Table 2 Pearson correlations between water-soluble ions for normal and dust storm days from March 1, 2021, to May 31, 2021 in Lanzhou, China.

From: Water-soluble ions and source apportionment of PM2.5 depending on synoptic weather patterns in an urban environment in spring dust season

Days

Ions

Na+

NH4+

K+

Mg2+

Ca2+

F

Cl

NO3

SO42−

Normal

Na+

1.00

        

NH4+

− 0.01

1.00

       

K+

0.14

0.72**

1.00

      

Mg2+

0.09

− 0.1

0.21

1.00

     

Ca2+

− 0.01

− 0.11

0.24*

0.90*

1.00

    

F

− 0.16

− 0.11

0.18

0.23

0.35*

1.00

   

Cl

− 0.28*

0.34**

0.62**

0.24*

0.30*

0.51**

1.00

  

NO3

0.03

0.94**

0.65**

− 0.10

− 0.11

− 0.08

0.20

1.00

 

SO42−

0.23

0.72**

0.56**

0.22

0.15

− 0.10

0.18

0.63**

1.00

Dust

Na+

1.00

        

NH4+

0.55*

1.00

       

K+

0.91**

0.74**

1.00

      

Mg2+

0.92**

0.58*

0.91**

1.00

     

Ca2+

0.93**

0.59*

0.95**

0.96**

1.00

    

F

-0.06

0.25

0.11

− 0.06

0.03

1.00

   

Cl

0.70**

0.83**

0.89**

0.78**

0.79**

0.32

1.00

  

NO3

0.38

0.89**

0.57*

0.44

0.39

0.12

0.64*

1.00

 

SO42−

0.92**

0.72**

0.97**

0.91**

0.97**

0.08

0.84*

0.49

1.00

  1. *p < 0.05; **p < 0.01.