Effects of molecular mass on the diffusion coefficient in a multiphase lattice Boltzmann model

We introduce a simplified expression for the diffusion coefficient (D) of a multicomponent Lattice Boltzmann model. For dilute solutions, this expression is reduced to have dependence only on the molecular mass and relaxation time of the solute. By altering the molecular mass, the value of D can be varied by several orders of magnitude, thus, providing an additional parameter for use in tuning LB model values to physical systems. The ability to adjust the values of molecular mass can also be used to decrease simulation times. This is advantageous as it allows application of the LB model to solve problems that previously required prohibitive computational resources. The capability to model a wide range of diffusion coefficients and decrease simulation times is illustrated in a simple case study.     

Environmental justice implications of Maritime Spatial Planning in the European Union

This paper examines the implications of environmental justice in the regime for Maritime Spatial Planning (MSP) currently developing in the European Union (EU). An ‘ecosystem-based approach’ to marine management is enshrined in the new Integrated Maritime Policy and Marine Strategy Framework Directive and forms the basis of MSP. This concept is intended to encompass all aspects of an ecosystem, including the human element. Yet the modes of including meaningful public participation in the decision-making process for MSP remain undetermined. At the same time, the Aarhus Convention (on access to information, public participation in decision making and access to justice in environmental matters) empowers non-governmental organisations to hold EU Member States to account. Consequently the issue of transparency will gain increased importance, as will linkages between human and environmental rights. Such public interest-based activism on the part of NGOs has the potential to enforce the developing framework for stakeholder engagement within MSP, but it also has implications worth considering regarding the appropriate role of interest-based organisations in the international political arena.     

Mapping of the Culann-Tohil region of Io from Galileo imaging data

We have used Galileo spacecraft data to produce a geomorphologic map of the Culann-Tohil region of Io's antijovian hemisphere. This region includes a newly discovered shield volcano, Ts?i Goab Tholus and a neighboring bright flow field, Ts?i Goab Fluctus, the active Culann Patera and the enigmatic Tohil Mons-Radegast Patera-Tohil Patera complex. Analysis of Voyager global color and Galileo Solid-State Imaging (SSI) high-resolution, regional (50-330 m/pixel), and global color (1.4 km/pixel) images, along with available Galileo Near-Infrared Mapping Spectrometer (NIMS) data, suggests that 16 distinct geologic units can be defined and characterized in this region, including 5 types of diffuse deposits. Ts?i Goab Fluctus is the center of a low-temperature hotspot detected by NIMS late during the Galileo mission, and could represent the best case for active effusive sulfur volcanism detected by Galileo. The Culann volcanic center has produced a range of explosive and effusive deposits, including an outer yellowish ring of enhanced sulfur dioxide (SO₂), an inner red ring of SO₂ with short-chain sulfur (S₃-S₄) contaminants, and two irregular green diffuse deposits (one in Tohil Patera) apparently produced by the interaction of dark, silicate lava flows with sulfurous contaminants ballistically-emplaced from Culann's eruption plume(s). Fresh and red-mantled dark lava flows west of the Culann vent can be contrasted with unusual red-brown flows east of the vent. These red-brown flows have a distinct color that is suggestive of a compositional difference, although whether this is due to surface alteration or distinct lava compositions cannot be determined. The main massif of Tohil Mons is covered with ridges and grooves, defining a unit of tectonically disrupted crustal materials. Tohil Mons also contains a younger unit of mottled crustal materials that were displaced by mass wasting processes. Neighboring Radegast Patera contains a NIMS hotspot and a young lava lake of dark silicate flows, whereas the southwest portion of Tohil Patera contains white flow-like units, perhaps consisting of ‘ponds’ of effusively emplaced SO₂. From 0°-15° S the hummocky bright plains unit away from volcanic centers contains scarps, grooves, pits, graben, and channel-like features, some of which have been modified by erosion. Although the most active volcanic centers appear to be found in structural lows (as indicated by mapping of scarps), DEMs derived from stereo images show that, with the exception of Tohil Mons, there is less than 1 km of relief in the Culann-Tohil region. There is no discernable correlation between centers of active volcanism and topography.     

