Abundances in the thin-disc (left column) and thick-disc (right column) stars of the main sample as a function of galactocentric radii. The lines (solid black for main and dashed red for clean samples) mark the linear fit to the data. Grey points mark the abundances of stars. Black squares show the mean value of stars in R_GC bins with standard deviations as error bars (every bin contains at least 8 points).