Impact of the observed chemical inhomogeneities on the Galactic gradients. Left panels: azimuth-averaged radial distribution for sample A in bins of 650 pc and excluding those with fewer than 20 stars. From top to bottom, we represent the excess of [Ca/Fe] and [Ca/H] in an azimuth-averaged radial distribution based on the currently known locations of the Galactic disc arms and inter-arm from the density distribution of the stars of the sample. Right panels: same as the left panels, but now for sample C, using bins of 350 pc in galactocentric radius R. Bins with fewer than 200 stars were excluded.