The Norma cluster (ACO 3627) – I. A dynamical analysis of the most massive cluster in the Great Attractor

A detailed dynamical analysis of the nearby rich Norma cluster (ACO 3627) is presented. From radial velocities of 296 cluster members, we find a mean velocity of 4871 ± 54 km s⁻¹ and a velocity dispersion of 925 km s⁻¹. The mean velocity of the E/S0 population (4979 ± 85 km s⁻¹) is offset with respect to that of the S/Irr population (4812 ± 70 km s⁻¹) by  Δ v = 164 km s⁻¹  in the cluster rest frame. This offset increases towards the core of the cluster. The E/S0 population is free of any detectable substructure and appears relaxed. Its shape is clearly elongated with a position angle that is aligned along the dominant large-scale structures in this region, the so-called Norma wall. The central cD galaxy has a very large peculiar velocity of 561 km s⁻¹ which is most probably related to an ongoing merger at the core of the cluster. The spiral/irregular galaxies reveal a large amount of substructure; two dynamically distinct subgroups within the overall spiral population have been identified, located along the Norma wall elongation. The dynamical mass of the Norma cluster within its Abell radius is  1–1.1 × 10¹⁵  h ⁻¹₇₃ M_⊙  . One of the cluster members, the spiral galaxy WKK 6176 which recently was observed to have a 70 kpc X-ray tail, reveals numerous striking low-brightness filaments pointing away from the cluster centre suggesting strong interaction with the intracluster medium.     

A preliminary investigation of siliceous microfossil succession in late Quaternary sediments from Lake Baikal, Siberia

Siliceous microfossil assemblage succession was analyzed in a 100 m sediment core from Lake Baikal, Siberia. The core was recovered from the lake's central basin at a water depth of 365 m. Microfossil abundance varied greatly within the intervals sampled, ranging from samples devoid of siliceous microfossils to samples with up to 3.49 × 10¹¹ microfossils g^-1 sediment. Fluctuations in abundance appear to reflect trends in the marine ¹⁸O record, with peak microfossil levels generally representing climate optima. Microfossil taxa present in sampled intervals changed considerably with core depth. Within each sample a small number of endemic diatom species dominated the assemblage. Changes in dominant endemic taxa between sampled intervals ranged from extirpation of some taxa, to shifts in quantitative abundance. Differences in microfossil composition and the association of variations in abundance with climate fluctuations suggest rapid speciation in response to major climatic excursions.     

Production of methyl bromide and methyl chloride in laboratory cultures of marine phytoplankton II

Methyl halides (monohalomethanes), especially methyl bromide, are known to contribute significantly to ozone destruction in the stratosphere. Budgets of natural and anthropogenic methyl bromide suggest that marine organisms may be the source of a significant proportion of the total global production. Since phytoplankton are abundant in surface waters, they are obvious candidates. Cultures of nine phytoplankton species were grown in CO₂-enriched, nitrate-limited medium in sealed glass vessels. Species tested include Chaetoceros calcitrans, Isochrysis sp., Porphyridium sp., Synechococcus sp., Phaeodactylum tricornutum, Tetraselmis sp., Prorocentrum sp., Emiliania huxleyi and Phaeocystis sp. Methyl bromide (CH₃Br) and methyl chloride (CH₃Cl) concentrations were determined by bubbling the cultures with high-purity air, cryotrapping the effluent and analyzing it on a gas chromatograph with an electron capture detector. The Phaeocystis sp. samples were monitored with GCMS. Cell population, bacterial population, Chl a, pH, and nitrate concentration were monitored for periods of at least two weeks. CH₃Cl was produced by all cultures. CH₃Br was absent in Tetraselmis sp. and Isochrysis sp. cultures, but present in all the others. Methyl iodide (CH₃I) was present in most cultures but could not be quantified due to analytical limitations. CH₃I and CH₃Br production was fastest in stationary phase and continued long after cell division had ceased. Axeic cultures of Phaeocystis sp. achieved almost identical production rates of CH₃Cl and CH₃Br as xenic cultures of the same species. Species from tropical waters had faster CH₃Cl and CH₃Br production rates than temperate species. Scaling the observed production rates using global standing stock estimates for Chl a and particulate nitrogen indicate that phytoplankton can account for only a fraction of the CH₃Cl and CH₃Br believed to be produced in the ocean. Calculations based on the estimated global biomass of Phaeocystis sp. and E. huxleyi blooms show that their contribution is insignificantly small.     

