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系統識別號 U0026-1606201419220100
論文名稱(中文) 利用珠江河口沉積物鈾釷同位素示蹤大陸風化過程及河口氧化還原環境之研究
論文名稱(英文) Tracing continental weathering and estuarine redox conditions with U/Th isotopes in Pearl River estuarine sediments
校院名稱 成功大學
系所名稱(中) 地球科學系
系所名稱(英) Department of Earth Sciences
學年度 102
學期 2
出版年 103
研究生(中文) 蔡孟涵
研究生(英文) Meng-Han Tsai
學號 L46014063
學位類別 碩士
語文別 英文
論文頁數 70頁
口試委員 指導教授-羅尚德
口試委員-李紅春
口試委員-梁碧清
中文關鍵字 自生相和碎屑相  鈾系不平衡  化學風化  氧化還原環境  珠江河口 
英文關鍵字 Authigenic and Detrital phases  U-series disequilibrium  Chemical weathering  Redox environment  Pearl River Estuary 
學科別分類
中文摘要 河口區域是大陸風化物質進入海洋的一個重要通道,並且在此區域伴隨著許多生物地球化學反應的發生。為了瞭解大陸風化過程及沉積環境的生物地球化學過程,本研究設計了一種新的方法,以6N鹽酸溶液淋溶並分析沉積物顆粒中「自生相」及「碎屑相」的放射性核素210Pb、234U、238U、230Th、232Th、228Th和228Ra,並根據鈾系同位素不平衡現象探討所代表的大陸風化歷程及河口沉積環境隨時間的變化。
結果顯示,P11沉積物岩芯經由過剩210Pb定年方法計算所得之平均沉積速率約為3.56±0.89 公分/年,且在過剩210Pb活度分布中觀察到具有規律性周期變化現象。自生相中234U、238U和230Th活度隨深度減少有增加的趨勢,意味著珠江河口的水體及沉積環境從過去到現在更趨向於還原性環境,使得鈾釷同位素在還原性環境下因化學特性而富集,此結果亦可由(228Th/228Ra)活度比值隨深度的變化及P11 沉積物之總有機碳分布來驗證,並且進一步了解各層位間氧化還原環境之變化。碎屑相中(228Ra/232Th)比值大致上都高於1,顯示出在深部層位有228Ra的富集,推測其原因可能與硫酸鋇礦物存於沉積物中有關。碎屑相中所觀察到(234U/238U)比值接近或等於1與(230Th/234U)比值大於1,都指示著此沉積物過去主要是受到化學風化過程為主。本研究也發現210Pbex 與化學風化之間的變化具有關聯性,且周期恰巧與「聖嬰現象南方震盪」及「太陽黑子」之氣候循環事件周期相符,這些訊號可能記錄著珠江河口氣候環境變化的重要歷程。
不同於前人多使用全溶法將沉積物溶解來進行各項後續分析,其所得到的結果代表整體趨勢分布,並無法有效得知各來源之貢獻及影響,所以本研究藉由分析沉積物中自生相及碎屑相鈾系同位素間不平衡現象,提供了一個有效的方法來更加深入探討大陸及河口間交互作用和來源之貢獻,也可用以了解大陸風化歷史、沉積物質的來源、氣候環境變化以及河口沉積環境之生物地球化學行為是由於人為活動或自然環境變化所趨使。
英文摘要 Estuary is an important region where the fluxes of dissolved and particulate weathering materials in rivers transport from continent into the ocean and lots of biogeochemical reactions occurred. To understand the weathering processes and deposited environment recorded in sediments. This study employed a new method to investigate the U/Th isotope disequilibrium respectively in authigenic and detrital phases of estuarine sediments and showed that U-series disequilibrium in authigenic and/or detrital phases of estuarine sediments could provide useful information on the changes of continental weathering and/or land-sea interactions at the estuary in the present and past. A sediment core (P11) was collected from the Pearl River estuary and sediments sampled from various depths of the core were further separated into the authigenic and detrital phases using 6N HCl leaching technique which has been confirmed that do not affect the U/Th activity ratio with a set of leaching experiment. U-series radioisotopes, 210Pb (via 210Po), 234U, 238U, 228Th, 230Th, 232Th and 228Ra in authigenic and detrital phases were measured respectively with alpha-counting techniques following radiochemical purification procedures.
