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Automated, Low-Power Chamber System for Measuring Nitrous Oxide Emissions
Continuous measurement of soil emissions is needed to constrain estimates of N2O loss to the atmosphere. Here, we describe the performance of a low-power, automated chamber system that can continuously measure N2O soil emissions, powered by wind and solar power. Laboratory testing of the Teledyne N2O analyzer revealed significant temperature sensitivity, causing zero drift of -10.6 ppb °C-1. However, temperature induced span drift is negligible, so the associated error in flux measurement for a typical chamber sampling period is on the order of only 0.016 nmol m-2 s-2. The 1 Hz precision of the analyzer over a 10 minute averaging interval, following wavelet decomposition, was 1.5 ppbv, equal to that of a tunable diode laser N2O analyzer. The power system performed well during summer, but system failures increased in frequency in spring and fall, usually at night. Although increased storage capacity would decrease down time, supplemental power from additional sources may still be needed to continuously run the system during spring and fall. The cumulative hourly flux data were used to assess the accuracy of integrated estimates derived from manually sampling static chambers at various frequencies (once every 4 days up to every 22 days) and at various times during the day. For all frequencies, cumulative estimates using only afternoon measurements were 15% to 43% greater than estimates using only morning measurements. Only the 7 and 19 day sampling frequencies happened to capture a spike in emissions following heavy rain on September 23, emphasizing the importance of continuous sampling.
John M Baker
greenhouse gas emissions
Journal of Environmental Quality 2013 v.42 no.2
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
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