Evidence for methane and hydrogen sulfide venting imprinted on a Quaternary eolianite from southern Israel

Two different and physically separated chemosynthetic communities of bacteria are responsible for the formation of the Beeri native sulfur deposit hosted in a Late Quaternary sandstone on the southern coastal plain of Israel. The enriched concentrations are distributed over an area of about 1 km², within a zone 2–3 m thick at 1–13 m below surface. Two hundred fifty meters below the sulfur deposit, sulfur-reducing bacteria, thriving on methane generated in Neogene marls, reduced the Messinian gypsum to generate hydrogen sulfide, which subaqueously vented together with methane into the siliciclastic Quaternary sequence. Another, different chemosynthetic community ofBeggiatoa-like and unidentified bacteria oxidized the hydrogen sulfide into native sulfur and secondary gypsum, alunite, and iron sulfates. The coupled chemical and bacterial processes attributed to the formation of the sulfur deposit at Beeri are strikingly similar to the processes occurring today in the context of submarine hydrocarbon vents associated with the salt diapirs in the Gulf of Mexico.     

Effects of beta-naphthoflavone on hepatic biotransformation and glutathione biosynthesis in largemouth bass (Micropterus salmoides)

We are investigating the effects of in vivo exposure of prototypical enzyme inducing agents on hepatic biotransformation enzyme expression in largemouth bass (Micropterus salmoides), a predatory game fish found throughout the United States and Canada. The current study targeted those genes involved in biotransformation and oxidative stress that may be regulated by Ah-receptor-dependent pathways. Exposure of bass to beta-naphthoflavone (beta-NF, 66 mg/kg, i.p.) elicited a 7-9-fold increase in hepatic microsomal cytochrome P4501A-dependent ethoxyresorufin O-deethylase (EROD) activities, but did not affect cytosolic GST catalytic activities toward 1-chloro-2,4-dinitrobenzene (CDNB) or 5-androstene-3,17-dione (ADI). Glutathione S-transferase A (GST-A) mRNA expression exhibited a transient, but non-significant increase following exposure to beta-NF, and generally tracked the minimal changes observed in GST-CDNB activities. Expression of the mRNA encoding glutamate-cysteine ligase catalytic subunit (GCLC), the rate-limiting enzyme in glutathione (GSH) biosynthesis, was increased 1.7-fold by beta-NF. Changes in GCLC mRNA expression were paralleled by increases in intracellular GSH. In summary, largemouth bass hepatic CYP1A-dependent and GSH biosynthetic pathways, and to a lesser extent GST, are responsive to exposure to beta-NF.     

Sediment transport pattern at the Barra Nova inlet, south Portugal: a conceptual model

The Barra Nova inlet, in south Portugal, is known to migrate progressively southeastwards under wave action. The morphodynamics of this system during a representative year suggests that this long-term evolution is dependent on a seasonal behavior of the tidal inlet which can be described through a three-stage model of post-storm, transition and extended fair-weather conditions. Processes involved in this evolution indicate that the historical migration of the Barra Nova is not dependent on the longshore drift forcing constricting the channel on the updrift coast, but rather on the adjustment of the system to a major erosion of the downdrift coast during short storm events.     

The buckling of plastic oblate hemi-ellipsoidal dome shells under external hydrostatic pressure

The paper presents a theoretical and an experimental investigation into the buckling of seven oblate hemi-ellipsoidal dome shells under external hydrostatic pressure. Four of the shells were made in glass reinforced plastic and three were made from a thermosetting plastic called solid urethane plastic. All the vessels were tested to destruction. The theoretical study was made with the aid of a non-linear finite element solution, where both geometrical and material non-linearity were allowed for. Good agreement was found between experiment and theory for all the vessels. The very oblate domes failed axisymmetrically. Theoretical convergence was good for the more oblate domes but it was not as good as for the less oblate domes. This may have been because the less oblate domes did not fail in a classical axisymmetric manner as was expected. This work is of much importance in ocean engineering.     

Water vapor in the atmosphere over the northern Tien Shan

Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity.     

Methods of fitting the Fisher-Tippett type 1 extreme value distribution

Methods are described for estimating the parameters of the Fisher-Tippet Type 1 extreme value distribution and associated return values from measured extremes, such as maximum wave height. A comparison of these methods, with simulated data, shows that those using Gumbel's plotting position are least satifactory. Maximum likelihood methods give the smallest mean square errors, but the very much simpler method of moments is nearly as good.     

A literature review of the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on OTEC heat exchangers

An investigation has been made of available data on the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on Ocean Thermal Energy Conversion (OTEC) heat exchangers. Pertinent oceanographic data is lacking at or near potential OTEC sites for the calculation of the degree of saturation of seawater with respect to calcium carbonate. Consequently, only “extrapolated” saturation values can be used. These indicate that near surface seawater is probably supersaturated, with respect to the calcium carbonate phases calcite and aragonite, at all potential OTEC sites. The deep seawater that would be brought to the surface at the potential Atlantic Ocean sites is also likely to be supersaturated with respect to calcium carbonate. The deep seawater at the potential Pacific Ocean sites may be slightly undersaturated.The fact that OTEC heat exchangers will be operating in seawater, which is supersaturated with respect to calcium carbonate, means that if nucleation of calcite or aragonite occurs on the heat exchanger surfaces, significant growth rates of calcium carbonate scale may be expected. The potential for calcium carbonate nucleation is highest at cathodic metal surface locations, which are produced as the result of aluminum corrosion in seawater. Consequently, corrosion and scale formation may be closely related. What the possible effects of biofouling may be on this process are not known.