Salt Plugs Research Articles

Contrasting Styles of Salt‐Tectonic Processes in the Ionian Zone (Greece and Albania): Integrating Surface Geology, Subsurface Data, and Experimental Models

AbstractThe Ionian Zone (IZ) is one of the key elements of the fold and thrust belt (FTB) of the Albanian and Hellenides orogen and contains large outcrops of Triassic evaporites. The IZ consists of various thrust sheets with a general westward vergence, stacking over the Apulian and Pre‐Apulian zones, and repeating a thick carbonate sequence of Upper Triassic to Eocene age. Thrusting becomes younger toward the west with a piggyback sequence, starting during the latest Oligocene Epoch in the Internal Ionian and ending in the Pliocene in the External Ionian. We have studied the IZ in southern Albania and northwestern Greece using field observations and borehole data and by fully interpreting a recently acquired 2D seismic data set. Our objectives are to establish the geometry and nature of the contacts associated with the major Triassic outcrops, to unravel precursor salt diapirs, and to assess their role during the Alpine contraction. Salt structures include gentle salt pillows, isolated salt plugs and diapirs, thrust welds, and salt walls. Combining these observations with experimental modeling results, we show how these structures control the geometry and kinematics of the Alpine thrusts or the location and kinematics of recent strike‐slip faults. Salt minibasins have also been identified, demonstrating salt mobility conditioned Mesozoic sedimentation in the Ionian Basin. The use of salt‐tectonics principles to evaluate the structural style and evolution of the IZ FTB also opens new directions for interpreting the subsurface structure and evolution of the region.

Investigating the geochemical behavior and exploration potential of lithium in brines; a case study of Bam salt plug, Zagros Zone, southern Iran

Lithium (Li) is a scarce and technologically important element; the demand for which has recently increased due to its extensive consumption, particularly in manufacturing of Li-ion batteries, renewable energy, and electronics. Li is extracted from brines, pegmatite, and clay minerals; though extraction from brines is economically preferred. More than 200 salt plugs are in the Zagros Mountains which represent potential sources for Li exploration. This preliminary study collected first data on the abundance of Li in the salt plugs in southern Iran, and investigated Li distribution during evaporation of halite-producing brine ponds. The XRD analysis of powdered samples showed that gypsum and halite are the dominant solid phases in the ponds in which Li is concentrated in gypsum, while halite is depleted of Li. ICP-MS and ICP-OES analyses showed that Li in brines is concentrated during the evaporation by factors up to 28 with total contents up to 40 mg kg‒1. The Mg/Li ratio was higher than 70, which makes the brine unsuitable for conventional evaporation extraction techniques which require Mg/Li ratios of less than 6. Considering that 25 mg kg‒1 is a suitable concentration of Li for exploration purposes, the results of this study suggest that with the advancement of extraction techniques, the depletion of presently used high-grade Li reserves, the increasing demand for lithium, the need for extraction from diverse sources, and the exploration of new resources, the salt plug brines have an exploratory potential for Li in the future.

Time-Scaling Creep in Salt Rocks for Underground Storage

Salt is an elastoviscoplastic material that exhibits time-dependent deformation (creep). Experimental measurements of salt creep behavior help predict underground gas repositories’ long-term geomechanical behavior. Previous time-scaling creep experiments have focused on the axial strain of unconsolidated sands. i.e., time-scaling creep effects under zero lateral strain conditions without describing the creep behavior of the radial strain. In addition, the time-scaling creep of the radial and axial strain has not been investigated in salts. A comparative testing procedure and analysis method was conducted on Spindletop salt plugs using triaxial tests for multistage triaxial tests (MST) and different holding time durations and stress regimes, resulting in time-dependent strain responses (creep tests). The MST showed evolving deformational mechanisms under the mapped yield surface based on the irrecoverable to recoverable strain ratio beginning with crack closure or conformance, plasticity, and ending at early crystal surface failure. Unlike unconsolidated sands, salts showed both time and strain amplitude scaling. The axial and radial strain data show scaling behavior under low and high levels of deviatoric stress separated by a transitional period. The salt showed only an axial creep response at low deviatoric stress distally from the yield surface (one-dimesional (1D) response or zero lateral strain), which indicates negative dilatant deformation or uniaxial compaction. In contrast, the salts showed equal strain amplitude scaling factors both axially and radially at high deviatoric stress proximal to the yield surface (two-dimensional (2D) response or unconstrained boundary condition), which suggests positive dilatant deformation. Microstructural images showed accumulated creep damage under high deviatoric stress associated with parallel planes of dislocation-intergranular slip, microcracking, and compaction-induced dilational strains. The period of scaling is interpreted as regions where a single mechanism is dominating. Strain amplitude scaling for both low and high deviatoric creep stress tests provides inputs for a constitutive model of creep response in understanding the magnitude of mechanical damage associated with time-independent stress-strain curves in salts for the structural integrity of salt caverns during cyclic fluid injection and depletion.

