Mv. Frontasyeva et E. Steinnes, EPITHERMAL NEUTRON-ACTIVATION ANALYSIS OF MOSSES USED TO MONITOR HEAVY-METAL DEPOSITION AROUND AN IRON SMELTER COMPLEX, Analyst, 120(5), 1995, pp. 1437-1440
The moss Hylocomium splendens was used as a biomonitor to study change
s in the atmospheric deposition of metals around an iron smelter compl
ex in Northern Norway between 1989 and 1993. Samples representing the
last three years' growth of moss, collected on the ground at 25 sites
located 1-25 km from the source area, were analysed by instrumental ne
utron activation analysis using epithermal neutrons. A total of 38 ele
ments were determined, including most of the heavy metals known to be
released into the air from this kind of industry. A re-orientation of
the industrial production occurred around 1990; the most important dev
elopments being the closing of an iron smelter and the starting-up of
a new ferrochrome smelter, Accordingly, the Cr deposition in the vicin
ity of the smelter increased by about a factor of 100, while the Fe de
position decreased by almost a factor of 10. Other elements showing a
decrease over this period were Mo, Sr, Se, Zr, Re, Hf, Ta, Th, and Il,
while there was an appreciable increase for Ni, W, and Au. Most other
elements, including V, Mn, Co, Cu, Zn, As and Sb, had similar levels
as before. A new method for the graphical representation of deposition
levels is introduced. Instead of constructing isopleths based on the
observed concentration values, each value is divided by a number repre
senting the background level found in moss in the area. The resulting
ratios are then used as a basis for the construction of isopleths. Exa
mples are shown for Cr, Fe and V levels in 1989 and 1993 respectively.