Risk assessment of heavy metal soil pollution through principal components analysis and false color composition in Hamadan Province, Iran

Environmental Systems Research

Table 7 Results of spatial correlation analysis and the fitted models

Element	No. sample	Interpolation method	Model	Nugget (C₀) (mg/kg)	Partial sill (C) (mg/kg)	Sill (C₀+C) (mg/kg)	Major range (km)	Mean	RMS	Root- mean standardized	Trend	MAE (mg/kg)	MBE (mg/kg)	Anisotropy
															Isotropy
As	286	Disjunctive kriging	Exponential	0.4	0.8	1.2	106	0.076	7.085	1.16	no	5.13	0.076		344.5
Zn	286	Disjunctive kriging	Exponential	0.36	0.54	0.9	29.39	−0.059	14.6	1.046	no	11.48	0.059	*
Cu	286	Radial basis function	-	-	-	-	-	.068	9.3	-	-	7.42	0.045	-	-
V	286	Disjunctive kriging	Exponential	0.31	0.6	0.91	16.919	−0.92	19.22	1.003	no	14.85	.094	*
Ni	286	Ordinary kriging	Spherical	177.29	437.7	614.99	178	.034	15.98	1.068	no	12.54	.34	*
Co	286	Ordinary kriging	Exponential	7.89	10.67	18.56	178.01	0.0005	3.21	1.025	no	2.53	0.005	*
Pb	286	Disjunctive kriging	Exponential	0.39	0.49	0.88	13.49	0.018	6.68	1.09	no	4.06	0.018	*
Cd	286	Radial basis function	-	-	-	-	-	0.002	0.097	-	-	0.67	0.002	-	-
Fe	286	Disjunctive kriging	Exponential	0.52	0.7	1.22	123.97	0.0005	0.58	1.05	no	0.46	0.00005	*
Cr	286	Ordinary kriging	Exponential	241	669	910	178	0.006	20	1.11	no	16.25	0.006	*
Sb	286	Ordinary kriging	Exponential	0.086	0.111	0.197	178	0.042	0.35	1.14	-	0.74	0.0048		325.5