ANALYSIS OF TREE SAMPLES FROM AN ACIDIC AND A LIMED ENVIRONMENT BY MEANS OF PIXE

Three tree core samples of Norway spruce (Picea Abies) have been analysed by PIXE. The concentration profiles for 17 elements heavier than sodium have been determined by means of one PIXE measurement every 2 mm along the samples. The samples were collected at Fäxboda, an experimental area north of Uppsala where artificially acidified and limed environmental experiments are made. One sample from each of an acidified, a limed and a reference area has been collected. The main interest is focused on potassium, calcium, manganese, iron, copper and zinc.

All three samples have about the same concentration profile in the heartwood. Large differences are observed in the sapwood. In the sample from the limed area the calcium content is much higher and the iron and chromium. contents are lower than in the sample from the reference area. In the sample from the acidified area the calcium and potassium contents are lower and the manganese, iron and chromium contents are much higher than in the sample from the reference area.

The observed concentration profiles of trace elements in trees indicate that changes in the environment due to acidification can be quantified at an early stage by means of PIXE.