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Source apportionment of PAHs in dated sediments from the Black River, Ohio
Sheng-He Gu1, Andrew C Kralovec, Erik R Christensen
1Department of Civil Engineering and Mechanics, University of Wisconsin-Milwaukee, 53201, USA.
Water Research
|April 15, 2003
Summary
Polycyclic aromatic hydrocarbons (PAHs) in Black River, OH, significantly decreased after a coking plant closure and sediment dredging. Source apportionment identified coke oven emissions, highway dust, and wood burning as key contributors, with remediation efforts showing lasting impacts.
Area of Science:
- Environmental Chemistry
- Sediment Analysis
- Pollutant Source Apportionment
Background:
- Black River, OH, historically contaminated with polycyclic aromatic hydrocarbons (PAHs) from US Steel Corp. coking plant operations.
- Plant closure in 1983 and subsequent sediment dredging in 1989-1990 aimed to reduce PAH levels.
Observation:
- Sediment cores collected in 1998 revealed PAH concentration variations over time, with peaks in 1949, 1969, and a notable increase in 1991 linked to remediation.
- Analysis of 18 PAHs using 210Pb and 137Cs dating provided a historical record of contamination.
Findings:
- Chemical mass balance modeling identified coke oven emissions (CO), highway dust (HWY), and wood burning (WB) as primary PAH sources.
- CO emissions were the dominant source, peaking in 1954 and resurging post-dredging (1992-1994), while HWY contribution increased after 1993.
- Minimal CO presence was observed in 1985, two years post-plant closure, and evidence suggests biodegradation or photolysis of phenanthrene at high concentrations.
Implications:
- Sediment remediation effectively reduced PAH levels, though dredging temporarily redistributed older contaminants.
- Understanding historical PAH sources is crucial for assessing the long-term effectiveness of environmental cleanup strategies.
- Further research into PAH degradation pathways in riverine sediments can inform future risk assessments.