A Model Study of Formaldehyde formation Under Reducing Conditions

抄録

Formaldehyde (HCHO) was a significant precursor for forming atmospheric organic molecules in the early Earth. And HCHO could have been produced by photochemical reactions[1]. Besides, the atmosphere in the Archean era was weakly reducing with less sunlight intensity than the present atmosphere. To understand the evolution of our Earth, in this study, we investigated the atmospheric formation of HCHO in the Archean using a 1D photochemical model. The model named PATMO[2] consists of 56 chemical species and 412 chemical reactions which simulated the atmosphere from surface to 100 km in 100 years. This model considered the attenuation of sunlight and the photodissociation reaction rate over time which helps estimate the photochemical HCHO concentration in the Archean. The results show that photochemical HCHO in Archean atmosphere ranging from 0.0002 to 0.017 ppm. The maximum HCHO concentration occurred at an altitude of 61 km corresponding to the maximum level of H2O in the Archean atmosphere.