AMS测定～(36)Cl研究灰岩的侵蚀速率
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摘要
~(36)Cl是一种长寿命放射性核素,它广泛存在于大气圈和岩石圈中。通过测定灰岩样品中的~(36)Cl含量,可以计算灰岩的侵蚀速率以及暴露年龄。但灰岩中的~(36)Cl含量很低,目前,加速器质谱(ANS)是测量灰岩中~(36)Cl的唯一有效的方法。研究不同环境下的侵蚀速率对科学和经济来说,都是很重要的。此研究方法可以推广到地壳的隆升和断代等,以及拓展加速器质谱(AMS)在环境样品中的应用。
灰岩中的~(36)Cl主要来源于以下几种反应:
~(40)Ca(n,2n3p)~(36)Cl;~(35)Cl(n,γ)~(36)Cl;~(40)Ca(μ,α)~(36)Cl。
在灰岩顶部数米范围内,前两种反应占主导地位。随着深度的增加,由~(40)Ca的负μ介子俘获反应产生的~(36)Cl的贡献会相应地增大。
地表灰岩中宇宙成因核素的浓度(N)要受到侵蚀(ε)的限制。对于侵蚀速率恒定的简单情况来说,宇宙成因核素~(36)Cl在灰岩表面中的浓度(N)由下列方程给出:
式中:N为经过暴露时间t时、灰岩表面以下深度z(米)处宇宙成因核素~(36)Cl的浓度(原子/克),λ为~(36)Cl的衰变常数(年~(-1)),ε为侵蚀速率(米/年),P(z)为~(36)Cl的总产生率(原子/(克·年))。据此,我们得到北京地区灰岩表面的侵蚀速率为(1.33±0.28)×10~(-5)米/年。
本论文研究内容主要包括以下五个部分:第一部分是侵蚀概述;第二部分是~(36)Cl的来源及利用~(36)Cl进行侵蚀速率计算的定量模型;第三部分是灰岩样品的采集和待测样品AgCl的制备,在此过程中主要是降低~(36)S的含量以减小在~(36)Cl测量过程中的干扰。同时,在AgCl样品制备的过程中需加适量的氯化物(NaCl)载体;第四部分是~(36)Cl的AMS测定。此工作是在中国原子能院串列加速器和日本Tsukuba大学的加速器上完成的;第五部分是结果与讨论。
~36Cl, the long-lived radioactive nuclide distributes abroad in atmosphere and lithosphere. By measuring the concentration of ~36C1 in limestone, the erosion rates and exposure ages of limestone can be determined. In recent years, Accelerator Mass Spectrometry (AMS) is the only effective tool to measure ~36C1 in limestone. It is very significant for science and economy to study the erosion rate of different circumstance .This technology and method can be extended to study the flourishing of the earth's crust and to judge the age of something and even can help to extend the applications of AMS in circumstance science.In the case of ~36C1 in limestone, the most important reactions are the followings:~40Ca(n, 2n3p)~36Cl; ~ 35Cl(n, γ)~36C1; ~40Ca(μ, α)~36ClIn the top meter of the limestone, the reactions of ~40Ca(n,2n3p)~36Cl and ~35Cl(n, γ )~36C1 are dominant. Following the depth increases, the contribution from slow μ capture by ~40Ca becomes progressively more important.As for as a radioactive nuclide ~36C1, its concentration in limestone can be expressed reasonably by the equation:
Where, P-the total production of ~36C1; N-the concentration of ~36C1; λ -the decay constant of 36C1; z-the depth of sample; t- exposure age; e- erosion rate. According to this equation , the erosion rate of limestone in Beijing City has been calculated and the erosion rate is (1.33 ± 0.28) × 10~-5m.a~-1.The article is composed of five sections. First, the review about erosion rate. Second, the origin of ~36C1 and the theory about calculation of erosion rate. Third, collecting of limestone samples and making of AgCl. For the AgCl sample preparation, the carrier of Cl is added to the limestone solution and a chemical procedure is used to reduce the abundance of sulfur. Fourth, AMS measurement, it is completed at CIAE-AMS system and Tsukuba university AMS system in Japanese. Fifth, conclusions and discussions.The author mainly do the following work: grasping the mechanism by which the cosmogenic nuclide of chlorine-36 produce, preparing and making the sample of AgCl, as a participant of AMS measurement, last but not least, searching for a reasonable math model and calculating erosion rate.
