Oxidative stress, genotoxicity and histopathology biomarker responses in mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) liver from Bizerte Lagoon (Tunisia)

The aim of the study was to evaluate the impact of environmental contaminants on oxidative stress, genotoxic and histopathologic biomarkers in liver of mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) collected from a polluted coastal lagoon (Bizerte Lagoon) in comparison to a reference site (the Mediterranean Sea). Antioxidant enzyme activities were lower in fish from the polluted site compared with fish from the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. DNA damage was higher in both fish species from the contaminated site indicating genotoxic effects. The liver histopathological analysis revealed alterations in fish from Bizerte Lagoon. Hepatocytes from both fish species featured extensive lipid-type vacuolation and membrane disruption. Results suggest that the selected biomarkers in both fish species are useful for the assessment of pollution impacts in coastal environments influenced by multiple pollution sources.     

The 5,660?yBP Boquerón explosive eruption, Teide–Pico Viejo complex, Tenerife

Quantitative hazard assessments of active volcanoes require an accurate knowledge of the past eruptive activity in terms of eruption dynamics and the stratified products of eruption. Teide–Pico Viejo (TPV) is one of the largest volcanic complexes in Europe, but the associated eruptive history has only been constrained based on very general stratigraphic and geochronological data. In particular, recent studies have shown that explosive activity has been significantly more frequently common than previously thought. Our study contributes to characterization of explosive activity of TPV by describing for the first time the subplinian eruption of El Boquerón (5,660?yBP), a satellite dome located on the northern slope of the Pico Viejo stratovolcano. Stratigraphic data suggest complex shifting from effusive phases with lava flows to highly explosive phase that generated a relatively thick and widespread pumice fallout deposit. This explosive phase is classified as a subplinian eruption of VEI 3 that lasted for about 9–15?h and produced a plume with a height of up to 9?km above sea level (i.e. 7?km above the vent; MER of 6.9–8.2?×?10⁵?kg/s). The tephra deposit (minimum bulk volume of 4–6?×?10⁷?m³) was dispersed to the NE by up to 10?m/s winds. A similar eruption today would significantly impact the economy of Tenerife (e.g. tourism and aviation), with major consequences mainly for the communities around the Icod Valley, and to a minor extent, the Orotava Valley. This vulnerability shows that a better knowledge of the past explosive history of TPV and an accurate estimate of future potentials to generate violent eruptions is required in order to quantify and mitigate the associated volcanic risk.     

Nocturnal basin low-level jets: an integrated study

Low-level jets (LLJs) are a very common feature in the nocturnal stably stratified boundary layer. Many factors can intervene in their generation, linked basically to effects of baroclinity. A special kind of low-level jets is composed by the nocturnal katabatic and basin flows, generated over terrain slopes. A study of observed LLJs in the Duero Basin is shown here, combining observational data and modelling experiments. Normalized in respect to the maximum wind height, the dynamic characteristics of the jets are similar: a two-layer system, with a stably stratified layer below the jet maximum and a near neutral layer above, with a very stable layer separating them at the level of the wind maximum. There is vertical mixing above and below the jet, and the connection between these layers takes place occasionally in a very turbulent manner.     

Metal concentrations, fluxes, inventories and chronologies in sediments from Sepetiba and Ribeira Bays: A comparative study

Three sediment cores were sampled at Sepetiba Bay and four cores at Ribeira Bay, Rio de Janeiro State, Brazil. Sediment accumulation rates and chronologies were obtained from ²¹⁰Pb activity-depth profiles. Sediment accumulation rates in Ribera Bay ranged from 1.2 mm y⁻¹ in the inner bay to 2.6 mm y⁻¹ close to its entrance. In Sepetiba Bay two sediment accumulation rates were observed: a lower rate of 0.35 cm y⁻¹ before the 1960s and 0.76 cm y⁻¹ since then. The cause of this change is due to the construction of the Santa Cecília impoundment (1955) that brings water from the Paraíba do Sul Basin into the Guandu River, which increased its flow from the original 20 m³ s⁻¹ to 160 m³ s⁻¹. Concentration of 44 elements was obtained by ICP-MS after total dissolution of samples from two selected cores. The relative differences between the concentrations of crustal elements, such as Al, Fe and Ti are only about 20% (p < 0.05). Cd and Zn are 15 and four times larger in Sepetiba Bay than in Ribeira Bay, respectively. Other major and minor elements show lower statistically significant differences. The enrichment factors and metal inventories show that Sepetiba Bay can be considered polluted with Bi, Cd, Cr, Cu, Sb and Zn. Particularly, Cd and Zn present concentrations three and four times higher than the Brazilian existing limits.     

Towards a better understanding of the evolution of the flood risk in Mediterranean urban areas: the case of Barcelona

Dam failure constitutes a grave threat to human life. However, there is still a lack of systematic and comprehensive research on the loss of life (L) caused by dam break in China. From the perspective of protecting human life, a new calculation method for L occurred in dam break floods is put forward. Fourteen dam failure cases in China are selected as the basic data by three-dimensional stratified sampling, balancing spatial, vertical elevation and temporal representations, as well as considering various conditions of the dam collapse. The method includes three progressive steps: Firstly, some impact factors of loss of life (IFL) are selected by literature survey, i.e., severity of dam break flood (S _F), population at risk (P _R), understanding of dam break (U _B), warning time (T _W) and evacuation condition (E _C). And the other IFL of weather during dam break (W _B), dam break mode (M _B), water storage (S _W), building vulnerability (V _B), dam break time (T _B) and average distance from affected area to dam (D _D) are also taken into account to get a more comprehensive consideration. According to disaster system and disaster risk, these eleven IFL are divided into four categories. Through the improved entropy method, eight key IFL are further selected out of the eleven. Secondly, four L modules are built based on four categories, which are L-causing factor module (M ₁), L-prone environment module (M ₂), affected body module (M ₃) and rescue condition module (M ₄). Eventually, by using two methods of multivariate nonlinear regression and leave-one-out cross-validation in combination with coupled four modules, the calculation method for L is established. Compared with the results of Graham method and D&M method, the result of the proposed one is much closer to the actual value and performs better in fitting effect and regional applicability. In the application, L calculation and consequence assessment are carried out in the example of Hengjiang reservoir that has already broken down. At the same time, L calculation and risk prediction are used in the analysis of Yunshan reservoir, which is under planning. The proposed method can not only be applied to estimate L and its rate (f _L ) under various types of dam break conditions in China, but also provide a reliable consequence assessment and prediction approach to reduce the risk of L.     

