Metal Outflow Research Articles

Mass to Light Ratio, Initial Mass Function, and Chemical Evolution in Disk Galaxies

AbstractCosmological simulations of disk galaxy formation, when compared to the observed Tully–Fisher relation, suggest a low mass to light (M/L) ratio for the stellar component in spirals. We show that a number of 'bottom-light' initial mass functions (IMFs) suggested independently in the literature, do imply M/L ratios as low as required, at least for late type spirals (Sbc–Sc). However the typical M/L ratio, and correspondingly the zero point of the Tully–Fisher relation, is expected to vary considerably with Hubble type.Bottom-light IMFs tend to have a metal production in excess of what is typically estimated for spiral galaxies. Suitable tuning of the IMF slope and mass limits, post-supernova fallback of metals onto black holes or metal outflows must then be invoked, to reproduce the observed chemical properties of disk galaxies.

Massive (?) starburst hosts of blue compact galaxies (BCGs)

We present optical spectroscopy and deep optical/near-IR photometry of 4 luminous metal-poor blue compact galax- ies (BCGs) and two of their companions. With the aid of spectral evolutionary models (SEMs) and structural parameters derived from the surface photometry we discuss the properties of the central starbursts and the halo populations of the galaxies. Special attention is paid to the eects of dust, chemical inhomogeneities and contamination of nebular emission to the halo light. The optical/near-IR colour index profiles show a sharp distinction between the starburst and the host. The hosts have luminosity profiles characteristic of massive ellipticals and remarkably red colours, typical of a relatively metal-rich stellar population of old age. These properties are in conflict with the relatively low luminosities. The situation can best be explained if the hosts have an unusually large amount of dark matter that can hinder the outflow of metals from the system.The indicated dierence in metallicity between the halo and the young starburst disproves the recurrent burst scenario and supports dierent origins of the two populations. We conclude that these BCGs are undergoing mergers between early type galaxies/thick disks and gas-rich galaxies or intergalactic HI clouds, in many respects reminiscent of a retarded formation of massive ellipticals.

URBAN METAL FLOWS - A CASE STUDY OF STOCKHOLM Review and Conclusions

Metals have rapidly accumulated in the anthroposphere, especiallyin urban areas, indicating possible environmental and resource problems. Here, Stockholm City was chosen for a case study of urban metal flows, i.e. metal inflow to, metals in the stock of,and metal outflow from the anthroposphere to the biosphere. Themetal stock of Stockholm is large and still growing. The large amounts of metals in the solid waste fraction totally dominatethe outflow from the city. For major parts of the stock, the emissions from goods in use are negligible. There are, however,goods applications corresponding to significant emissions: e.g. the traffic sector (Cu, Zn, Cr, Ni, Pb), the tapwater system (Cu), roofs/fronts or other metal surfaces (Cu, Zn). Today's known metal flows from the anthroposphere of Stockholm to the biosphere and sewage sludge are quantitatively dominated by Zn(34 ton y-1) and Cu (14 ton y-1). Historical and present emissions have resulted in high metal concentrations insediments (especially Cd, Hg and Pb, but also Cu and Zn), groundwater (Cu, Hg) and in soils (Hg, Cu, Pb). At present theannual median concentrations are below the Swedish limits for metals in sewage sludge, even if the safety margins aresmall for Cd, Hg and to some extent Cu. The flows of Cu and Zn to Stockholm soils are high with a significant accumulationindicating an environmental impact in a longer time perspective.High levels of metals in surface sediments in the waterenvironments reflects an ongoing input where these metals aretransported from known (Cu, Zn) and or partly unknown (Cd, Hg, Pb) sources. In future urban areas, monitoring of metal flows must be performed both in the anthroposphere and the biospherein order to have a pro active approach to urban environmentalproblems and to get prompt answers to measures taken.

Preliminary Investigations of High-Frequency Atmospheric-Pressure Plasma Jet for Atomic Emission Spectrometry

The 27.12- and 13.56-MHz plasma-jet discharges are generated in argon at atmospheric pressure. The plasma originates inside the nozzle of the bored metal power electrode and outflows against the counter-electrode. The discharge has a column shape with the diameter about 0.7-1.5 mm and the length 5-30 mm. The 27.12 MHz/100 W and 13.56 MHz/1 500 W generators are operated at a power of 100 and 200 W, respectively. Stable discharges are obtained within the range from 0.3 to 0.9 dm3 min-1 Ar. The 27.12 MHz/100 W discharge is capable of accepting dry aerosol while the wet aerosol extinguishes this plasma. On the contrary, wet aerosol can be introduced into the 13.56 MHz/200 W plasma. The vibrational temperature of 3 000 K has been determined based on the intensity of the molecular band of the N2 2nd positive system (365-383 nm) in the 27.12 MHz discharge. Intensity vs concentration dependences have been measured with Li 670.784, Na 588.995, Na 589.592, K 766.491 and Rb 780.023 nm lines. Limits of detection in the 27.12 MHz/100 W discharge coupled to an ultrasonic nebulizer with desolvation are 0.1 Li, 30 Na, 10 K and 3 ng cm-3 Rb. Limits of detection in the 13.56 MHz/200 W discharge connected to a pneumatic concentric Meinhard nebulizer is 8 ng cm-3 Li.

