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Research on Measurement of Lead Isotopes in Corals with HR-ICP-MS

Author: DaiJie
Tutor: ZuoJianGuo
School: East China Normal University
Course: Environmental Science
Keywords: High Resolution Inductively Coupled Plasma Mass Spectrometry Coral Lead Isotope ratios Separation and enrichment
CLC: X830
Type: Master's thesis
Year: 2010
Downloads: 115
Quote: 0
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Abstract

Lead has become one of the most widely distributed pollutants in the environment due to the rapid industrial development, automobile exhaust emissions, coal combustion, waste incineration, as well as industrial \sources. Pb Pb isotopic composition of natural substances not subject to the influence of the chemical or physical processes that lead has a different fingerprint characteristics of different ore sources environment can retrospectively according to their specific isotope ratio - \sources. Corals, because of the growth rings of trees similar, that is an excellent carrier record lead changes in the tropical marine historic environment. Therefore, the determination of lead isotope ratios in different years coral, can be traced to the sources of lead in the historical period of the marine environment, and to explain the impact of human activities on the environment. Coral reefs are mainly formed by the coral skeleton, calcium carbonate and magnesium carbonate content of up to 95%, very low content of trace heavy metal (as Pb :0-1μg / g), the direct determination of these difficult using conventional instruments trace amounts of heavy metals in high matrix samples need to be taken to the the appropriate sample separation enrichment technology for pre-treatment. The same time, the coral aragonite lattice Pb can really reflect the pollution particular year, it must be on the corals steps of cleaning to ensure the accuracy of the measurement results. Long sequence of the paper by the method and the optimization of the experimental conditions, screening out the coral samples Prepared an accurate and reliable method of cleaning and separation enrichment Pb sample pre-treatment technology, to carry out the coral Pb isotopic ratios to The Pb pollution situation in the reconstruction of the marine environment provides a reliable analysis techniques and methods to trace the source of pollution. Concluded as follows: (1) to establish the accurate determination of Pb isotope ratios using HR-ICP-MS method. Comparison of different correction methods, we found that the use of an external standard to be able to maximize the mass discrimination correction HR-ICP-MS determination process, such a method of determination of Pb isotope ratios accurate error lt; 0.015% precision RSD of 0.04% -0.1%. (2) matrix effects on the accurate determination of trace elements (determination of isotope ratios) has caused great difficulties. Internal standard elements Rh in Pb Determination of mass discrimination can be corrected to some extent, but the correction capability is limited. The accurate determination of coral in the Pb isotope ratios must be high matrix Ca and trace elements Pb, effective separation of the inhibitory effect of the matrix is ??reduced to a minimum or not affect, in order to ensure the reliability of the measurement results. (3) the establishment of the the Hainan Orange Porites (porites lutea) sample preparation method, MQ water cleaning, and, ultimately, the state of the samples of the coral aragonite lattice Pb 0.02 mol / L HNO3 washing, cleaning and oxide reduction cleaning / Ca 15nmol/mol. (4) On the basis of the self-made miniature ion exchange column, screening and coral resin AG1-X8 anion exchange separation and enrichment of trace elements Pb pretreatment methods on the previous three types eluent (6mol/LHCl 0.5mol / L HNO3 containing 0.25mol / L HBr MQ water) and the experimental envisaged 0.5mol/LHNO3 comparison found 0.5mol / L HNO3 elution best results, the method the full blank value 18pg 208pb, 207pb, 206pb recoveries were 99.8%, 100.4% and 100.1%, and joint HR-ICP-MS technology, determination of coral samples 207pb/206pb 0.8505, RSD 0.12%, 208pb/206pb to 2.0870, and the RSD 0.11% Pb pollution in the marine environment to provide a reliable analysis techniques and methods to carry out a study of the long time series of Pb in coral reconstruction.

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