Experimental biological effects assessment associated with on-shore brine discharge from the creation of gas storage caverns

Most of the studies on biological and ecological effects associated with brine discharge into the marine environment are related to the operation of desalination plants, for the production of freshwater. In this study we analysed the biological effects of a brine effluent from a completely different source, produced from the lixiviation of rock salt caves, for the creation of natural gas storage caverns. Lethal and sub-lethal endpoints following exposure to the brine were studied in a range of macrofauna species characteristic of the soft and hard bottom habitats in the vicinity of the discharge area, namely the isopod Eurydice pulchra, the annelids Sabellaria alveolata and Ophelia radiata, the sea-urchin Paracentrotus lividus and the bivalve Mytilus galloprovincialis. In a first series of experiments, brine, with salinity above 300, was diluted in distilled water to a salinity value close to that of the seawater in the discharge area (salinity 36) and, surprisingly, none of the exposed species was able to survive or develop into viable larvae. A second series of experiments exposed the species to brine diluted with seawater, simulating more realistic discharge circumstances. All the tested species at all the measured endpoints (adult survival, larval abnormal development, sperm fertilization success) showed negative biological effects in brine solutes always at a lower salinity than that of a salinity control obtained with concentrated seawater. The sub-lethal experiments with larval development of P. lividus, S. alveolata and M. galloprovincialis, and the fertilization success of P. lividus gave EC₅₀ values for the brine solute with salinity in the range of 40.9–43.5, whereas the EC₅₀ values for the concentrated seawater were in the range of salinity 44.2–49.0. It is hypothesised that differences in the ionic composition of the brine cause the inability of the species to tolerate the exposure to brine.     

Propagation of local errors in the solutions of the differential equations for orbital elements

The propagation of errors in the solutions of the differential equations for the orbital elements of perturbed two-body motion is investigated. It is shown that the error in the time-element grows linearly for differential equations for orbital elements when only perturbations are present on the right-hand side, cubically for formulations which have a two-body term on the right-hand side, and linearly for formulations based upon extended phase space Hamiltonians.     

Thermodynamics of mixing in diopside–jadeite,CaMgSi<Subscript>2</Subscript>O<Subscript>6</Subscript>–NaAlSi<Subscript>2</Subscript>O<Subscript>6</Subscript>, solid solution from static lattice energy calculations

Static lattice energy calculations (SLEC), based on empirical interatomic potentials, have been performed for a set of 800 different structures in a 2 × 2 × 4 supercell of C2/c diopside with compositions between diopside and jadeite, and with different states of order of the exchangeable Na/Ca and Mg/Al cations. Excess static energies of these structures have been cluster expanded in a basis set of 37 pair-interaction parameters. These parameters have been used to constrain Monte Carlo simulations of temperature-dependent properties in the range of 273–2,023 K and to calculate a temperature–composition phase diagram. The simulations predict the order–disorder transition in omphacite at 1,150 ± 20°C in good agreement with the experimental data of Carpenter (Mineral Petrol 78:433–440, 1981). The stronger ordering of Mg/Al within the M1 site than of Ca/Na in the M2 site is attributed to the shorter M1–M1 nearest-neighbor distance, and, consequently, the stronger ordering force. The comparison of the simulated relationship between the order parameters corresponding to M1 and M2 sites with the X-ray refinement data on natural omphacites (Boffa Ballaran et al. in Am Mineral 83:419–433, 1998) suggests that the cation ordering becomes kinetically ineffective at about 600°C.     

Behavior of Major and Trace Elements during Ore Deposition: Example from the Low-Sulfidation Pantingan Gold System, Mount Mariveles, Bataan, Philippines

The evaluation of the relatively fresh host rock and altered rock samples associated with the Pantingan Gold System exposed in Mount Mariveles, Bataan yield several notable observations that are useful in pinpointing potential gold pathfinder elements. Geochemical and petrologic analysis showed that the altered rocks can be subdivided into rocks that underwent propylitic alteration (group 1), argillized rocks with silica contents similar to those of the fresh host rocks (group 2), argillized but not strongly silicified rocks (group 3) and argillized and strongly silicified rocks (group 4). Selected element ratio patterns in the altered rocks and gold concentrations in gold‐bearing quartz veins vary between the rock groups. Moreover, mass balance calculation also reflected the geochemical observations pertaining to the gains and losses of SiO_2, Fe₂O₃+ MgO, CaO + Na₂O and K₂O, which are believed to be chemical reactions (i.e. breakdown of plagioclase, silica inundation or leaching, sulfide and calcite formation) caused by the influx of hydrothermal fluids.     

