Determining the History and Sources of Contaminants in Sediments in the Tamar Estuary, Tasmania, Using (210)Pb Dating and Stable Pb Isotope Analyses

(210)Pb dating and heavy metal analyses (Cd, Cu, Pb, Zn) have been combined to establish ail historical profile Of Pollutant levels in sediments in the Tamar Estuary (Tasmania, Australia) over the past century. Heavy metal profiles through the core show a strong correlation with mining activities and industrialization during the past Century, reflecting catchment disturbance in one of Australia's earliest settled areas. A source apportionment of Pb in the sediment core using stable Pb isotope ratios ((204)Pb, (206)Pb, (207)Pb, (208)Pb) shows that mine pollution has been contributing 10-25 mg kg(-1) to Tamar Estuary sediments since the start of mining in the early 1890s, whilst non-mining inputs were not significant until post-1930 and became increasingly significant post-World War II. Since the 1950s-1960s, non-mining anthropogenic Pb inputs have become as significant as Pb from mining activities. although there does appear to be a decline in non-mining inputs during the past 20 years, which is consistent with findings elsewhere where reductions in atmospheric Pb levels have been observed and are attributed to the phasing-out of leaded gasoline. The Source apportionment does, however, Suggest that Pb from mine pollution at Storys and Aberfloyle Creeks continues to impact upon upper Tamar Estuary sediment quality.