Study On The Modeling Environmental Behaviors And Bioavailability Of REEs In Soil

Through data process, the primary goal of this investigation is to validate the experimental phenomenon and disclose the practical regulations in the field of environment science. The degree of influence of several factors on the environmental chemical behaviors and bioavailability of Rare Earth Elements (REEs) in soil is investigated by some statistical and reasoning methods in this paper.Linear Regression and Least Square are conducted to revert experimental data to experimental equations of REEs accumulation in wheat and many such single factors as pH, EDTA, Humic acid (HA), Fulvic acid (FA), sulfate and phosphate. Then the quantitative data, from these equations, is representatively extracted as simulated data, some of which is collected for correlation analysis.Method of Partial Correlation Coefficient (MPCC) is developed to estimate the influential ability of each factor on REEs accumulation, which can overcome the problems resulting from dimension difference among different factors and can calculate their correlativity under the same standard in REEs research to some extent.But, MPCC is not adopted directly in the condition of two-factor cross effect on REEs accumulation due to the limitation of the experimental data. Thus the two-factor numerical equations are established to fit the experimental data by the method of Reconstruct Kernel Equation (RKE) for further evaluation. During the resolution, MATLAB, as a programming tool, is also applied in order to get the value of weights in the equations. These numerical models, about HA & pH, HA & REE concentration, pH & REE concentration, should be able to predict the REEs environmental chemical behaviors in the condition of low concentration. The results of this study, by comparing each factor's partial correlation coefficient, indicate that pH value and the concentration of REEs in soil and some organic ligands, i.e., EDTA and FA, play important roles in the environmental behaviors and bioavailability of REEs in soil. On the contrary, the ligands, i.e., HA, sulfate and phosphate, play minor. The data about phosphate is divided into some parts and discussed respectively in that the phosphate ion is liable to from sediments when meeting with REE ion. The discussion shows that, when its concentration<0.001mol/L, it is closely correlated with the accumulation; when above this level, badly correlated.Multiple Linear Regression is conducted to derive the numerical models, in which the accumulation of La or Gd in wheat is resultant variable; pH value together with the concentration of EDTA, FA, HA and REE, which are selected as important influential factors on the basis of MPCC, are independent variables.