Ranking list of linear multiple regression models applied to describe the effect of main natural water ions on mercury removal efficiency by Akaike's Information Criterion (AIC).

Model elementsa	Coefficient	Standard error	T value	Pr(>|t|)	P-value
Intercept	105.47	5.23	20.15	0.0001	0.001
NO3−	0.70 (a)	0.43	1.62	0.120	0.1
SO42−	0.17 (b)	0.05	2.8	0.009	0.001
Cl−	0.31 (c)	0.08	3.66	0.001	0.001
HCO3−	0.15 (d)	0.04	3.51	0.002	0.001
Na+	−0.29 (e)	0.14	−1.95	0.064	0.05
K+	−0.47 (f)	−0.27	−1.75	0.093	0.05
Mg2+	−1.15 (g)	−0.29	−3.89	0.0008	0.001
Ca2+	−0.73 (h)	−0.15	−4.69	0.0001	0.001

^aMultiple R²: 0.81, adjusted R²: 0.73.