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Near-surface mercury and ozone depletion events occur in the lowest part of the atmosphere during Arctic spring. Mercury depletion is the first step in a process that transforms long-lived elemental mercury to more reactive forms within the Arctic that are deposited to the cryosphere, ocean, and other surfaces, which can ultimately get integrated into the Arctic food web. Depletion of both mercury and ozone occur due to the presence of reactive halogen radicals that are released from snow, ice, and aerosols. In this work, we added a detailed description of the Arctic atmospheric mercury cycle to our recently published version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem 4.3.3) that includes Arctic bromine and chlorine chemistry and activation/recycling on snow and aerosols. The major advantage of our modelling approach is the online calculation of bromine concentrations and emission/recycling that is required to simulate the hourly and daily variability of Arctic mercury depletion. We used this model to study coupling between reactive cycling of mercury, ozone, and bromine during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) spring season in 2020 and evaluated results compared to land-based, ship-based, and remote sensing observations. The model predicts that elemental mercury oxidation is driven largely by bromine chemistry and that particulate mercury is the major form of oxidized mercury. The model predicts that the majority (74%) of oxidized mercury deposited to land-based snow is re-emitted to the atmosphere as gaseous elemental mercury, while a minor fraction (4%) of oxidized mercury that is deposited to sea ice is re-emitted during spring. Our work demonstrates that hourly differences in bromine/ozone chemistry in the atmosphere must be considered to capture the springtime Arctic mercury cycle, including its integration into the cryosphere and ocean.

Atmospheric mercury (Hg) cycling in polluted coastal atmosphere is complicated and not fully understood. Here, we present measurements of total gaseous mercury (TGM) monitored at a coastal mountaintop in Hong Kong downwind of mainland China. Sharp TGM peaks during cold front passages were frequently observed due to Asian pollution outflow with typical TGM/CO slopes of 6.8 +/- 2.2 pg m-3 ppbv-1. Contrary to the daytime maximums of other air pollutants, TGM exhibited a distinct diurnal variation with a midday minimum. Moreover, we observed four cases of extremely fast TGM depletion after sunrise, during which TGM concentrations rapidly dipped to 0.3-0.6 ng m-3 accompanied by other pollutants on the rise. Simulated meteorological fields revealed that morning upslope flow trans-porting anthropogenically polluted but TGM-depleted air masses from the mixed layer caused morning TGM depletion at the mountaintop location. The TGM-depleted air masses were hypothesized to result mainly from fast photooxidation of Hg after sunrise with minor contributions from dry deposition (5.0%) and nocturnal oxidation (0.6%). A bromine-induced two-step oxidation mechanism involving abundant pollutants (NO2, O3, etc.) was estimated to play a dominant role, contributing 55%-60% of depleted TGM and requiring 0.20-0.26 pptv Br, an amount potentially available through sea salt aerosol debromination. Our findings suggest significant effects of the interaction between anthropogenic pollution and marine halogen chemistry on atmospheric Hg cycling in the coastal areas.

High-temperature superconductivity (HTS) was supposed to change the world. And it did, albeit less dramatically than previously predicted over 40 years ago. Thin films of HTS materials have been applied in qubits for quantum computing, analog-to-digital converters, and neuromorphic circuits; and are necessary for the most sensitive magnetometers used in geological surveys and medical technology. This technological revolution hinges on Yttrium Barium Copper Oxide, or YBa2Cu3Ox+6 (YBCO). This ceramic oxide from the cuprate family has been the benchmark for “high temperature” superconductors, in which the superconducting state is reached above the boiling temperature of nitrogen. However, its processing and technical implementation in thin films come with challenges. It is a non-stoichiometric crystal, and its superconducting properties are highly dependent on its concentration of oxygen (and therefore the variable oxidation state of copper). Most importantly – and the focus of this dissertation – is its stability as a thin film under 40 nanometers thick: YBCO expands differently from its substrates under thermal cycling, loses oxygen at high temperatures, and in air, reacts to form non-superconducting (and oxygen-depleted) products. The work presented here explores how YBCO thin films fail, and how to protect their surface and preserve thin-film superconductivity. The focus lies on the use of bromine – a halogen that tightly binds to the YBCO surface – as a means of chemical passivation, protecting YBCO from being reduced in the atmosphere without harming the desirable superconducting properties, and also without harming the performance of superconducting devices such as YBCO-based nanoelectronics. We found that thermal stress is not the root cause of failure in superconducting thin films, which led the study into further chemistry. Remarkably, treatment with dilute bromine in ethanol solutions was found to have little effect on the material’s performance and does not

