. 123–129

Buschmann, J., Kappeler, A., Lindauer, U., Kistler, D., Berg, M., & Sigg, L. (2006). Arsenite and arsenate binding to dissolved humic acids: Influence of pH, type of humic acid, and aluminum. Environmental Science & Technology, 40(19), 6015-6020. doi: 10.1021/es061057+

Butler, I. B., Schoonen, M. A. A., & Rickard, D. T. (1994). Removal of dissolved-oxygen from water - a comparison of 4 common techniques. Talanta, 41(2), 211-215. doi: 10.1016/0039-9140(94)80110-x

Catrouillet, C., Davranche, M., Dia, A., Bouhnik-Le Coz, M., Marsac, R., Pourret, O., & Gruau, G. (2014). Geochemical modeling of Fe(II) binding to humic and fulvic acids. Chemical Geology, 372, 109-118. doi: 10.1016/j.chemgeo.2014.02.019

Cheng, C. H., Lehmann, J., Thies, J. E., Burton, S. D., & Engelhard, M. H. (2006). Oxidation of black carbon by biotic and abiotic processes. Organic Geochemistry, 37(11), 1477-1488. doi: 10.1016/j.orggeochem.2006.06.022

Dumitrascu, M., Meltzer, V., Sima, E., Virgolici, M., Albu, M. G., Ficai, A., . . . Scarlat, F. (2011). Characterization of clcctron beam irrdiated collagen-polyvinylpyrrolidone (PVP) and collgen-dextrav (DEX) blends. Digest Journal of Nanomaterials and Biostructures, 6(4), 1793-1803.

Guan, X. H., Chen, G. H., & Shang, C. (2007). ATR-FTIR and XPS study on the structure of complexes formed upon the adsorption of simple organic acids on aluminum hydroxide. Journal of Environmental Sciences, 19(4), 438-443. doi: 10.1016/s1001-0742(07)60073-4

Hollinger, G., Skheyta-Kabbani, R., & Gendry, M. (1994). Oxides on GaAs and InAs surfaces: An x-ray-photoelectron-spectroscopy study of reference compounds and thin oxide layers. Physical Review B, 49(16), 11159-11167. doi: 10.1103/PhysRevB.49.11159

Jia, Y., Xu, L., Wang, X., & Demopoulos, G. P. (2007). Infrared spectroscopic and X-ray diffraction characterization of the nature of adsorbed arsenate on ferrihydrite. Geochimica et Cosmochimica Acta, 71(7), 1643-1654. doi: http://dx.doi.org/10.1016/j.gca.2006.12.021

Kim, E. J., Hwang, B. R., & Baek, K. (2015). Effects of natural organic matter on the coprecipitation of arsenic with iron. Environ Geochem Health, 37(6), 1029-1039. doi: 10.1007/s10653-015-9692-1

Liu, Z. G., Chen, X., Jia, Y., Liu, J. H., & Huang, X. J. (2014). Role of Fe(III) in preventing humic interference during As(III) detection on gold electrode: spectroscopic and voltammetric evidence. J Hazard Mater, 267, 153-160. doi: 10.1016/j.jhazmat.2013.12.054

Mikutta, C., & Kretzschmar, R. (2011). Spectroscopic Evidence for Ternary Complex Formation between Arsenate and Ferric Iron Complexes of Humic Substances. Environmental Science & Technology, 45(22), 9550-9557. doi: 10.1021/es202300w

Muehlhoff, L., Choyke, W. J., Bozack, M. J., & Yates, J. T. (1986). Comparative electron spectroscopic studies of surface segregation on SiC(0001) and SiC(0001̄). Journal of Applied Physics, 60(8), 2842-2853. doi: doi:http://dx.doi.org/10.1063/1.337068

Omoregie, E. O., Couture, R. M., van Cappellen, P., Corkhill, C. L., Charnock, J. M., Polya, D. A., . . . Lloyd, J. R. (2013). Arsenic Bioremediation by Biogenic Iron Oxides and Sulfides. Applied and Environmental Microbiology, 79(14), 4325-4335. doi: 10.1128/aem.00683-13

