The distribution of total and electrochemically available copper in the northwestern atlantic ocean

Copper in a series of samples from the northwestern Atlantic has been determined by anodic stripping voltammetry (ASV) and atomic absorption spectrometry after preconcentration by cobalt—APDC coprecipitation. Samples from a transect across the continental shelf directly off the New York Bight showed a linear relationship between total copper and salinity (31–34‰) and less than 5% of the total copper was detectable by ASV. A slope water station showed less than 9% of the total copper to be ASV detectable in the upper 780m, below which the ASV detectable copper increased to 70% at 3000 m. The Sargasso Sea profiles showed less than 7% ASV detectable copper in the upper 150 m; the fraction of the total copper detected by ASV increased to about 80% of the total copper at greater depths. The reduced availability of copper to the ASV measurement in coastal waters and open ocean surface waters appears to be related to recent contact with waters where biological productivity occurs.     

Numerical simulation of the weak turbulence excited by a beam of electrons in the interplanetary plasma

The electron distribution functions measured at 1 AU in an electron stream passing the ISEE-3 spacecraft (Lin et al., 1981) are used as input data to a programme which simulates in a one-dimensional model the interaction between fast electrons and plasma waves (quasi-linear relaxation) together with the plasma wave scattering off the background ions. While the computed spectral energy density of the plasma waves excited in resonance with the streaming of electrons is below Zakharov's threshold of strong turbulence, it is sufficiently high to undergo a fast induced scattering off the background ions. The resulting spectrum is concentrated around the wave vector k = 0. Some simple analytic considerations show that this stage leads necessarily to the crossing of Zakharov's threshold and therefore this indirect excitation of strong turbulence seems to play an essential role in understanding the Langmuir turbulence generated by the motion of fast electron beams in the interplanetary plasma.     

Fluids in granulites of the Southern Marginal Zone of the Limpopo Belt, South Africa

The Southern Marginal Zone of the Limpopo Belt in South Africa is characterised by a granulite and retrograde hydrated granulite terrane. The Southern Marginal Zone is, therefore, perfectly suitable to study fluids during and after granulite facies metamorphism by means of fluid inclusions and equilibrium calculations. Isolated and clustered high-salinity aqueous and CO₂(-CH₄) fluid inclusions within quartz inclusions in garnet in metapelites demonstrate that these immiscible low H₂O activity fluids were present under peak metamorphic conditions (800-850 °C, 7.5-8.5 kbar). The absence of widespread high-temperature metasomatic alteration indicates that the brine fluid was probably only locally present in small quantities. Thermocalc calculations demonstrate that the peak metamorphic mineral assemblage in mafic granulites was in equilibrium with a fluid with a low H₂O activity (0.2-0.3). The absence of water in CO₂-rich fluid inclusions is due to either observation difficulties or selective water leakage. The density of CO₂ inclusions in trails suggests a retrograde P-T path dominated by decompression at T<600 °C. Re-evaluation of previously published data demonstrates that retrograde hydration of the granulites at 600 °C occurred in the presence of H₂O and CO₂-rich fluids under P-T conditions of 5-6 kbar and ~600 °C. The different compositions of the hydrating fluid suggest more than one fluid source.     

东昆仑活动断裂带西大滩段断层气(Rn,CO2)的释放特征

通过在东昆仑活动断裂带西大滩段进行断层气测试,首次获取了该断裂带中Rn和CO2的释放量。在2004年开挖的2～3m深的探槽内,氡浓度可达20732Bq.m-3,氡发射率可达433mBq.m-2.s-1,远高于在地表的氡浓度505～2380Bq.m-3与氡发射率7～28.19mBq.m-2.s-1(地表氡发射率均值为14.7mBq.m-2.s-1,与世界平均值相当)。从而我们推断该断裂具有从上部第四系覆盖物到深部花岗岩之间的良好连通性。在地表CO2的析出率平均值为18.9g.m-2.d-1,与通常的背景值相当,在探槽中和距离断层1km的地方没有明显的空间变化,但是在断层北侧3km处的一个近乎直立的千枚岩小山上,CO2的析出率却很高,为421g.m-2.d-1,同时该处氡的发射率也高,达503mBq.m-2.s-1,因此,有必要在该断裂附近进行长期监测     

PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project, which aims at characterizing one of these foreground sources, the polarized continuum emission by dust in the diffuse interstellar medium. The PILOT experiment also constitutes a test-bed for using multiplexed bolometer arrays for polarization measurements. This paper presents the instrument and its expected performances. Performance measured during ground calibrations of the instrument and in flight will be described in a forthcoming paper.     