High-temperature superconductivity (HTS) was supposed to change the world. And it did, albeit less dramatically than previously predicted over 40 years ago. Thin films of HTS materials have been applied in qubits for quantum computing, analog-to-digital converters, and neuromorphic circuits; and are necessary for the most sensitive magnetometers used in geological surveys and medical technology. This technological revolution hinges on Yttrium Barium Copper Oxide, or YBa2Cu3Ox+6 (YBCO). This ceramic oxide from the cuprate family has been the benchmark for “high temperature” superconductors, in which the superconducting state is reached above the boiling temperature of nitrogen. However, its processing and technical implementation in thin films come with challenges. It is a non-stoichiometric crystal, and its superconducting properties are highly dependent on its concentration of oxygen (and therefore the variable oxidation state of copper). Most importantly – and the focus of this dissertation – is its stability as a thin film under 40 nanometers thick: YBCO expands differently from its substrates under thermal cycling, loses oxygen at high temperatures, and in air, reacts to form non-superconducting (and oxygen-depleted) products. The work presented here explores how YBCO thin films fail, and how to protect their surface and preserve thin-film superconductivity. The focus lies on the use of bromine – a halogen that tightly binds to the YBCO surface – as a means of chemical passivation, protecting YBCO from being reduced in the atmosphere without harming the desirable superconducting properties, and also without harming the performance of superconducting devices such as YBCO-based nanoelectronics. We found that thermal stress is not the root cause of failure in superconducting thin films, which led the study into further chemistry. Remarkably, treatment with dilute bromine in ethanol solutions was found to have little effect on the material’s performance and does not

Information about biological significance and possible phytotoxicity of many trace elements is still scarce. Bromine and neodymium are among the poorly investigated trace elements. In the research, greenhouse experiment was conducted to study the effects of bromide of neodymium on wheat seedlings grown in soil and water. The wheat seedlings were capable of accumulating large amounts of both Br and Nd. Compared to the soil-grown plants, the water-grown plants accumulated higher concentrations of the trace elements. The bioaccumulation of Br and Nd resulted in statistically significant variations in the concentrations of several elements. The concentrations of P, Cl, and Ca in roots and Cl in leaves of the plants grown in the contaminated water and the concentration of I in roots of the soil-grown plants decreased. In the water-grown seedlings, the concentrations of Na and P were higher and concentrations of Mg and K were lower than those in the seedlings grown in soil. In leaves of the plants grown in water, the concentration of Cl was lower than that in leaves of the soil-grown plants. In roots of the water-grown plants, the concentration of Zn was higher, and in leaves, it was lower compared with Zn content in roots and leaves of the plants grown in soil. The K/Na ratios were 4 (leaves) and 20 (roots) times higher in the soil-grown plants, while the Ca/Mg ratios were 8–19 times higher in the water-grown plants. Marked distinctions were also observed in relationships between different elements in the soil-grown and water-grown plants.

