Effects Of Typical Indicators Of Farmland Soil On Cadmium Activity

Cadmium pollution of farmland soils is affected by various factors and there are many interactions between these factors.Previous studies only considered the effects of a few soil indicators on soil cadmium activity,and neglected the relationship between the factors,which could easily lead to inaccurate analysis of soil cadmium pollution.The main purpose of this paper is to study the correlation between typical indicators of farmland soil and the effect on soil cadmium activity by using the methods of entropy weight,orthogonal experiment and Hassen matrix,which is of great significance for the prevention and control of cadmium pollution.The final conclusion is as follows:1.Through the entropy weight analysis of each typical index,the weights of each index are as follows:Ca>K>Na>Mn>Mg>Cu>Se>CEC>Fe>Zn>As>SOM>Si>pH.2.By comparing the correlation between the content value and entropy weight of each indicator and the soil cadmium activity,it is concluded that there is no clear correlation between the content of each index and soil cadmium activity,and when the entropy weight is analyzed by the same method,the correlation is significantly enhanced,and the average correlation coefficient is increased from 0.051 to 0.228.The fitting of soil Si weight value to soil cadmium activity R~2 is the highest,reaching 0.781,followed by Ca and Se,and the fitting R~2 exceeded 0.6,indicating strong correlation.According to the three indicators with the highest entropy weight(Ca,K,Na),the three indicators with the highest correlation between entropy weight and soil cadmium activity(Si,Se,Ca),the three most studied indicators(pH,CEC,SOM)and three indicators(Mg,As,Mn;Cu,Fe,K;Mn,CEC,K)are randomly selected,and their content values and soil cadmium activities are subjected to multiple linear regression to obtain multiple regression fitting based on entropy weight.The effect is obviously better than the other two methods;the fitting effects of pH,CEC and SOM of the three most studied indicators in the past are even lower than those of the three randomly selected indicators.3.The main factors for calculating farmland soil in this area by using entropy weight method,orthogonal test method and Hasen matrix method are Ca,K,Na;CEC,As,Zn,Se,Mg;Na,Mn and pH.It can be seen that the main factors affecting soil cadmium activity are different due to the different principles of each research method.4.The data are processed and analyzed by orthogonal experiment method.It is concluded that CEC,As,Zn,Se and Mg are the main factors affecting soil cadmium activity without considering the interaction.In the case of considering interaction,Zn*The extreme difference between Mg,Zn,CEC*Zn,Zn*Se and As*Zn is large,indicating that other elements interact with Zn will have a greater impact on soil cadmium activity.5.The second-order partial derivative matrix of soil index at the mean value is calculated by using Hussein matrix,and the relationship between soil index and main influencing factors is analyzed.Ca,Cu,As,K,Mn,pH,CEC,SOM;Ca,Cu,As,K,Na,pH,CEC,SOM and Ca,Cu,As,K,Mn,Na,CEC,SOM and the cumulative second-order reciprocal with Na,Mn,and pH is80.52%,81.92%,and 84.45%,respectively.The results showed that Ca,Cu,As,K,CEC and SOM have a greater influence on soil cadmium activity when coexisting with the main factors Na,Mn and pH.