Results show that excess 210Pb activity exhibits frequent fluctuation with a general decreasing trend, suggesting periodic changes in 210Pb flux driven by climate change. From this decreasing trend, the average sedimentation rate of P11 core is dated to be 3.56 ± 0.89 cm/yr. In the authigenic phases, both 238U and 234U activities decrease with the depth, implying that the estuarine water and the underlying sediments become more and more reducing toward the present which supported by the (228Th/228Ra) activity ratio. (228Ra/232Th) ratios show that there is an enrichment of 228Ra and seem to correlate with the BaSO4 in detrital phase. The (234U/238U) ratio in the detrital phase is measured to be mostly near unity, reflecting that the Pearl River sediments have experienced a relatively rapid chemical weathering. The relatively lower ratios at some depths are mostly due to alpha recoil effect in association with the physical weathering of rocks. This conclusion is further supported by (230Th/234U) in the detrital phases, with (230Th/234U) > 1 indicating the preferential release of 234U due to chemical weathering. The correlation between chemical weathering and 210Pbex can also be found and is coincident with the significant climate circulation.
This study shows that by separating authigenic from detrital phases, uranium isotope disequilibrium can provide more valuable information than that based on total sediments. It will be a useful tool to understand a variety of continental/estuarine processes such as the origin of estuarine sediments, the chemical/physical weathering rate of continental rocks, and changes in estuarine biogeochemical process driven by human activity and/or natural climate change.
論文目次 摘要 I
Abstract III
Acknowledgments V
Contents VI
List of Figures IX
List of Tables XI

1. Introduction 1
1-1 Uranium-series isotopes and disequilibrium 1
1-2 Alpha-recoil effect 3
1-3 U-series disequilibrium during weathering and transported processes 4
1-4 Definition of Authigenic and Detrital phases 7
1-5 Pearl River Estuary 8
2. Material and analytical methods 9
2-1 Study area 9
2-2 Experimental analytic procedures 10
2-2-1 U-Th isotope analysis 10
2-2-2 X-ray diffraction analysis 11
2-3 Instrument and Methods 13
2-3-1 X-ray Powder Diffractometer 13
2-3-2 Alpha Spectrometer 14
2-3-3 Isotope dilution method 16
2-3-4 Leaching experiment 17
3. Results 23
3-1 210Pb activity 23
3-2 Uranium isotopes and (234U/238U) activity ratio 23
3-3 Thorium isotopes and U/Th activity ratios 24
3-4 Radium isotopes and Th/Ra activity ratios 25
4. Discussion 36
4-1 Evaluation of 6N HCl leaching method 36
4-1-1 Effects of mineral composition of rocks 36
4-1-2 Effects of grain size 42
4-2 210Pb dating of P11 sediment core 42
4-3 The geochemical/environmental indicators of U/Th isotopes in authigenic phase of sediments 45
4-4 U-Th isotope ratios in detrital phase of sediments: An indicator of rock weathering intensity 49
4-5 232Th-228Ra-228Th disequilibria in both authigenic and detrital phases of sediments: insight on the groundwater Ra transport associated with paleo-redox changes 52
4-6 Climate changes recorded by U-series radioisotopes in P11 sediment core 55
5. Conclusions 58
References 60
Appendix 69
1. Activity calculation- 228Th 69
2. Activity calculation- 228Ra 70
3. Element analysis of P11 sediment core 71
參考文獻 Andersson, P.S., Porcelli, D., Wasserburg, G.J. and Ingri, J. (1998). "Particle transport of U-234-U-238 in the Kalix River and in the Baltic Sea." Geochimica et Cosmochimica Acta 62: 385-392.
