An improved method for measuring soil N2O fluxes using a quantum cascade laser with a dynamic chamber
An improved method for measuring soil N2O fluxes using a quantum cascade laser with a dynamic chamber
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DOI：
10.1111/ejss.12168
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发表时间：
2014-09-01
影响因子：
4.2
通讯作者：
Skiba, U. M.
中科院分区：
文献类型：
--
作者：
Cowan, N. J.;Famulari, D.;Skiba, U. M.
通过使用量子级联激光（QCL），开发了一种动态室方法，以比以前更高的精度测量土壤中N2O的通量。动态方法与传统的静态室方法进行了比较，其中样品随后在气相色谱仪上进行分析。结果表明，由于QCL的精度和时间分辨率更高，动态方法能够测量土壤N2O通量，其不确定度通常小于1-2 μ g N2O- n m(-2) h (-1) (0.24-0.48 g N2O- n ha(-1) day(-1))，远远小于传统的静态室法。在室封闭期间，N2O和CO2浓度在1hz下的连续记录提供了对封闭时间和使用不同回归方法可能引入的影响的深入了解，当采用类似设计的静态室系统时。结果表明，长封闭时间会显著影响腔室通量测量的不确定度。非线性模型受长封闭时间的影响较小，但即使这些模型也不总是充分描述当封闭时间超过10分钟时观测到的浓度，特别是在通量大的情况下。
A dynamic chamber method was developed to measure fluxes of N2O from soils with greater accuracy than previously possible, through the use of a quantum cascade laser (QCL). The dynamic method was compared with the conventional static chamber method, where samples are analysed subsequently on a gas chromatograph. Results suggest that the dynamic method is capable of measuring soil N2O fluxes with an uncertainty of typically less than 1-2 mu g N2O-N m(-2) hour(-1) (0.24-0.48 g N2O-N ha(-1) day(-1)), much less than the conventional static chamber method, because of the greater precision and temporal resolution of the QCL. The continuous record of N2O and CO2 concentration at 1 Hz during chamber closure provides an insight into the effects that enclosure time and the use of different regression methods may introduce when employed with static chamber systems similar in design. Results suggest that long enclosure times can contribute significantly to uncertainty in chamber flux measurements. Non-linear models are less influenced by effects of long enclosure time, but even these do not always adequately describe the observed concentrations when enclosure time exceeds 10 minutes, especially with large fluxes.