Chemical abundance patterns at z=1-7: Carbon, Nitrogen, Neon, Sulphur, and Argon abundances from JWST spectroscopy

The relative abundances of chemical elements in the interstellar medium (ISM) trace the history of star formation and chemical enrichment in galaxies. We investigate the abundance patterns of carbon (C), nitrogen (N), neon (Ne), sulfur (S), and argon (Ar) in star-forming galaxies at z=1-7, combining ultra-deep JWST/NIRSpec observations from the MARTA survey with archival spectroscopy. We assemble 244 galaxies with [OIII]4363 detections and derive direct Te-based abundances. New empirical strong-line calibrations for N/O, Ne/O, S/O, and Ar/O extend the analysis to an additional 514 galaxies. We find distinct abundance-metallicity trends. N/O is enhanced by 0.18 dex in median relative to local galaxies, with a stronger enhancement at low metallicity. Direct measurements reveal decreasing S/O and Ar/O with increasing metallicity, while strong-line measurements suggest a flattening at higher metallicities, especially for S/O. We also identify a stellar-mass dependence in the O/Ar-Ar/H plane, with lower-mass galaxies exhibiting lower O/Ar at fixed Ar/H, consistent with differences in star-formation efficiency and delayed SNe Ia enrichment. Ne/O remains approximately constant up to 12+log(O/H)=8.2, with a mild increase at higher metallicities and no significant redshift evolution. C/O tentatively increases with metallicity, broadly following the local relation. Finally, a forward model shows that observational selection affects the abundance ratios differently: it mainly restricts the accessible metallicity range for Ne/O and Ar/O, but preferentially selects galaxies with enhanced N/O at low metallicity, with a weaker effect for S/O. These results provide new constraints on chemical enrichment at high redshift and highlight the importance of accounting for selection effects when interpreting abundance-metallicity trends.