灰岩中的~(36)Cl主要来源于以下几种反应:
~(40)Ca(n,2n3p)~(36)Cl;~(35)Cl(n,γ)~(36)Cl;~(40)Ca(μ,α)~(36)Cl。
在灰岩顶部数米范围内,前两种反应占主导地位。随着深度的增加,由~(40)Ca的负μ介子俘获反应产生的~(36)Cl的贡献会相应地增大。
地表灰岩中宇宙成因核素的浓度(N)要受到侵蚀(ε)的限制。对于侵蚀速率恒定的简单情况来说,宇宙成因核素~(36)Cl在灰岩表面中的浓度(N)由下列方程给出:
式中:N为经过暴露时间t时、灰岩表面以下深度z(米)处宇宙成因核素~(36)Cl的浓度(原子/克),λ为~(36)Cl的衰变常数(年~(-1)),ε为侵蚀速率(米/年),P(z)为~(36)Cl的总产生率(原子/(克·年))。据此,我们得到北京地区灰岩表面的侵蚀速率为(1.33±0.28)×10~(-5)米/年。
本论文研究内容主要包括以下五个部分:第一部分是侵蚀概述;第二部分是~(36)Cl的来源及利用~(36)Cl进行侵蚀速率计算的定量模型;第三部分是灰岩样品的采集和待测样品AgCl的制备,在此过程中主要是降低~(36)S的含量以减小在~(36)Cl测量过程中的干扰。同时,在AgCl样品制备的过程中需加适量的氯化物(NaCl)载体;第四部分是~(36)Cl的AMS测定。此工作是在中国原子能院串列加速器和日本Tsukuba大学的加速器上完成的;第五部分是结果与讨论。
~36Cl, the long-lived radioactive nuclide distributes abroad in atmosphere and lithosphere. By measuring the concentration of ~36C1 in limestone, the erosion rates and exposure ages of limestone can be determined. In recent years, Accelerator Mass Spectrometry (AMS) is the only effective tool to measure ~36C1 in limestone. It is very significant for science and economy to study the erosion rate of different circumstance .This technology and method can be extended to study the flourishing of the earth's crust and to judge the age of something and even can help to extend the applications of AMS in circumstance science.In the case of ~36C1 in limestone, the most important reactions are the followings:~40Ca(n, 2n3p)~36Cl; ~ 35Cl(n, γ)~36C1; ~40Ca(μ, α)~36ClIn the top meter of the limestone, the reactions of ~40Ca(n,2n3p)~36Cl and ~35Cl(n, γ )~36C1 are dominant. Following the depth increases, the contribution from slow μ capture by ~40Ca becomes progressively more important.As for as a radioactive nuclide ~36C1, its concentration in limestone can be expressed reasonably by the equation:
Where, P-the total production of ~36C1; N-the concentration of ~36C1; λ -the decay constant of 36C1; z-the depth of sample; t- exposure age; e- erosion rate. According to this equation , the erosion rate of limestone in Beijing City has been calculated and the erosion rate is (1.33 ± 0.28) × 10~-5m.a~-1.The article is composed of five sections. First, the review about erosion rate. Second, the origin of ~36C1 and the theory about calculation of erosion rate. Third, collecting of limestone samples and making of AgCl. For the AgCl sample preparation, the carrier of Cl is added to the limestone solution and a chemical procedure is used to reduce the abundance of sulfur. Fourth, AMS measurement, it is completed at CIAE-AMS system and Tsukuba university AMS system in Japanese. Fifth, conclusions and discussions.The author mainly do the following work: grasping the mechanism by which the cosmogenic nuclide of chlorine-36 produce, preparing and making the sample of AgCl, as a participant of AMS measurement, last but not least, searching for a reasonable math model and calculating erosion rate.
引文
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[3] Olley, J. M., Murry. Identifying Sediment Sources in a Gullied Catchment Using Natural and Anthropogenic Radioactivity. Water Resources Research, 1993,26(4): 1037-1043.
[4] 张信宝,赫吉特,D.L 沃林 D.E.~(137)Cs法测算黄土高原土壤侵蚀速率的初步研究.地球化学,1991,3:212-218.
[5] 李小龙,苏春江,白立新等.小流域泥沙来源的~(226)Ra分析法.山地研究,1995,13(3),199-202.
[6] 马建国,柴之芳,毛雪英等.可活化稳定同位素示踪法研究泥沙运动初探.和技术,1990,3(10):612-616.
