INVESTIGATING POLLUTION CAPTURED IN DUNE SANDS TO BETTER UNDERSTAND AIR DEPOSITION OF HEAVY METAL PARTICULATE FROM INDUSTRIAL FACILITIES IN GARY, INDIANA

The Great Lakes form the largest surface freshwater system on Earth, and their beaches are visited by millions of people every year. Past and present heavy metal industrial activities in Northwestern Indiana are thought to cause great ecological strain and potential environmental health risks to the southern Lake Michigan region. Whether key dune systems are directly impacted by pollution is not fully understood. One such setting is the Mt. Baldy sand dune which has undergone dynamic physical changes since the early 20^th century, moving inland over a forested late Holocene terrain in response to shoreline disturbance. Located along the southern shore of Lake Michigan, Mt. Baldy is regarded as one of most active and largest coastal dunes. An initial scanning electron microscope (SEM) investigation of samples from Mt. Baldy has demonstrated the presence of some pollutant technogenic spherules. Some of these spherules have distinctive minor or trace manganese. The size range of spherules is on the order of several micrometers and textures indicate no demonstrable abrasion. Chemical compositions and textures are consistent with some technogenic spherules observed in road sediment previously analyzed from Gary Indiana, which is located upwind of Mt. Baldy. This dune environment poses a challenge for pollution studies because the granular media enables translocation of particulate pollution from the active surface and the dynamic sedimentary system redistributes sand and entrained material routinely. Still, the observed pollutant particles and the context of the site currently suggest major steel manufacturing as a probable source as well as other local coal burning activities. Further SEM and transmission electron microscope (TEM) work is planned using heavy liquid separation techniques. Results suggest that careful electron microscopy work can be used to routinely identify technogenic particles in dune environments in this setting and may be able to provide source constraints on technogenic particles in sand and other environmental media of the region.