Water and organic matter D/H ratios in the solar system: a record of an early irradiation of the nebula?

Water and organic molecules are intimately mixed in the primitive planetary objects of the solar system such as Meteorites and Comets. In few rare examples, the D/H ratios of both water and organic matter (OM) have been measured independently. A critical review of these data are presented. on the comparison between the water and OM D/H ratios, it seems possible that the origin of the deuterium enrichment in the solar system is linked to an early X-ray irradiation of the protosolar nebula, where ion–molecule reactions took place at the very surface of the disk.