Abundance ratios as a function of the galactocentric distance. Our sample of Cepheids (blue circles) is compared with our sample of open clusters (symbols color-coded according to the stellar age). The Fe and O abundance ratios are taken from Magrini et al. (2023), whereas the S abundances are taken from the present work. The black line displays a linear regression fitted to Cepheids in the range of galactocentric distance from 4 to 12.5 kpc, and the dashed line is the extrapolation up to 17 kpc. The red line shows a logarithmic fit over the whole range of galactocentric distances. The corresponding equations are also shown. The shaded area shows one standard deviation around the running mean, weighted with a Gaussian function taking the errors into account.