Interfacial tension measurements and wettability evaluation for geological CO2 storage

Interfacial interactions, namely interfacial tension, wettability, capillarity and interfacial mass transfer are known to govern fluid distribution and behavior in porous media. Therefore the interfacial interactions between CO₂, brine and oil and/or gas reservoirs have a significant influence on the effectiveness of any CO₂ storage operations. However, data and knowledge of interfacial properties in storage conditions are scarce. This issue becomes particularly true in the case of deep saline aquifers where limited, economically driven, data collection and archiving are available. In this paper, we present a complete set of brine–CO₂ interfacial tension data at pressure, temperature and salinity conditions, representative of a CO₂ storage operation. A semi-empirical correlation is proposed to calculate the interfacial tension from the experimental data. Wettability is studied at pore scale, using glass micromodels in order to track fluids distribution as a function of the thermodynamic properties and wettability conditions for water–CO₂ systems. With this approach, we show that, in strongly hydrophilic porous media, the CO₂ does not wet the solid surface whereas; if the porous media has less hydrophilic properties the CO₂ significantly wets the surface.     

Diamond precipitation from ascending reduced fluids in the Kaapvaal lithosphere: Thermodynamic constraints

Previous research has shown that the Kaapvaal lithospheric mantle is generally reduced and characterised by a decreasing redox state with increasing depth. As a consequence, C-O-H fluids in the Kaapvaal lithospheric mantle are dominated by H₂O, CH₄, and C₂H₆. Thermodynamic calculations demonstrate that diamond precipitation from such a fluid during ascend is possible as it is exposed to a more oxidised environment and both CH₄ and C₂H₆ are oxidised. However, the calculations also demonstrate that the diamond precipitation potential from such a fluid decreases when: (1) the mantle is either more reduced or oxidised compared to the Kaapvaal mantle, or (2) the change in temperature with pressure is smaller compared to that of the Kaapvaal mantle. Therefore, the presence of reduced mantle fluid species and a generally decreasing oxygen fugacity with increasing depth do not necessarily warrant diamond precipitation from a rising reduced fluid.     

http://www.sciencedirect.com/science/article/pii/S1674987114000218

Fluid infiltration into retrograde granulites of the Southern Marginal Zone(Limpopo high grade terrain)is exemplified by hydration reactions.shear zone hosted metasomatism,and lode gold mineralisation.Hydration reactions include the breakdown of cordierite and orthopyroxene to gedrite kyanite,and anthophyllite,respectively.Metamorphic petrology,fluid inclusions,and field data indicate that a low H_2O-activity carbon-saturated CO_2-rich and a saline aqueous fluid infiltrated the Southern Marginal Zone during exhumation.The formation of anthophyllite after orthopyroxene eslablished a regional retrograde anthophyllite-in isograd and occurred at P-T conditions of- 6 kbar and 610 C,which fixes the minimum mole fraction of II.0 in the CO_2-rich fluid phase at- 0.1.The maximum H_2O mole fraction is hxed by the lower temperature limit(~800℃) for partial melting at ~0.3.C-O-H fluid calculations show that the CO_2-rich fluid had an oxygen fugacity that was 0.6 log10 units higher than that of the fayalite-magnetitequartz buffer and that the CO_2/(CO_2+CH_4) mole ratio of this fluid was 1.The presence of dominantly relatively low density CO_2-rich fluid inclusions in the hydrated granulites indicates that the fluid pressure was less than the lithostatic pressure.This can be explained by strike slip faulting and/or an increase of the rock permeability caused by hydration reactions.