Badea Silviu-Laurentiu, Botoran Oana Romina, Ionete Roxana Elena
National Research and Development Institute for Cryogenics and Isotopic Technologies-ICSI Rm. Valcea, 4th Uzinei Street, 240050 Râmnicu Vâlcea, Romania.
Plants (Basel). 2021 Dec 13;10(12):2743. doi: 10.3390/plants10122743.
In this work, the challenges and progression in stable isotope investigation, from the analytical tools and technical sample preparation procedures to the dendroclimatological experiments, were reviewed in terms of their use to assess tree physiological responses to environmental changes. Since the isotope signature of whole wood is not always a reliable tool in studying the climate changes, cellulose is often preferred as the study material in paleoclimatic studies. Nevertheless, the isotope analysis of cellulose is challenging due to the difficulty to remove the other wood components (extractives, lignin, pectin, and hemicelluloses). Additionally, in the case of hydrogen isotope analysis, about 30% of the hydrogen atoms of cellulose are exchanged with the surrounding water, which complicates the isotope analysis. In recent years, more automated isotope analysis methods were developed based on high temperature pyrolysis of cellulose, followed by the chromatographic separation of H from CO and by their individual isotope analysis using isotope ratio mass spectrometry. When used to investigate climate factors, the combined isotope analysis δC and δO appears to be the most promising isotope tool. In contrast, the role of δH values is yet to be elucidated, together with the development of new methods for hydrogen isotope analysis.
在这项工作中,从分析工具和技术样品制备程序到树木年轮气候学实验,对稳定同位素研究中的挑战和进展进行了综述,探讨了其在评估树木对环境变化的生理响应方面的应用。由于全木的同位素特征在研究气候变化时并不总是可靠的工具,因此在古气候研究中,纤维素常被优先选作研究材料。然而,纤维素的同位素分析具有挑战性,因为难以去除其他木材成分(提取物、木质素、果胶和半纤维素)。此外,在氢同位素分析中,纤维素中约30%的氢原子会与周围的水发生交换,这使同位素分析变得复杂。近年来,基于纤维素的高温热解,开发了更多自动化同位素分析方法,随后通过色谱法从CO中分离出H,并使用同位素比率质谱仪对其进行单独的同位素分析。当用于研究气候因素时,碳同位素和氧同位素的联合分析似乎是最有前景的同位素工具。相比之下,氢同位素值的作用以及氢同位素分析新方法的开发仍有待阐明。