Correction to “Reanalysis of the Viking results suggests perchlorate and organics at midlatitudes on Mars”

摘要

In the paper “Reanalysis of the Viking results suggests perchlorate and organics at midlatitudes on Mars” by R. Navarro‐Gonzalez et al. (Journal of Geophysical Research, 115, E12010, doi:10.1029/2010JE003599), the concentrations of carbon dioxide (CO_2), oxygen (O_2), nitric oxide (NO), nitrous oxide (N_2O), benzene (C_6H_6), toluene (C6H5‐CH3), chloromethane (CH_3Cl) and dichloromethane (CH_2Cl_2), produced by thermal volatilization (TV) of Atacama soils with and without added perchlorate, were estimated from a calibration curve of carbon dioxide assuming that all chemical species would have a similar response to CO_2 by gas chromatography coupled to mass spectrometry (GC‐MS). This was an oversimplification and the concentrations of all species, except for carbon dioxide, should be taken as a first order of approximation, particularly since no calibration curves were done for each individual compound detected. A known amount of CO_2 was introduced into the pyrolyzer probe cavity by varying the gas pressure of a calibration mixture (396 ppm carbon dioxide in helium) inside a sampling gas loop of fixed volume at a constant room temperature. The volume of the sampling loop could be changed to increase/ decrease the amount of gas injected into the pyrolyzer cavity in the experiments. This volume was fixed for all experiments reported; however, it was incorrectly taken to be 40 cm3 when it was actually 10 cm3. This resulted in an over estimation of the concentration of all chemical species measured experimentally by a factor of 4 and reported in Figure 4. We have revised Figure 4 to show the actual estimated concentrations of CO_2, O_2, NO, N_2O, C_6H_6, C_6H_5‐CH_3, CH_3Cl and CH_2Cl_2. In addition, the conversion factor from organic carbon to benzene was incorrectly given as 1 ppm organic carbon = 6.5 ppm of benzene, when in fact, it is 1.1 ppm of benzene. This error was only made in the legend and does not alter any data cited in the main text of the paper. Figure 4 and its legend are completely revised.