Fig. 2From: Rare earth element geochemistry in soils along arid and semiarid grasslands in northern Chinaa Relative geochemical fractions (carbonate-bound, reducible, oxidizable and residue) of rare earth elements (REE) vs. aridity index (AI) in topsoils (0–10 cm). b Upper continental crust (UCC) normalized patterns of bulk REE in topsoils (0–10 cm) along the northern China transect (S01–S21)Back to article page