Lastly using more complex multiple regression models, taking into
account the two sources of contamination plus the soil parameters
(Table 5), only improved the assessment of Cd, Cr and Pb accumulation.
For Cd, both soil content, plant content and soil organic carbon significantly influenced the concentration in snail's viscera. For Cr, the
observed increased in the r 2 adj was only due to the soil's parameters
(pH and CaCO 3 ). For Pb, the concentration in snail's viscera was significantly influenced by plant content and soil parameters (i.e., pH)
but not by total content in soil. For the other TE (As, Cu, Ni and Zn),
complex multiple regression models did not improve the r 2 adj values,
as compared with those using only soil or plant TE contents as explanatory variables.