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.

From: Variability in plant trace element uptake across different crops, soil contamination levels and soil properties in the Xinjiang Uygur Autonomous Region of northwest China

 

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

  1. All p values from Bartlett's Test of Sphericity < 0.001. The eigenvalues > 1 were extracted.
  2. **Correlation is significant at the 0.01 level (2-tailed).
  3. * Correlation is significant at the 0.05 level (2-tailed).
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