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- Svengren, Henrik, et al.
(författare)
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Radioisotope and metal content in a Lake Nakuru sediment core – accumulation rate and 3 inventories
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Nakuru environment is a hot spot both for human population and for biological conservation with a large number of species protected in the well visited Lake Nakuru National Park. Reoccurring mass die-off of the Lesser Flamingo in Lake Nakuru as well as cases of intoxication of humans within the water catchment area have gained attention and dedicated a significant amount of research over the recent decades. The toxicological histories of natural and anthropogenic activities are reflected by accumulated compounds in the water body sediments. In this study, a sediment core obtained from the central and deepest point of Lake Nakuru was sliced with 5 mm resolution and analyzed with the 210Pb dating method. The results show a linear accumulation rate of 1.3 mm y-1 and a mass accumulation rate of 0.027 g cm-2 y-1. Further analysis resulted in core profiles of organic material decay, phosphorus concentration gradient and total content of heavy metals in the lake water and in the sediment. In addition, analysis of 226Ra, 137Cs, 239+240Pu, 228Th/232Th was performed.
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- Josefsson, Sarah, 1976-, et al.
(författare)
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Capping efficiency of various carbonaceous and mineral materials for in situ remediation of marine sediments contaminated with PCDD/Fs, OCS and HCB
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The efficiency of various thin-layer capping materials in reducing the sediment-to-water flux and benthic organism bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), hexachlorobenzene (HCB) and octachlorostyrene (OCS) was investigated in a boxcosm experiment. The influence of cap layer thickness (0.5-5 cm) and different cap materials were tested using a three-factor experimental design. The capping materials consisted of a passive carrier (coarse or fine limestone material, or a marine clay sediment), and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants and decrease their bioavailability. Macrofauna was added to the boxes to get a semi-natural bioturbation. The sediment-to-water flux was measured using passive (SPMD) samplers, and the bioaccumulation by the surface-dwelling gastropod Hinia reticulata and the deep-burrowing polychaetes Nereis spp. was determined. Results showed substantial decreases in both flux and bioaccumulation as a result of thin-layer capping. The thickness of the capping layer and the choice of active material were important factors, while the use of different types of passive materials was not statistically significant for any of the observed endpoints. Flux and bioaccumulation decreased with increased cap thickness, and could be further decreased with addition of active material. Activated carbon was more efficient than lignin, and a ~90% reduction of the flux and bioaccumulation, compared to uncapped control sediment, could be achieved with 3 cm caps with 3.3% AC (g C/g ww clay). The reduction was generally larger in the surface-dwelling H. reticulata than in Nereis spp., and the magnitude of the reduction was frequently similar between Nereis spp. and sediment-to-water fluxes. The latter was interpreted to indicate a link between Nereis spp. bioirrigation and sediment-to-water fluxes. Furthermore, the reduction in sediment-to-water flux was dependent on the hydrophobicity of the congeners, with less hydrophobic congeners achieving a larger reduction than more hydrophobic congeners.
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- Ribbenstedt, Anton, 1986-, et al.
(författare)
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Toxicometabolomics and biotransformation in single zebrafish embryos exposed to carbamazepine
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report here on the high throughput determination of biotransformation products(bioTPs) and toxicometabolomics in single zebrafish (ZF) embryos exposed to carbamazepine(CBZ). Exposures were carried out in 96-well plates with six CBZ concentrations ranging from 0.5 μg/L to 50 mg/L (n=12 embryos/dose). In the 50 mg/L dose group 33% of the embryos developed edema during the exposure (120hpf) while hatching was significantly delayed in three of the lower dose groups (0.46, 3.85 and the 445 μg/L) compared to the control at 48 hpf. Toxicometabolomic analysis together with random forest modelling revealed a total of 80 significantly affected metabolites (22 identified via targeted lipidomics and 58 via non-target analysis). The wide range of doses tested enabled observation of both monotonic and nonmonotonic dose-responses which fit the known mode of action of CBZ. A novel pathway was also proposed based on changes in PE-Cer (d16:2/24:1; CL 2-3) which could be the result of CBZ induced apoptosis via induction of the enzyme SAMD8. In addition, 2 CBZ bioTPs were identified without additional exposure experiments. Overall this work showcases the potential of toxicometabolomics and bioTP determination in single ZF embryos for improved and comprehensive chemical hazard assessment.
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