Commercial use of lead halide perovskites requires improved thermal stability and therefore a better understanding of their degradation mechanisms. The thermal degradation of three clean perovskite single crystal surfaces (MAPbI3, MAPbBr3, FAPbBr3) was investigated using synchrotron-based photoelectron spectroscopy. Central findings are that the halide has a large impact on thermal stability and that the degradation of formamidnium results in the formation of a new organic species at the FAPbBr3 crystal surface., QC 20230614

PM2.5 element data in Hong Kong as measured by online XRF monitors in Hong Kong. (2022-07-20)

Among all halogens fluorine (F) and chlorine (Cl) have the highest concentrations in soil followed by bromine (Br) and iodine (I). The variability of halogen contents in soils is high, which depends to a major degree on atmospheric deposition (Cl, Br, I), parent material (F), organic matter (Cl, Br, I), secondary minerals (F, Br), and local pollution (F, Cl). The enzyme-mediated reaction between halide ions and organic matter known as halogenation is considerable in some soils for Cl, Br and I, and should be accounted for in future ecosystem halogen budgets.

The focus of this thesis is computationally investigating the reaction between mercury and halogens. Namely, the reactions including mercury and iodine/bromine radicals as reactants are of interest, along with the biradical reactions induced further down the reaction chain. The reaction mechanisms proposed for the Arctic Mercury Depletion Event (AMDE) by (Schroeder 1998) and (Jaio 2015) are investigated. Reactions of iodine radicals and mercury are investigated in this thesis and compared to computations carried out on mercury bromine reactions in this thesis and literature. Gibbs free energies, 0 K formation enthalpies and frequencies have been calculated with the Coupled Cluster singlet, doublet and perturbative triplets method (CCSD(T)) method, using the ma-def2-TZVP basis set and effective core potential for treating relativistic effects. Reaction kinetics have been investigated with variational transition state theory based on geometric scans of bond dissociations at the ZORA DFT/B3LYP def2-mTZVP level. The B3LYP energy from the geometric scans have been readjusted by multiplying a constant to match the reaction energy calculated with the CCSD(T) method. In doing so, using computational inexpensive methods for treating the rate of a large number of reactions and estimate this methods usefulness of biradical reactions, instead of treating the reactions with expensive methods such as multi reference configuration interaction (MRCI) or Coupled Cluster singlet, doublet, triplet CCSDT, The focus of this thesis is computationally investigating the reaction between mercury and halogens. Namely, the reactions including mercury and iodine/bromine radicals as reactants are of interest, along with the biradical reactions induced further down the reaction chain. The reaction mechanisms proposed for the Arctic Mercury Depletion Event (AMDE) by (Schroeder 1998) and (Jaio 2015) are investigated. Reactions of iodine radicals and mercury are investigated in this thesis and compared to computations carried out on mercury bromine reactions in this thesis and literature. Gibbs free energies, 0 K formation enthalpies and frequencies have been calculated with the Coupled Cluster singlet, doublet and perturbative triplets method (CCSD(T)) method, using the ma-def2-TZVP basis set and effective core potential for treating relativistic effects. Reaction kinetics have been investigated with variational transition state theory based on geometric scans of bond dissociations at the ZORA DFT/B3LYP def2-mTZVP level. The B3LYP energy from the geometric scans have been readjusted by multiplying a constant to match the reaction energy calculated with the CCSD(T) method. In doing so, using computational inexpensive methods for treating the rate of a large number of reactions and estimate this methods usefulness of biradical reactions, instead of treating the reactions with expensive methods such as multi reference configuration interaction (MRCI) or Coupled Cluster singlet, doublet, triplet CCSDT