Bene, P. (1982). "Physico-chemical forms and migration in continental waters of radium from uranium mining and milling." Proceedings of the International Symposium on Migration in the Terrestrial Environment of Long-lived Radionuclides from the Nuclear Fuel Cycle. pp.3-23. The international Atomic Energy Agency, Vienna.
Boryło, A. (2012). "Determination of uranium isotopes in environmental samples." Journal of Radioanalytical and Nuclear Chemistry 295: 621-631.
Chabaux, F., Riotte, J. and Dequincey, O. (2003). "U-Th-Ra fractionation during weathering and river transport." Uranium-Series Geochemistry 52: 533-576.
Chu, W.L. (2008). "Uranium-series radioisotopes as a tracer to understand the continental weathering and marginal-sea geochemical processes." Unpublished Doctoral Dissertation. University of Cheng Kung, Taiwan.
DePaolo, D.J., Maher, K., Christensen, J.N. and McManus, J. (2006). "Sediment transport time measured with U-series isotopes: Results from ODP North Atlantic drift site 984." Earth and Planetary Science Letters 248: 394-410.
Dosseto, A., Bourdon, B., Gaillardet, J., Allègre, C.J. and Filizola, N. (2006a). "Time scale and conditions of weathering under tropical climate: Study of the Amazon basin with U-series." Geochimica et Cosmochimica Acta 70: 71-89.
Dosseto, A., Bourdon, B., Gaillardet, J., Mauricebourgoin, L. and Allègre, C.J. (2006b). "Weathering and transport of sediments in the Bolivian Andes: Time constraints from uranium-series isotopes." Earth and Planetary Science Letters 248: 759-771.
Dosseto, A., Bourdon, B. and Turner, S.P. (2008). "Uranium-series isotopes in river materials: Insights into the timescales of erosion and sediment transport." Earth and Planetary Science Letters 265: 1-17.
Dosseto, A., Buss, H. L. and Suresh, P.O. (2012). "Rapid regolith formation over volcanic bedrock and implications for landscape evolution." Earth and Planetary Science Letters 337-338: 47-55.
Dosseto, A., Turner, S. P. and Chappell, J. (2008). "The evolution of weathering profiles through time: New insights from uranium-series isotopes." Earth and Planetary Science Letters 274: 359-371.
Goldich, S.S. (1938). "A study in rock weathering." Journal Geology 46: 17-58.
Gong, J., Ran, Y., Chen, D., Yang, Y. and Zeng, E.Y. (2012). "Association of endocrine-disrupting chemicals with total organic carbon in riverine water and suspended particulate matter from the Pearl River, China." Environ Toxicol Chem 31: 2456-2464.
Granet, M., Chabaux, F., Stille, P., Dosseto, A., France-Lanord, C. and Blaes, E. (2010). "U-series disequilibria in suspended river sediments and implication for sediment transfer time in alluvial plains: The case of the Himalayan rivers." Geochimica et Cosmochimica Acta 74: 2851-2865.
Granet, M., Chabaux, F., Stille, P., France-Lanord, C. and Pelt, E. (2007). "Time-scales of sedimentary transfer and weathering processes from U-series nuclides: Clues from the Himalayan rivers." Earth and Planetary Science Letters 261: 389-406.
Handley, H.K., Turner, S., Afonso, J.C., Dosseto, A. and Cohen, T. (2013). "Sediment residence times constrained by uranium-series isotopes: A critical appraisal of the comminution approach." Geochimica et Cosmochimica Acta 103: 245-262.
Handley, H.K., Turner, S.P., Dosseto, A., Haberlah, D. and Afonso, J.C. (2013). "Considerations for U-series dating of sediments: Insights from the Flinders Ranges, South Australia." Chemical Geology 340: 40-48.
Halbach, P., von Borstel, D. and Gundermann, K.D. (1980). "The uptake of uranium by organic substances in a peat bog environment on a granitic bedrock." Chemical Geology 29: 117-138.
Horel, J.D and Wallace, J.M. (1981). "Planetary-scale atmospheric phenomena associated with the southern oscillation." Monthly Weather Review 109: 813-829.
