铅在粘土矿物上的吸附特征及其与金属氧化物的关系

A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system.COnvective and dispersive transport processes of cadmium in soil profile are embedded.Simulations on a daily base have been done up to a total simulating time of 250 years,Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil,and cadmium accumulation would be levelling off,reaching an equilibrium concentrations layer by layer downward after certain time.The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers.Plant cadmium uptake would increase from 52um m^-2 under initial soil cadmium concentrations to 65ug m^-2 under equilibrium soil cadmium concentrations,which would not exceed the maximum allowable cadmium concentration in wheat grains.Main parameters which influence cadmium accumulation and transport in soil are total cadmium input,rainfall,evaporation,plant uptake and soil properties.

Characteristics of lead sorption on clay minerals in relation to metal oxides

A model for simulating cadmium transport in a soil-plant system was built using a commercial simu lating program named Powersim on the basis of input-output processes happening in the soil-plant system.Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52 ug m-2 under initial soil cadmium concentrations to 65 μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.