Dendroanalysis of metal pollution from the Sydney Steel Plant in Sydney, Nova Scotia

The Sydney Steel Plant emitted toxic pollutants into the local area for almost 100 years. Although no paper record exists of the amount and spatial variability of the pollutants emitted, a natural record exists locked in the annual growth of native tree species in the region. Studies have shown that temperate trees can incorporate local metal pollution into their annual rings, creating a temporal and spatial record of the pollution. Two abundant species were sampled within a 5-km radius of the steel plant site. Using dendrochronology, atomic absorption spectroscopy (AAS) and energy dispersive X-ray fluorescence (EDXRF) on white birch, Betula papyrifera, and eastern larch, Larix laricina, a new methodology was developed to determine levels of pollutants in a given year. Atomic absorption spectroscopy did not produce accurate results with the small sample sizes we were able to process, but energy dispersive X-ray fluorescence determined that the hardwood birch better incorporated both lead and zinc into annual rings than the softwood larch. The technique provides an interesting area for further study, because it provides a time efficient and repeatable method of analyzing chemicals stored in wood tissue.