U-Pb geochronology on zircon and columbite-group minerals of the Cap de Creus pegmatites,NE Spain

Mineralogy and Petrology - The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-Pb geochronology by laser ablation ICP-MS on zircon and columbite-group...     

A High-Speed Erupting-Prominence CME: A Bridge Between Types

Solar Physics - Several studies have indicated that there may be two distinct types of coronal mass ejections (CMEs); a high-velocity bright energetic type associated with flares, and a smaller...     

Trace/minor element:calcium ratios in cultured benthic foraminifera. Part II: Ontogenetic variation

Ontogenetic (developmental stage) measurements of Mg/Ca and Sr/Ca were made on the benthic foraminifer Bulimina aculeata, which were cultured under controlled physicochemical conditions of temperature, pH, alkalinity, salinity, and trace- and minor-element concentrations. We utilized two methods of ontogenetic sampling—whole specimens progressively increasing in length and laser microdissection of a single specimen with subsequent analysis of dissected portions. A novel high-resolution laser-microdissection (HRLM) method allowed for precise (10 μm) cuts of the foraminiferal tests (shells) along the geometrically complex sutures distinguishing individual chambers. This new microdissection method limited sample loss and cross-contamination between foraminiferal chambers. Little or no variation in D_Sr was observed at different foraminiferal developmental stages. Conversely, D_Mg was enriched during a mid-developmental stage of whole-specimen samples (150-225 μm D_Mg = 1.6 × 10⁻³) compared to earlier and later stages (<150 μm, >225 μm D_Mg = 8.3 × 10⁻⁴). Further analysis of HRLM ontogenetic samples showed a larger, age-dependent D_Mg signature variation. This increase in shell Mg/Ca may contribute substantially to the measured inter-individual variability in Mg/Ca temperature prediction for cultured B. aculeata. Due to relatively large Mg/Ca inter- and intra-individual variability, measuring similar-size foraminiferal samples may improve the precision of paleotemperature prediction. Additionally, partial dissolution of the highest ontogenetically Mg-enriched calcite (D_Mg = 1.3 × 10⁻²-1.6 × 10⁻²) may occur in undersaturated bottom-water environments or during reductive cleaning procedures. Thus, the calcite phases remaining after partial dissolution by either natural or laboratory cleaning processes may not accurately represent the calcification environment.     

Two‐hourly surface change on supra‐tidal rock (Marengo,Victoria, Australia)

A traversing micro‐erosion meter was used to measure rock surface micro‐topography over 40 cm² on a supra‐tidal cliff face from early morning to late evening in late spring. From 06:00 hours to 22:00 hours the relative heights of 188 coordinates were obtained using the meter at 2‐hour intervals, resulting in a data set of 1607 readings. Monitoring shows that rock surfaces are dynamic entities, with significant rise and fall relative to the first measurement at shorter timescales than previously reported. The maximum positive rise between readings was 0·261 mm and lowering was 0·126 mm. The pattern of change did not relate as expected to environmental variables such as temperature or insolation. Rather, the surface showed greater surface change in the early morning and late afternoon. It is hypothesized that this pattern relates to the expansion and contraction of lichen thalli as moisture is absorbed during higher humidity in the morning and late afternoon. The implications of these results for weathering studies are considered. Copyright © 2006 John Wiley & Sons, Ltd.     

Hydrogen Peroxide at the Bermuda Atlantic Time Series Station. Part 1: Temporal Variability of Atmospheric Hydrogen Peroxide and Its Influence on Seawater Concentrations

Diurnal and seasonal variations in atmospheric hydrogen peroxideconcentrations wereinvestigated during a summer and winter cruise aboard the R.V. `Endeavor' atthe BermudaAtlantic Time Series Station. Rainwater peroxide concentrations in Augustdisplayed dielvariability while no temporal H₂O₂ pattern was evidentin March rain. Averageconcentrations in March were also significantly lower than August whichindicates photochemicalprocesses are involved in controlling hydrogen peroxide concentrations inmarine rainwaterfalling over the open ocean. The range of gas phase hydrogen peroxideconcentrations wasbetween 1 and 6 ppbv and also exhibited a strong diurnal pattern during bothAugust and Marchwith concentration maxima in the early evening. The influence of atmosphericdeposition onsurface seawater hydrogen peroxide levels was also evaluated. Hydrogenperoxide depth profileswere measured on four separate occasions before and after rain events duringthe Augustsampling period. The input of rainfall hydrogen peroxide was observedthroughout the 25 metermixed layer with surface concentrations two fold larger in the morning aftera rain event. Theintegrated increase in hydrogen peroxide after the rain from 0 to 90 meterswas 1,720 molalmost all of which could be accounted for by the peroxide added from rain.The data presentedin this study represent the first detailed, simultaneous measurements ofhydrogen peroxide inmarine air, rain and surface seawater.