title: Increased atmospheric deposition of mercury in reference lakes near major urban areas.
abstract: Atmospheric deposition of Hg is the predominant pathway for Hg to reach sensitive ecosystems, but the importance of emissions on near-field deposition remains unclear. To better understand spatial variability in Hg deposition, mercury concentrations were analyzed in sediment cores from 12 lakes with undeveloped watersheds near to (<50 km) and remote from (>150 km) several major urban areas in the United States. Background and focusing corrected Hg fluxes and flux ratios (modern to background) in the near-urban lakes (68 ± 6.9 μg m(-2) yr(-1) and 9.8 ± 4.8, respectively) greatly exceed those in the remote lakes (14 ± 9.3 μg m(-2) yr(-1) and 3.5 ± 1.0) and the fluxes are strongly related to distance from the nearest major urban area (r(2) = 0.87) and to population and Hg emissions within 50-100 km of the lakes. Comparison to monitored wet deposition suggests that dry deposition is a major contributor of Hg to lakes near major urban areas.
authors.affiliation: US Geological Survey, Austin, TX 78754, USA. pcvanmet@usgs.gov
authors.forename: Peter C
authors.initials: PC
authors.lastname: Van Metre
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring; D060106:Lakes / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D014504:Urban Health; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D014874:Water Pollutants, Chemical; D008628:Mercury