The quantification and distribution of pollution Pb at a woodland in rural south central Ontario, Canada.
Lead concentrations and Pb isotope ratios were measured in the forest floor, mineral soil and vegetation at a white pine and a sugar maple stand in a woodland in south central Ontario. Lead concentrations decreased and 206Pb/207Pb ratios increased with mineral soil depth reflecting the mixing of pollution and natural Pb sources. Lead concentrations and 206Pb/207Pb ratios at 20-30 cm depth were approximately 6-7 mg/kg and 1.31-1.32, respectively. Assuming an integrated 206Pb/207Pb ratio in deposition over time of 1.18, estimated from lichen measurements and published data for the region, approximately 65% of Pb in the surface (0-1 cm) mineral soil is from anthropogenic sources. Approximately 90% of pollution Pb is found in the 0-10 cm soil layer (Ah) and less than 3% of the pollution Pb is present in the forest biomass and mull-type forest floor combined. Despite low Pb concentrations in vegetation (<2.5 mg/kg), we estimate that between 65 and 100% of the Pb in vegetation and approximately 75% of the Pb in the forest floor is from pollution sources. In total, the pollution Pb burdens at the pine and maple stands are estimated to be 860 and 750 mg/m2, respectively.
Watmough
Shaun A
SA
ERS Department, Trent University, Peterborough, Ontario, Canada K9J 7B8. swatmough@trentu.ca
Hutchinson
Thomas C
TC
D031002:Acer / Q000378:metabolism; D004784:Environmental Monitoring; D007854:Lead / Q000032:analysis* / Q000378:metabolism; D008011:Lichens / Q000378:metabolism; D009864:Ontario; D028223:Pinus / Q000378:metabolism; D010944:Plants / Q000378:metabolism; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D014197:Trees
D012989:Soil Pollutants; D007854:Lead