RADIOCARBON STEP-COMBUSTION OXIDATION METHOD AND FTIR ANALYSIS OF TRONDHEIM CaCO3 PRECIPITATES OF ATMOSPHERIC CO2 SAMPLES: FURTHER INVESTIGATIONS AND INSIGHTS

IF 2 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Radiocarbon Pub Date : 2023-12-12 DOI:10.1017/rdc.2023.106

Guaciara M Santos, Christopher A Leong, Pieter M Grootes, Martin Seiler, Helene Svarva, Marie-Josée Nadeau

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Abstract

Eight atmospheric carbon dioxide samples (as calcium carbonate—CaCO3—precipitates) from Lindesnes site (58ºN, 7ºE), belonging to 1963 and 1980 (four samples from each year) and stored at the National Laboratory for Age Determination (NTNU), have been reevaluated through radiocarbon (14C) analysis. Previous 14C results indicated the presence of a contaminant, which was not removed through different chemical cleansing procedures (e.g., hydrochloric acid—HCl and/or hydrogen peroxide—H2O2). Here, we present a follow up investigation using 14C step-combustion and Fourier-transform infrared spectroscopy (FTIR) analysis. Results from 14C data indicate unsuccessful removal of the contaminant, while further FTIR analysis displayed the presence of moisture. This finding alludes to the possibility that the contaminant is of ambient air-CO2 deeply embedded in CaCO3 powders (within clogged CaCO3 pores and/or bonded to the lattice). Samples were found exposed to air-CO2 and humidity. These conditions may have lasted for years, possibly even decades, leading to the 14C offsets detected here.

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对大气二氧化碳样品的 TRONDHEIM CaCO3 预沉淀物的放射性碳梯级凝聚氧化法和傅立叶分析：进一步的研究和见解

通过放射性碳（14C）分析，对林德内斯遗址（北纬 58 度，东经 7 度）1963 年和 1980 年（每年四个样本）储存在国家年龄测定实验室（NTNU）的八个大气二氧化碳样本（碳酸钙-CaCO3-沉淀物）进行了重新评估。之前的 14C 分析结果表明存在污染物，但通过不同的化学净化程序（如盐酸-HCl 和/或过氧化氢-H2O2）也无法去除污染物。在此，我们利用 14C 梯度燃烧和傅立叶变换红外光谱（FTIR）分析进行了后续调查。14C 数据的结果表明，污染物的去除并不成功，而进一步的傅立叶变换红外光谱分析则显示出水分的存在。这一发现表明，污染物可能是深藏在 CaCO3 粉末中的环境空气-CO2（在堵塞的 CaCO3 孔隙中和/或与晶格结合）。发现样品暴露在空气-CO2 和湿度中。这些条件可能已持续数年，甚至数十年，从而导致在此检测到 14C 偏移。

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来源期刊

Radiocarbon 地学-地球化学与地球物理

CiteScore

16.20

自引率

6.00%

发文量

审稿时长

6-12 weeks

期刊介绍： Radiocarbon serves as the leading international journal for technical and interpretive articles, date lists, and advancements in 14C and other radioisotopes relevant to archaeological, geophysical, oceanographic, and related dating methods. Established in 1959, it has published numerous seminal works and hosts the triennial International Radiocarbon Conference proceedings. The journal also features occasional special issues. Submissions encompass regular articles such as research reports, technical descriptions, and date lists, along with comments, letters to the editor, book reviews, and laboratory lists.