Eddy covariance measurements of CH4 and N2O using quantum cascade laser spectrometry on peat lands
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A quantum cascade laser was evaluated for eddy covariance measurements of CH4 and N2O using laboratory tests and three months of continuous measurements. Moreover, an indication was given of CH4 and N2O exchange. All four required criteria for EC-measurements related to continuity, sampling frequency, precision and stationarity were checked. The system had been running continuously using an automatic liquid nitrogen filling system at a dairy farm on peat grassland in the Netherlands from August 17th to November 6th 2006. A sampling frequency of 10 Hz was obtained and a precision of 2.6 and 0.3 ppb Hz-1/2 was obtained for CH4 and N2O, respectively. However, it was important to calibrate the equipment frequently using a low and a high standard. Drift in the system was removed using a 120 s running mean filter. Average fluxes of 464 ± 485 ngC m-2s-1 (2.23 ± 2.33 mg m-2hr-1) and 38 ± 64 ngN m-2s-1 (0.21 ± 0.36 mg m-2hr-1) were observed. About 40% of the total N2O emission was due to a fertilizing event. Besides, uptake of CH4 and N2O occurred in short periods of 30 to 180 minutes.
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TNO Identifier
845748
Publisher
ECN
Collation
2 p.
Place of publication
Petten
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