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应用生态学报 ›› 2021, Vol. 32 ›› Issue (6): 1963-1970.doi: 10.13287/j.1001-9332.202106.019

• 稳定同位素生态学专栏 • 上一篇    下一篇

聚四氟乙烯塑料管研磨法对测定C4植物碳同位素比值的影响

李蕾1,2, 汪旭明1,2, Rudi Schäufele3, 蔡炳贵1, 巩晓颖1,2*   

  1. 1福建师范大学地理科学学院, 湿润亚热带生态-地理过程教育部重点实验室, 福州 350007;
    2福建省植物生理生态重点实验室, 福州 350007;
    3慕尼黑工业大学生命科学学院, Freising 85354
  • 收稿日期:2021-01-09 接受日期:2021-04-16 发布日期:2021-12-15
  • 通讯作者: * E-mail: xgong@fjnu.edu.cn
  • 作者简介:李 蕾, 女, 1986年生, 实验师。主要从事稳定同位素技术和生态学研究。E-mail: ll0710@fjnu.edu.cn
  • 基金资助:
    国家自然科学基金项目(31870377)和广东省自然科学基金项目(2018A030313450)资助

Influence of ball milling with PTFE plastic tube on carbon isotope ratio measurement of C4 plants.

LI Lei1,2, WANG Xu-ming1,2, Rudi Schäufele3, CAI Bing-gui1, GONG Xiao-ying1,2*   

  1. 1Key Laboratory of Humid Subtropical Eco-Geographical Processes of the Ministry of Education, College of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China;
    2Fujian Provincial Key Laboratory of Plant Ecophysiology, Fuzhou 350007, China;
    3School of Life Sciences, Technical University of Munich, Freising 85354, Germany
  • Received:2021-01-09 Accepted:2021-04-16 Published:2021-12-15
  • Contact: * E-mail: xgong@fjnu.edu.cn
  • Supported by:
    National Natural Science Foundation of China (31870377) and Guangdong Natural Science Foundation (2018A030313450).

摘要: 聚四氟乙烯(PTFE)塑料管研磨法是测定植物碳同位素比率(δ13C)值常用的前处理方法。该方法处理样品高效快捷,但对植物δ13C可能存在污染。本研究利用人工气候室开展双因素交互试验,包括空气相对湿度(50%和80%)和空气δ13C(13C富集和贫化的空气)两个因素,对比了PTFE塑料管研磨法和不锈钢管研磨法处理C4植物糙隐子草δ13C的结果。结果表明: 在相同湿度条件下,不同空气δ13C处理的植物13C分馏值(Δ13C,矫正了光合作用底物的δ13C差异)原本可以视为重复,但由于PTFE塑料颗粒的混入,相同湿度不同13C丰度空气培养下植物叶片Δ13C平均差值为4.8‰。该污染效应导致单个叶片δ13C测定的误差高达8‰。考虑到C4植物的Δ13C较低(通常为1‰~8‰),这种污染效应已经超出了可以接受的误差范围。通过建立类似Keeling曲线的二元混合模型对误差进行了有效消除,并准确估算了植物样品和污染物的δ13C。说明广泛采用的PTFE管研磨方法对研究C4植物Δ13C并不适用,将导致较大的误差。对精度要求较高的研究内容建议使用不锈钢瓶进行研磨。

关键词: 球磨仪, 塑料污染, 稳定碳同位素, 二元混合模型, 水分利用效率, 同位素样品制备

Abstract: Before the measurement of stable carbon isotope signatures (δ13C), plant samples should be well homogenized. Using a ball-mill fitted with poly tetra fluoroethylene (PTFE) plastic tubes is one of the most efficient and convenient methods. However, sample-tube plastic might contaminate plant samples during milling. In this study, a two-factor experiment was carried out using four growth chambers, with different relative humidity of the air (50% and 80%) and δ13C of the air (13C depleted and enriched). Leaf samples of Cleistogenes squarrosa (C4) were milled and homogenized using a ball-mill fitted with PTFE tubes and measured for δ13C, and the results were compared with that of leaf samples milled using metal tubes. Due to plastic contamination, 13C discrimination (Δ13C) of the two groups of plants, which were grown in CO2 with different δ13C and could be assumed as replicates, were significantly different (with an offset of 4.8‰ on average). The contamination led to errors in δ13C of individual leaves up to 8‰. Given the lower Δ13C value of C4 plants (normally about 1‰-8‰) compared with that of C3 plants, such an error caused by plastic contamination far exceeded the acceptable error range. By using a two-member mixing model that was similar to the ‘Keeling plot', such errors could be effectively eliminated, and the δ13C of plant samples and pollutants were accurately estimated. Our results showed that the widely applied method of using PTFE tubes for ball-mill homogenization is not suitable for examining Δ13C of C4 plants, as it might lead to large errors. For studies with high precision requirements, samples should be milled in stainless-steel tubes.

Key words: ball-mill, plastic contamination, stable carbon isotope, two-member mixing model, water use efficiency, pretreatment of isotope samples