Longitudinal and lateral circulation and tidal impacts in salt-plug estuaries

This study presents a comparison of forcings between density gradient and tides in idealized funnel-shaped salt-plug estuaries. Three-dimensional numerical model results also examine longitudinal and lateral circulations. In salt-plug estuaries, a positive longitudinal estuarine circulation is observed landward of a salinity maximum zone or salt plug. Seaward of the salt plug, the estuary shows an inverse circulation cell. The longitudinal flows show a fortnightly variability inside the salt plug. Also, the salt plug is saltier in spring tides than in neap tidal cycles mainly owing to higher landward salt transport by tidal advection during the spring tides. The lateral circulation and divergence dv/dy have the influence of Coriolis acceleration. In the absence of Earth’s rotation, the tidally averaged lateral circulations have nearly the same directions within the positive and inverse cells. Directions of lateral flow reverse in the salt-plug area. Inside this area, the lateral circulation also shows clear neap–spring variability, including downwelling cells during spring tides and upwelling in neap tides. The salinity maximum zone exhibits a vertically homogeneous condition particularly in meso-tidal salt-plug estuaries. Finally, this study introduces the threshold of “log(tidal Froude number)=3” (tidal forcing 3 orders of magnitude ≥ density gradients) for salt-plug estuaries as the condition under which the tidal forcing can overcome the density gradient, and consequently salinity inside the salt plug zone is reinforced by tides with a landward movement. This robust salinity maximum zone is also identified by a high Ekman number (log(Ekman number)>0.25).

Natural Radioactivity and its Hazards of Infracambrian Rocks at Jabal Sanam Structure, Southern Iraq

The Jabal Sanam, a piercement salt plug, represents a unique geological phenomenon in southern Iraq. It is a remarkable geological landmark that rises about 141 m above sea level and covers approximately 2 km2, surrounded by flat areas on all sides. A radiological survey was conducted on the Jabal Sanam structure to determine the natural radioactivity levels and related radiation hazard indices. Eleven different rock types from several locations at Jabal Sanam were collected. An optical microscope and X-ray diffraction (XRD) were used to examine and identify the variable rock types in this structure. Natural radioactivity using field and laboratory equipment for these rocks was measured. The findings indicated that the average activity concentrations of the 226Ra, 232Th, and 40K radionuclides of the Jabal Sanam rocks are 6.5 Bq kg−1, below the minimum detectable activity (MDA), and 83.3 Bq kg−1, respectively. The average radium equivalent (Raeq) activity value of the investigated rocks is 12.87 Bq kg-1, below the world recommended rate of 370 Bq kg−1. Moreover, the average absorbed dose rate (Dg) is 6.51 nGy h-1, less than 60 nGy h-1. Furthermore, the average values of the external (Hex) and internal (Hin) hazard indices are 0.035 and 0.052, respectively, which are also lower than the allowed limit value of 1.0 set by the international agencies. Overall, the findings of this investigation conclude that Jabal Sanam rocks do not have a radioactive health hazard.

