Abstract

The highest content of dioxine has been identified in the soil cover of the weathering crust derived from olivine basalt (average content: 26.5 ppm), especially in the Bù Gia Mập Airport (43.2-236.3 ppm), which is higher than its permitted limit for agricultural-forestry land.

Isometric agents of dioxine have been found in 100% of bed load samples with their content varying from 0.001 to 5.9 ppm.

The content of dioxine gradually decreases by the depth. The humus ratio and grain size of soil determine the injection of dioxine by depth. The soil having high total humus ratio and percentage of coarse grains creates favourable conditions for dioxine to deeply penetrate.

The results of survey have been confirming the persistence of dioxine with considerable amount in the soil cover of the weathering crust of different rocks and in bed load of the Bù Gia Mập Airport although the chemical war by USA stopped more than 30 years in the past.