Method and system for high-resolution determination of organic carbon isotopes in stalagmite

Abstract

The invention discloses a method and a system for high-resolution determination of organic carbon isotopes in stalagmite. The method comprises the following steps: loading a stalagmite powder sample into an inverted Y-shaped sample bottle; at the bottom of a first branch, adding 1 mol / L of hydrochloric acid into the stalagmite powder sample; after chromic acid is added to the bottom of a second branch, screwing a bottle pad and a bottle cap which are used for sealing to the first branch; connecting the first branch with a vacuum pipeline of a vacuum system; separating the vacuum system from the first branch, and then inserting a double-hole needle into the bottle cap and the bottle pad; filling the sample bottle with helium through the double-hole needle; fully mixing chromic acid in the second branch with the acidified stalagmite powder sample in the first branch; and inserting the double-hole needle into the bottle cap and the bottle pad. Organic CO2 flowing through a silver wire purification tube is enriched and purified, and then is introduced into a mass spectrometer to determine the carbon isotope composition, so that high-resolution determination of the organic carbon isotope in the stalagmite powder sample is realized.

Description

technical field [0001] The invention relates to the field of mass spectrometry detection, in particular to a method and system for high-resolution determination of organic carbon isotopes in stalagmites. Background technique [0002] Due to its precise dating and multiple proxy indicators, stalagmites have become very important carriers in the field of paleoclimate and paleoenvironmental research. The main component of stalagmites is calcium carbonate, and the carbon and oxygen isotopes are mainly derived from the respiration of plants or CO produced by the decomposition of plant residues 2 , which is usually used to reflect changes in ancient vegetation, and then used to reconstruct the paleoenvironment. [0003] There are two main sources of carbon pools in stalagmites: inorganic carbon in calcium carbonate and carbon in organic matter. At present, the existing technology mainly uses stalagmite inorganic carbonate carbon isotope as a commonly used surrogate indicator. Th...

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Problems solved by technology

In terms of system structure, if the sample bottle in CN109557225B is used, and the oxidant is added to the sample bottle through the bottle pad with a syringe, the organic matter in the bottle pad may be oxidized and brought into the sample to cause pollution, and it will also affect the bottle pad. sealing effect, which is also clearly not suitable for high-resolution determination of organic carbon isotopes in stalagmites

Moreover, there are many interfering elements in the stalagmite organic carbon isotope determination process, and the purification step in CN109557225B will not remove these elements

In addition, since the sample ring in CN109557225B does not have a liquid nitrogen cold trap, it requires a large amount of sample (at least 150 micrograms of stalagmite powder is required, corresponding to 15 micrograms of C), and if the stalagmite wants to contribute 15 micrograms of organic C, then Nearly 150mg of stalagmite powder is required, so CN109557225B cannot realize high-resolution sampling of stalagmites

[0010] In general, the various methods provided in the prior art require a relatively large amount of samples, and are not conducive to the application of stalagmite high-resolution organic carbon isotope records in paleoenvironment

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