Simulation and Prediction of Cd Cumulation Insoil Irrigated By Reclaimed Water Based Onmatlab

Based on the hypothesis that reclaimed water for irrigating is the cardinal source of heavy metals pollution in soil, and the heavy metals leave from soil mainly by plant harvest, the article constructs a differential equation and simulates the cumulation of Cd in wheat soil of southeast suburb in Beijing based on simulink of matlab. With the data relative Cd mass proportion in soil as predictor parameter in stems and leaves as response ones, the fitting curves are produced respectively. The curves show that the amount of Cd leave from soil is very small compared with the amount entering into soil via irrigation water. But in the condition of lower concentration in soil, the proportion of Cd left from soil is bigger relatively. The prediction shows that the content of Cd will exceed the national standard of China after 40 years in the condition of the content of Cd in reclaimed water with 10mg m and concentration in soil with 0.1333mg kg, but it should be 100 years if the concentration of Cd in reclaimed water for irrigation reduced to 5mg m.