Sodium transport and attenuation in soil cover materials for oil sands mine reclamation

0883-2927/ © 2018 Elsevier Ltd. All rights reserved.Funding was provided to MBJL by the Natural Sciences and Engineering Council of Canada (NSERC) and Syncrude Canada Ltd. through the Industrial Research Chairs program (Grant No. IRCPJ 450684−13). Additional support awarded to CVJ through the Brian and Elaine Russel Undergraduate Research Fund and the NSERC Canadian Graduate Scholarships – Master’s (NSERC CGS-M) Program.Peer ReviewedReclamation soil covers are used in oil sands mine closure to support vegetative growth over tailings. Geochemical processes within these covers may impact solute transport during upward migration of oil sands process-affected water (OSPW) from the underlying tailings. In this study, we examined the geochemical processes controlling Na transport and attenuation within the peat and clay-till cover soils at Sandhill Fen in northern Alberta, Canada. We analyzed soil core samples collected along transects of this 54-ha pilot-scale oil sands mine reclamation wetland. The geochemical (Na, Ca, Mg, K, Cl, SO4, HCO3) and isotopic (δ2H, δ18O) compositions of extracted pore water were analyzed statistically to identify OSPW and fresh surface water within the cover. Depth-dependent trends in pore water sodium concentrations were not apparent, suggesting that the soil cover had been fully flushed by a mixture of OSPW and fresh surface water used to flood the fen. Relative concentrations of Na, Ca and Mg were used to define the extent of cation exchange within the clay cover. Complementary laboratory column experiments showed that cation exchange removed up to 50% of dissolved Na as the first pore volume of simulated OSPW passed through the peat and till. However, Na attenuation by these materials declined rapidly and was limited after 4 (peat) to 7 (till) pore volumes of OSPW flushing. Reactive transport modeling confirmed that cation exchange was the dominant control on Na attenuation and corresponding Ca and Mg release within the till and peat columns. Mineral precipitation-dissolution reactions also influenced dissolved Ca and Mg concentrations and, therefore, indirectly impacted Na attenuation. Overall, this study helps constrain the geochemical processes controlling Na transport and attenuation in oil sands reclamation soil covers exposed to OSPW, and indicates that the attenuation of Na from OSPW by these covers is short-lived

Random Matrices and the Convergence of Partition Function Zeros in Finite Density QCD

We apply the Glasgow method for lattice QCD at finite chemical potential to a schematic random matrix model (RMM). In this method the zeros of the partition function are obtained by averaging the coefficients of its expansion in powers of the chemical potential. In this paper we investigate the phase structure by means of Glasgow averaging and demonstrate that the method converges to the correct analytically known result. We conclude that the statistics needed for complete convergence grows exponentially with the size of the system, in our case, the dimension of the Dirac matrix. The use of an unquenched ensemble at $\mu=0$ does not give an improvement over a quenched ensemble. We elucidate the phenomenon of a faster convergence of certain zeros of the partition function. The imprecision affecting the coefficients of the polynomial in the chemical potential can be interpeted as the appearance of a spurious phase. This phase dominates in the regions where the exact partition function is exponentially small, introducing additional phase boundaries, and hiding part of the true ones. The zeros along the surviving parts of the true boundaries remain unaffected.Comment: 17 pages, 14 figures, typos correcte

Chemical mass transport between fluid fine tailings and the overlying water cover of an oil sands end pit lake

NSERC Grant No. CRDPJ 476388; NSERC Grant No. IRCPJ 428588–11Peer ReviewedFluid fine tailings (FFT) are a principal by-product of the bitumen extraction process at oil sands mines. Base Mine Lake (BML)—the first full-scale demonstration oil sands end pit lake (EPL)—contains approximately 1.9 3 108 m^3 of FFT stored under a water cover within a decommissioned mine pit. Chemical mass transfer from the FFT to the water cover can occur via two key processes: (1) advection-dispersion driven by tailings settlement; and (2) FFT disturbance due to fluid movement in the water cover. Dissolved chloride (Cl) was used to evaluate the water cover mass balance and to track mass transport within the underlying FFT based on field sampling and numerical modeling. Results indicated that FFT was the dominant Cl source to the water cover and that the FFT is exhibiting a transient advection-dispersion mass transport regime with intermittent disturbance near the FFT-water interface. The advective pore water flux was estimated by the mass balance to be 0.002 m^3 m^-2 d^-1, which represents 0.73 m of FFT settlement per year. However, the FFT pore water Cl concentrations and corresponding mass transport simulations indicated that advection rates and disturbance depths vary between sample locations. The disturbance depth was estimated to vary with location between 0.75 and 0.95 m. This investigation provides valuable insight for assessing the geochemical evolution of the water cover and performance of EPLs as an oil sands reclamation strategy

Abelian Dominance of Chiral Symmetry Breaking in Lattice QCD

Calculations of the chiral condensate on the lattice using staggered fermions and the Lanczos algorithm are presented. Four gauge fields are considered: the quenched non-Abelian field, an Abelian projected field, and monopole and photon fields further decomposed from the Abelian field. Abelian projection is performed in maximal Abelian gauge and in Polyakov gauge. The results show that monopoles in maximal Abelian gauge largely reproduce the chiral condensate values of the full non-Abelian theory, in both SU(2) and SU(3) color.Comment: 13 pages in RevTex including 6 figures, uucompressed, self-extractin