The calculation of flushing time for the upper Pasur River Estuary, Bangladesh

Estimation of estuarine flushing time, a time required to transport of pollutants or any other properties from estuaries to the coast, is very important for its resource management. In this study, we estimated flushing time (T) of the upper Pasur River Estuary (UPRE) for understanding the water quality condition in the dry and wet seasons. High-resolution salinity data were collected from the PRE at high water in the dry and wet seasons in 2014 and 2019. Flushing time was calculated using the freshwater fraction method (FFM) as well as e-folding flushing time scales was estimated empirically using the salinity (non-reactive conservative) and monthly river discharge data. System flushing during the dry season was thirteen times weaker than flushing during the wet season owing to decreasing river discharge by nearly 94%. In addition, the daily exchange volume was decreased by eight times during the dry season than during the wet season. As a consequence, the conditions of the UPRE are more dynamic during the wet season due to receiving huge amount of river discharge. During the dry season, only the e-folding time scales showed higher values in the salinity maximum zone (salt plug area). This implied that the e-folding time scale is an empirical approach and was able to encompass the tidal dispersion process whereas the FFM was unable to include that process. As the PRE is a macrotidal estuary, the tide assists to flush dissolved substances from the UPRE to the coast during the dry season having negligible river discharge. In addition, there was no significant variation in water quality parameter between the salt plug area (SP) and downstream of salt plug area (DSP) during the dry season. In order to have more accuracy, a three-dimensional hydrodynamic model would be useful to compute estuarine time scales precisely.

Mechanisms of Estuarine Salt‐Plug Formation by an Along‐Shelf Buoyant Current: A Numerical Model Approach

AbstractWhile estuarine salt plugs can develop worldwide in basins adjacent to buoyant coastal currents, their formation has been scarcely documented. This study aims to investigate a mechanism for salt‐plug formation that disregards evaporation processes but involves a buoyant coastal current modified by wind stresses. A numerical model, Delft3D, is used to study the salt‐plug formation in an idealized bay connected to the ocean by a single inlet. Inspired by recent observations, the numerical experiments simulate eight different scenarios of tidal and wind forcing under the influence of an along‐shelf buoyant current. Results show salt‐plug formation that induces inverse exchange at the inlet, with inflow at the surface and outflow underneath. This exchange circulation is modified by wind action. The persistence of the salt plug depends on tidal flushing and on wind forcing. Two numerical experiments with nonstationary buoyant currents and nonstationary winds indicate that: (a) a salt plug forms when a buoyant current is active on the shelf and traps salty water that enters the bay during times of buoyant current relaxation; (b) the presence of the buoyant current induces an inverse circulation at the inlet, modified by the wind action; and (c) onshore and then downwelling winds enhance the inverse circulation at the inlet, while offshore and then upwelling winds stall it. Bay flushing times increase due to the presence of the salt plug. This study represents an initial attempt to identify the role of wind and buoyant coastal currents on salt‐plug formation.

Emulsions of glycerol in olefin: A critical evaluation for application in oil well drilling fluids

Drilling in ultra-deep waters presents a series of difficulties and specificities, related to well depth, water depth, high pressures and saline formations found in the pre-salt basins. In addition, there is still a need to use fluids that meet environmental legislation for cleaning and disposal of cuttings in the sea. In view of these requirements, the invert emulsion fluids, of brine in olefin, are promising and have been extensively used for this application. These fluids need to maintain their rheological properties throughout the drilling, also considering the temperature variation, in order to minimize the formation of hydrates, interaction with clay areas, interaction with saline zones and damages to the permeable rock. The hypothesis of this research is that the substitution of brine by glycerol in the drilling fluid can lead to the following advantages: (a) maintenance of rheological properties; (b) mitigation of interactions with clay and saline areas; (c) no formation of hydrates, due to absence of water in the fluid; and (d) introduction of a new economic effectiveness for glycerol waste disposal. For this, crude glycerol was used to replace saturated NaCl brine in the invert emulsion drilling fluid. The interaction with saline and clay-rich zones was investigated by evaluating the interaction of the dispersed phase and the continuous phase using clay and salt plugs. Among the main results, crude glycerol obtained as a by-product of biodiesel was compatible with commercial additives used in drilling fluids based on brine in olefin emulsions, demonstrating feasibility of immediate application in drilling fluids, in view of the maintenance of rheological properties, reduction of filtrate volume and lower reactivity with salt and clay areas. Thus, the article presents a new composition of drilling fluid for ultra-deep waters, with the potential to minimize damage to the rock formation, through the use of a waste from the biodiesel production industry, without the need of previous treatments.

