158-10 Reconstructing Antimony Atmospheric Fluxes in Northern Lake Michigan Over the Last Century

Session: Redox-Driven Nutrient and Contaminant Dynamics in Terrestrial Systems

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The Great Lakes are the largest freshwater lakes in North America. They support a variety of economic industries from tourism to fishing, making environmental protection from contamination vital. Toxic trace elements, like antimony (Sb), can be harmful for the aquatic biota and human health. Despite this risk, assessment of atmospheric deposition of Sb within the Great Lakes area is scarce. Beaver Island’s remote location and its absence of industrial activity make it an ideal site for studying the impact of long-range pollution transport. Antimony (Sb) is a metalloid with four oxidation states; Sb (III) and Sb (V) being the most common under natural conditions. It has been mainly used to make alloys, paints, and pharmaceutical products. Antimony is also a byproduct of smelting primary lead ores. Currently, it is a catalyst in making PET (polyethylene terephthalate) and is used as a flame retardant in adhesives, textiles, rubbers, and paper. Antimony is toxic to humans at low concentrations and has no known biological functions.  

The objective of this study was to reconstruct the fluxes of Sb that reached the sediment-water interface over the last century in Fox Lake using sediment dating and ICP-MS elemental analysis. Fox Lake is a dimictic lake located on Beaver Island (Northern Lake Michigan). It reaches a maximum depth of 8 meters. When collecting sediment cores, the bottom layer was anoxic with sulfides present due to microbial sulfate reduction. Sampling took place during July 2024. First, a probe was used to construct an oxygen profile and locate the chemocline. A sediment core (30-40 cm) was collected with a gravity corer and extruded every centimeter within 1 hour from top to bottom. Sediment samples were transferred in previously acid washed HDPE vials and placed in a cooler for transport. Sediment samples were freeze dried and digested with a combination of ultra-pure acids under ultra-clean conditions. Total trace metal concentrations were measured with an inductively coupled plasma mass spectrometer (ICP-MS) using external calibration. Sediments were dated by gamma spectrometry to determine the activities of 210Pb and 137Cs. Our preliminary data show that the atmospheric deposition of Sb has constantly increased over the last century until the present, suggesting that better environmental regulations for Sb should be implemented. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-9942

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