The focus of this thesis is computationally investigating the reaction between mercury and halogens. Namely, the reactions including mercury and iodine/bromine radicals as reactants are of interest, along with the biradical reactions induced further down the reaction chain. The reaction mechanisms proposed for the Arctic Mercury Depletion Event (AMDE) by (Schroeder 1998) and (Jaio 2015) are investigated. Reactions of iodine radicals and mercury are investigated in this thesis and compared to computations carried out on mercury bromine reactions in this thesis and literature. Gibbs free energies, 0 K formation enthalpies and frequencies have been calculated with the Coupled Cluster singlet, doublet and perturbative triplets method (CCSD(T)) method, using the ma-def2-TZVP basis set and effective core potential for treating relativistic effects. Reaction kinetics have been investigated with variational transition state theory based on geometric scans of bond dissociations at the ZORA DFT/B3LYP def2-mTZVP level. The B3LYP energy from the geometric scans have been readjusted by multiplying a constant to match the reaction energy calculated with the CCSD(T) method. In doing so, using computational inexpensive methods for treating the rate of a large number of reactions and estimate this methods usefulness of biradical reactions, instead of treating the reactions with expensive methods such as multi reference configuration interaction (MRCI) or Coupled Cluster singlet, doublet, triplet CCSDT, The focus of this thesis is computationally investigating the reaction between mercury and halogens. Namely, the reactions including mercury and iodine/bromine radicals as reactants are of interest, along with the biradical reactions induced further down the reaction chain. The reaction mechanisms proposed for the Arctic Mercury Depletion Event (AMDE) by (Schroeder 1998) and (Jaio 2015) are investigated. Reactions of iodine radicals and mercury are investigated in this thesis and compared to computations carried out on mercury bromine reactions in this thesis and literature. Gibbs free energies, 0 K formation enthalpies and frequencies have been calculated with the Coupled Cluster singlet, doublet and perturbative triplets method (CCSD(T)) method, using the ma-def2-TZVP basis set and effective core potential for treating relativistic effects. Reaction kinetics have been investigated with variational transition state theory based on geometric scans of bond dissociations at the ZORA DFT/B3LYP def2-mTZVP level. The B3LYP energy from the geometric scans have been readjusted by multiplying a constant to match the reaction energy calculated with the CCSD(T) method. In doing so, using computational inexpensive methods for treating the rate of a large number of reactions and estimate this methods usefulness of biradical reactions, instead of treating the reactions with expensive methods such as multi reference configuration interaction (MRCI) or Coupled Cluster singlet, doublet, triplet CCSDT

The risk of accidental bromine (Br2) exposure to the public has increased due to its enhanced industrial use. Inhaled Br2 damages the lungs and the heart; however, adverse effects on the brain are unknown. In this study, we examined the neurological effects of inhaled Br2 in Sprague Dawley rats. Rats were exposed to Br2 (600 ppm for 45 min) and transferred to room air and cage behavior, and levels of glial fibrillary acidic protein (GFAP) in plasma were examined at various time intervals. Bromine exposure resulted in abnormal cage behavior such as head hitting, biting and aggression, hypervigilance, and hyperactivity. An increase in plasma GFAP and brain 4-hydroxynonenal (4-HNE) content also was observed in the exposed animals. Acute and delayed sympathetic nervous system activation was also evaluated by assessing the expression of catecholamine biosynthesizing enzymes, tryptophan hydroxylase (TrpH1 and TrpH2), and tyrosine hydroxylase (TyrH), along with an assessment of catecholamines and their metabolites. TyrH was found to be increased in a time-dependent manner. TrpH1 and TrpH2 were significantly decreased upon Br2 exposure in the brainstem. The neurotransmitter content evaluation indicated an increase in 5-HT and dopamine at early timepoints after exposure; however, other metabolites were not significantly altered. Taken together, our results predict brain damage and autonomic dysfunction upon Br2 exposure.

