title: The impact of drought and air pollution on metal profiles in peat cores.
abstract: Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands.
authors.affiliation: Environmental and Life Sciences Program, Trent University, Peterborough, ON K9J 7B8, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Souter
authors.affiliation: Environmental Resource Studies Program, Trent University, Peterborough, ON K9J 7B8, Canada. Electronic address: swatmough@trentu.ca.
authors.forename: Shaun A
authors.initials: SA
authors.lastname: Watmough
mesh_terms: D000397:Air Pollution / Q000706:statistics & numerical data*; D055864:Droughts / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D008670:Metals / Q000032:analysis*; D009864:Ontario; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D044003:Sphagnopsida
chemical_list: D008670:Metals; D012987:Soil; D012989:Soil Pollutants
keywords: Air pollution; Drought; Metals; Mineratrophic fens; Peat cores; Sphagnum