Effects of Tree Plantations on Sequestration of Soil Cd, Zn, Pb and Mn (Case Study: Forest Stands around Ilam Cement Factory)

Todays the pollution of air, water and soil caused by industrial units, has been proved in the world. Among them, the cement industry is one of the most important environmental pollutants that have adverse environmental effects on the surroundings. The aim of this study was to evaluate the effects of afforestation on sequestration of Cd, Zn, Pb and Mn in soil of 7 stands around the Ilam Cement Factory.

In each stands, some plots (10 × 10 m) were established systematically. Soil sampling was done from the depths of 0-10 and 10-20 cm. Also, heavy metals from the soil samples and electro filter were measured.

Results showed that the amount of Cd in the electro filter was similar to Cd in soil of the stands, but the amounts of Pb, Zn and Mn in electro filter are more than of those that in soils of the stands (0-10 cm and 10-20 cm depth). The results also showed that with increasing soil depth the amount of Pb sequestration decreased. In natural Oak stand, the most amount of Cd was seen in surface soil (0-10 cm depth), the most Zn were in deep soil (10-20 cm depth) and the Most amount of Mn sequestration in both depths were observed.  

In general, we can say there are direct relationship between the degree of tree mixing and sequestration of heavy metals. In addition, in the natural Oak stand, the amount of heavy metal sequestration was higher than other stands.