Influence of a Xenobiotic Mixture (PCB and TBT) Compared to Single Substances on Swimming Behavior or Reproduction of Daphnia magna

Aroclor 1254, a technical PCB mixture (polychlorinated biphenyls) and TBT (tributyltinchloride) are environmental pollutants that cause a broad spectrum of acute toxic and chronic effects in aquatic animals. In this paper, the sensitivity of Daphnia magna to chronic exposure to mixed xenobiotics was evaluated under laboratory conditions. The results show that xenobiotic mixtures (50 % each of the single compounds) were more toxic than individual xenobiotics alone. By measuring behavioral parameters of animals, it becomes evident that exposure to single xenobiotics significantly affects daphnids: exposure led finally to a rapid decrease in mean swimming activity and also caused changes in preferred swimming depth, with daphnids preferring the upper layers of aquaria. The mixture altered the swimming behavior even more strongly compared to the group stressed by single chemicals. Finally, all daphnids sank to the bottom of the aquaria, still alive, but inactive at the end of the exposure period. In addition, we investigated the reproductive capacity (number of newborn per female and day). PCB did not affect the number of newborn significantly, TBT‐stress led to an evidently decreased number of young daphnids and the xenobiotic mixture decreased reproduction even more. In conclusion, we found significant effects of the single compounds as well as approximately additive (swimming behavior) and synergistic (reproduction) effects of the chemical mixture on daphnids indicating the possibility of dramatic ecological consequences of the occurrence of mixed xenobiotic substances in the aquatic environment.     

Age of Jurassic continental tholeiites of French Guyana, Surinam and Guinea: Implications for the initial opening of the Central Atlantic Ocean

A detailed ⁴⁰Ar/³⁹Ar study, of mineral separates from the Jurassic Atlantic Continental Tholeiites (JACT) of Guyana (French Guyana and Surinam, South America), and Guinea (West Africa) related to the initial opening of the Central Atlantic, has been carried out. In French Guyana, plateau ages of 196.0 ± 5.7 Ma and 196.1 ± 7.5 Ma were obtained on single, small amphibole grains from NNW—SSE trending dykes. In Guinea, single biotite grains from intrusive formations from the Kakoulima and Fouta Djalon areas yielded plateau ages of 200.4 ± 0.2 Ma and 194.8 ± 0.5 Ma, concordant with high temperature apparent ages on other biotites. The bulk plagioclase samples display disturbed age spectra due to alteration and excess argon. However, intermediate temperature, weighted mean plagioclase ages are similar in both regions of Guyana and Guinea, ranging from 200.2 ± 2.4 Ma to 188.7 ± 1.9 Ma, partly in agreement with the amphibole and biotite data.

These data, combined with previous ⁴⁰Ar/³⁹Ar and U/Pb results from the northern part of the Central Atlantic margins, indicate intense magmatic activity distributed over a large area from Iberia to Liberia (ca. 4500 km long) for a short period of time (204-195 Ma, perhaps less for the bulk of the magmatism) during the initial break-up of Pangea continent. These data do not support an initiation of the magmatism from a radial volcano-tectonic system centred in the south of the region, as suggested by May [1], and the initial break-up seems to affect the whole Central Atlantic during a period of 9 Ma.     

Future extreme events in European climate: an exploration of regional climate model projections

This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape. The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures of temperature but that ground station data may still be preferred for measuring precipitation in rural settings.     

Microstructures of structure I and II gas hydrates from the Gulf of Mexico

Gas hydrate samples from various locations in the Gulf of Mexico (GOM) differ considerably in their microstructure. Distinct microstructure characteristics coincide with discrete crystallographic structures, gas compositions and calculated thermodynamic stabilities.     