Geologic sources and geographic distribution of sand tempers in prehistoric potsherds from the Mariana Islands

Temper sands in prehistoric potsherds of the Mariana Islands include terrigenous detritus derived from Paleogene volcanic bedrock and calcareous grains derived chiefly from modern fringing reefs, but also in part from uplifted Neogene limestones overlying volcanic bedrock. Calcareous sands are nondiagnostic of island of origin, but volcanic sands and the terrigenous component of hybrid sands composed of mixed terrigenous and calcareous grain types can be traced to geologic sources on Saipan and Guam, the only occupied islands where volcanic bedrock is extensively exposed. Quartzose tempers of several types were derived exclusively from dacitic volcanic rocks on Saipan. Nonquartzose tempers of andesitic parentage derive from both Saipan and Guam, but abundance of orthopyroxene as well as clinopyroxene is diagnostic of Saipan andesitic tempers, the presence of olivine is diagnostic of selected tempers from Guam, and placer temper sands rich in heavy ferromagnesian minerals occur only in sherds on Guam. Temper analysis documents widespread ceramic transfer from Saipan to other islands throughout Mariana prehistory, and more restricted ceramic transfer from Guam to nearby Rota, although the origin of some andesitic temper types is petrographically indeterminate. © 2001 John Wiley & Sons, Inc.     

Watershed morphometric analysis of Wadi Baish Dam catchment area using integrated GIS-based approach

The integration of Remote Sensing (RS) and Geographic Information Systems (GIS) constitutes a powerful tool for the evaluation of watershed morphometric parameters. The benefits of this integration include saving time and effort as well as improving the accuracy of the analysis. Moreover, this technique is appropriate for describing the watershed and its streams. In this study, a detailed morphometric analysis of the Wadi Baish catchment area has been performed using the Shuttle Radar Topography Mission (SRTM). The performed morphometric analysis includes linear, areal, and relief aspects. The results of the morphometric analysis reveal that the catchment can be described as of eighth stream order and consists of an area of 4741.07 km². Additionally, the basin is characterized by a relatively high mean value of bifurcation (4.012), indicative of the scarcity of permeable rocks with high slope in the area. This value of bifurcation ratio is consistent with the high drainage density value of 2.064 km/km² and confirms the impermeability of the subsurface material and mountainous relief. The hypsometric integral of the catchment is 47.4%, and the erosion integral of the catchment is 52.6%, both were indications of a mature catchment area.     

Recent shifts in coastline change and shoreline stabilization linked to storm climate change

Since cuspate coastlines are especially sensitive to changes in wave climate, they serve as potential indicators of initial responses to changing wave conditions. Previous work demonstrates that Cape Hatteras and Cape Lookout, North Carolina, which are largely unaffected by shoreline stabilization efforts, have become increasingly asymmetric over the past 30 years, consistent with model predictions for coastline response to increases in Atlantic Ocean summer wave heights and resulting changes in the distribution of wave‐approach angles. Historic and recent shoreline change observations for Cape Fear, North Carolina, and model simulations of coastline response to an increasingly asymmetric wave climate in the presence of beach nourishment, produce comparable differences in shoreline change rates in response to changes in wave climate. Results suggest that the effect of beach nourishment is to compensate for – and therefore to mask – natural responses to wave climate change that might otherwise be discernible in patterns of shoreline change alone. Therefore, this case study suggests that the effects of wave climate change on human‐modified coastlines may be detectable in the spatial and temporal patterns of shoreline stabilization activities. Similar analyses of cuspate features in areas where the change in wave climate is less pronounced (i.e. Fishing Point, Maryland/Virginia) and where local geology appears to exert control on coastline shape (i.e. Cape Canaveral, Florida), suggest that changes in shoreline configuration that may be arising from shifting wave climate are currently limited to sandy wave‐dominated coastlines where the change in wave climate has been most pronounced. However, if hurricane‐generated wave heights continue to increase, large‐scale shifts in patterns of erosion and accretion will likely extend beyond sensitive cuspate features as the larger‐scale coastline shape comes into equilibrium with changing wave conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Reservoir construction from the Newberry Volcano EGS Demonstration

The Newberry Volcano EGS Demonstration in central Oregon tests recent technological advances designed to reduce the cost of power generated by EGS in a hot, dry well (NWG 55-29) drilled in 2008. An EGS reservoir was created by injecting large volumes of cold water, causing existing fractures to slip in shear (known as hydroshearing) generating the seismic waves that can be used to map fracture location and size. At the Newberry Demonstration the final injectivity ranged between 1.4 and 1.7 L/s/MPa a ~6x improvement over the initial injectivity of the well. The injectivity improvement and seismic analysis indicate that previously impermeable fractures were enhanced during the NWG 55-29 stimulation.     

