Abstract
Purpose: In contaminated streams, understanding the role of streambank and streambed source contributions is essential to developing robust remedial solutions. However, identifying relationships can be difficult because of the lack of identifying signatures in source and receptor pools. East Fork Poplar Creek (EFPC) in Oak Ridge, TN, USA received historical industrial releases of mercury that contaminated streambank soils and sediments. Here, we determined relationships between the contaminated streambank soils and sand-sized streambed sediments. Materials and methods: Field surveys revealed the spatial trends of the concentrations of inorganic total mercury (Hg) and methyl mercury (MeHg), Hg lability as inferred by sequential extraction, particle size distribution, and total organic carbon. Statistical tests were applied to determine relationships between streambank soil and streambed sediment properties. Results and discussion: Concentrations of Hg in streambank soils in the upper reaches averaged 206 mg kg −1 (all as dry weight) (n = 457), and 13 mg kg −1 in lower reaches (n = 321), while sand-sized streambed sediments were approximately 16 mg kg −1 (n = 57). Two areas of much higher Hg and MeHg concentrations in streambank soils were identified and related to localized higher Hg concentrations in the streambed sediments; however, most of the streambank soils have similar Hg concentrations to the streambed sediments. The molar ratio of Hg to organic carbon, correlation between MeHg and Hg, and particle size distributions suggested similarity between the streambank soils and the fine sand-sized fraction (125–250 μm) collected from the streambed sediments. Mercury in the fine sand-sized streambed sediments, however, was more labile than Hg in the streambank soils, suggesting an in-stream environment that altered the geochemistry of sediment-bound Hg. Conclusions: This study revealed major source areas of Hg in streambank soils, identified possible depositional locations in streambed sediments, and highlighted potential differences in the stability of Hg bound to streambank soils and sediments. This work will guide future remedial decision making in EFPC and will aid other researchers in identifying source–sink linkages in contaminated fluvial systems.
| Original language | English |
|---|---|
| Pages (from-to) | 2007-2019 |
| Number of pages | 13 |
| Journal | Journal of Soils and Sediments |
| Volume | 19 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 10 2019 |
Funding
Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The US Government retains and the publisher, by accepting the article for publication, acknowledges that the US Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). Funding information This work was funded by the U.S. Department of Energy’s (DOE) Oak Ridge Office of Environmental Management (ORO-EM) and URS | CH2M Oak Ridge LLC (UCOR) and is a product of ORNL’s Mercury Remediation Technology Development Program. The sponsor was not involved in study design, data collection, interpretation, manuscript preparation, or decisions to submit this manuscript. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract No. DE-AC05-00OR22725.
Keywords
- Erosion
- Fluvial
- Methylmercury
- Source–sink