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Dongmei Xue Bernard De Baets Jan Vermeulen Jorin Botte Oswald Van Cleemput Pascal Boeckx 《Rapid communications in mass spectrometry : RCM》2010,24(14):1979-1984
Currently, bacterial denitrification is becoming the accepted method for δ15N‐ and δ18O‐NO determination. However, proper correction methods with international references (USGS32, USGS34 and USGS35) are needed. As a consequence, it is important to realize that the corrected isotope values are derived from a combination of several other measurements with associated uncertainties. Therefore, it is necessary to consider the propagated uncertainty on the final isotope value. This study demonstrates how to correctly estimate the uncertainty on corrected δ15N‐ and δ18O‐NO values using a first‐order Taylor series approximation. The bacterial denitrification method errors from 33 batches of 561 surface water samples varied from 0.2 to 2.1‰ for δ15N‐NO and from 0.7 to 2.3‰ for δ18O‐NO, which is slightly wider than the machine error, which varied from 0.2 to 0.6‰ for δ15N‐N2O and from 0.4 to 1.0‰ for δ18O‐N2O. The overall uncertainties, which are composed of the machine error and the method error, for the 33 batches ranged from 0.3 to 2.2‰ for δ15N‐NO and from 0.8 to 2.5‰ for δ18O‐NO. In addition, the mean corrected δ15N and δ18O values of 132 KNO3‐IWS (internal working standard) measurements were computed as 8.4 ± 1.0‰ and 25.1 ± 2.0‰, which is a slight underestimation for δ15N and overestimation for δ18O compared with the accepted values (δ15N = 9.9 ± 0.3‰ and δ18O = 24.0 ± 0.3‰). The overall uncertainty of the bacterial denitrification method allows the use of this method for source identification of NO. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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