Spreading of a NAPL lens in a double-porosity medium

Spreading of a non-aqueous phase liquid (NAPL) denser than water (DNAPL) lens (mound) in the unsaturated zone of double-porosity aquifer above an impervious plane boundary is investigated. The double-porosity aquifer is conceptualized as a fracture network surrounding pervious blocks. Vertical gravity equilibrium is assumed to prevail in each one of the two media, fractures and blocks. Through vertical integration, two coupled partial differential equations for the DNAPL content in each medium are obtained. The mass exchange rate between high- and low-permeability media is considered as a function of NAPL content. The dominant effect is gravity, whereas capillary forces are negligible. Analytical solutions for one-dimensional and axisymmetric problems of mound spreading are obtained.     

Mangrove zonation in the dry life zone of the Gulf of Fonseca, Honduras

The structural attributes and zonation patterns of mangrove forests in a dry environmental setting were evaluated in relation to gradients of soil resources, soil regulators, and hydroperiod between October 2000 and August 2001 in the Gulf of Fonseca, Honduras. Transects perpendicular to the edge of tidal channels were established at four mangrove sites, each sectioned into three mangrove zones (fringe, transition, and scrub) based upon distinct tree-height gradients. Porewater sulfide concentrations among zones were normally below levels of detection (<0.03 mM) and mean redox values ranged from 163.4±9.9 to −42.4±15.8 mv, indicating slightly reducing conditions in all zones. Mean porewater NO_x ⁻ and PO₄ ³⁻ concentrations were not significantly different among zones and ranged from 3.3±0.5 to 4.5±0.4 μM and from 0.05 ±0.02 to 0.18±0.04 μM, respectively. Soil nitrogen concentrations were 1–3 mg g⁻¹ in all zones, and mean nitrogen:phosphorus atomic ratios were <20 (range: 12.9–14.9), indicative of fertile wetland soils. Mean basal areas were significantly different among mangrove zones (fringe > transition) and were coupled with differences in height within species and zones.Avicennia germinans occupied areas with higher elevations associated with higher salinities ranging from 80 to 140 g kg⁻¹ in the dry season.Rhizophora mangle dominated lower elevations where salinities ranged from 38 to 57 g kg⁻¹ in both the dry and wet seasons. Spatial analysis on mangrove seedlings along transects confirmed that seedling distribution along the intertidal profile was statistically correlated with conspecific adults, indicating that survival and growth of seedlings in different intertidal locations are closely matched to canopy membership. The sharp transition (<100 m) in forest structure and distribution of mangrove species along the intertidal zone of subhumid coastal environments demonstrate common zonation patterns where species distribution and species-specific habitat suitability are mediated closely with tolerance to soil regulators (high soil salinity) rather than resource availability.     

The relativistic dynamics of a thin spherically symmetric radiating shell in the presence of a central body

We construct an idealized spherically symmetric relativistic model of an exploding object within the framework of the theory of surface layers in GR. A Vaidya solution for a radially radiating star is matched through a spherical shell of dust to a Schwarzschild solution. The (incomplete) equations for the motion of the spherical shell of dust and the radiation density of the Vaidya solution, as given by the matching conditions, are reduced to a first-order system and a general analysis of the characteristics of the motion is given. This system of differential equations is completed, adding a relation between the unknowns which represents the simplest way to avoid an unphysical singularity in the motion. The results of a numerical integration of the equations are presented in two cases which we think may have some relationship to stellar explosions. A comparative set of results for other solutions is also given, and some possible generalizations of the model are pointed out.     

New Trends in Numerical Simulation of the Motion of Small Bodies of the Solar System

A brief survey of the results obtained by the authors in the development and investigation of the algorithms of numerical simulation of the motion of solar system small bodies is given. New approaches to the construction of the algorithms of high-accuracy numerical simulation of the dynamics of small bodies and the methods of the determination of the domain of their possible motions are presented.