. 2021 Mar 2;28(26):34621–34629. doi: 10.1007/s11356-021-13083-6

Table 2.

Correlation coefficient among various indicators in 30 provinces of China

Indicators	CH^a	SO₂^a	NO₂^a	CO^a	O₃^a	T^a	Pb^b	Hg^b	As^b	Cd^b
CH^a	1.000	0.107	0.307	−0.068	0.435*	0.233	0.156	−0.084	0.058	0.148
SO₂^a		1.000	0.406*	0.619^#	0.144	−0.534^#	−0.025	−0.009	−0.047	0.005
NO₂^a			1.000	0.465^#	0.473^#	−0.368^#	−0.337	−0.333	−0.403*	−0.323
CO^a				1.000	0.001	−0.345	0.157	0.251	0.085	0.143
O₃^a					1.000	−0.028	−0.034	−0.124	−0.139	−0.012
T^a						1.000	0.301	0.181	0.200	0.273
Pb^b							1.000	0.803^#	0.924^#	0.916^#
Hg^b								1.000	0.805#	0.834^#
As^b									1.000	0.913^#
Cd^b										1.000

*p<0.05; ^# p<0.01

^aVariables obey normal distribution, the correlation coefficient according to Pearson bivariate analysis

^bVariables do not obey normal distribution, the correlation coefficient between b and a or b according to Spearman bivariate analysis