On the effects of a sudden change in the albedo of the Earth

Acquisition by the upper atmosphere of some 10¹⁴ gm of cometary dust would have major implications on the Earth's climate. Pluvial activity would increase dramatically as temperature differences between sea and land widened. Global distribution of precipitation would be controlled by the density of the dust in the atmosphere; for a partially reflective blanket, a fraction of solar energy would still reach ground level creating new climatic zones. The totally undecomposed state of the interiors of Siberian Mammoths and the curious distribution, often uphill, of erratic boulders point to unbelievably sudden and severe conditions at the onset and possibly end of a glacial period. We suggest that a reflective blanket of particles could produce such conditions.     

Particle Retention in a Submerged Meadow and Its Variation Near the Leading Edge

The retention of particles within meadows of submerged aquatic vegetation impacts the fate of organic matter, pollen, and larvae. Because flow conditions near the leading edge differ from those over the bulk of the canopy, particle retention is likely to differ as well. In particular, near the leading edge of a wide meadow, flow deceleration generates a vertical updraft, which impacts particle fate. In the fully developed region of the meadow, shear layer vortices at the top of the meadow may also influence particle fate. In this study, the retention of particles was measured along the length of a 10-m model meadow (height h?=?0.1 m) and was connected to the evolving flow field. Two particle sizes, with settling velocity w _s50?=?0.00075?,?0.018 m s^?1, were released at two heights within the model meadow \( \left(\frac{Z_{rel}}{h}=0.31,0.81\right). \) The retention of particles was measured using microscope slides distributed along the flume bed. Retention increased with distance from the leading edge, associated with the decrease in vertical updraft. Retention was also greater for the particles with higher settling velocity. In the fully developed region of the meadow, particle retention was lower for particles influenced by the shear layer vortices at the top of the meadow (\( \frac{Z_{rel}}{h}=0.81 \)).     

Sulfur isotope and trace element data from ore sulfides in the Noranda district (Abitibi,Canada): implications for volcanogenic massive sulfide deposit genesis

We examine models for volcanogenic massive sulfide (VMS) mineralization in the ~2.7-Ga Noranda camp, Abitibi subprovince, Superior Province, Canada, using a combination of multiple sulfur isotope and trace element data from ore sulfide minerals. The Noranda camp is a well-preserved, VMS deposit-rich area that is thought to represent a collapsed volcanic caldera. Due to its economic value, the camp has been studied extensively, providing a robust geological framework within which to assess the new data presented in this study. We explore previously proposed controls on mineralization within the Noranda camp and, in particular, the exceptional Au-rich Horne and Quemont deposits. We present multiple sulfur isotope and trace element compositional data for sulfide separates representing 25 different VMS deposits and “showings” within the Noranda camp. Multiple sulfur isotope data for this study have δ³⁴S_V-CDT values of between ?1.9 and +2.5?‰, and Δ³³S_V-CDT values of between ?0.59 and ?0.03?‰. We interpret the negative Δ³³S values to be due to a contribution of sulfur that originated as seawater sulfate to form the ore sulfides of the Noranda camp VMS deposits. The contribution of seawater sulfate increased with the collapse and subsequent evolution of the Noranda caldera, an inference supported by select trace and major element analyses. In particular, higher concentrations of Se occur in samples with Δ³³S values closer to 0?‰, as well as lower Fe/Zn ratios in sphalerite, suggesting lower pressures and temperatures of formation. We also report a relationship between average Au grade and Δ³³S values within Au-rich VMS deposits of the Noranda camp, whereby higher gold grades are associated with near-zero Δ³³S values. From this, we infer a dominance of igneous sulfur in the gold-rich deposits, either leached from the volcanic pile and/or directly degassed from an associated intrusion.