History of atmospheric deposition of trace elements in lake sediments, ~1880 to 2007

Abstract

AbstractWe report measurements of 30 major and trace elements (TEs) in sediment cores from two high‐altitude lakes, West Pine Pond (WPP), and Clear Pond (CP), in the Adirondack Mountains of New York State using inductively coupled plasma–mass spectrometry. The data are used to deduce atmospheric deposition histories of TEs over ~130 years. The cores were collected using a gravity corer, sliced, freeze dried, and ages determined using 210Pb and 137Cs techniques. TE data in WPP were supplemented with our earlier elemental carbon (EC) measurements. Lithophilic elements showed no systematic temporal pattern or any significant enrichment over their crustal abundances. Anthropogenic TEs exhibited distinct increases beginning ~1900, and peaked around 1920–1970, due apparently to energy‐related emissions. Peak concentrations of most TEs, except Pb and Hg, were observed at ~1921 in WPP and ~1940s in CP. Concentration of Pb peaked in 1973 in both lakes and Hg only in CP at ~1965. Lead fluxes were reflective of historical smelter production and combustion of coal and leaded gasoline. Copper and zinc fluxes mimicked corresponding primary production, while EC fluxes followed the long‐term trend for fossil and biofuel combustion. TE and EC flux trends were closely related to the growth of industrialization in the Central and Midwestern U.S. and changing fuel consumption patterns. Compared to peak values, the modern TE fluxes decreased by 25–85%, whereas EC decreased by 96%. Apparently, the regulations intended to control pollutant emissions have succeeded in reducing atmospheric concentrations of the species studied and have improved air quality.