Salt extrusion kinematics: insights from existing data, morphology and InSAR modelling of the active emergent Anguru diapir in the Zagros fold and thrust belt, Iran

Emergent salt diapirs are highly mobile geological objects, the kinematics of which pose essential pure and applied problems for geologists and engineers. Movement and deformation of buried salt after its ejection onto the surface is a multivariable process that is susceptible to plenty of intrinsic and ambient factors. As a result, existing data acquisition approaches give extremely variable movement rates for subaerial salt extrusions. The Anguru diapir in the Zagros fold and thrust belt (ZFTB) is a typical emergent intra-anticlinal salt plug that demonstrates very recent activity, and hence was selected to be studied for quantifying salt kinematics under relatively well-defined physical conditions. We used interferometric synthetic aperture radar (InSAR) time-series data to evaluate surface displacement over the salt dome by constructing 236 interferograms derived from 47 Envisat ASAR (time span: 2003–10) and 12 ALOS PALSAR (time span: 2006–10) images, which, combined with other lines of evidence, suggest a very recent extrusion history. The maximum line of sight (LOS) displacement rates of the diapir surface are −2.6 and + 1.4 cm a −1 . Modelling of the Anguru salt plug surface suggests a bilobed pattern of LOS movements that allows interpretation of the interferometric patterns observed over active upwelling (doming) or downwarping structures. Supplementary material: Time series maps of the ALOS 565 ascending track and Envisat 435 descending track interferogramsare available at https://doi.org/10.6084/m9.figshare.c.5413388

Late Miocene-Quaternary thrusting in the Utique-Kechabta foreland basin of the Tell, Northern Tunisia

Northern Tunisia is characterized by a complex orogenic system, the Tell fold-and-thrust belt (FATB), part of the Maghrebides, associated, to the South, to the Atlas FATB intra-continental chain. The South Tellian Front (STF) separating the two FATBs is bounded by Upper Miocene to Quaternary of the Mejerda wedge-top basin to the South-West and Utique-Kechabta basin to the North-East. The first one corresponds to an extensional basin developed during the Late Miocene to Quaternary compressions. On the other hand, field mapping and seismic profiles interpretations indicate that the Utique-Kechabta is characterized by tectonic accretion, thrusting of the Tell onto its foreland basin. In Bizerte Area (to the North of Utique-Kechabta basin), the subsurface structures underneath the Tell are characterized by pop-up/pop-down structures and important horizontal displacement. These Tellian structures are transported toward the SE over the major decollement level which corresponds to the Triassic salt and bounded southeastwards by the South Tellian Front. The latter, separating the Tell, propagates through Utique-Kechabta basin within the Upper Miocene series and cutting through apical parts of Triassic diapiric structures with transported salt plugs. The drastic change of the structural style from the Mejerda to the Utique-Kechabta basins can be partly controlled by the evaporites differential repartition, from Tell to Atlas. A tentative facies distribution map of the Late Triassic is presented, and it shows an evaporitic dominant facies in onshore Tunisia and along its coast, except in and Gulf of Tunis characterized by carbonate facies. These carbonates are analog of the dolostones of Southern Sicily known as good source rock and then offer an interesting potential to the Petroleum exploration in North Tunisia.

Evaporation-Induced Clogging of an Artificial Sweat Duct.

Metal-based antiperspirants have been in use for centuries; however, there is an increasing consumer demand for a metal-free alternative that works effectively. Here, we develop an artificial sweat duct rig and demonstrate an alternative, metal-free approach to antiperspiration. Instead of clogging sweat ducts with metal salts, we use a hygroscopic material to induce the evaporation of sweat as it approaches the outlet (i.e. pore) of the sweat duct. As a result, the sweat dehydrates almost completely while still being inside of the duct, forming a natural gel-like salt plug that halts the flow. We show that the critical pressure gradient within the duct (∼3 kPa), beneath which clogging occurs, can be rationalized by balancing the mass flow rates of the liquid (Poiseuille's law) and the evaporative vapor (Fick's law).