Recent explosive eruptions and volcano hazards at Soputan volcano—a basalt stratovolcano in north Sulawesi, Indonesia

Soputan is a high-alumina basalt stratovolcano located in the active North Sulawesi-Sangihe Islands magmatic arc. Although immediately adjacent to the still geothermally active Quaternary Tondono Caldera, Soputan’s magmas are geochemically distinct from those of the caldera and from other magmas in the arc. Unusual for a basalt volcano, Soputan produces summit lava domes and explosive eruptions with high-altitude ash plumes and pyroclastic flows—eight explosive eruptions during the period 2003–2011. Our field observations, remote sensing, gas emission, seismic, and petrologic analyses indicate that Soputan is an open-vent-type volcano that taps basalt magma derived from the arc-mantle wedge, accumulated and fractionated in a deep-crustal reservoir and transported slowly or staged at shallow levels prior to eruption. A combination of high phenocryst content, extensive microlite crystallization and separation of a gas phase at shallow levels results in a highly viscous basalt magma and explosive eruptive style. The open-vent structure and frequent eruptions indicate that Soputan will likely erupt again in the next decade, perhaps repeatedly. Explosive eruptions in the Volcano Explosivity Index (VEI) 2–3 range and lava dome growth are most probable, with a small chance of larger VEI 4 eruptions. A rapid ramp up in seismicity preceding the recent eruptions suggests that future eruptions may have no more than a few days of seismic warning. Risk to population in the region is currently greatest for villages located on the southern and western flanks of the volcano where flow deposits are directed by topography. In addition, Soputan’s explosive eruptions produce high-altitude ash clouds that pose a risk to air traffic in the region.     

Estimation of forest harvesting-induced stream temperature changes and bioenergetic consequences for cutthroat trout in a coastal stream in British Columbia, Canada

Data from a paired-catchment study in south coastal British Columbia, Canada, were analyzed to assess the thermal effects of clearcut harvesting with no riparian buffer on a fish-bearing headwater stream. The approach used time series of daily mean water temperatures for East Creek (control) and A Creek (treatment), both before and after harvest. Statistical models were developed to predict (a) what the temperatures would have been in the post-harvest period had harvesting not occurred, and (b) what temperatures would have been in the pre-harvest period had harvesting already occurred. The Wisconsin Bioenergetics Model was used to simulate growth of coastal cutthroat trout (Oncorhynchus clarki clarki) for the first year following fry emergence using the predicted and observed stream temperatures to generate scenarios representing with-harvest and no-harvest thermal regimes. A Monte Carlo approach was used to quantify the effects of uncertainty associated with the regression models on predicted stream temperature and trout growth. Summer daily mean temperatures in the with-harvest scenario were up to $5^{\circ}\hbox{C}$ higher than those for the no-harvest scenario. Harvesting-induced warming reduced growth rates during summer, but increased growth rates during autumn and spring. In the with-harvest scenario, trout were 0.2?C2.0?g (absolute weight) smaller throughout the winter period than in the no-harvest scenario. However, the bioenergetic simulations suggest that trout growth may be more sensitive to potential changes in food supply following harvesting than to direct impacts of stream temperature changes.     

Plastic ingestion by planktivorous fishes in the North Pacific Central Gyre

A significant amount of marine debris has accumulated in the North Pacific Central Gyre (NPCG). The effects on larger marine organisms have been documented through cases of entanglement and ingestion; however, little is known about the effects on lower trophic level marine organisms. This study is the first to document ingestion and quantify the amount of plastic found in the gut of common planktivorous fish in the NPCG. From February 11 to 14, 2008, 11 neuston samples were collected by manta trawl in the NPCG. Plastic from each trawl and fish stomach was counted and weighed and categorized by type, size class and color. Approximately 35% of the fish studied had ingested plastic, averaging 2.1 pieces per fish. Additional studies are needed to determine the residence time of ingested plastics and their effects on fish health and the food chain implications.