Determining noble gas partitioning within a CO2–H2O system at elevated temperatures and pressures

Quantifying the distribution of noble gases between phases is essential for using these inert trace gases to track the processes controlling multi-phase subsurface systems. Here we present experimental data that defines noble gas partitioning for two phase CO2–water systems. These are at the pressure and temperature range relevant for engineered systems used for anthropogenic carbon capture and geological storage (CCS) technologies, and CO2-rich natural gas reservoirs (CO2 density range 169–656 kg/m3 at 323–377 K and 89–134 bar). The new partitioning data are compared to predictions of noble gas partitioning determined in low-pressure, pure noble gas–water systems for all noble gases except neon and radon. At low CO2 density there was no difference between measured noble gas partitioning and that predicted in pure noble gas–water systems. At high CO2 density, however, partition coefficients express significant deviation from pure noble gas–water systems. At 656 kg/m3, these deviations are −35%, 74%, 113% and 319% for helium, argon, krypton and xenon, respectively. A second order polynomial fit to the data for each noble gas describes the deviation from the pure noble gas–water system as a function of CO2 density. We argue that the difference between pure noble gas–water systems and the high density CO2–water system is due to an enhanced degree of molecular interactions occurring within the dense CO2 phase due to the combined effect of inductive and dispersive forces acting on the noble gases. As the magnitude of these forces are related to the size and polarisability of each noble gas, xenon followed by krypton and argon become significantly more soluble within dense CO2. In the case of helium repulsive forces dominate and so it becomes less soluble as a function of CO2 density

Note: a dual temperature closed loop batch reactor for determining the partitioning of trace gases within CO2-water systems

An experimental approach is presented which can be used to determine partitioning of trace gases within CO2-water systems. The key advantages of this system are (1) The system can be isolated with no external exchange, making it ideal for experiments with conservative tracers. (2) Both phases can be sampled concurrently to give an accurate composition at each phase at any given time. (3) Use of a lower temperature flow loop outside of the reactor removes contamination and facilitates sampling. (4) Rapid equilibration at given pressure/temperature conditions is significantly aided by stirring and circulating the water phase using a magnetic stirrer and high-pressureliquid chromatography pump, respectively

The application of Monte Carlo modelling to quantify in situ hydrogen and associated element production in the deep subsurface

The subsurface production, accumulation, and cycling of hydrogen (H2), and cogenetic elements such as sulfate (SO42-) and the noble gases (e.g., 4He, 40Ar) remains a critical area of research in the 21st century. Understanding how these elements generate, migrate, and accumulate is essential in terms of developing hydrogen as an alternative low-carbon energy source and as a basis for helium exploration which is urgently needed to meet global demand of this gas used in medical, industrial, and research fields. Beyond this, understanding the subsurface cycles of these compounds is key for investigating chemosynthetically-driven habitability models with relevance to the subsurface biosphere and the search for life beyond Earth. The challenge is that to evaluate each of these critical element cycles requires quantification and accurate estimates of production rates. The natural variability and intersectional nature of the critical parameters controlling production for different settings (local estimates), and for the planet as a whole (global estimates) are complex. To address this, we propose for the first time a Monte Carlo based approach which is capable of simultaneously incorporating both random and normally distributed ranges for all input parameters. This approach is capable of combining these through deterministic calculations to determine both the most probable production rates for these elements for any given system as well as defining upper and lowermost production rates as a function of probability and the most critical variables. This approach, which is applied to the Kidd Creek Observatory to demonstrate its efficacy, represents the next-generation of models which are needed to effectively incorporate the variability inherent to natural systems and to accurately model H2, 4He, 40Ar, SO42- production on Earth and beyond

Nanostructure of the deep eutectic solvent/platinum electrode interface as a function of potential and water content

