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

Starr, Lindsay D
http://orcid.org/0000-0002-0336-2459
http://rave.ohiolink.edu/etdc/view?acc_num=akron149434254589456

Abstract Details

2017, Master of Science, University of Akron, Geology.
Anthropogenic contributions of mercury (Hg) and other contaminant metals to northeast Ohio likely derive from a variety of sources including coal combustion, waste incineration, and landfills. This Hg is transported through the environment and can accumulate in the bottom sediments of rivers and lakes. For this study, Hg concentrations were measured in soil, surface lake sediment, and sediment cores from Summit Lake, which is situated within the urban core of Akron, Ohio and Rex Lake, which is located 8 km to the south in a suburban setting. These two lakes were sampled because of their contrasting locations to potential Hg point sources. Around Summit Lake, soil samples collected in 2016 have Hg concentrations that range from 0.06 ± 0.01 µg/g to 0.85 ± 0.01 µg/g. Surface sediment was collected from Summit Lake in 2001 and 2015. For samples collected in 2001, Hg concentrations in organic rich mud range from 0.23 ± 0.01 µg/g to 1.05 ± 0.02 µg/g and in samples from 2015, values range from 0.10 ± 0.01 µg/g to 0.58 ± 0.02 µg/g. Locations having elevated Hg concentrations in soil and lake surface sediment within Summit Lake are associated with a land-fill in the southeast area of the lake. A sediment core collected from Summit Lake displays a record of change from pre-industrial (depth below 308 cm) through industrial, to post-industrial (depth above 97 cm). The change in the surrounding land is reflected in the change in the organic carbon concentration and C:N ratios. During the pre-industrial period ratios average 11 ± 1 (n = 8), and then during industrialization C:N ratios significantly (p < 0.05) increase to 33 ± 1, with the industrialization period having an average C:N ratio of 20 ± 7 (n = 55). During industrialization organic carbon decreases with an increase in Hg and other contaminant metals (chromium, copper, lead, mercury, and zinc) concentrations. These additional metals were analyzed on many of the same materials as the Hg concentrations and were presented previously (Haney, 2004; Mitchell, 2014). Chromium, copper, and lead begin to increase at a depth of 280 cm and remain elevated throughout the industrial period, until a depth of 97 cm, when contaminant metal concentrations decrease. The first contaminant metal to peak in the sediment core was mercury (10.9 µg/g) at a depth of 236 cm, with zinc (8010 µg/g) concentrations peaking at 235 cm. C:N ratios for post-industrialization period average 15 ± 3 (n = 39) with uniform delivery 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 land uses and forests. Soil samples collected around Rex Lake in 2016 have Hg concentrations that range from 0.03 ± 0.01 µg/g to 0.13 ± 0.01 µg/g and uniform C:N ratios 16 ± 2. Surface sediment samples collected from Rex Lake in 2014 range from 0.05 ± 0.01 µg/g to 0.79 ± 0.02 µg/g. Two lake surface samples from Rex Lake have significantly (p < 0.05) higher Hg concentrations than other samples collected, and were collected in the north central area of Rex Lake. Organic rich mud samples from Rex Lake have a uniform distribution of organic matter with C:N ratios averaging 12 ± 2 (n = 8). The sediment core collected from Rex Lake also shows a steady increase in organic carbon and contaminant metals beginning at a depth of 63 cm. Prior work showed that chromium, copper, lead, and zinc all begin to increase during the start of industrialization, and then decrease at the start of post-industrialization, around a depth of 30 cm. Similarly, our study suggests that although anthropogenic activities continue to contribute to soil and lake sediment Hg concentrations, these contributions have been decreasing since the enforcement of the Clean Air Act in 1970. Hg variations between and within the systems are likely impacted by both previous or “legacy” anthropogenic activities as well as ongoing activities. Urban Summit Lake has significantly higher Hg concentrations compared to suburban Rex Lake for soil, surface sediments, and within the sediment core. Despite these elevated contaminant metal concentrations, there appears to be an overall declining trend in contaminant metal concentrations consistent with the broader decline since the peak concentrations observed in the sediment cores.
James McManus (Advisor)
John Peck (Advisor)
John Senko (Committee Member)
110 p.
Environmental Science; Geochemistry; Geology
mercury; urban; suburban; lake; sediment core; soil

Recommended Citations

Citations

  • Starr, L. D. (2017). Mercury pollution in an urban and suburban lacustrine system in Summit County, Ohio [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron149434254589456

    APA Style (7th edition)

  • Starr, Lindsay. Mercury pollution in an urban and suburban lacustrine system in Summit County, Ohio. 2017. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron149434254589456.

    MLA Style (8th edition)

  • Starr, Lindsay. "Mercury pollution in an urban and suburban lacustrine system in Summit County, Ohio." Master's thesis, University of Akron, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron149434254589456

    Chicago Manual of Style (17th edition)

akron149434254589456
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This open access ETD is published by University of Akron and OhioLINK.
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