Investigation of microbial influences on seafloor gas-hydrate formations

Microbial communities flourish at gas hydrate occurrences in ocean sediments. Studies are reported in this paper on the laboratory production, separation, characterization and hydrate catalysis of biosurfactants from cultures of the Bacillus subtilis bacterium associated with Gulf of Mexico gas-hydrate accumulations. The B. subtilis bacterium from ATCC 21332 species was cultured anaerobically with glucose as carbon-source to produce surfactin, one of the more potent surface active agents known. The surface-active agent was removed from the broth in foam created by bubbling inert gas through the mixture, and biosurfactant was then recovered from the collapsed-foam distilled water solution by acid precipitation and dichloromethane extraction. According to HPLC spectra, five surfactin isomers were identified in the sample of laboratory-generated biosurfactant. Recovered surfactin was then used to perform gas-hydrate formation studies in porous media saturated with the surfactin-water solution. Gas-hydrate induction time and formation rate determinations showed that the anaerobically-produced biosurfactants catalyzed hydrate formation markedly. The tests suggest prolific surfactin production by the B. subtilis bacterium and of other species under prevailing anaerobic conditions around seafloor gas hydrates that promotes hydrate formation and the propensity of the bioproduct to be dispersed in the porous media by natural gas vents.     

ASIANS,PACIFIC ISLANDERS,AND ETHNOBURBS IN AUCKLAND,NEW ZEALAND

ABSTRACT. Recent work on Asian ethnic minority immigrants to cities in the Anglophone Pacific Rim argues that their settlement patterns do not conform to those of earlier migrant streams. Instead of concentrating in high‐density, low‐quality, inner‐city housing, these new residents are moving directly to suburban areas where they form much less intensive concentrations—ethnoburbs—than has been typical of other culturally distinct migrant groups. We evaluate this thesis for Asian migrants in the Auckland metropolitan area, whose numbers more than quadrupled between 1991 and 2006. Their residential pattern is compared with that of Pacific Islanders also resident there, providing supporting evidence for the ethnoburb hypothesis.     

Assessment of a Bayesian Belief Network-GIS framework as a practical tool to support marine planning

For the UK continental shelf we developed a Bayesian Belief Network-GIS framework to visualise relationships between cumulative human pressures, sensitive marine landscapes and landscape vulnerability, to assess the consequences of potential marine planning objectives, and to map uncertainty-related changes in management measures. Results revealed that the spatial assessment of footprints and intensities of human activities had more influence on landscape vulnerabilities than the type of landscape sensitivity measure used. We addressed questions regarding consequences of potential planning targets, and necessary management measures with spatially-explicit assessment of their consequences. We conclude that the BN-GIS framework is a practical tool allowing for the visualisation of relationships, the spatial assessment of uncertainty related to spatial management scenarios, the engagement of different stakeholder views, and enables a quick update of new spatial data and relationships. Ultimately, such BN-GIS based tools can support the decision-making process used in adaptive marine management.     

Hard X-ray and low-energy gamma-ray spectrometers

Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resolution for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.     

In defense of anti-matter

There appears to be a prejudice in the astronomical world against an obvious high-energy source—the mutual annihilation of matter and anti-matter. In favor of this prejudice is the lack of any convincing evidence of the presence of naturally occurring anti-matter. Only recently have cosmic-ray antiprotons been detected (cf. Goldenet al., 1979), and then in numbers consistent with secondary production in flight, while annihilation X-rays have also been detected, but again in circumstances where they might well be attributed to secondary effects of some other high-energy process.     

Determination of Selenium and Tellurium in Basalt Rock Reference Materials by Isotope Dilution Hydride Generation-Inductively Coupled Plasma-Mass Spectrometry (ID-HG-ICP-MS)

Promising methods have been developed recently for the determination of selenium (Se) and tellurium (Te) in geological materials at ng g⁻¹ and lower levels, using hydride generation-inductively coupled plasma-mass spectrometry. Here we report on a new isotope dilution-hydride generation-inductively coupled plasma-mass spectrometry (ID-HG-ICP-MS) method for the simultaneous determination of Se and Te, which is applied to basalts, and modified compared to previous work. The basalts were attacked and dissolved with hydrofluoric and nitric acid, spiked with enriched isotopes, and passed through a cation exchange column (AG 50-X8 100–200 mesh) to separate the major cations that interfere with Se and Te detection (e.g., Fe). The detection limits of this method were 0.010 ng g⁻¹ for Se and 0.0030 ng g⁻¹ for Te, well below the concentrations of Se and Te expected in basalts. The precision of the method for Se was 12.2 to 15.1% and for Te was 4.6 to 7.2% RSD from replicate analyses of basalt reference samples. The accuracy for Se determinations was 61 to 94% and for Te 28 to 100% of values previously reported in the literature for selected USGS reference materials.     

A review of conventional techniques for subsurface characterization of landslides

Naturally occurring landslides can be difficult to characterize and often exhibit anomalies in controlling geometry and consistency. The characterization of landslides in engineering geology practice is usually based on program of subsurface exploration; focused on identifying subsurface materials, structure and stratigraphy, hydrologic conditions, and appropriate strength parameters. On native slopes bereft of anthropogenic modification (excavation), geomorphic evidence of previous movement and its relative depth and scale are often discernible to the experienced eye. This paper seeks to describe the various techniques that have been successfully employed in site-specific subsurface investigations of prehistoric landslides. These include considerations of limiting geometry (for planning subsurface exploration and sampling), overcoming problems with site access, exploratory trenches, small diameter borings, downhole logging of large diameter borings, and geophysical techniques. These procedures can be combined to develop more realistic cross sections along the vector of maximum landslide movement, so the displaced mass can be realistically analyzed. The respective advantages and disadvantages of these techniques are discussed, with baseline references on subsurface exploration.