Abstracts Category : Other

Mercury pollution in an urban and suburban lacustrine systemin Summit County, Ohio

by Lindsay D Starr

Anthropogenic contributions of mercury (Hg) and othercontaminant metals to northeast Ohio likely derive from a varietyof sources including coal combustion, waste incineration, andlandfills. This Hg is transported through the environment and canaccumulate in the bottom sediments of rivers and lakes. For thisstudy, Hg concentrations were measured in soil, surface lakesediment, and sediment cores from Summit Lake, which is situatedwithin the urban core of Akron, Ohio and Rex Lake, which is located8 km to the south in a suburban setting. These two lakes weresampled because of their contrasting locations to potential Hgpoint sources. Around Summit Lake, soil samples collected in 2016have Hg concentrations that range from 0.06 0.01 g/g to 0.85 0.01 g/g. Surface sediment was collected from Summit Lake in 2001and 2015. For samples collected in 2001, Hg concentrations inorganic rich mud range from 0.23 0.01 g/g to 1.05 0.02 g/gand in samples from 2015, values range from 0.10 0.01 g/g to0.58 0.02 g/g. Locations having elevated Hg concentrations insoil and lake surface sediment within Summit Lake are associatedwith a land-fill in the southeast area of the lake. A sediment corecollected from Summit Lake displays a record of change frompre-industrial (depth below 308 cm) through industrial, topost-industrial (depth above 97 cm). The change in the surroundingland is reflected in the change in the organic carbon concentrationand C:N ratios. During the pre-industrial period ratios average 11 1 (n = 8), and then during industrialization C:N ratiossignificantly (p < 0.05) increase to 33 1, with theindustrialization period having an average C:N ratio of 20 7 (n =55). During industrialization organic carbon decreases with anincrease in Hg and other contaminant metals (chromium, copper,lead, mercury, and zinc) concentrations. These additional metalswere analyzed on many of the same materials as the Hgconcentrations and were presented previously (Haney, 2004;Mitchell, 2014). Chromium, copper, and lead begin to increase at adepth of 280 cm and remain elevated throughout the industrialperiod, until a depth of 97 cm, when contaminant metalconcentrations decrease. The first contaminant metal to peak in thesediment core was mercury (10.9 g/g) at a depth of 236 cm, withzinc (8010 g/g) concentrations peaking at 235 cm. C:N ratios forpost-industrialization period average 15 3 (n = 39) with uniformdelivery of organic carbon from 0 to 39 cm (9.2 1.1%, n = 39).Rex Lake, 8 km south of Summit Lake, is surrounded by suburban landuses and forests. Soil samples collected around Rex Lake in 2016have Hg concentrations that range from 0.03 0.01 g/g to 0.13 0.01 g/g and uniform C:N ratios 16 2. Surface sediment samplescollected from Rex Lake in 2014 range from 0.05 0.01 g/g to 0.79 0.02 g/g. Two lake surface samples from Rex Lake havesignificantly (p < 0.05) higher Hg concentrations than othersamples collected, and were collected in the north central area ofRex Lake.Advisors/Committee Members: McManus, James (Advisor), Peck, John (Advisor).