Development And Application Of DTPA-LDHs-DGT In Soil Rice Cadmium Transport Model

Cadmium is a highly toxic heavy metals in the environment,which can cause harm to food safety and human health.However,it is difficult to solve the problem that how to characterize the bioavailability of Cd,so as to establish soil-rice Cd transport model.Diffusive gradients in thin-films technique(DGT)is a new extraction technology of heavy metals,which can effectively reflect the situation of rice from the soil to absorb heavy metals.This paper based on a lot of early work to further explore,improving the productive technology of completely independent intellectual property rights of nanometer material Mg-Al-DTPA-LDHs(hereinafter referred to DTPA-LDHs)and studying in depth the material properties of DTPA-LDHs.Then use DTPA-LDHs as binding phase to make DTPA-LDHs-DGT(hereinafter referred to New DGT).By the measurement of available composition and dissociation kinetics of metals in water using New DGT and the application of New DGT in soil-rice cadmium transport model.The main results are as follows:(1)DTPA-LDHs has many characteristics that high adsorption capacity,long sustainable adsorption time,wide application range of pH and the adsorption process is not affected by electrolyte.The DTPA-LDHs binding phase was uniform under the microscope,and the adsorption of heavy metals could be sustained with the increase of time.The results show that the performance of nanometer material DTPA-LDHs is much higher than that of granular material Chelex 100.(2)The principles of different thickness diffusion layer of diffusive gradients in thin films(DGT)with different dissociate ability to metal complexes were used to determine the dissociation rate constants,component composition of metal available concentrations.A theoretical model based on this principle were developed and were used to analysis the differences of the metals forms and dissociation kinetic constants of Zn、Ni、Fe、Cu、Cd、Mn、Pb in freshwater.The contribution of metal complexes to the available concentrations were better reflect easily.The theoretical model have less parameters,hypothesis and the effects of the metal valence,organic components can be neglected in our system.(3)Using Cubist multivariate mixed linear regression technique to construct soil-rice Cd transmission model,the consistency between the predicted value and the measured value was significantly better than that of the conventional regression analysis.The results showed that Cubist technology is one of the most effective methods to construct the Cd transmission model.(4)DGT can dissolve the soil environmental factors which affecting rice Cd uptake,then build Cubist model again,the rules are reduced from 7 to 4,and the parameter are reduced from 6 to 5.The detection parameters are reduced,the parameter indication is more clear,the model accuracy is improved.