| Title | Sub-bottom acoustic profiling as a remediation assessment tool for contaminated lakes |
| |
| Author | Menard, E; Nasser, N A; Patterson, R T; Galloway, J M ; Cott, P A; Hanna, B W; Falck, H |
| Source | SN Applied Sciences vol. 1, issue 6, 572, 2019 p. 1-15, https://doi.org/10.1007/s42452-019-0588-z  Open Access |
| Image |  |
| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20190077 |
| Publisher | Springer Nature |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf (Adobe® Reader®); html |
| Province | Northwest Territories |
| NTS | 85J/08 |
| Area | Frame Lake; Yellowknife |
| Lat/Long WENS | -114.5000 -114.0000 62.5000 62.2500 |
| Subjects | surficial geology/geomorphology; geophysics; stratigraphy; environmental geology; geochronology; Science and Technology; Nature and Environment; surface waters; lakes; lake sediments; pollution;
arsenic; mining; gold; geophysical surveys; seismic surveys, lake; heavy metals contamination; mass spectrometer analysis; core samples; radiometric dating; radiocarbon dating; depositional history; paleoenvironment; mine site rehabilitation; land
use; Contaminated sites; lacustrine sediments; Geographic data; Geographic information systems; Phanerozoic; Cenozoic; Quaternary |
| Illustrations | location maps; geoscientific sketch maps; tables; photographs; geochemical profiles; fence diagrams; geophysical profiles |
| Program | Environmental
Geoscience Shale Gas - seismicity |
| Released | 2019 05 16 |
| Abstract | Frame Lake, a small (88.4 ha), shallow (< 6.5 m maximum depth), high-latitude lake found within the city limits of Yellowknife, Northwest Territories, Canada was selected due to the known legacy
contamination of the lake's sediments to test the feasibility of using seismic sub-bottom profiling to estimate total volumes of heavy metal contaminated sediments in lacustrine environments. To ground-truth the sub-bottom profiling results, physical
and ICP-MS analyses were carried out on freeze cores collected from Frame Lake's southern basin, and sedimentological marker beds and 14C dating was used to chronologically constrain the lake depositional history. ICP-MS results showed high levels of
arsenic contamination (up to 1538 micrograms/g) in late twentieth-century lake sediments, which contrasts sharply with measured Holocene values that averaged only 16 micrograms/g (n = 41, ± 5.4 SD). The high arsenic content in lakebed sediments,
which tends to be concentrated within specific horizons, results in distinct seismic reflectors within the acquired Sonar data. Stratigraphic horizons where arsenic was concentrated do not necessarily correlate with actual depositional events as
changes in lake hydrology and redox conditions have resulted in remobilization and migration of arsenic in lake sediments. Direct GIS software comparison of core data against the sub-bottom profiler transect results permitted an interpolated lateral
and vertical reconstruction of the distribution of variously contaminated sediments throughout the entire lake basin. Based on our analysis, a minimum of ~ 230,000 m3 of contaminated sediments would need to be dredged from Frame Lake to achieve a
minimum residual sediment arsenic concentration of < 150 micrograms/g. |
| Summary | (Plain Language Summary, not published)
Sediment cores were collected from Frame Lake, located within the City of Yellowknife, and evaluated for total concentrations of metal(loids) and
sedimentary grain size. Combined with radiocarbon dating, the depositional history of the southern basin of the lake was reconstructed. High levels of arsenic contamination (up to 1538 ppm) occurred in late 20th century sediments. In contrast, the
arsenic concentration in pre 20th c. sediments was only 16 ppm (n=41, +/- 5.4 SD). The high arsenic content in the lakebed was concentrated at discrete horizons and were used as seismic reflectors for Sonar sub-bottom profiling throughout the lake.
Direct GIS software comparison of core data against the sub-bottom profile transects was used to interpolate lateral and vertical reconstruction of the distribution of high-arsenic sediments thoughtout the entire lake basin. Based on the analysis, a
minimum of ~230,000 m3 of contaminated sediments would need to be removed from Frame Lake to achieve a minimum residual sediment arsenic concentration of <150 ppm. |
| GEOSCAN ID | 314711 |
|
|