The burning issue of large-scale energy storage for the use in combination with a rapidly growing renewable energy sector could be resolved by wide-ranging commercialisation of reliable redox flow battery (RFB) systems. In the RFB systems, high energy density is achieved by increasing the concentration of active redox species in the electrolyte or compressing gas in hybrid systems, such as the hydrogen-bromine redox flow battery (HBRFB). High electrolyte concentration, although favourable from the practical perspective, poses serious difficulties in modelling and simulation of energy storage devices. The presented work describes an experimental study employing liquid junction-free potentiometric technique to measure cell potential and ultramicrolectrodes (UMEs) to determine diffusion coefficients of both reduced and oxidized species in concentrated electrolytes (1-8 mol L-1). The experiments are performed in an exemplary HBRFB electrolyte of diluted and concentrated hydrobromic acid and bromine. Experimental results are then analysed by means of mathematical modelling utilising more advanced treatment of mass transport than e.g. simple Fick’s law and enhanced Nernst equation, which takes into account electrolyte activity and homogeneous ionic equilibria. It is considered that strong ionic interactions, variations of electrolyte viscosity with concentration and the impact of ionic activity on diffusion coefficient introduce non-linearities in mass transport phenomena. An improved parametrisation of cell thermodynamics and diffusional mass fluxes enhances model credibility and generalizes the mathematical description, without resorting to formal potentials or empirical formulae. The work is performed within the FlowCamp project, a part of Maria Skłodowska-Curie Actions from the EU Horizon 2020 programme.

Bromine complexing agents (BCA) are used to improve the safety of aqueous bromine electrolytes versus bromine outgassing in bromine electrolytes. In this work, cycling performance of hydrogen-bromine redox flow battery cells with 1-ethylpyridin-1-ium bromide ([C2Py]Br) as BCA in a bromine electrolyte with a theoretical capacity of 179.6 A h L−1 is investigated for the first time. The BCA leads to increased ohmic overvoltages. One cause of the ohmic drop can be attributed to [C2Py]+ cation interaction with the perfluorosulfonic acid (PFSA) membrane, which results in a drop of its conductivity. The BCA also interacts with bromine in the cell, by forming a non-aqueous fused salt second phase which exhibits a ten times lower conductivity compared to the aqueous electrolyte. A steep rise in cell voltage at the beginning of the charge curve followed by a regeneration of the cell voltage is attributed to this effect. Electrolyte crossover leads to an accumulation of [C2Py]+ in the electrolyte solution and intensifies both adverse processes. Under this condition only 30% of the theoretical electrolyte capacity of 179.6 A h L−1 is available under long term cycle conditions. However, electrolyte capacity is high enough to compete with other flow battery technologies.

Hydrogen–bromine redox flow batteries (H2/Br2-RFB) are a promising stationary energy storage solution, offering energy storage densities up to 200 W h L−1. In this study, high energy density electrolytes of concentrated hydrobromic acid of up to 7.7 M are investigated. Particular polybromide ion (Br2n+1−; n = 1–3) concentrations in the electrolyte at different states of charge, their effect on the electrolytic conductivity and cell operation limits are investigated for the first time. The concentrations of individual polybromides in the electrolytes are determined by Raman spectroscopy. Tribromide (Br3−) and pentabromide (Br5−) are predominantly present in equal concentrations over the entire concentration range. Besides Br3− and Br5−, heptabromide (Br7−) exists in the electrolyte solution at higher bromine concentrations. It is shown that polybromide equilibria and their constants of Br3− and Br5− from literature are not applicable for highly concentrated solutions. The conductivity of the electrolytes depends primarily on the high proton concentration. The presence of higher polybromides leads to lower conductivities. The solubility of bromine increases disproportionately with increasing bromide concentration, since higher polybromides such as Br7− or Br5− are preferably formed with increasing bromide concentration. Cycling experiments on electrolyte in a single cell are performed and combined with limitations due to electrolyte conductivity and bromine solubility. Based on these results concentrations of the electrolyte are defined for potential operation in a H2/Br2-RFB in the range 1.0 M < c(HBr) < 7.7 M and c(Br2) < 3.35 M, leading to a theoretical energy density of 196 W h L−1.

