Table 2.

Pearson correlation among trace elements and matrix of the principal component analysis (PCA) loadings for three farmland soils. KMO indexes of grain field, orchard, and vegetable patch were 0.68, 0.61 and 0.66 in PCA, respectively.

	Correlation analysis								PCA
	As	Cd	Cr	Hg	Pb	Cu	Zn	Ni	PC1	PC2	PC3
Grain field									31.88%	26.89%	20.00%
As	1								0.73	− 0.38	− 0.46
Cd	0.59**	1							0.89	0.08	− 0.14
Cr	− 0.32*	0.02	1						− 0.02	0.97	− 0.06
Hg	− 0.19	− 0.13	− 0.31*	1					0.02	− 0.36	0.78
Pb	0.74**	0.43**	0.02	− 0.28*	1				0.68	− 0.09	− 0.42
Cu	0.40**	0.69**	0.05	0.15	0.09	1			0.85	0.14	0.36
Zn	− 0.37**	− 0.21	0.18	0.39**	− 0.22	0.20	1		− 0.01	0.22	0.75
Ni	− 0.36**	0.10	0.93*	− 0.20	− 0.13	0.21	0.21	1	0.05	0.97	0.10
Orchard									45.13%	17.00%	13.32%
As	1								0.16	0.08	0.92
Cd	0.06	1							0.21	0.75	0.04
Cr	0.18*	0.31**	1						0.90	0.05	0.16
Hg	0.21*	0.52**	0.15	1					− 0.04	0.85	0.27
Pb	0.25*	0.30**	0.54**	0.01	1				0.78	0.15	0.05
Cu	− 0.04	0.33**	0.41**	0.30**	0.49**	1			0.60	0.50	− 0.03
Zn	0.04	0.53**	0.21*	0.49**	0.50**	0.67**	1		0.37	0.78	− 0.19
Ni	0.14	0.36**	0.91**	0.30**	0.51**	0.54**	0.45**	1	0.87	0.26	0.08
Vegetable patch									35.58%	23.34%	13.10%
As	1								− 0.05	0.76	0.18
Cd	0.17**	1							0.58	0.40	0.17
Cr	0.02	0.43**	1						0.94	− 0.01	− 0.06
Hg	0.20**	0.29**	0.01	1					− 0.04	0.63	0.23
Pb	0.49**	0.46**	0.46**	0.29**	1				0.42	0.73	− 0.04
Cu	0.20**	0.29**	0.18**	0.39**	0.28**	1			0.16	0.22	0.87
Zn	0.42**	0.19**	0.06	0.16**	0.09	0.69**	1		− 0.01	0.16	0.91
Ni	− 0.04	0.41**	0.85**	− 0.06	0.40**	0.11*	0.02	1	0.94	− 0.09	0.02

All p values from Bartlett's Test of Sphericity < 0.001. The eigenvalues > 1 were extracted.

**Correlation is significant at the 0.01 level (2-tailed).

* Correlation is significant at the 0.05 level (2-tailed).