Sedimentary records of mercury stable isotopes in Lake Michigan

• DOI: 10.12952/journal.elementa.000086
• Publication Date: 2016-01-27T16:34:51Z
• Authors: Runsheng Yin; Ryan F. Lepak; David P. Krabbenhoft; James P. Hurley
• Keywords: Mercury; TRACER

Abstract Mercury (Hg) concentrations and Hg isotopic composition were investigated in three sediment cores Lake Michigan (LM). Two collected from Green Bay, a region heavily impacted by contamination one core an offshore of LM absent direct point source Hg. Historical trends influxes suggest increased deposition began the 1890s Bay early 1800’s LM. Recently deposited reflecting more anthropogenic influence shows similar δ202 values (-1.0 to -0.5‰) for all however, deep sediments, pre-industrial eras, show much lower δ202Hg (-1.7 -1.2‰). Using binary mixing model based on signatures, proportion was estimated. Model output confirms that is contaminated local than An increase positive Δ199Hg (-0.02 +0.27‰) observed inner LM, which may indicate input atmospheric decreased watershed inputs along this transect. Overall, study suggests sedimentary isotopes maybe useful tracer understanding sources history large lakes.