Eddavidite is a new mineral species (IMA2018-010) with ideal formula Cu12Pb2O15Br2. It has cubic Fm3m symmetry; a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromide analog of murdochite, with which it forms a solid solution series. The type locality is the Southwest mine, Bisbee, Arizona, U.S.A. Eddavidite also occurs in the Ojuela mine, Mapimí, Durango, Mexico. Eddavidite forms zones within mixed murdochite-eddavidite crystals. Spot analyses of Bisbee samples show up to 67% eddavidite component while Ojuela samples show up to 62%. Eddavidite-murdochite crystals show forms {100} and {111}; the habit grades from simple cubic through cuboctahedral to unmodified octahedral. Eddavidite is black and opaque with submetallic luster, and visually indistinguishable from intergrown murdochite. Its Mohs’ hardness is 4. Eddavidite exhibits good cleavage on {111}. The empirical formula, normalized to 12 Cu apfu is Cu12(Pb1.92Fe0.06Si0.06) (O15.08F0.02) (Br0.99Cl0.89•0.12). dcalc. = 6.33 g/cm3. dmeas. = 6.45 g/cm3. The crystal structure consists of corner sharing square planar CuO4 units, arranged in Cu12O24 metal oxide clusters, which encapsulate Br atoms. PbO8 cubes share edges with Cu12O24 clusters in a continuous framework. Eddavidite is one of only 10 mineral species with essential Br. Eddavidite crystallizes from bromine enriched fluids leftover from desiccation of paleo-seawater at its two known localities.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

The risk of accidental bromine (Br2) exposure to the public has increased due to its enhanced industrial use. Inhaled Br2 damages the lungs and the heart; however, adverse effects on the brain are unknown. In this study, we examined the neurological effects of inhaled Br2 in Sprague Dawley rats. Rats were exposed to Br2 (600 ppm for 45 min) and transferred to room air and cage behavior, and levels of glial fibrillary acidic protein (GFAP) in plasma were examined at various time intervals. Bromine exposure resulted in abnormal cage behavior such as head hitting, biting and aggression, hypervigilance, and hyperactivity. An increase in plasma GFAP and brain 4-hydroxynonenal (4-HNE) content also was observed in the exposed animals. Acute and delayed sympathetic nervous system activation was also evaluated by assessing the expression of catecholamine biosynthesizing enzymes, tryptophan hydroxylase (TrpH1 and TrpH2), and tyrosine hydroxylase (TyrH), along with an assessment of catecholamines and their metabolites. TyrH was found to be increased in a time-dependent manner. TrpH1 and TrpH2 were significantly decreased upon Br2 exposure in the brainstem. The neurotransmitter content evaluation indicated an increase in 5-HT and dopamine at early timepoints after exposure; however, other metabolites were not significantly altered. Taken together, our results predict brain damage and autonomic dysfunction upon Br2 exposure.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

The application of statistical modeling is still infrequent in mercury research in peat, despite the ongoing debate on the weight of the diverse factors (climate, peat decomposition, vegetation changes, etc.) that may affect mercury accumulation. One of the few exceptions is the Hg record of Pinheiro mire (souheast Brazil). Previous studies on this mire modeled mercury using principal components regression and partial least squares. These methods assume independence between factors, which is seldom the case in natural systems, thus hampering the identification of mediating effects and interactions. To overcome these limitations, in this reserach we use structural equation modeling (PLS-SEM) to model mercury and bromine peat records - bromine has been used in some investigations to normalize mercury accumuation. The mercury model explained 83% of the variance and suggested a complex control: increased peat decomposition, dust deposition and humid dimates enhanced mercury accumulation, while increased mineral fluxes resulted in a decrease in mercury accumulation. The bromine model explained 90% of the variation in concentrations: increased dust deposition and peat decomposition promoted bromine accumulation, while time (i.e. peat age) promoted bromine depletion. Thus, although mercury and bromine are both organically bound elements with relevant atmospheric cycles the weights of the factors involved in their accumulation differed significantly. Our results suggest caution when using bromine to normalize mercury accumulation. PLS-SEM results indicate a large time dependence of peat decomposition, catchment mineral fluxes, long-term climate change, and atmospheric deposition: while atmospheric dust, mineral fluxes and peat decomposition showed high to moderate climate dependency. In particular, they also point to a relevant role of autogenic processes (i.e. the build up and expansion of the mire within the catchment), which controlled local mineral fluxes; an aspect tha

