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Based on the Kaiser criterion only two PCs can be retained and have eigenvalues greater than 1 (Kaiser 1958). However, after a number of tests, three PCs were extracted explaining 84% of the total variance in the data set (Table 1).

Table 1

PC loadings and explained variance for three components with Varimax rotation

Parameter	PC1	PC2	PC3
Ca²⁺	0.168	0.650	0.667
Mg²⁺	0.524	0.625	0.428
Na⁺	0.916	0.104	0.182
K⁺	0.824	0.139	0.123
HCO₃⁻	0.007	0.933	−0.139
Cl⁻	0.783	−0.001	0.381
SO₄²⁻	0.331	−0.099	0.878
Eigenvalue	3.69	1.40	0.79
Explained variance (%)	52.67	20.10	11.30
Cumulative % of variance	52.67	72.72	83.98

Parameter	PC1	PC2	PC3
Ca²⁺	0.168	0.650	0.667
Mg²⁺	0.524	0.625	0.428
Na⁺	0.916	0.104	0.182
K⁺	0.824	0.139	0.123
HCO₃⁻	0.007	0.933	−0.139
Cl⁻	0.783	−0.001	0.381
SO₄²⁻	0.331	−0.099	0.878
Eigenvalue	3.69	1.40	0.79
Explained variance (%)	52.67	20.10	11.30
Cumulative % of variance	52.67	72.72	83.98

Variables with PC loadings greater than 0.6 are considered to be significant and are marked in bold.

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