Horvatinčić, N., Barešić, J., Babinka, S., Obelić, B., KrajcarBronić, I., Vreča, P. and Suckow, A. (2008). "Towards a deeper understanding of how carbonate isotopes reflect environmental changes: a study with recent 210Pb dated sediments of Plitvice lake." Radiocarbon 50: 1–21.
Huang, W.H., Keller, W.D. (1970). "Dissolution of rock-forming silicate minerals in organic acids: simulated first-stage weathering of fresh mineral surfaces." American Mineralogist 55: 2076-2094.
Huang, Z.G., Li, P.R., Zhang, Z.Y., Li, K.H. and Qiao, P.N. (1982). "Formation, Development and Evolution of the Pearl River Delta. The Guangzhou Branch of Popular Science Press, Guangzhou (in Chinese).
Hu, D., Clift, P.D., Böning, P., Hannigan, R., Hillier, S., Blusztajn, J., Wan, S. and Fuller, D.Q. (2013). "Holocene evolution in weathering and erosion patterns in the Pearl River delta." Geochemistry, Geophysics, Geosystems 14: 2349-2368.
Jia, G.D. and Peng, P.A. (2003). "Temporal and spatial variations in signatures of sedimented organic matter in Lingding Bay (Pearl estuary), southern China." Marine Chemistry 82: 47-54.
Jiang, X., Yu, Z., Ku, T.L., Kang, X., Wei, W. and Chen, H. (2009). "Distribution of uranium isotopes in the main channel of Yellow river (Huanghe), China." Continental Shelf Research 29: 719-727.
Kigoshi, K. (1971). "Alpha-recoil thorium-234: Dissolution into water and uranium-234/uranium-238 disequilibrium in nature." Science 173: 47-&.
Ku, T.L., Knauss, K.G. and Mathieu, G.G. (1977). "Uranium in open ocean concentration and isotopic composition." Deep-Sea Research 24: 1005-1017.
Langmuir, D. (1978). "Uranium solution-mineral equilibria at low temperatures with applications to sedimentary ore deposits." Geochimica et Cosmochimica Acta 42: 547-569.
Lenhart, J.J., Cabanis, S.E., McCarthy, P. and Honeymann, B.D. (2000). "Uranium (VI) complexation with citric humic and fulvic acids." Radiochimica Acta 58: 5455-5463.
Lima, V.L., Souza, V.L.B., Nascimento, R.K., Santos, P.N.C., Almeida, M.G.O. and Hazin, C.A., (2014). "Metal fractionation in sediments as a tool for assessing the availability of trace metals : the case of Apipucos Reservoir." Radiation Physics and Chemistry 95: 329–332.
Lin, R.F., Min, Y.S., Wei, K.Q., Zhang, G., Yu, F.J. and Yu, Y.L. (1998) "210Pb dating of sediment cores from the Pearl River mouth and its environmental geochemistry implications." Geochimica 27: 401–411 (in Chinese).
Liu, B.L., Yang, J., Hu, K., Luo, X.M., Jiang, Z.L. and Liu, A.H. (2011). "Distribution and enrichment of heavy metals in a sediment core from the Pearl River Estuary." Enviromental Earth Sciences 62: 265-275.
Luo, S.D., Ku, T.L., Roback, R., Murrel, M. and McLing, T.L. (2000). "In-situ radionuclide transport and preferential groundwater flows at INEEL (Idaho) decay-series disequilibrium studies." Geochimica et Cosmochimica Acta 64: 867-881.
Luo, S.D., Shi, W.Y., Chen, Z. and Huang, Y.P. (1987). "A new method for separation and determination of U and Th in deep-sea manganese nodules." Acta Oceanologica Sinica 6: 87-93.
Ma, H., Zeng, Z., Yu, W., He, J., Chen, L., Cheng, J., Yin, M. and Zeng, S. (2011). "234Th/238U disequilibrium and particulate organic carbon export in the northwestern South China Sea." Acta Oceanologica Sinica 30: 55-62.