The application of statistical modeling is still infrequent in mercury research in peat, despite the ongoing debate on the weight of the diverse factors (climate, peat decomposition, vegetation changes, etc.) that may affect mercury accumulation. One of the few exceptions is the Hg record of Pinheiro mire (souheast Brazil). Previous studies on this mire modeled mercury using principal components regression and partial least squares. These methods assume independence between factors, which is seldom the case in natural systems, thus hampering the identification of mediating effects and interactions. To overcome these limitations, in this reserach we use structural equation modeling (PLS-SEM) to model mercury and bromine peat records - bromine has been used in some investigations to normalize mercury accumuation. The mercury model explained 83% of the variance and suggested a complex control: increased peat decomposition, dust deposition and humid dimates enhanced mercury accumulation, while increased mineral fluxes resulted in a decrease in mercury accumulation. The bromine model explained 90% of the variation in concentrations: increased dust deposition and peat decomposition promoted bromine accumulation, while time (i.e. peat age) promoted bromine depletion. Thus, although mercury and bromine are both organically bound elements with relevant atmospheric cycles the weights of the factors involved in their accumulation differed significantly. Our results suggest caution when using bromine to normalize mercury accumulation. PLS-SEM results indicate a large time dependence of peat decomposition, catchment mineral fluxes, long-term climate change, and atmospheric deposition: while atmospheric dust, mineral fluxes and peat decomposition showed high to moderate climate dependency. In particular, they also point to a relevant role of autogenic processes (i.e. the build up and expansion of the mire within the catchment), which controlled local mineral fluxes; an aspect tha

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

Hydrogen–bromine redox flow batteries (H2/Br2-RFB) are a promising stationary energy storage solution, offering energy storage densities up to 200 W h L−1. In this study, high energy density electrolytes of concentrated hydrobromic acid of up to 7.7 M are investigated. Particular polybromide ion (Br2n+1−; n = 1–3) concentrations in the electrolyte at different states of charge, their effect on the electrolytic conductivity and cell operation limits are investigated for the first time. The concentrations of individual polybromides in the electrolytes are determined by Raman spectroscopy. Tribromide (Br3−) and pentabromide (Br5−) are predominantly present in equal concentrations over the entire concentration range. Besides Br3− and Br5−, heptabromide (Br7−) exists in the electrolyte solution at higher bromine concentrations. It is shown that polybromide equilibria and their constants of Br3− and Br5− from literature are not applicable for highly concentrated solutions. The conductivity of the electrolytes depends primarily on the high proton concentration. The presence of higher polybromides leads to lower conductivities. The solubility of bromine increases disproportionately with increasing bromide concentration, since higher polybromides such as Br7− or Br5− are preferably formed with increasing bromide concentration. Cycling experiments on electrolyte in a single cell are performed and combined with limitations due to electrolyte conductivity and bromine solubility. Based on these results concentrations of the electrolyte are defined for potential operation in a H2/Br2-RFB in the range 1.0 M < c(HBr) < 7.7 M and c(Br2) < 3.35 M, leading to a theoretical energy density of 196 W h L−1.

Bromine complexing agents (BCA) are used to improve the safety of aqueous bromine electrolytes versus bromine outgassing in bromine electrolytes. In this work, cycling performance of hydrogen-bromine redox flow battery cells with 1-ethylpyridin-1-ium bromide ([C2Py]Br) as BCA in a bromine electrolyte with a theoretical capacity of 179.6 A h L−1 is investigated for the first time. The BCA leads to increased ohmic overvoltages. One cause of the ohmic drop can be attributed to [C2Py]+ cation interaction with the perfluorosulfonic acid (PFSA) membrane, which results in a drop of its conductivity. The BCA also interacts with bromine in the cell, by forming a non-aqueous fused salt second phase which exhibits a ten times lower conductivity compared to the aqueous electrolyte. A steep rise in cell voltage at the beginning of the charge curve followed by a regeneration of the cell voltage is attributed to this effect. Electrolyte crossover leads to an accumulation of [C2Py]+ in the electrolyte solution and intensifies both adverse processes. Under this condition only 30% of the theoretical electrolyte capacity of 179.6 A h L−1 is available under long term cycle conditions. However, electrolyte capacity is high enough to compete with other flow battery technologies.

