Some New Observed Properties of Elliptical Galaxies

We suggest that elliptical galaxies, as stellar systems in a stage of quasi-equilibrium, may have a specific entropy. We use the Sérsic law to describe the light profile. The specific entropy (the Boltzmann–Gibbs definition) is then calculated assuming that the galaxy behaves as a spherical, isotropic, one-component system. We predict a relation between the three parameters of the Sérsic law linked to the specific entropy, defining a surface in the parameter space, an ‘entropic plane’. We have analysed a sample of simulated merging elliptical galaxies (virtual) and a sample of galaxies belonging to the Coma Cluster (real). Both virtual and realgalaxies are: 1) located in their own ‘entropic plane‘ and 2) in this plane, they are located on a straight line, indicating constant entropy: another physical property A careful examination of the value of the specific entropy indicates a very small increase in the specific entropy with the generation after merging (virtual sample). Although one cannot distinguish between various generations for real galaxies, the distribution of specific entropy in this sample is very similar to that in the virtual sample. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationships between Campi Flegrei and Mt. Somma volcanism: evidence from melt inclusions in clinopyroxene phenocrysts from volcanic breccia xenoliths

Summary We present compositions of reheated melt inclusions in clinopyroxene phenocrysts from three mafic xenoliths in Breccia Museo, Campi Flegrei, Italy. Melt inclusion compositions are remarkably different from the compositions of known contemporary Campi Flegrei lavas, being significantly enriched in K₂O and depleted in Na₂O. Some differences are also evident in FeO^* (total Fe as FeO) and TiO₂ contents. The clinopyroxene phenocrysts could not have crystallised from Campi Flegrei magmas. We suggest that they originated from a volcanic system genetically very similar to, and possibly linked with, the >14 ka volcanic system of Mt. Somma, another Campanian volcano ∼ 30 km east from Campi Flegrei, from which Vesuvius subsequently developed. This result indicates a close relationship (or link) between the two volcanic systems which have until now been considered separate. We speculate that the link was established prior to eruption of the Neapolitan Yellow Tuff (NYT) (∼ 12 ka). The xenoliths were derived from a volcanic system older than the host breccias themselves. We suggest that this older volcanism had close similarities with the volcanism of the older products of Mt. Somma (∼25 ka). Received March 20, 2000; accepted November 2, 2000     

Spatial assessment and redesign of a groundwater quality monitoring network using entropy theory, Gaza Strip, Palestine

Using entropy theory, a methodology was developed for the evaluation and redesign of groundwater quality monitoring wells in the Gaza Strip in Palestine. Essential to the methodology is the development of a Transinformation Model (TM) which yields the amount of information transfer and the dependency between the wells as a function of distance. The TM parameters, such as the minimum transinformation and the range, were employed for evaluating the network which revealed that most of the distances between wells were less than the range. It also indicated that a high percentage of redundant information existed in the network. Therefore, the network was reduced by superimposing a square pattern over the monitored area and selecting one well per square block in a stratified pattern. The methodology was tested using the chloride data collected from 1972–2000 from 417 groundwater quality monitoring wells in the Gaza Strip. The number of the groundwater quality monitoring wells in the Gaza Strip was reduced by 53%, while there was 26% redundant information based on the minimum existing distance between wells. This methodology is meant to help monitor the groundwater quality (salinity) in the Gaza Strip.     

