title: Anthropogenic forcings on the surficial osmium cycle.
abstract: Osmium is among the least abundant elements in the Earth's continental crust. Recent anthropogenic Os contamination of the environment from mining and smelting activities, automotive catalytic converter use, and hospital discharges has been documented. Here we present evidence for anthropogenic overprinting of the natural Os cycle using a ca. 7000-year record of atmospheric Os deposition and isotopic composition from an ombrotrophic peat bog in NW Spain. Preanthropogenic Os accumulation in this area is 0.10 +/- 0.04 ng m(-2) y(-1). The oldest strata showing human influence correspond to early metal mining and processing on the Iberian Peninsula (ca. 4700-2500 cal. BP). Elevated Os accumulation rates are found thereafter with a local maximum of 1.1 ng m(-2) y(-1) during the Roman occupation of the Iberian Peninsula (ca. 1930 cal. BP) and a further increase starting in 1750 AD with Os accumulation reaching 30 ng m(-2) y(-1) in the most recent samples. Osmium isotopic composition ((187)Os/(188)Os) indicates that recent elevated Os accumulation results from increased input of unradiogenic Os from industrial and automotive sources as well as from enhanced deposition of radiogenic Os through increased fossil fuel combustion and soil erosion. We posit that the rapid increase in catalyst-equipped vehicles, increased fossil fuel combustion, and changes in land-use make the changes observed in NW Spain globally relevant.
authors.affiliation: Department of Civil and Environmental Engineering, Chalmers University of Technology, 41296 Goteborg, Sweden. sebastien.rauch@chalmers.se
authors.forename: Sebastien
authors.initials: S
authors.lastname: Rauch
authors.forename: Bernhard
authors.initials: B
authors.lastname: Peucker-Ehrenbrink
authors.forename: Malin E
authors.initials: ME
authors.lastname: Kylander
authors.forename: Dominik J
authors.initials: DJ
authors.lastname: Weiss
authors.forename: Antonio
authors.initials: A
authors.lastname: Martinez-Cortizas
authors.forename: David
authors.initials: D
authors.lastname: Heslop
authors.forename: Carolina
authors.initials: C
authors.lastname: Olid
authors.forename: Tim M
authors.initials: TM
authors.lastname: Mighall
authors.forename: Harold F
authors.initials: HF
authors.lastname: Hemond
mesh_terms: D004785:Environmental Pollutants / Q000737:chemistry*; D049668:History, 15th Century; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049674:History, 21st Century; D049690:History, Ancient; D049691:History, Medieval; D006802:Human Activities / Q000266:history*; D006801:Humans; D009992:Osmium / Q000737:chemistry*; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D009992:Osmium