Using Spatial Regression to Model Potentially Toxic Metal (PTM) Mobility Based on Physicochemical Soil Properties

Table 4

Spatial multivariate regression results.

Diagnostic		Zn	Mn	Cu	Pb	Cd
Distance threshold (m)		150	300	200	150	150
Best spatial model		Spatial error	Spatial error	Spatial error	Spatial error	Spatial lag
R^2	OLS	0.371	0.162	0.366	0.515	0.558
	SLag	0.384	0.186	0.369	0.615	0.617
	SError	0.400	0.212	0.369	0.694	0.587
AIC	OLS	762.255	827.317	406.895	779.265	290.25
	SLag	763.487	828.315	408.711	772.458	286.875
	SError	760.706	825.638	406.729	762.513	288.248
	Soil properties retained	pH (+); CEC (−)	Moisture content (−); % silt (−)	% sand (−); % silt (−); BD (−)	pH (+); CEC (+); λ (−)	pH (+); % sand (−); % silt (−); Wy (−)

λ is a spatial autoregressive error term; Wy is a spatially lagged dependent variable; and (+) and (−) indicate the sign of the coefficient.