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(δ^(13)C)值常用的前处理方法。该方法处理样品高效快捷,但对植物δ^(13)C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δ^(13)C(^(13)C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δ^(13)C的结果。结果表明:在相同湿度条件下,不同空气δ^(13)C处理的植物^(13)C分馏值(Δ^(13)C,矫正了光合作用底物的δ^(13)C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^(13)C丰度空气培养下植物叶片Δ^(13)C平均差值为4.8‰。该污染效应导致单个叶片δ^(13)C测定的误差高达8‰。考虑到C4植物的Δ^(13)C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δ^(13)C。说明广泛采用的PTFE管研磨方法对研究C4植物Δ^(13)C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。
Before the measurement of stable carbon isotope signatures(δ^(13)C),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%)andδ^(13)C of the air(^(13)C depleted and enriched).Leaf samples of Cleistogenes squarrosa(C4)were milled and homogenized using a ball-mill fitted with PTFE tubes and measured forδ^(13)C,and the results were compared with that of leaf samples milled using metal tubes.Due to plastic contamination,^(13)C discrimination(Δ^(13)C)of the two groups of plants,which were grown in CO2 with differentδ^(13)C and could be assumed as replicates,were significantly different(with an offset of 4.8‰on average).The contamination led to errors inδ^(13)C of individual leaves up to 8‰.Given the lowerΔ^(13)C 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 theδ^(13)C 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 examiningΔ^(13)C of C4 plants,as it might lead to large errors.For studies with high precision requirements,samples should be milled in stainless-steel tubes.
作者
李蕾
汪旭明
Rudi Schäufele
蔡炳贵
巩晓颖
LI Lei;WANG Xu-ming;Rudi Schäufele;CAI Bing-gui;GONG Xiao-ying(Key Laboratory of Humid Subtropical Eco-Geographical Processes of the Ministry of Education,College of Geographical Sciences,Fujian Normal University,Fuzhou 350007,China;Fujian Pro-vincial Key Laboratory of Plant Ecophysiology,Fuzhou 350007,China;School of Life Sciences,Technical University of Munich,Freising 85354,Germany)
出处
《应用生态学报》
CAS
CSCD
北大核心
2021年第6期1963-1970,共8页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(31870377)
广东省自然科学基金项目(2018A030313450)资助。
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
ball-mill
plastic contamination
stable carbon isotope
two-member mixing model
water use efficiency
pretreatment of isotope samples