An assessment of monitoring requirements and costs of 'Reduced Emissions from Deforestation and Degradation'

Background  

Negotiations on a future climate policy framework addressing Reduced Emissions from Deforestation and Degradation (REDD) are ongoing. Regardless of how such a framework will be designed, many technical solutions of estimating forest cover and forest carbon stock change exist to support policy in monitoring and accounting. These technologies typically combine remotely sensed data with ground-based inventories. In this article we assess the costs of monitoring REDD based on available technologies and requirements associated with key elements of REDD policy.     

The liver of wrasse - morphology and function as a mirror of point source chemical impact.

Corkwing wrasse (Symphodus melops L.), a protogynous, non-migratory lipfish species, living close to rocky shores was chosen as an indicator species for the monitoring of biological effects of contaminants. Fish were caught by local fisherman at the Norwegian west coast in fjord sites within the framework of the EU BEEP project. The sites represented different point source impacts of (I) copper (a former copper mine), (II) polycyclic aromatic hydrocarbons (PAHs, aluminium smelter discharge), (III) formaldehyde plus PAHs (kelp-factory and influence of the aluminium smelter). Livers of wrasse were studied for histopathological alterations and compared to healthy livers of fish from a reference location. Besides liver morphology, different functional and metabolic parameters were measured to link pathological alterations to functional disorders. The integrity of the lysosomal compartment was tested by the assessment of lysosomal membrane stability (lys), and the accumulation of neutral lipids and lipofuscin. Activity and intracellular localisation of the NADPH-producing enzymes in the liver were assessed histochemically and measured by computer-assisted image analysis. Histopathological alterations were most severe at the site impacted by formaldehyde and PAHs. These findings were associated with highest tumor prevalence, lowest membrane stabilities in hepatocytes and highest accumulation rates of lipofuscin in the liver. The activities of the NADPH-producing enzymes phosphogluconate dehydrogenase (PGDH) and glucose-6-phosphate dehydrogenase (G6PDH) were significantly lower compared to unimpacted reference fish. Histopathological alterations showed clear differences dependent on the input source. Potential links between specific contaminant impact and functional and morphological disorders are discussed.     

Indices for the assessment of environmental pollution of the Baltic Sea coasts: integrated assessment of a multi-biomarker approach

Two mathematical methods to assess the "health status" of flounder (Platichthys flesus), eelpout (Zoarces viviparus) and blue mussel (Mytilus spp.) populations of the Baltic Sea were applied on selected biomarker data collected during the EU project "BEEP" (Biological Effects of Environmental Pollution on Marine Coastal Ecosystems). The Bioeffect Assessment Index (BAI) and the Integrated Biomarker Index (IBR) combine different biomarkers to single values, which can be used to describe the toxically-induced stress level of populations in different areas. Both indices determined here produced essentially similar results, which in most cases agreed with the known contamination levels in the different study areas. Advantages and limitations of index applications and interpretations are critically discussed. The use of indices provides comprehensive information about biological effects of pollution in marine organisms and may therefore serve as a useful tool for environmental management by ranking the pollution status of marine coastal areas.     

Multi-isotope (Ba,C, O) partitioning during experimental carbonatization of a hyper-alkaline solution

Carbonates formed from hyperalkaline aqueous solutions at the Earth?s surface are known to bear the most extreme disequilibrium isotope signatures reported so far in nature. We present here the results for stable carbon (C), oxygen (O), and barium (Ba) isotope fractionation during the precipitation of witherite (BaCO₃) induced by the chemical absorption of atmospheric carbon dioxide (CO₂) into an aqueous hyper-alkaline solution (at 4° and 21?°C; 1?atm total pressure). Independent from temperature, the barium carbonate formation was associated with a substantial enrichment of the lighter C and O isotopes in the solid compared to the atmosphere (C, O), close to previous results found in experiments and nature. A new approach is introduced to explain oxygen isotope fractionation upon hydroxylation of CO₂. With Ba isotope enrichment factors between ?0.45 and ?0.53‰ (^138/134ε) or ?0.34 and ?0.40‰ (^137/134ε), respectively, the synthesized BaCO₃ displays the highest kinetic enrichment of the light Ba isotope in the carbonate solid reported so far.