Prediction of Blast Furnace Performance with Top Gas Recycling.

Top gas recycling has been suggested as a method for reducing blast furnace fuel rates and thus reducing carbon emissions from the ironmaking process. Three methods of top gas recycling are numerically investigated using a mathematical model to predict the furnace performance at fixed blast volume and constant coke, ore and pulverised coal compositions with varying recycle volumes. For each recycling method, a first calculation sequence is performed varying recycle volume at fixed ore : fuel ratio, and also a second sequence at fixed average liquid metal outflow temperature. Simple replacement of normal blast gases with recycled top gas is predicted to cause the production rate to decrease and the fuel rate to increase. Likewise, oxygen enriched blast replacement has similar effects, although the severity is less as the blast oxygen rate is maintained in this case. Both of these methods reduce furnace efficiency. Hot reducing gas (HRG) replacement, where CO2 is stripped from the recycled gas, leads to an increase in production of up to 25 % with a simultaneous decrease in fuel rate of 20 % at fixed metal temperature. These calculations show that top gas recycling could be used to increasing furnace efficiency while decreasing carbon emissions thus making a positive contribution to efforts to prevent global warming.

高エネルギービームによる溶接特性(第1報)

As the first report of serial studies on welding by high energy beams, penetration mechanisms by an electron beam for mild steel, stainless steel, aluminum and copper were discussed. Bead-on-plate tests at flat welding position were carried out under various conditions. The cross sectional shapes of the welds were estimated, and their melting efficiencies were compared with the theoretical values calculated by heat conduction models. The results obtained are as follows: (1) Deep penetration is dependent not only on a depth but an opening of key hole to promote molten metal outflow. Effective beam diameter to keep the opening can be approximated to penetration width. (2) Melting efficiency of welding is expressible by the equation with beam power, welding speed, penetration depth and average width. Then it can be caluclated on the basis of the heat conduction theory assuming moving heat source models. (3) The theoretical melting efficiency of a wedge type volume heat source model, substituting penetration depth for the height and width for the base, is similar to the melting efficiency of actual welds by an electron beam.

Outflow of trace metals into the Laptev Sea by the Lena River

Abstract Freshwater concentrations confirm the pristine character of the Lena River environment as already pointed-out in a previous study with a limited set of data (Martin et al., 1993). Total dissolved concentrations of the freshwater are 13.8 ± 1.6 nM, Cu, 4.4 ± 0.1 nM, Ni, 0.054 ± 0.047 nM, Cd, 642 ± 208 nM, Fe, 0.2–0.3 nM Pb and 1.2 ± 1.0 nM, Zn. For Zn and Pb, a simple mixing of the Lena River waters with the Arctic waters is observed. Relationships with salinity suggest that for Cu, Ni and Cd, there is a mobilization of the dissolved fraction from the suspended matter, with an increase of the dissolved concentration of 1.5, 3 and 6 times, respectively. For Fe, the total dissolved concentrations follow an exponential decrease in the mixing zone and 80% of the total “dissolved” Fe is removed from the solution. For Cu, Ni, Cd and Fe, the riverine end-members are 20 nM, 12 nM, 0.3 nM and 47 nM, respectively. When considering the input of total dissolved metals to the Arctic Ocean, the fraction attributed to the freshwaters from the Arctic rivers appears to be small (4% of the input of dissolved metal to the Arctic Ocean for Cd, 27% for Cu, 11 % for Ni and 2% for Zn). Metal concentrations in the Laptev Sea and Arctic Ocean are very similar, indicating a generally homogeneous distribution in the areas sampled.