The interfacial nanostructure of the three most widely-studied Deep Eutectic Solvents (DESs), choline chloride:urea (ChCl:Urea), choline chloride:ethylene glycol (ChCl:EG), and choline chloride:glycerol (ChCl:Gly) at a Pt(111) electrode has been studied as a function of applied potential and water content up to 50 wt%. Contact mode atomic force microscope (AFM) force–distance curves reveal that for all three DESs, addition of water increases the interfacial nanostructure up to ∼40 wt%, after which it decreases. This differs starkly from ionic liquids, where addition of small amounts of water rapidly decreases the interfacial nanostructure. For the pure DESs, only one interfacial layer is measured at OCP at 0.5 nm, which increases to 3 to 6 layers extending ∼5 nm from the surface at 40 or 50 wt% water. Application of a potential of ±0.25 V to the Pt electrode for the pure DESs increases the number of near surface layers to 3. However, when water is present the applied potential attenuates the steps in the force curve, which are replaced by a short-range exponential decay. This change was most pronounced for ChCl:EG with 30 wt% or 50 wt% water, so this system was probed using cyclic voltammetry, which confirms the interfacial nanostructure is akin to a salt solution

Hydrogen and 40Ar/39Ar isotope evidence for multiple and protracted paleofluid flow events within the long‐lived North Anatolian Keirogen (Turkey)

We present a new approach to identifying the source and age of paleofluids associated with low‐temperature deformation in the brittle crust, using hydrogen isotopic compositions (δD) and 40Ar/39Ar geochronology of authigenic illite in clay gouge‐bearing fault zones. The procedure involves grain‐size separation, polytype modeling, and isotopic analysis, creating a mixing line that is used to extrapolate to δD and age of pure authigenic and detrital material. We use this method on samples collected along the surface trace of today's North Anatolian Fault (NAF). δD values of the authigenic illite population, obtained by extrapolation, are −89 ± 3‰, −90 ± 2‰, and −97 ± 2‰ (VSMOW) for samples KSL, RES4‐1, and G1G2, respectively. These correspond to δD fluid values of −62‰ to −85‰ for the temperature range of 125°C ± 25°, indistinguishable from present‐day precipitation values. δD values of the detrital illite population are −45 ± 13‰, −60 ± 6‰, and −64 ± 6‰ for samples KSL, G1G2, and RES4‐1, respectively. Corresponding δD fluid values at 300°C are −26‰ to −45‰ and match values from adjacent metamorphic terranes. Corresponding clay gouge ages are 41.4 ± 3.4 Ma (authigenic) and 95.8 ± 7.7 Ma (detrital) for sample G2 and 24.6 ± 1.6 Ma (authigenic) and 96.5 ± 3.8 Ma (detrital) for sample RES4‐1, demonstrating a long history of meteoric fluid infiltration in the area. We conclude that today's NAF incorporated preexisting, weak clay‐rich rocks that represent earlier mineralizing fluid events. The samples preserve at least three fluid flow pulses since the Eocene and indicate that meteoric fluid has been circulating in the upper crust in the North Anatolian Keirogen since that time.Key Points:Illite preserves the hydrogen isotopic signature and age of paleofluids in the earth's upper crustThree fluid events are pinpointed in the NAKThe NAF exploited zones of preexisting weak clay material during its formationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112210/1/ggge20754.pd

The GALNT9, BNC1 and CCDC8 genes are frequently epigenetically dysregulated in breast tumours that metastasise to the brain.

Tumour metastasis to the brain is a common and deadly development in certain cancers; 18-30 % of breast tumours metastasise to the brain. The contribution that gene silencing through epigenetic mechanisms plays in these metastatic tumours is not well understood

Age and work-related motives: Results of a meta-analysis

Item does not contain fulltextAn updated literature review was conducted and a meta-analysis was performed to investigate the relationship between age and work-related motives. Building on theorizing in life span psychology, we hypothesized the existence of age-related differences in work-related motives. Specifically, we proposed an age-related increase in the strength of security and social motives, and an age-related decrease in the strength of growth motives. To investigate life span developmental theory predictions about age-related differences in control strategies, we also examined the relationship between age and intrinsic and extrinsic motives. Consistent with our predictions, meta-analytic results showed a significant positive relationship between age and intrinsic motives, and a significant negative relationship between age and strength of growth and extrinsic motives. The predicted positive relation between age and strength of social and security motives was only found among certain subgroups. Implications of these findings for work motivation and life span theories and future research are discussed