[7] 王秀玉,曾尔康,万玉松等。应用~(210)pb测定鄱阳湖底泥砂的沉积速率.核技术,1987,10(27):15-18.
[8] 桑海清,第四纪地质年代学和定年方法及其应用.质谱学报,1997,18(2)
[9] Alvarez L W, Cornog R.. ~3He in Helium.Phys Rev, 56(1939):379-383.
[10] Bennett C.l., Beuken R.P, et al..Science, 1977198,508.
[11] Nelson D.E.,Korteling R.G.,et al.Science. 198,507,1977.
[12] Muller R A. Radioisotope Dating with a cyclotron. Science, 1977,196:489～494.
[13] 蒋崧生.加速器质谱学研究工作进展[J].青岛大学学报,1997,10(2).
[14] 马配学,郭之虞,李坤.~(10)Be和~(26)Al就地产率与在地表岩石中浓度的定量模型.地球物理学进展,1998.13(1):101-114.
[15] 同参考文献14
[16] YiouF, Raisbeck G M, Klein and Middleton R.~(26)Al/~(10)Be in terrestrial impact glasses.J. NonCryst.Solids, 1984,67,503-519.
[17] Gosse J C, Klein J, Evenson E B, Lawn B and Middleton R. ~(10)Be dating of the duration and retreat of the last Pinedal Glacial sequence.Science, 1995,268:1329-1333.
[18] Nishiizumi K, Kohl C P ,Shoemaker E M ,Arnold J R, Klein J, Fink D and MiddletonR. In situ ~(10)Be and ~(26)Al exposure ages at Meteor Crater, Arizona. Geochimca et Cosmochimica Acta, 1990, 53, 2699-2703.
[19] Lal D and Peters B. Cosmic ray produced radioactivity on the earth .In: Handbuch der Physik, ⅩL Ⅵ/2,Springer, Berlin, 1967,551-612.
[20] 黄麒.~(36)Cl断代法.第四纪研究,1997.8(3).
[21] 孔屏.宇宙成因核素在地球科学中的应用.地学前缘,2002.9(3).
[22] LAL D. Cosmic ray Labeling of erosion surface; In-situ nuclide production rates and erosion models [J].Earth Planet Sci Lett, 1991,104:424-439.
[23] 徐孝彬,王建,Francoise Yiou,Grant Raisbeck..地貌学与第四纪研究的新手段-陆地宇生 核素.地理科学,2002.22(5).
[24] 万军伟,刘存富,王增银,王佩仪等.用~(36)Cl研究灰岩侵蚀速率的理论和方法.地球科学.中国地质大学学报,2002.27(2)
[25] Marek G.. Zreda, Fred M.Phillips David Elmore. Cosmogenic chlorine-36 rates in terrestrial rocks .Earth and Planetary Science Letters, 1991,105:94-109.
[26] J.Stone ,G.L.Allan,L.K.Fifield, J.M.Evans and A.R.Chivas .Nucl.Instr.Meth B 92(1994)311.
[27] F.M.Phillips, M.G.Zreda, M.R.Flinsch, et al, Geophys.Res.Lett. submitted for publication.
[28] H.Bilokon,G.Cini Castagnoli, A Catellina, B.D.Ettore Piazzoli,et al,Res, 94(1989) 145.
[29] T.Von Egidy and F.J.Hartman. Phys Rev.A26(1982)2355.
[30] J.D.Knight, C.J.Orth, M.E.Schiallaci, R.A.Naamann, F.J.Hartmann, J.J.Reidy and H.Schneuwly.Phys.Lett,79A(1980)315.
[31] M.Eckhouse, R.T.Siegel, R.E.Welsh and T.A.Filippas.Nucl,Phys.81 (1966)575.
[32] E.Strack, B.Heisinger, B.Dockhorn,F.J.Hartmann,G.Korschinek, E.Nolte,et al.Nucl. Instr and Meth B 92(1994)317.
[33] B.Heisinger, M.Niedermayer, F.J.Hartman et al.In-situ production of radionuclides at great depths.Nucl.Instr and Meth in phys.Res B 123(1997)341-346.
[34] G.T.Zatsepin,A.V.Kopylov and E.K.Shirokova, Sov.J.Nucl.Phys.33(1981)200.
[35] Lal D.In situ-production of terrestrial cosmogenic rocks. Annual Review of Earth and Planetary .Science,1988,16:355-388.
[36] Nuclear Instruments and Methods in Physics Research B52(1990)608-611.
