Abstract: Based on analysis of the soil samples collected in Southeast Zunyi from 2003 to 2008, an early warning model and a deterioration speed model for heavy metal contamination of agricultural soil is worked out with the modified analytic hierarchy process and time series technique. The second exponential smoothing method is used to forecast index of soil pollution and speed of soil deterioration. Results show that in 37 years beginning from 2008, heavy metal contents in the soil will be to the grade of slight contamination in the region if no any protective measures taken on purpose. Verification reveals that the predicted values tally well with the measured, with an average relative error being <6%. The models are fit for agricultural areas where no serious accidents of heavy metal pollution have ever occurred and the heavy metal contents in the soil are relatively stable.

Key words: Agricultural soil, heavy metal, early warning model, time series, modified analytic hierarchy process