High-resolution historical records from Pettaquamscutt River basin sediments: 2. Pb isotopes reveal a potential new stratigraphic marker

A high-resolution record of Pb deposition in Rhode Island over the past 250 yr was constructed using a sediment core from the anoxic Pettaquamscutt River basin. The sedimentary Pb concentration record shows the well-described maximum associated with leaded gasoline usage in the United States. Diminished Pb variability during recorded periods of local industrial activity (1735 to 1847) supports the greater importance of regional atmospheric lead transport vs. local inputs. The Pb isotopic composition at this site shows a clear maximum in anthropogenic ²⁰⁶Pb/²⁰⁷Pb in the mid-1800s. Similar peaks have also been observed in sediments from Chesapeake Bay and the Great Lakes, suggesting a common source. Possible causes for this event include mining and smelting of Pb ores in the Upper Mississippi Valley district, which accounted for almost all Pb production in the United States in that period. The timing of this event can provide an important stratigraphic marker for sediments deposited in the past 200 yr in the Northeastern United States. The downcore profile of anthropogenic ²⁰⁶Pb/²⁰⁷Pb provides a classic example of how changes in the mixture of ores for production of tetraethyl lead caused a regional-scale shift in the sedimentary record, and suggests that coal could have played a secondary role in Pb emissions after 1920.     

High-resolution historical records from Pettaquamscutt River basin sediments: 1. Pb and varve chronologies validate record of Cs released by the Chernobyl accident

Cesium-137 derived from the explosion of the Chernobyl reactor in 1986 was preserved in anoxic sediments from a coastal environment in southern Rhode Island. Although the radioactive plume was detected in surface air samples at several locations in the United States, this is the first known record of a Chernobyl ¹³⁷Cs peak in sediments from North America. The inventory of Chernobyl ¹³⁷Cs that was preserved in the Pettaquamscutt River is small compared to European counterparts and should only be detectable for the next 15-20 yr. However, the presence of two ¹³⁷Cs peaks (1963 and 1987) identifies a well-dated segment of the sediment column that could be exploited in understanding the decomposition and preservation of terrestrial and aquatic organic matter. Different methods for calculating the ²¹⁰Pb chronology were also evaluated in this study and checked against independent varve counting. The end result is a detailed chronology of a site well suited for reconstruction of historical records of environmental change.     

Glacier outburst floods reconstructed from lake sediments and their implications for Holocene variations of the plateau glacier Folgefonna in western Norway

A sudden release of large volumes of water during a glacier outburst flood (GLOF) is a major hazard worldwide. Here, we identify the sedimentary signature of glacial and non‐glacial processes, including GLOFs, based on lacustrine sediments from the distal glacier‐fed Lake Buarvatnet in western Norway. Historically documented GLOFs in 2002 CE and during the 1980s CE are identified in the ²¹⁰Pb‐ and ¹⁴C‐dated sediments. These events have the same sedimentary signature as 12 earlier events throughout the Holocene interpreted to represent previous GLOFs in the catchment. The GLOFs are interpreted to have occurred during periods when the glacier extent was similar to the modern positions, and the events are thus used to pinpoint past positions of the glacier terminus and, hence, the equilibrium line altitudes (ELAs). The results indicate that the glacier Svartenutbreen, located at the eastern part of Folgefonna, had a similar size in 2002 CE as c. 8200–8300 cal. a BP, corresponding to the 8.2 ka event in the North Atlantic region. The regrowth of Sørfonna after the Holocene Thermal Optimum occurred at c. 6900 cal. a BP and Svartenutbreen was at modern size and extent in the periods c. 6400, c. 5450, c. 4850, c. 3850, c. 3550 and c. 1650 cal. a BP. Since 1650 cal. a BP, we infer that the glacier was larger than the 2002 CE glacier extent until 1910 CE when a GLOF occurred. Svartenutbreen has been retreating since 1910 CE, which led to the ice damming of the two historical GLOFs in the 1980s and 2002 CE separated by a glacier advance in the 1990s CE. The findings are discussed and compared to other regional glacier reconstructions in Norway, and emphasize the value of identifying and utilizing GLOFs as an indicator of past ELA variability.     

