Fig. 5. Cross-sectional view of horizontal and vertical As content (mg/kg) distributions. (a) Drilling stations in the west–east direction. (b) Drilling stations in the north–south direction. The dotted and solid lines represent the tops of the aquitards and the aquifers, respectively. The solid triangles represent the locations at which the cores were sampled. The number on the top of each figure specifies the drilling station.