Fig. 6.

Using ICP-MS technology detected 23 kinds of trace element ion levels, roughly divided into 3 groups of main elements: macroelements (Na, Mg, K, Ca), essential trace elements (Fe, Zn, B, Cu, Mn, Ni, Ba, Sb, Se, Ti, and V), and toxic trace elements (Al, Li, As, Cd, Pd, Sn, and Sr). The ∗ indicates significant differences (∗P < 0.05, ∗∗P < 0.002, ∗∗∗P < 0.0002, ∗∗∗∗P < 0.0001) between the 2 groups, and the data are presented as the mean ± SD (n = 6). ICP-MS = inductively coupled plasma mass spectroscopy.