Ma, L., Chabaux, F., Pelt, E., Blaes, E., Jin, L. and Brantley, S. (2010). "Regolith production rates calculated with uranium-series isotopes at Susquehanna/Shale Hills Critical Zone Observatory." Earth and Planetary Science Letters 297: 211-225.
Mizugaki S, Onda Y, Fukuyama T, Koga S, Hiramatsu S. (2006). "A method of fingerprinting the sources of fluvial sediment using environmental radionuclides—a case study of Tsuzura River watershed" Proceedings of the Seventh Workshop on Environmental Radioactivity: 159–167.
Moore, J., Grinsted, A. and Jevrejeva, S. (2006). "Is there evidence for sunspot forcing of climate at multi-year and decadal periods?" Geophysical Research Letters 33.
Nagy, B., Gauthier-Lafaye, F., Holliger, P., Davis, D.W., Mossman, D.J., Leventhal, J.S., Rigali, M.J. and Parnell, J. (1991). "Organic matter and containment of uranium and fissiogenic isotopes at the Oklo natural reactors." Nature 354: 472-475.
Neymark, L.A. (2011). "Potential effects of alpha-recoil on uranium-series dating of calcrete." Chemical Geology 282: 98-112.
Niu, J. (2012). "Precipitation in the Pearl River basin, South China: scaling, regional patterns, and influence of large-scale climate anomalies." Stochastic Environmental Research and Risk Assessment 27: 1253-1268.
Owens, S.A., Buesseler, K.O. and Sims, K.W.W. (2011). "Re-evaluating the 238U-salinity relationship in seawater: Implications for the 238U–234Th disequilibrium method." Marine Chemistry 127: 31-39.
Paces, J.B., Nichols, P.J., Neymark, L.A. and Rajaram, H. (2013). "Evaluation of Pleistocene groundwater flow through fractured tuffs using a U-series disequilibrium approach, Pahute Mesa, Nevada, USA." Chemical Geology 358: 101-118.
Pérez, J.T., Vargas, M.J., Sánchez, A.M., Montero, M.P.R. and Sánchez, A.B.R.
(2013). "Determination of alpha activity in solid samples by leaching or
digestion." Applied Radiation and Isotopes 81: 49-52.
Pogge von Strandmann, P.A.E., Burton, K.W., Porcelli, D., James, R.H., van Calsteren, P. and Gislason, S.R. (2011). "Transport and exchange of U-series nuclides between suspended material, dissolved load and colloids in rivers draining basaltic terrains." Earth and Planetary Science Letters 301(1-2): 125-136.
Porcelli, D., Andersson, P.S., Baskaran, M. and Wasserburg, G.J. (2001). " Transport of U- and Th-series nuclides in a Baltic shield watershed and the Baltic sea." Geochimica et Cosmochimica Acta 65: 2439-2459.
Qi, S., Leipe, T., Rueckert, P., Di, Z. and Harff, J. (2010). "Geochemical sources, deposition and enrichment of heavy metals in short sediment cores from the Pearl River Estuary, Southern China." Journal of Marine Systems 82: S28-S42.
Reid, G. (1991). "Solar total irradiance variations and the global sea surface temperature record." Journal of Geophysical Research 96: 2835-2844.
Ropelewski, C.F. and Halpert, M.S. (1986). "North America precipitation and temperature patterns associated with the El Niño-Southern Oscillation (ENSO)." Monthly Weather Review 114: 2352-2362.
Rosholt, J.N., Doe, B.R. and Tatsumoto, M. (1966). "Evolution of the Isotopic Composition of Uranium and Thorium in Soil Profiles." Geological Society of America Bulletin 77: 987.
Rosholt, J. (1982). "Mobilization and weathering. In: Uranium-series Disequilibrium: Application to Environmental Problems. Ivanovich, M., Harmon, R.S. (Eds.) Oxford Sciences Publications, Oxford.167–180.
