Natural Background Level and Contamination of Shallow Groundwater Salinity in Various Aquifers in a Coastal Urbanized Area, South China

Table 4

Principal component (PC) loadings for proportions of groundwater salinity contamination and socioeconomic parameters in various cities in the Pearl River Delta

Items	PCs
	PC1	PC2	PC3	PC4
GDP	0.990	−0.06	−0.051	−0.057
DSD	0.975	0.07	0.055	−0.188
PD	0.966	0.16	−0.136	−0.109
RUA	0.940	0.062	−0.243	0.019
IE	0.833	0.482	−0.159	0.13
PGSC^a	0.095	0.956	0.104	0.136
TVE	−0.075	0.943	0.111	−0.276
IWD	0.386	0.819	−0.247	0.081
LO	−0.051	−0.113	0.976	−0.098
AO	−0.207	0.153	0.949	−0.008
LD	−0.142	−0.017	−0.083	0.985
Eigenvalue	4.7	2.8	2.1	1.1
Explained variance (%)	42.4	25.3	18.7	10.5
Cumulative % of variance	42.4	67.7	86.4	96.8

^a PGSC: proportion of groundwater salinity contamination. Bold numbers represent maximum absolute PC loading of one parameter.