Influence of acidification on metal fluxes in Swedish forest lakes

Five soft water forest lakes in southern Sweden were studied during 1981–1984. The mean pH values were 4.8–6.6 and the total organic carbon (TOC) concentrations were 2–9 mg l −1. Water was sampled for determination of chemical parameters and the concentrations of Al, Fe, Mn, Zn, Cu, Pb and Cd at lake outlets 10–12 times throughout the year. The metals were fractionated by filtration (0.4 μm) and in situ dialysis (0.002 μm). Sediment traps were used to collect particulate material for determination of sedimenting metals. Metal levels were measured by graphite furnace or flame atomic absorption spectroscopy (AAS). Metal concentrations were maximal when water discharge was highest and pH was lowest. Metal outflow was also highest during spring and the output was higher from acidified than from circumneutral lakes. Cadmium occurred mainly in dialysable form, while Pb was mainly in particulate form. The proportion of both Cd and Pb in dialysable form increased at lower pH. Iron, Al, Cu and Pb were largely deposited in the sediments, and pH had a relatively small influence on the sedimentation. In contrast, the distribution of Zn, Cd and Mn was obviously more influenced by pH and their sedimentation was substantially lower in the acidified lakes, about 5–40% of the input, compared with 70–95% in the lakes with higher pH.

耐熱性ファインセラミックスの接合に関する研究 ＩＩＩ Ｃｕ基インサート金属によるＳｉ３Ｎ４と金属の接合性に関する基礎的検討

Bonding of Si3N4 to metal using liquid insert metals of Cu-base binary alloys containing Cr, Nb, V, Ti or Zr was conducted in vacuum of about 6 mPa. Joint strength was evaluated by tensile-shear tests. The heighest strength of Si3N4 to W joints bonded using Cu-5%Cr, Cu-1 %Nb, Cu-3%V, Cu-5%Ti and Cu-10%Zr insert metals were about 150 MPa, 140 MPa, 140 MPa, 180 MPa and 180 MPa, respectively. Effect of bonding conditions on area fraction of void in Si3N4 to W joints was investigated. Area fraction of void increased with increasing bonding temperature and holding time. It was considered that formation of void was mainly caused by outflow or vaporization of insert metal.

Leaching of metals from forest soils as influenced by tree species and management

The leaching of metals (Na, K, Mg, Ca, Fe, Mn, Al, Cu, Zn, Cd, Pb, Cr and Ni) in a brown forest soil (Sjöbo) and a podzol (Horröd) with adjacent stands of spruce, beech and an open regeneration area in South Sweden were quantified using lysimeter techniques. The two localities differed in soil properties: glacifluvial sand deposit at Sjöbo; acid glacial till, poor in carbonates, at Horröd. Generally, the leaching of base cations was greatest from the brown forest soil, while the leaching of Al was greater from the podzol. Soil solution pH was lowest in the spruce forests, highest in the regeneration areas. The spruce increased soil acidification and leachability of metals most pronouncedly in the podzol. Soil acidification and leaching of metals were usually less under beech than under spruce. Soil solution metal concentrations were generally lowest in the regeneration areas, as was the outflow of metals. In an opening outside the spruce canopy at Horröd, soil acidification did not penetrate as deep as beneath the canopy; also the metal flux was considerably lower in the opening. In the spruce soil at Sjöbo and in all soils at Horröd, Al was the metal most clearly affected by variations in soil acidity. The solubility of Al increased suddenly within a small pH range (4.5-4.0) in the B horizon. Concentration of Al in soil solution increased from 2 to 10 mg l −1 when pH decreased from 4.4 to 4.2. In the brown forest soil at Sjöbo, particularly in the beech stand and in the regeneration area, the increase of base cation concentrations corresponded to the soil acidity in this pH range.

Modeling heavy metals transport in an arctic fjord system polluted from mine tailings

A computerized mathematical model has been used to describe the dissolution and transport of lead, zinc, and cadmium in the Agfardlikavsa Fjord, Marmorilik, West Greenland, where tailings from the Greenex A/S lead/zinc mine and concentrator are being deposited. The hydraulic model basis is a quasi-stationary box model representation which has been calibrated using salinity profiles. The superimposed metals model assumes equilibrium between dissolved and particulate metal forms using Langmuir adsorption isotherms to calculate particulate concentrations from concentrations of dissolved metals and suspended solids, respectively. Calibration of the model parameters (sedimentation rates and dissolution rates) has been made observing quite narrow constraints established by field observations and laboratory experiments. In the course of the time period being modeled, 1978–1980, the pollution with heavy metals has been mitigated significantly. The abatement measures undertaken include: (1) alteration of the lead flotation process and lime addition to tailings by June/July 1978; (2) alum coagulation of the effluent by January 1979; and (3) establishment of a new tailings discharge system in December 1979. The model has been used to estimate the reductions brought about in inputs of dissolved metals as well as to quantify the dynamics of the heavy metals transport in the fjord system. A particular important objective was to estimate the net outflow of metals to the adjacent Quamarujuk Fjord and to predict how the outflow responded to a decreased pollution load. A further result from the model study was the finding that routine monitoring of soluble metals in the discharged tailings as assayed by a specific method did in fact approximate model estimates of metals discharge rates if pH in the test was changed from pH 7.0 to pH 8.0.