Spatial Variation of Arsenic in Soil, Irrigation Water, and Plant Parts: A Microlevel Study

Table 4

(a) Comparison of variogram models for soil As. (b) Comparison of variogram models for straw As. (c) Comparison of variogram models for husk As. (d) Comparison of variogram models for grain As.

(a)

Parameters	Spherical	Exponential	Linear	Linear to sill	Gaussian
Range (m)	31.1	39.6	76.1	144.7	25.8
Lag distance	80	80	80	80	80
Lag interval	8	8	8	8	8
Nugget ()	0.290	0.010	3.125	3.140	1.060
Sill ( + )	5.548	5.732	6.379	9.287	5.541
Proportion of structural variance to total sampling variance: =	0.95	1.00	0.51	0.66	0.81
	5.0	0.0	49.0	34.0	19.0
	0.98	0.97	0.58	0.58	0.98
RSS	0.388	0.531	36.7	6.74	0.388
AIC	−555.75	−524.06	−96.25	−267.41	−555.75
Neighborhood	10	10	10	10	10

(b)

Parameters	Spherical	Exponential	Linear	Linear to sill	Gaussian
Range (m)	52.5	75.3	75.8	159.7	44.3
Lag distance	80	80	80	80	80
Lag interval	8	8	8	8	8
Nugget ()	0.028	0.001	0.156	0.158	0.096
Sill ( + )	0.459	0.505	0.535	0.949	0.458
Proportion of structural variance to total sampling variance: =	0.94	1.00	0.71	0.83	0.79
	6.0	0.0	29.0	14.0	21.0
	0.96	0.96	0.79	0.79	0.94
RSS	0.0068	0.0067	0.554	0.0324	0.0088
AIC	−964.20	−965.70	−519.78	−806.52	−938.16
Neighborhood	8	8	8	8	8

(c)

Parameters	Spherical	Exponential	Linear	Linear to sill	Gaussian
Range (m)	74.4	162.3	84.2	183.6	68.2
Lag distance	92.0	92.0	92.0	92.0	92.0
Lag interval	9.2	9.2	9.2	9.2	9.2
Nugget ()	0.059	0.055	0.105	0.107	0.098
Sill ()	0.312	0.397	0.349	0.614	0.317
Proportion of structural variance to total sampling variance: =	0.81	0.86	0.70	0.83	0.69
	18.9	13.9	30.1	14.4	30.9
	0.96	0.94	0.88	0.88	0.96
RSS	0.002	0.004	0.225	0.007	0.002
AIC	−1087.80	−1017.79	−610.78	−961.27	−1087.80
Neighborhood	8	8	8	8	8

(d)

Parameters	Spherical	Exponential	Linear	Linear to sill	Gaussian
Range (m)	410.9	1232.7	379.8	379.8	646.4
Lag distance	190	190	190	190	190
Lag interval	19	19	19	19	19
Nugget ()	0.001	0.001	0.001	0.001	0.058
Sill ()	0.683	1.154	0.909	0.909	2.126
Proportion of structural variance to total sampling variance: =	1.00	0.99	0.99	0.99	0.97
	0	0.1	0.1	0.1	0.3
	0.98	0.93	0.96	0.96	0.98
RSS	0.0014	0.018	0.011	0.011	0.003
AIC	−1123.83	−865.88	−915.62	−915.62	−1046.85
Neighborhood	10	10	10	10	10