Paparazzo, E. (1987). XPS and auger-spectroscopy studies on mixtures of the oxides SiO2, Al2O3, Fe2O3, and Cr2O3. Journal of Electron Spectroscopy and Related Phenomena, 43(2), 97-112. doi: 10.1016/0368-2048(87)80022-1

Reza, A., Jean, J. S., Lee, M. K., Kulp, T. R., Hsu, H. F., Liu, C. C., & Lee, Y. C. (2012). The binding nature of humic substances with arsenic in alluvial aquifers of Chianan Plain, southwestern Taiwan. Journal of Geochemical Exploration, 114, 98-108. doi: 10.1016/j.gexplo.2012.01.002

Robertson, R. A., Irvine, J. C., & Dobson, M. E. (1907). A contribution to the chemistry and physiological action of the humic acids. Biochemical Journal, 2, 458-U457.
Rose, A. L., & Waite, T. D. (2003). Kinetics of iron complexation by dissolved natural organic matter in coastal waters. Marine Chemistry, 84(1-2), 85-103. doi: 10.1016/s0304-4203(03)00113-0

Saikia, B. K., Boruah, R. K., & Gogoi, P. K. (2007). FT-IR and XRD analysis of coal from Makum coalfield of Assam. Journal of Earth System Science, 116(6), 575-579. doi: 10.1007/s12040-007-0052-0

Sharma, P., Ofner, J., & Kappler, A. (2010). Formation of Binary and Ternary Colloids and Dissolved Complexes of Organic Matter, Fe and As. Environmental Science & Technology, 44(12), 4479-4485. doi: 10.1021/es100066s

Sherman, D. M., & Randall, S. R. (2003). Surface complexation of arsenic(V) to iron(III) (hydr)oxides: structural mechanism from ab initio molecular geometries and EXAFS spectroscopy. Geochimica et Cosmochimica Acta, 67(22), 4223-4230. doi: 10.1016/s0016-7037(03)00237-0

Silva, G. C., Vasconcelos, I. F., de Carvalho, R. P., Dantas, M. S. S., & Ciminelli, V. S. T. (2009). Molecular modeling of iron and arsenic interactions with carboxy groups in natural biomass. Environmental Chemistry, 6(4), 350-356. doi: 10.1071/en09031

Sutton, R., & Sposito, G. (2005). Molecular structure in soil humic substances: The new view. Environmental Science & Technology, 39(23), 9009-9015. doi: 10.1021/es050778q

Thoral, S., Rose, J., Garnier, J. M., Van Geen, A., Refait, P., Traverse, A., . . . Bottero, J. Y. (2005). XAS study of iron and arsenic speciation during Fe(II) oxidation in the presence of As(III). Environmental Science & Technology, 39(24), 9478-9485. doi: 10.1021/es047970x

Warwick, P., Inam, E., & Evans, N. (2005). Arsenic's interaction with humic acid. Environmental Chemistry, 2(2), 119-124. doi: 10.1071/en05025

Waychunas, G. A., Rea, B. A., Fuller, C. C., & Davis, J. A. (1993). Surface-chemistry of Ferrihydrite .1. EXAFS studies of the geometry of copecipitated and adsorbed arsenate. Geochimica et Cosmochimica Acta, 57(10), 2251-2269. doi: 10.1016/0016-7037(93)90567-g

張立信. (2012). 表面化學分析技術. [Surface Chemical Analysis Techniques]. 國家奈米元件實驗室奈米通訊, 19(4), 17-23.

林宜. (2015). 臺灣嘉南平原溪口鄉地下水層砷之礦物學特徵及釋出機制. (碩士), 國立臺灣大學, 台北市.

肖彦春, 窦. (2007). <土壤腐植質各組分紅外光普研究.>. 分析化學, 11, 1596-1600.

李文德,林志明,黃彥衡,吳恭德,陳昌祈 (2002) X光吸收光譜數據處理(1).黎明學報15:1 頁33-40.

李文德,林志明,黃彥衡,吳恭德,陳昌祈 (2003) X光吸收光譜數據處理(2).黎明學報.15:2 頁57-67.