Human and ecological remediation goals for soil mercury at East Fork Poplar Creek, Oak Ridge, TN
- Science Applications International Corp., McLean, VA (United States). Engineering and Environmental Compliance Group
Mercury, used in the past production of enriched lithium by the Department of Energy, is the principal chemical of concern in the 14-mile floodplain of East Fork Poplar Creek (EFPC). SAIC has developed risk-based remediation goal options (RGOS) for mercury in EFPC soils to protect the most sensitive human receptors. The existing chronic oral RfD for mercury is based on exposure of laboratory species to mercuric chloride. However, speciation and leaching/availability studies (conducted by EPA EMSL and Oak Ridge National Laboratory) indicated less soluble and less toxic mercury species, principally mercuric sulfide, with measurable quantities of metallic mercury also present, predominate in EFPC floodplain soils. SAIC derived human health RGOs using deterministic and probabilistic methods and incorporated the probability density function for bioavailability of mercury species from leaching/availability data generated by ORNL. Monte Carlo simulation was used in uncertainty analysis and supported the derivation of a protective, but realistic risk-based remediation goal of 400 mg mercury/kg soil. For ecological risk assessment, RGOs were based on risks through food chains from contaminants in soil. The authors describe a terrestrial food-chain model of contaminant transfer to primary producers, first-order consumers, mid-level predators, and top-level predators. The model uses published toxicity data, site-specific contaminant concentrations, and bioaccumulation factors calculated from measured body burdens of floodplain organisms to compute RGOs for various combinations of exposure parameters. Model calculations show that under reasonably conservative conditions, mid-level predators have the highest exposures relative to dietary limits and, therefore, require the lowest soil-mercury RGOs. Mercury concentrations of {approximately}500 mg/kg are protective of the receptor populations exposed through food chains at this site.
- OSTI ID:
- 242412
- Report Number(s):
- CONF-9511137-; ISBN 1-880611-03-1; TRN: 96:013689
- Resource Relation:
- Conference: 2. Society of Environmental Toxicology and Chemistry (SETAC) world conference, Vancouver (Canada), 5-9 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Second SETAC world congress (16. annual meeting): Abstract book. Global environmental protection: Science, politics, and common sense; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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