UCAMM nitrogen abundances relative to carbon (atomic ratio) are compared to solar system solids: meteorites (Kerridge 1985; Alexander et al. 2007, green and purple circles, respectively; labels correspond to meteorites groups as reported in these articles), the Bulk Silicate Earth (BSE, Bergin et al. 2015), and the interstellar medium (see text for details). Left: reported in function of bulk nitrogen weight fraction; right: reported in function of heliocentric distance. Figure A.1 summarizes the distance, N/C, and N weight fraction information in a single plot. UCAMMs values are reported in Table B.1.