Pointlike structure for super p-branes

We present an efficient method to understand the p-brane dynamics in a unified framework. For this purpose, we reformulate the action for super p-branes in the form appropriate to incorporate the pointlike (parton) structure of higher dimensional p-branes and intend to interpret the p-brane dynamics as the collective dynamics of superparticles. In order to examine such a parton picture of super p-branes, we consider various superparticle configurations that can be reduced from super p-branes, especially, a supermembrane, and study the partonic structure of classical p-brane solutions.Comment: 22 pages, corrected typos, to appear in Phys. Rev. D58, 085018 (1998

Level Crossing for Hot Sphalerons

We study the spectrum of the Dirac Hamiltonian in the presence of high temperature sphaleron-like fluctuations of the electroweak gauge and Higgs fields, relevant for the conditions prevailing in the early universe. The fluctuations are created by numerical lattice simulations. It is shown that a change in Chern-Simons number by one unit is accompanied by eigenvalues crossing zero and a change of sign of the generalized chirality \tGf= (-1)^{2T+1} \gf which labels these modes. This provides further evidence that the sphaleron-like configurations observed in lattice simulations may be viewed as representing continuum configurations.Comment: Latex file, 29 pages + 13 figure

Moderate deviations via cumulants

The purpose of the present paper is to establish moderate deviation principles for a rather general class of random variables fulfilling certain bounds of the cumulants. We apply a celebrated lemma of the theory of large deviations probabilities due to Rudzkis, Saulis and Statulevicius. The examples of random objects we treat include dependency graphs, subgraph-counting statistics in Erd\H{o}s-R\'enyi random graphs and $U$-statistics. Moreover, we prove moderate deviation principles for certain statistics appearing in random matrix theory, namely characteristic polynomials of random unitary matrices as well as the number of particles in a growing box of random determinantal point processes like the number of eigenvalues in the GUE or the number of points in Airy, Bessel, and $\sin$ random point fields.Comment: 24 page

QED_3 theory of underdoped high temperature superconductors II: the quantum critical point

We study the effect of gapless quasiparticles in a d-wave superconductor on the T=0 end point of the Kosterlitz-Thouless transition line in underdoped high-temperature superconductors. Starting from a lattice model that has gapless fermions coupled to 3D XY phase fluctuations of the superconducting order parameter, we propose a continuum field theory to describe the quantum phase transition between the d-wave superconductor and the spin-density-wave insulator. Without fermions the theory reduces to the standard Higgs scalar electrodynamics (HSE), which is known to have the critical point in the inverted XY universality class. Extending the renormalization group calculation for the HSE to include the coupling to fermions, we find that the qualitative effect of fermions is to increase the portion of the space of coupling constants where the transition is discontinuous. The critical exponents at the stable fixed point vary continuously with the number of fermion fields $N$, and we estimate the correlation length exponent (nu = 0.65) and the vortex field anomalous dimension(eta_Phi=-0.48) at the quantum critical point for the physical case N=2. The stable critical point in the theory disappears for the number of Dirac fermions N > N_c, with N_c ~ 3.4 in our approximation. We discuss the relationship between the superconducting and the chiral (SDW) transitions, and point to some interesting parallels between our theory and the Thirring model.Comment: 13 pages including figures in tex

Finite, diffeomorphism invariant observables in quantum gravity

Two sets of spatially diffeomorphism invariant operators are constructed in the loop representation formulation of quantum gravity. This is done by coupling general relativity to an anti- symmetric tensor gauge field and using that field to pick out sets of surfaces, with boundaries, in the spatial three manifold. The two sets of observables then measure the areas of these surfaces and the Wilson loops for the self-dual connection around their boundaries. The operators that represent these observables are finite and background independent when constructed through a proper regularization procedure. Furthermore, the spectra of the area operators are discrete so that the possible values that one can obtain by a measurement of the area of a physical surface in quantum gravity are valued in a discrete set that includes integral multiples of half the Planck area. These results make possible the construction of a correspondence between any three geometry whose curvature is small in Planck units and a diffeomorphism invariant state of the gravitational and matter fields. This correspondence relies on the approximation of the classical geometry by a piecewise flat Regge manifold, which is then put in correspondence with a diffeomorphism invariant state of the gravity-matter system in which the matter fields specify the faces of the triangulation and the gravitational field is in an eigenstate of the operators that measure their areas.Comment: Latex, no figures, 30 pages, SU-GP-93/1-

Dynamical fermion mass generation at a tricritical point in strongly coupled U(1) lattice gauge theory

Fermion mass generation in the strongly coupled U(1) lattice gauge theory with fermion and scalar fields of equal charge is investigated by means of numerical simulation with dynamical fermions. Chiral symmetry of this model is broken by the gauge interaction and restored by the light scalar. We present evidence for the existence of a particular, tricritical point of the corresponding phase boundary where the continuum limit might possibly be constructed. It is of interest as a model for dynamical symmetry breaking and mass generation due to a strong gauge interaction. In addition to the massive and unconfined fermion F and Goldstone boson $\pi$, a gauge ball of mass $m_S \simeq 1/2 m_F$ and some other states are found. Tricritical exponents appear to be non-classical.Comment: 21 page