Estimation of Blockage Position, Geometry, and Solidity in Molten Salt Pipelines.

In solar thermal plants, the use of molten salt as a heat transfer fluid is an advantageous alternative, although it has some disadvantages such as the formation of salt plugs in the pipes due to possible stratification of the salt or its solidification. The aim of this study was to implement an electromagnetic acoustic transducer (EMAT) not only capable of identifying the position of the plug, but also of determining whether the plug blocks the entire conductive surface or, on the contrary, is partial, allowing the fluid to pass through a smaller section. The proposed transducer is intended to be minimally invasive, allowing it to be used in the same way as a temperature probe. To do so, it creates torsional waves in the pipe, which are then used for a combination of measurements: pulse-echo and attenuation of the acoustic waves. Two materials with different densities (silicone and cement) were used in the tests carried out, which made it possible to check that for a given size of blockage, it is possible to identify the type of material from which it is formed.

Numerical and experimental investigation of a new conceptual fluoride salt freeze valve for thorium-based molten salt reactor

To improve the reliability and reduce energy consumption, a conceptual design of a freeze valve is proposed for the thorium-based molten salt reactor (TMSR) concept. Fins were utilized in this new design to enhance heat transfer and realize passive shut-off function, which could not be realized by the previous design. An experimental apparatus using the fluoride salt FLiNaK was constructed to conduct a series of preliminary solidification and melting experiments. In addition, the enthalpy-porosity method of ANSYS® Fluent solver was applied to simulate the solidification process of the salt at a specified operating temperature. Temperature distributions of the fluoride salt, solidification/melting time, and frozen plug effect were analyzed under natural convection heat transfer in an open space. The calculated salt temperatures exhibited good agreement with the experimental values. The results indicated that the range of effective operating temperature is 530–600 °C for the finned freeze valve. In this study, the ideal set operating temperature of the finned freeze valve was chosen as 560 °C to achieve competent performance. Moreover, 560 °C is additionally the highest set operating temperature for maintaining excellent cooling performance and sustaining deep-frozen condition of the salt plug. At this set operating temperature, the simulation data indicated that the molten salt in the flat part of the finned freeze valve will completely solidify at 10.5 min. The percentage of solid salt in the flat and lower transitional parts of the valve reaches 29.60% in 30.0 min. Furthermore, the surface temperature of the proposed freeze valve is 11.10% lower compared with that of the TMSR freeze valve at a cooling gas supply of 173 m3/h. Therefore, the new freeze valve was proven to be capable of reducing the energy consumption and realizing the passive shut-off function.

Estuarine salt-plug induced by freshwater pulses from the inner shelf

Estuarine salt plugs can cause water quality problems and are usually attributed to hypersaline conditions in low-inflow estuaries, where evaporation rates exceed or match freshwater input rates. However, salt plugs may also develop in typical estuaries, in brackish waters, by an additional freshwater influence from the estuary's mouth. In this study, month-long and years-long data showed the formation of a salt plug by a freshwater pulse from the ocean into Barataria Bay, in the Mississippi River Delta. Month-long currents showed an inverse estuarine circulation at Barataria Pass with inflow in the surface and outflow underneath. A dimensionless analysis showed that the dynamics governing the inverse circulation was related to a density gradient reversal, which was related to a salt-plug. Empirical Orthogonal Functions applied to nine years of salinity values along the estuary showed that Mode 1 (EOF1) represented the salt-plug structure and explained 86% of the variability. The salt-plug structure was most pronounced during winter, under minimum river discharge, and least evident in summer. Wavelet coherence analysis showed an annual relationship between EOF1 weights and both, river discharge and along-channel wind-stress. This study shows evidence of a salt-plug development by buoyant water pulses from outside an estuary.

