土壤温室气体测定方法研究进展

A review of methods for measuring soil greenhouse gases

土壤温室气体测量方法复杂多样,不同方法之间的差异性为土壤温室气体测量带来较多不确定性,综合评估比对各类方法有助于提高测量土壤温室气体的准确性,进而对研究温室气体源汇机理、制定排放清单和减排措施具有重要意义.本文通过对国内外温室气体测量研究文献的梳理,总结常用的土壤温室气体观测方法:箱法/碱液吸收法、箱法/气相色谱法、箱法/吸收光谱法、微气象学法、土壤浓度廓线法、稳定同位素法等,系统阐述常用土壤温室气体测量方法的原理、优缺点、不确定性以及改进历程,分析其使用特点与范围.几乎每种方法都有其优势和局限性,箱法操作简单,目前应用较为广泛,但密闭静态箱对观测有一定的扰动,而微气象法对观测下垫面均有极为严格的要求,同位素法更精确,但价格昂贵,难以广泛使用.目前传统测量方法存在实验过程复杂、研究成本高、精度低、不可原位、参数有限等问题,未来土壤温室气体测量的仪器更注重与新技术的结合使用,例如连续量子级联合激光器(CW-QCL)与可调谐二极管激光吸收光谱技术(TDLAS)及波长调制技术(WMS)的结合,向着原位无损、长时间、全参数、高精度、便携式、一体化、自动化和远程操控等方向发展.

Differences across a diverse range of methods cause many uncertainties for soil greenhouse gas measurement.Therefore,a comprehensive comparison and evaluation of available methods is needed to help improve the accuracy of soil greenhouse gas measurement.The accurate measurement of greenhouse gas emissions from the soil is necessary for a better understanding of their source and sink mechanisms,formulating an emission inventory,and implementing emission reduction measures.Based on the principles of the assays,common soil greenhouse gas measurement methods were divided into box/alkali absorption methods,box/gas chromatography,box/absorption spectrometry,micro-meteorology methods,soil concentration profile methods,and stable isotope methods.The principle,advantages and disadvantages,uncertainties,application scope,and development history of the different measurement methods for soil greenhouse gases,identified from a search of the literature,were systematically discussed.Almost every method has advantages and limitations.For example,the box method is simple to operate and widely used at present;however,this closed static box method makes certain observations difficult.Almost all the micrometeorological methods have extremely strict requirements for the underlying surface.Although the isotope method is more accurate,it is too expensive to be widely used.Traditional measurement methods have many problems,such as a complicated experimental process,high cost,low precision,inability to be used in situ,and limited measurable parameters.Future developments of soil greenhouse gas measurement instruments should focus on combinations of new technology,such as the Continuous Wave-Quantum Cascade Laser(CW-QCL) combined with the Tunable Diode Laser Absorption Spectroscopy(TDLAS) and Wavelength Modulation Spectroscopy(WMS) techniques.New instruments should be able to perform in situ measurements over a long period of time,measure all parameters,and be precise and portable;moreover,they should be capable of integration,automation,and remote control.