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利用外标法对大气CO_2及其δ~13C进行标定,并对3种不同的δ~13C(CO_2)标定方法进行比对评估,结果表明:FTIR和G2201i(WS-CRDS)在观测大气CO_2时均表现出较好的精度及线性相关性,而在观测δ~13C时,Allan方差结果显示相较于G2201i,FTIR具有更好的稳定性;经标气标定后CO_2观测结果准确度大大提高,待测目标气CO_2浓度误差不超过±0.05×10~(-6),FTIR和G2201i标定结果之间无显著差异(不超过±0.05×10-6);由两套系统直接测得的δ~13C值存在较大误差,经标定后其结果误差显著减小,FTIR由3种标定方法计算的结果误差均在±0.1‰以内,3种标定方法无显著差异;G2201i由第2种和第3种标定方法计算的结果误差也在±0.1‰以内,而第1种标定方法计算的结果误差则在±(0.1~0.2)‰之间。
The atmospheric CO 2 and δ 13 C were calibrated by external standard method, and the calibration of three different δ 13 C (CO 2) methods was evaluated. The results showed that FTIR and G2201i (WS-CRDS) The results of Allan variance show that FTIR has better stability than that of G2201i at the observation of δ ~ 13C; the accuracy of CO_2 observation after standard gas calibration is greatly improved, The error of CO 2 concentration in the target gas to be measured does not exceed ± 0.05 × 10 -6, no significant difference (≤ ± 0.05 × 10 -6) between the calibration results of FTIR and G2201i; 13C value has a big error, after calibration, the result error is significantly reduced. The error of FTIR calculated by three calibration methods is less than ± 0.1 ‰, and there is no significant difference among the three calibration methods. G2201i consists of the second and third The calibration error of the calibration method is within ± 0.1 ‰, while the calibration error of the first calibration method is between ± (0.1 ~ 0.2) ‰.