Table 2. Metal accumulation factors (mean ± standard deviation) of the most abundant perennial species in the center tailing of Nacozari.

Accumulation factors are calculated as element concentration in leaves/element concentration in the rhizosphere.

Plant species	Baccharis sarotroides	Gnaphalium leucocephalum	Brickellia coulteri	Acacia farnesiana	Prosopis velutina
Element
Cu	0.26 ± 0.10	0.8 ± 0.31	0.22 ± 0.08	0.44 ± 0.15	0.51 ± 0.24
Fe	0.006 ± 0.002	0.13 ± 0.06	0.01 ± 0.005	0.04 ± 0.15	0.05 ± 0.02
K	1.32 ± 0.43	2.35 ± 0.56	1.57 ± 0.30	0.68 ± 0.16	0.63 ± 0.32
Mn	0	3.44 ± 2.40	1.25 ± 0.65	0	0
Mo	0.23 ± 0.06	0.27 ± 0.08	0.19 ± 0.05	0.26 ± 0.06	0.22 ± 0.03
Rb	0.24 ± 0.08	0.38 ± 0.23	0.21 ± 0.07	0.21 ± 0.03	0.17 ± 0.04
Sr	0.58 ± 0.62	0.52 ± 0.33	0.51 ± 0.13	0.97 ± 1.0	2.20 ± 1.9
Zn	3.45 ± 3.6*	9.11 ± 8.5*	1.7 ± 2.6	1.6 ± 1.9	1.55 ± 2.8
Zr	0.06 ± 0.03	0.11 ± 0.03	0.05 ± 0.006	0.07 ± 0.005	0.064 ± 0.008

Notes.

Mean ratios (leaves/rhizosphere) for all species were evaluated using a χ² test.

^*Ratios that were significantly greater than 1.