Investigating zinc distribution in aggregates interior and exteriors of different soils

Soil chemical properties may vary from one point to another even in small scale. One-of the major reasons for this small-scale heterogeneity is aggregation of the soil. This study was conducted to compare zinc concentration between aggregate exteriors and interiors of some contaminated soils. Aggregates were collected from 5 depths of 4 soil profiles with different texture and were separated mechanically into exterior and interior fractions. The results showed that there were no significant difference between the amounts of all metal sorbents (clay, organic matter and free iron oxides) in the exterior and the interior. Total zinc concentration was measured for exterior and interior parts of aggregates. The total concentration of zinc was higher in the exterior than in the interior part of aggregates and difference of mean concentration between these two parts was significant at 0.01. The difference of zinc concentration between the interior and exterior decreased in order of clay loam > sandy clay loam > loam > sandy loam. Concentration of zinc in different depths of soil was significant at 0.01.