[37] 王夔.生命科学中的微量元素分析与数据手册.北京:中国计量出版社,1998.53-80.
[38] R.A.Dayras,R.G.Stokstad and Z.E.Switkowski et.al .Nucl.Phys A261 (1976)478.
[39] P.R.Christensen, Z.E.Switkowski and R.A.Dayras,.Nucl.Phys A280(1977)189.
[40] R.G.Stokstad, Z.E.Switkowski and R.A.Dayras, et.al. Phys.Rev.lett 37(1976)888.
[41] 卢希庭.原子核物理[M].北京:原子能出版社,1981.192—193.
[42] J.E.Mcaninch, G.S.Bench et al. PXAMS-Projectile X-ray AMS:X-ray Yields and Application .Nucl.Instr.Meth.B99(1995)519-523.
[43] 蒋崧生,姜山,马铁军等.科学通报,37(1992)505.
[44] S.S.Jiang, S.Jiang, H.Guo,et al. Nucl.Instr Meth B 92(1994)61.
[45] 姜山,蒋崧生,郭宏.核技术 27(1993) 393.
[46] 周炼,刘存富,姜山等.矿物岩石地球化学通报,2001,20(4):418.
[47] L.K.Fifield,T.R.Bird, et al.The Chlorine-36 Measurement Program at the Australian National University. Nucl.Instr. Meth.B29(1987) 114-119.
[48] D.L.Knies, D.Elmore, et al.. ~7Be, ~(10)Be and ~(36)Cl in Precipititation. Nucl.Instr. Meth. B 92(1994) 134.
[49] B.Heisinger, E.Nolte .Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates [J]. Nucl Instr and Meth in Phys Res, 2000, B 172: 790-795.
[2] Knaus,R.M.,et al. Accretion and canal impacts in a rapidly subsiding wetland .Ⅲ A new soil horizon maker method for measuring recent accretion .Estuaries, 1989,12(4):269-283.
[3] Olley, J. M., Murry. Identifying Sediment Sources in a Gullied Catchment Using Natural and Anthropogenic Radioactivity. Water Resources Research, 1993,26(4): 1037-1043.
[4] 张信宝,赫吉特,D.L 沃林 D.E.~(137)Cs法测算黄土高原土壤侵蚀速率的初步研究.地球化学,1991,3:212-218.
[5] 李小龙,苏春江,白立新等.小流域泥沙来源的~(226)Ra分析法.山地研究,1995,13(3),199-202.
[6] 马建国,柴之芳,毛雪英等.可活化稳定同位素示踪法研究泥沙运动初探.和技术,1990,3(10):612-616.
[7] 王秀玉,曾尔康,万玉松等。应用~(210)pb测定鄱阳湖底泥砂的沉积速率.核技术,1987,10(27):15-18.
[8] 桑海清,第四纪地质年代学和定年方法及其应用.质谱学报,1997,18(2)
[9] Alvarez L W, Cornog R.. ~3He in Helium.Phys Rev, 56(1939):379-383.
[10] Bennett C.l., Beuken R.P, et al..Science, 1977198,508.
[11] Nelson D.E.,Korteling R.G.,et al.Science. 198,507,1977.
[12] Muller R A. Radioisotope Dating with a cyclotron. Science, 1977,196:489～494.
[13] 蒋崧生.加速器质谱学研究工作进展[J].青岛大学学报,1997,10(2).
[14] 马配学,郭之虞,李坤.~(10)Be和~(26)Al就地产率与在地表岩石中浓度的定量模型.地球物理学进展,1998.13(1):101-114.
[15] 同参考文献14
[16] YiouF, Raisbeck G M, Klein and Middleton R.~(26)Al/~(10)Be in terrestrial impact glasses.J. NonCryst.Solids, 1984,67,503-519.
[17] Gosse J C, Klein J, Evenson E B, Lawn B and Middleton R. ~(10)Be dating of the duration and retreat of the last Pinedal Glacial sequence.Science, 1995,268:1329-1333.
[18] Nishiizumi K, Kohl C P ,Shoemaker E M ,Arnold J R, Klein J, Fink D and MiddletonR. In situ ~(10)Be and ~(26)Al exposure ages at Meteor Crater, Arizona. Geochimca et Cosmochimica Acta, 1990, 53, 2699-2703.
[19] Lal D and Peters B. Cosmic ray produced radioactivity on the earth .In: Handbuch der Physik, ⅩL Ⅵ/2,Springer, Berlin, 1967,551-612.