Sedimentary environment and diapirism of the Pleistocene–Holocene deposits of the Zirku salt plug, southern Arabian Gulf

The Zirku salt plug is one of eleven emergent salt plugs in the southern Arabian Gulf. Its diapiric core consists of the Late Neoproterozoic–Early Cambrian ‘Hormuz Series’, which are unconformably overlain by ‘post-Hormuz’ calcarenite and breccia. The lithological and sedimentological characteristics of the calcarenite and breccia indicate that they were deposited in a beach and adjacent intertidal flats. It is suggested on stratigraphic grounds and the consideration of previous works that the ‘post-Hormuz’ deposits may be considered Pleistocene–Holocene in age. Diapirism affected the Pleistocene–Holocene deposits and produced mini-diapirs, intrusion and piercement structures, extruded gypsum flows, clastic dykes and diapiric uplift shown by elevated marine terraces and tidal notches. The elevated terraces and notches record sea-level high stands, uplift rates and sea-level fluctuations during the late Quaternary. The calculated rate of uplift of the Zirku salt plug during the period between 128 ka and 11 ka, is nearly constant at 1.05 mm/yr. Periods of transgressions and regressions were inferred from the late Quaternary sea-level curves. In the field, transgression is marked by onlap and the filling up of wadi channels, and regression by producing a new lower base level of wadis and the occurrence of gypcrete interbedded with calcarenite.

Salt tectonics in the Bend Zone segment of the Carpathian fold and thrust belt, Romania

The Carpathian Bend Zone is part of the Eastern Romanian Carpathians. The stratigraphic profile contains two levels of salt: Lower Miocene (Lower Burdigalian) and Middle Miocene (Badenian). The studied segment of the fold belt was deformed during the Middle Miocene (Badenian-to-Middle Sarmatian phase) and during the Late Miocene to present (Wallachian phase). During this latter phase, the Lower Burdigalian salt was remobilized and reached the surface on several locations piercing through 2–3 km-thick post-tectonic deposits. The salt outcrops and contractional structures now form a 30 km long, NE–SW lineament at the surface. This contribution proposes kinematic models for the Lower Burdigalian salt movement during both tectonic phases. The lineament was a detachment fold in the Middle Miocene phase. Thickened Burdigalian salt and Oligocene s.l. duplex filled the core of the detachment fold. The detachment fold was subsequently peneplained with the Burdigalian salt exposed on the paleo-surface that locally redeposited during the Badenian. The Wallachian evolution is less clear and we propose two viable kinematic models. It is possible that the salt rise kept up with sedimentation and halokinetic sequences formed at the salt–sediment interface. Alternatively, the area was reactivated in a thin-skinned, right-lateral strike–slip manner with local pull-apart basins (1–2 km across) providing space for salt plugs. Currently available data do not allow us to pick a preferred model for the kinematics during the Wallachian phase. Both kinematic models are novel and are in contrast with earlier ideas.

Simplified 0-D semi-analytical model for fuel draining in molten salt reactors

A key feature of molten salt reactors is the possibility to reconfigure the fuel geometry (actively or passively driven by gravitational forces) in case of accidents. In this regard, the design of reference molten salt reactor of Generation IV International Forum, the MSFR, foresees the Emergency core Draining System (EDS). Therefore, the research and development of MSFRs move in the direction to study and investigate the dynamics of the fuel salt when it is drained in case of accidental situations. In case of emergency, the salt could be drained out from the core, actively or passively triggered by melting of salt plugs, and stored into a draining tank underneath the core. During the draining transient, it is relevant from a safety point of view that thermal and mechanical damages to core internal surfaces and to EDS structure – caused by the temperature increase due to the decay heat – are avoided. In addition, the subcriticality of the fuel salt should be granted during all the draining transients. A simplified zero-dimensional semi-analytical model is developed in this paper to capture the multiphysics interactions, to separate and analyse the different physical phenomena involved and to focus on time evolutions of temperature and system reactivity. Results demonstrate that the fuel draining occurs in safe conditions, both from the thermal (temperature-related internal surface damages) and neutronic (sub-critical states dominate the transient) view points and show which are the main characteristics of the fuel salt draining transient.

