摘要
植物叶片、茎秆和土壤水δ18O和δD是研究土壤植被大气系统生态水文循环过程的重要示踪剂。与传统的稳定同位素质谱(IRMS)技术相比,稳定同位素红外光谱(IRIS)技术具有测量速度快、运行成本低等优势,将促进稳定同位素生态学的发展。但是利用低温真空蒸馏抽提技术获得的植物叶片和茎秆水中含有甲醇和乙醇类有机污染物,造成δ18O和δD的IRIS测量值偏离IRMS测量值(2.64±0.43)‰和(3.6±0.8)‰,超过了仪器精度。本研究利用纯水混入不同浓度的色谱纯甲醇或乙醇,结合Los Gatos公司的光谱分析软件确定甲醇(NB)和乙醇(BB)类物质污染程度的光谱度量值,建立了δ18O和δD的光谱污染校正方法。研究表明,同一台分析仪建立的校正曲线无明显的时间漂移;不同分析仪建立的校正曲线存在显著差异;IRIS校正值与IRMS测量值的交叉验证表明,IRIS测定冬小麦和夏玉米叶片和茎秆水的δ18O和δD可以被准确地校正,与IRMS的差值分别为(0.11±0.12)‰和(0.7±0.4)‰。
There is considerable interest in the use of δ18O and δD of leaf（δL）,xylem（δX） and soil water（δS） as important tracers in analyzing the role of terrestrial biosphere in eco-hydrological cycle.Isotope ratio infrared spectroscopy（IRIS） has emerged as a faster,more cost-effective and field-deployable method for water stable isotope analysis.However,previous studies have also demonstrated the potential for large errors in IRIS.These errors included considerable deviation from isotope ratio mass spectrometry（IRMS） values in the range of（2.64±0.43）‰ for δ18O and（3.6±0.8）‰ for δD when water stable isotopes were cryogenically extracted from plants/soils with methanol/ethanol-based organic contaminants.As this study focused mainly on establishing correction methods,deionized water spiked with varying amounts of methanol（MeOH,10~800 μL.L 1） and ethanol（EtOH,2~40 mL.L 1） was used to create correction curves for δ18O and δD associated with metrics of narrow-band（MeOH,NB） contamination and broad-band（EtOH,BB） determined using Spectral Contamination Identifier（of Los Gatos Research Inc.software,United States）.The results showed that while no significant time drift（P 0.01） existed in correction curves of liquid water δ18O and δD analyzer（Los Gatos Research Inc.）,it varied significantly from other analyzers（P 0.01）.The lightly contaminated（NB 4 000 and BB 1.2） δLand δXof winter wheat（Triticum aestivum L.） and summer maize（Zea mays L.） were accurately corrected.The mean differences in isotope ratios between corrected IRIS and measured IRMS were（0.11±0.12）‰ for δ18O and（0.7±0.4）‰ for δD.The study discussed the necessity for further validation of the established correction methods for highly contaminated samples（NB 4 000 or BB 1.2）.It recommended cross-validation between corrected IRIS and measured IRMS using random investigation of small amounts of each unknown species of plants or soils.
出处
《中国生态农业学报》
CAS
CSCD
北大核心
2012年第10期1359-1365,共7页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(91125002
31070408)
中国科学院知识创新工程重要方向项目青年人才项目(KZCX2-EW-QN305)资助