[20] 黄麒.~(36)Cl断代法.第四纪研究,1997.8(3).
[21] 孔屏.宇宙成因核素在地球科学中的应用.地学前缘,2002.9(3).
[22] LAL D. Cosmic ray Labeling of erosion surface; In-situ nuclide production rates and erosion models [J].Earth Planet Sci Lett, 1991,104:424-439.
[23] 徐孝彬,王建,Francoise Yiou,Grant Raisbeck..地貌学与第四纪研究的新手段-陆地宇生 核素.地理科学,2002.22(5).
[24] 万军伟,刘存富,王增银,王佩仪等.用~(36)Cl研究灰岩侵蚀速率的理论和方法.地球科学.中国地质大学学报,2002.27(2)
[25] Marek G.. Zreda, Fred M.Phillips David Elmore. Cosmogenic chlorine-36 rates in terrestrial rocks .Earth and Planetary Science Letters, 1991,105:94-109.
[26] J.Stone ,G.L.Allan,L.K.Fifield, J.M.Evans and A.R.Chivas .Nucl.Instr.Meth B 92(1994)311.
[27] F.M.Phillips, M.G.Zreda, M.R.Flinsch, et al, Geophys.Res.Lett. submitted for publication.
[28] H.Bilokon,G.Cini Castagnoli, A Catellina, B.D.Ettore Piazzoli,et al,Res, 94(1989) 145.
[29] T.Von Egidy and F.J.Hartman. Phys Rev.A26(1982)2355.
[30] J.D.Knight, C.J.Orth, M.E.Schiallaci, R.A.Naamann, F.J.Hartmann, J.J.Reidy and H.Schneuwly.Phys.Lett,79A(1980)315.
[31] M.Eckhouse, R.T.Siegel, R.E.Welsh and T.A.Filippas.Nucl,Phys.81 (1966)575.
[32] E.Strack, B.Heisinger, B.Dockhorn,F.J.Hartmann,G.Korschinek, E.Nolte,et al.Nucl. Instr and Meth B 92(1994)317.
[33] B.Heisinger, M.Niedermayer, F.J.Hartman et al.In-situ production of radionuclides at great depths.Nucl.Instr and Meth in phys.Res B 123(1997)341-346.
[34] G.T.Zatsepin,A.V.Kopylov and E.K.Shirokova, Sov.J.Nucl.Phys.33(1981)200.
[35] Lal D.In situ-production of terrestrial cosmogenic rocks. Annual Review of Earth and Planetary .Science,1988,16:355-388.
[36] Nuclear Instruments and Methods in Physics Research B52(1990)608-611.
[37] 王夔.生命科学中的微量元素分析与数据手册.北京:中国计量出版社,1998.53-80.
[38] R.A.Dayras,R.G.Stokstad and Z.E.Switkowski et.al .Nucl.Phys A261 (1976)478.
[39] P.R.Christensen, Z.E.Switkowski and R.A.Dayras,.Nucl.Phys A280(1977)189.
[40] R.G.Stokstad, Z.E.Switkowski and R.A.Dayras, et.al. Phys.Rev.lett 37(1976)888.
[41] 卢希庭.原子核物理[M].北京:原子能出版社,1981.192—193.
[42] J.E.Mcaninch, G.S.Bench et al. PXAMS-Projectile X-ray AMS:X-ray Yields and Application .Nucl.Instr.Meth.B99(1995)519-523.
[43] 蒋崧生,姜山,马铁军等.科学通报,37(1992)505.
[44] S.S.Jiang, S.Jiang, H.Guo,et al. Nucl.Instr Meth B 92(1994)61.
[45] 姜山,蒋崧生,郭宏.核技术 27(1993) 393.
[46] 周炼,刘存富,姜山等.矿物岩石地球化学通报,2001,20(4):418.
[47] L.K.Fifield,T.R.Bird, et al.The Chlorine-36 Measurement Program at the Australian National University. Nucl.Instr. Meth.B29(1987) 114-119.
[48] D.L.Knies, D.Elmore, et al.. ~7Be, ~(10)Be and ~(36)Cl in Precipititation. Nucl.Instr. Meth. B 92(1994) 134.
[49] B.Heisinger, E.Nolte .Cosmogenic in situ production of radionuclides: Exposure ages and erosion rates [J]. Nucl Instr and Meth in Phys Res, 2000, B 172: 790-795.