Petro-elastic modelling and characterization of solid-filled reservoirs: Comparative analysis on a Triassic North Sea reservoir

One of the most common problems in the North Sea is the occurrence of salt (solid) in the pores of Triassic sandstones. Many wells have failed due to interpretation errors based conventional substitution as described by the Gassmann equation. A way forward is to device a means to model and characterize the salt-plugging scenarios. Modelling the effects of fluid and solids on rock velocity and density will ascertain the influence of pore material types on seismic data. In this study, two different rock physics modelling approaches are adopted in solid-fluid substitution, namely the extended Gassmann theory and multi-mineral mixing modelling. Using the modified new Gassmann equation, solid-and-fluid substitutions were performed from gas or water filling in the hydrocarbon reservoirs to salt materials being the pore-filling. Inverse substitutions were also performed from salt-filled case to gas- and water-filled scenarios. The modelling results show very consistent results - Salt-plugged wells clearly showing different elastic parameters when compared with gas- and water-bearing wells. While the Gassmann equation-based modelling was used to discretely compute effective bulk and shear moduli of the salt plugs, the algorithm based on the mineral-mixing (Hashin-Shtrikman) can only predict elastic moduli in a narrow range. Thus, inasmuch as both of these methods can be used to model elastic parameters and characterize pore-fill scenarios, the New Gassmann-based algorithm, which is capable of precisely predicting the elastic parameters, is recommended for use in forward seismic modelling and characterization of this reservoir and other reservoir types. This will significantly help in reducing seismic interpretation errors.

Spatiotemporal variation of Van der Burgh's coefficient in a salt plug estuary

Abstract. Salt water intrusion in estuaries is expected to become a serious global issue due to climate change. Van der Burgh's coefficient, K, is a good proxy for describing the relative contribution of tide-driven and gravitational (discharge-driven and density-driven) components of salt transport in estuaries. However, debate continues over the use of the K value for an estuary where K should be a constant, spatially varying, or time-independent factor for different river discharge conditions. In this study, we determined K during spring and neap tides in the dry (< 30 m−3 s−1) and wet (> 750 m−3 s−1) seasons in a salt plug estuary with an exponentially varying width and depth, to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine K. Discharge-driven gravitational circulation (K ∼ 0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season, to the extent that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, K increased gradually seaward (K ∼ 0.74) and landward (K ∼ 0.74) from the salt plug area (K ∼ 0.65) during the dry season, similar to an inverse and positive estuary, respectively. As a result, density-driven inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river arose due to density-driven positive gravitational circulation during the dry season, causing the upstream intrusion of high-salinity bottom water. Our results explicitly show that K varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties.

Proteomic Analysis of Chorion-Derived Mesenchymal Stem Cells: Combination of 2D Nano-HPLC in Tandem with ESI Mass Spectrometry

The human placenta plays an important role in foetus development and growth and is also well known as the reservoir of the mesenchymal stem cells (MSCs), which are characterized by significantly higher plasticity in comparison to adult stem cells as well as by the ability to differentiate into multiple cell types. Therefore, they are promising candidates for stem-cell therapy. To understand that mechanism the description of their proteomic profile is required. In this context, the goal of the present study was to isolate and analyse the proteome from chorionic membrane of the human placenta. The whole-cell protein extracts were analysed by LC MS/MS utilizing bottom-up proteomic approach. To maximize the number of identified proteins, two different nanoLC approaches were used. In the first approach only one-dimensional pre-concentration setup (C18 reverse-phase column) was used; whereas, the second approach utilized the two-dimensional LC in a salt plug setup (first dimension—SCX column and second dimension—C18 reverse-phase column). The method validation was accomplished using foetal membranes of six donors. Identification of 334, respectively, 500 proteins as part of chorionic MSCs proteome is reported here, supported by gene ontology classification and systematic protein family ordering. Complete characterization of chorionic stem-cell proteome profile will contribute to identification and understanding of the molecular pathways involved in the cell processes such as self-renewal, proliferation and differentiation.