Proportion (%)

Cr

Cd

Zn

Ni

Pb

As

Hg

Cu

F

Rainfall and fallen dust

80.76

85.76

67.55

22.66

22.86

66.44

67.04

57.22

31.19

Irrigation

13.17

12.28

29.97

75.39

72.30

26.02

23.09

38.87

18.80

fertilization

5.93

1.95

2.47

1.95

4.72

7.59

8.81

3.90

50.01

Pesticides

0.15

0.003

0.001

0.006

0.003

0.015

0.010

0.011

0.02