Improving correction quality for in-situ portable X-ray fluorescence (PXRF) using robust geographically weighted regression with categorical land-use types at a regional scale

•RGWR with land-use types (RGWR-LUT) was proposed to correct in-situ PXRF Pb.•The spatially varying correction coefficient surface was generated by RGWR-LUT.•RGWR-LUT obtained the highest correction quality than traditional correction models.•SGS-PXRF* was proposed to incorporate the corrected PXRF Pb for spatial simulation.•SGS-PXRF* obtained the highest spatial simulation quality.