Sani, R.K., Peyton, B.M., Amonette, J.E. and Geesey, G.G. (2004). "Reduction of uranium(VI) under sulfate-reducing conditions in the presence of Fe(III)-(hydr)oxides." Geochimica et Cosmochimica Acta 68: 2639-2648.
Sarin, M.M., Krishnaswami, S., Somayajulu, L.K. and Moorer, W.S. (1990). "Chemistry of uranium, thorium, and radium isotopes in the Ganga-Brahmaputra river system Weathering processes and fluxes to the Bay of Bengal." Geochimica et Cosmochimica Acta 54: 1387-1396.
Schmeide, K., Pompe, S., Bubner, M., Heise, K.H., Bernhard, G. and Nitsche, H. (2000). "Uranium (VI) sorption onto phyllite and selected minerals in the presence of humic acid." Radiochimica Acta 88: 723-728.
Shukla, J. and Paolino, D.A. (1983). "The Southern Oscillation and long-range forecasting of the summer monsoon rainfall over India." Monthly Weather Review 111: 1830-1837.
Somayajuku, B.L.K. and Goldberg, E.D. (1966). "Thorium and uranium isotopes in seawater and sediments" Earth and Planetary Science Letters 1: 102-106.
Suresh, P.O., Dosseto, A., Handley, H.K. and Hesse, P.P. (2014). "Assessment of a sequential phase extraction procedure for uranium-series isotope analysis of soils and sediments." Applied Radiation and Isotopes 83: 47-55.
Suresh, P.O., Dosseto, A., Hesse, P.P. and Handley, H.K. (2013). "Soil formation rates determined from Uranium-series isotope disequilibria in soil profiles from the southeastern Australian highlands." Earth and Planetary Science Letters 379: 26-37.
Swarzenski, P., Campbell, P., Porcelli, D. and McKee, B. (2004). "The estuarine chemistry and isotope systematics of 234,238U in the Amazon and Fly Rivers." Continental Shelf Research 24: 2357-2372.
Tripathi, R.M., Sahoo, S.K., Mohapatra, S., Lenka, P., Dubey, J.S. and Puranik, V.D. (2012). "Study of uranium isotopic composition in groundwater and deviation from secular equilibrium condition." Journal of Radioanalytical and Nuclear Chemistry 295: 1195-1200.
Vigier, N., Bourdon, B., Turner, S. and Allègre, C.J. (2001). "Erosion timescales derived from U-decay series measurements in rivers." Earth and Planetary Science Letters 193: 549-563
Walling, D.E., Collins, A.L. and Sichingabula, H.M. (2003). "Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in small Zambian catchment." Geomorphology 52: 193–213.
Wang, R.M. and You, C.F. (2013). "Uranium and strontium isotopic evidence for strong submarine groundwater discharge in an estuary of a mountainous island: A case study in the Gaoping River Estuary, Southwestern Taiwan." Marine Chemistry 157: 106-116.
Welch, S.A. and Ullman, W.J. (1993). "The effect of organic acids on plagioclase dissolution rates and stoichiometry." Geochimica et Cosmochimica Acta 57: 2725-2736.
Wu, Y.C. (2008). "Material flux and cycling in riverine-estuary system: a constraint from decay-series disequilibria in Pearl-River sediments." Unpublished Doctoral Dissertation. University of Cheng Kung, Taiwan.
Yang, W., Guo, L., Chuang, C.Y., Schumann, D., Ayranov, M. and Santschi, P.H. (2013). "Adsorption characteristics of 210Pb, 210Po and 7Be onto micro-particle surfaces and the effects of macromolecular organic compounds." Geochimica et Cosmochimica Acta 107: 47-64.
Zhou, H. Y., Peng, X.T. and Pan, J.M. (2004). "Distribution, source and enrichment of some chemical elements in sediments of the Pearl River Estuary, China." Continental Shelf Research 24: 1857-1875.
Zuyi, T., Jinzhou, D. and Jun, L. (1996). "Use of the ion exchange method for determination of stability constants of uranyl ions with three soil fulvic acids." Radiochimica Acta 72: 51-54.
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