Fig. 1: Concentrations of soil organic carbon (SOC), amorphous and crystalline iron minerals (Feamorphous and Fecrystalline), selenium (Se), arsenic (As) and sulfur (S) along the Kohala rainfall gradient.
Correspondence between soil horizons and soil depths is given in Supplementary Table 1. The concentrations of Feamorphous and Fecrystalline (b and c) were measured by Helfenstein et al.67 on sampled soil horizon A and B without triplicate and thus no standard deviation value is available. The concentrations of SOC (a) and of total Se, As, and S (d–f) were determined in triplicate for each analyzed soil depth samples, and the presented standard deviations (error bars) consider both the analytical standard deviation (resulting from the analysis in triplicate) and the standard deviation resulting from averaging the measured concentrations for soil depth samples to obtain the concentrations for soil A and B horizons. Invisible error bars for SOC, Se, As, and S concentrations mean that they are within the symbol.
