ACCUMULATION OF ELEMENTS IN THE ANNUAL RINGS OF SCOTS PINE TREES IN THE VICINITY OF A COPPER-NICKEL SMELTER MEASURED BY SCANNING EDXRF

Trees growing near smelters are severely affected by airborne pollutio n. In several projects the effects of heavy metals on the vegetation h ave been investigated. One method used is to measure the elemental con centrations in tree rings, which gives the possibility of comparing co ncentrations for different years since the tree rings to some extent r eflect the conditions during the growth years. In this study, the poll ution from a smelter plant in the south-western part of Finland was mo nitored. In the past, the emissions of heavy metals, such as copper, n ickel and zinc, have been high in the area close to the smelter, but d uring the last 5 years the emissions from the smelter have decreased o wing to new cleaning techniques. The forests in the vicinity of the sm elter were studied by the Finnish Forest Research Institute, using ind uctively coupled plasma atomic emission spectrometry (ICP-AES) for mea surements of elements in the plants. As a complement to these measurem ents, high-resolution individual tree ring measurements with the energ y-dispersive x-ray fluorescence (EDXRF) technique have been made. The aim was to see if any detectable change in wood chemistry occurred whe n the pollution burden was reduced. The results from trees growing in an area close to the smelter were compared with the results from trees 8 km away. Tree rings from two time periods, 1971-75 and 1991-93, wer e examined. Differences in the levels of K, Ca, Mn, Fe, Ni, Cu, Zn, Rb and Sr were found between the areas. The Cu/Zn ratio was found to dec rease in the last annual rings in the trees from the most polluted are a. The results from the EDXRF measurements were also compared with the corresponding results from the ICP-AES measurements. (C) 1998 John Wi ley & Sons, Ltd.