2.3 Soil metallomics analysis
In this study, the concentrations of Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Kr, and Pb in soil samples were detected by Inductively coupled plasma-mass spectrometry (ICP-MS). Shortly, 0.5 g of the soil samples were digested with 1 mL HCl, 1 mL HF, and 3 mL HNO3 at 150 ℃ for 8 hours, then raise the temperature to 200 ℃ to remove the acid. The remaining ash was resuspend using 10 mL 2% diluted HNO3 before using ICP-MS to detect metals concentrations.