Microfibril angle in wood of Scots pine trees (Pinus sylvestris) after irradiation from the Chernobyl nuclear reactor accident

The secondary cell wall structure of tracheids of Scots pine (Pinus sylvestris L.), especially the angle of microfibrils in the S2 layer, was examined in wood deposited prior to and after the Chernobyl accident in 1986. Microscopic analysis was carried out on wood samples collected in October 1997 from breast height of three pine trees 16, 30 and 42 years old. The polluted site was located in a distance of 5 km south from the Chernobyl nuclear power plant where radioactive contamination in 1997 was 3.7 × 105 kBq m−2. Anatomical analysis showed that the structure of the secondary cell wall in tracheids formed after the Chernobyl accident was changed. Changes occurred both in S2 and S3 layers. The angle of microfibrils in S2 layer in wood deposited after the Chernobyl accident was different in comparison to this measured in wood formed prior to the disaster. The intensity of the changes, i.e. alteration of the microfibrils angle in S2 layer and unusual pattern of the S3 layer, depended on the age of the tree and was most intensive in a young tree.