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- Liljedahl, B. E., et al.
(författare)
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Some ecological effects of underwater self-explosion of ammunition in Lake Lomtjärn Sweden : The impact from mercury
- 2012
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Ingår i: International Journal of Design & Nature and Ecodynamics. - 1755-7437 .- 1755-7445. ; 7:2, s. 210-226
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Tidskriftsartikel (refereegranskat)abstract
- After the Second World War, dumping in lakes was a rational way to solve the security problem with the extensive amount of unreliable or unused ageing ammunition. Most commonly the ammunition was dumped in sealed boxes or as pieces. In some cases the ammunition was deliberately detonated when dumped. In Lake Lomtjärn, a small lake in central Sweden, extremely high levels of mercury (300 mg/kg dry weight Hg) were detected in the sediments. The mercury was expected to originate from years of dumping followed by an underwater self-explosion of ignition capsule containing mercury. The lake is unique in the sense that the mercury levels are among the highest found so far in Sweden and that no other source of pollutant is present in the area. The aim of this study was to evaluate the environmental impact from the underwater explosion. Samples of sediment, bottom water, surface water, bottom fauna, littoral fauna and fi sh (muscle and liver) were analysed for metals as well as physical parameters in order to investigate effects on biota. Acute toxicity of bottom water was determined by Daphnia magna. Results showed very high mercury content (2–338 mg/kg dry weight) in sediment down to 15 cm depth evenly distributed over the whole lake and low levels for other heavy metals (As, Cd, Cu, Pb and Zn). Water showed low levels of mercury (0.02 μg/L in bottom and surface water) as for the other heavy metals (As, Cd, Cu, Pb and Zn). Disturbance of bottom fauna was found for BQI index and O/C index. Disturbance in littoral fauna was seen around the lake (low taxa in six families, ASPT index 5.4. Danish fauna index 4 and acidity index 2). Acute toxicity (Daphnia magna ) was high. Levels of mercury in perch were high (muscle 0.6–3.59 mg/kg and liver 1.05–7.64 mg/kg). It was concluded that the underwater detonation of ammunition in Lake Lomtjärn has caused very high levels of mercury in the sediment and a high impact on the ecological chain. In risk assessments aiming to remediation decisions it is recommended early to highlight expected ecological pathways of (mercury) and relevant biomarkers in the ecosystem of concern.
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- Screaton, E., et al.
(författare)
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Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan : Results from IODP Expedition 316 Sites C0006 and C0007
- 2009
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 10, s. Q0AD01-
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Tidskriftsartikel (refereegranskat)abstract
- Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since similar to 0.78-0.436 Ma and accommodated similar to 13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated decollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region.
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