An adjoint-based optimization method for gas production in shale reservoirs

In this work, we consider a new model for flow in a multiporosity shale gas reservoir constructed within the framework of an upscaling procedure where hydraulic fractures are treated as (\(n-1\)) interfaces (\(n=2,3\)). Within this framework, the hydrodynamics is governed by a new pressure equation in the shale matrix which is treated as a homogenized porous medium composed of organic matter (kerogen aggregates with nanopores) and inorganic impermeable solid (clay, calcite, quartz) separated from each other by a network of interparticle pores of micrometer size. The solution of the pressure equation is strongly influenced by the constitutive response of the retardation parameter and effective hydraulic conductivity where the former incorporates gas adsorption/desorption in the nanopores of the kerogen. By focusing our analyses on this nonlinear diffusion equation in the domain occupied by the shale matrix, an optimization strategy seated on the adjoint sensitivity method is developed to minimize a cost functional related to gas production and net present value in a single hydraulic fracture. The gradient of the objective functional computed with the adjoint formulation is explored to update the controlled pressure drop aiming to optimize production in a given window of time. The combination of the direct approach and gradient-based optimization using the adjoint formulation leads to the construction of optimal production scenarios under controlled pressure decline in the well. Numerical simulations illustrate the potential of the methodology proposed herein in optimizing gas production.     

Metal-enriched nanoparticles and black carbon: A perspective from the Brazil railway system air pollution

Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public transport. This study measured, for the first time in Brazil, nanoparticles (NPs) and black carbon (BC) on two ground-level platforms and inside trains of the Metropolitan Area of Porto Alegre (MAPA). An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy techniques. The results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger densities. Also, internal and external sources of pollution at the stations were identified. The predominance of NPs enriched with metals that increase oxidative stress like Cd, Fe, Pb, Cr, Zn, Ni, V, Hg, Sn, and Ba both on the platforms and inside trains, including Fe-minerals as hematite and magnetite, represents a critical risk to the health of passengers and employees of the system. This interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols.     

Natural contribution of harmful elements in thermal groundwaters of Ischia Island (southern Italy)

Minor and trace element investigations have been performed on groundwaters of Ischia Island, which is located at the western edge of the bay of Naples. Ischia is formed entirely of Quaternary volcanic rocks. Intense seismicity, widespread fumaroles and thermal springs witness the persistent state of activity of its magmatic system. Groundwater samples, 58 from shallow thermal wells and 15 from thermal springs, were analysed for 72 elements by ICP-MS; temperature, pH and electrical conductivity (EC) were measured at the sampling site. Analytical data indicate clearly that the concentrations in the water of some elements, such as As, Be, Cu, Fe, Mn, Sb, Se and Tl, are often higher and sometimes much higher than the intervention limits fixed by the Italian Law DM 471 (25/10/1999) for water. Worthy of mention are the very high As values, reaching >1,000 µg/l in some wells. By means of R-mode factor analysis, 30 of 72 analysed elements were grouped as elemental associations representative of lithological type, water composition and, possibly, mineralization. Ischia thermal groundwaters are the result of mixing, in variable amounts, of deep magmatic fluids that are rich in metallic elements, with marine and/or meteoric waters. R-mode factor analysis and elemental association factor score distributions of the four-factor model confirm the existence of flux of magmatic mineralised fluids with marine and/or meteoric waters. Recharge by seawater intrusions occurs mostly in the north-western area of the island whereas the influence and control of magmatic mineralised fluids is clearly accentuated in the areas of Panza-Citara, Porto di Forio-Fango and Citara-Lido dei Maronti fracture alignments. The observed compositional variability of the analysed groundwaters, even in wells lying close to one another, is due to the local hydrodynamic conditions, controlled mostly by complex fault and fracture systems, which may represent preferential thermal water outflow routes. In general, the average minor and trace element compositions of Ischia thermal waters, when compared with the composition of sea and river water, show an enrichment in metallic elements such as As, Sc, V, Cr, Zn, Mo, U, W, Au, Hg. This paper points out that, in addition to the anthropogenic source, natural contribution also plays an important role in determining the high concentrations of toxic elements in groundwaters, which create health and acceptability problems.