The burning issue of large-scale energy storage for the use in combination with a rapidly growing renewable energy sector could be resolved by wide-ranging commercialisation of reliable redox flow battery (RFB) systems. In the RFB systems, high energy density is achieved by increasing the concentration of active redox species in the electrolyte or compressing gas in hybrid systems, such as the hydrogen-bromine redox flow battery (HBRFB). High electrolyte concentration, although favourable from the practical perspective, poses serious difficulties in modelling and simulation of energy storage devices. The presented work describes an experimental study employing liquid junction-free potentiometric technique to measure cell potential and ultramicrolectrodes (UMEs) to determine diffusion coefficients of both reduced and oxidized species in concentrated electrolytes (1-8 mol L-1). The experiments are performed in an exemplary HBRFB electrolyte of diluted and concentrated hydrobromic acid and bromine. Experimental results are then analysed by means of mathematical modelling utilising more advanced treatment of mass transport than e.g. simple Fick’s law and enhanced Nernst equation, which takes into account electrolyte activity and homogeneous ionic equilibria. It is considered that strong ionic interactions, variations of electrolyte viscosity with concentration and the impact of ionic activity on diffusion coefficient introduce non-linearities in mass transport phenomena. An improved parametrisation of cell thermodynamics and diffusional mass fluxes enhances model credibility and generalizes the mathematical description, without resorting to formal potentials or empirical formulae. The work is performed within the FlowCamp project, a part of Maria Skłodowska-Curie Actions from the EU Horizon 2020 programme.

Eddavidite is a new mineral species (IMA2018-010) with ideal formula Cu12Pb2O15Br2. It has cubic Fm3m symmetry; a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromide analog of murdochite, with which it forms a solid solution series. The type locality is the Southwest mine, Bisbee, Arizona, U.S.A. Eddavidite also occurs in the Ojuela mine, Mapimí, Durango, Mexico. Eddavidite forms zones within mixed murdochite-eddavidite crystals. Spot analyses of Bisbee samples show up to 67% eddavidite component while Ojuela samples show up to 62%. Eddavidite-murdochite crystals show forms {100} and {111}; the habit grades from simple cubic through cuboctahedral to unmodified octahedral. Eddavidite is black and opaque with submetallic luster, and visually indistinguishable from intergrown murdochite. Its Mohs’ hardness is 4. Eddavidite exhibits good cleavage on {111}. The empirical formula, normalized to 12 Cu apfu is Cu12(Pb1.92Fe0.06Si0.06) (O15.08F0.02) (Br0.99Cl0.89•0.12). dcalc. = 6.33 g/cm3. dmeas. = 6.45 g/cm3. The crystal structure consists of corner sharing square planar CuO4 units, arranged in Cu12O24 metal oxide clusters, which encapsulate Br atoms. PbO8 cubes share edges with Cu12O24 clusters in a continuous framework. Eddavidite is one of only 10 mineral species with essential Br. Eddavidite crystallizes from bromine enriched fluids leftover from desiccation of paleo-seawater at its two known localities.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

Sea ice plays a pivotal role in Earth's climate and its past reconstruction is crucial to investigate the connections and feedbacks with the other components of the climate system. Among the available archives that store information of past sea ice are marine and ice cores. Recent studies on the IP 25 biomarker extracted from marine sediments has shown great skill to infer past changes of Arctic sea ice. In ice matrixes, sodium, bromine and iodine have shown potential to store the fingerprint of sea ice presence. The development of an unambiguous sea ice proxy from ice cores, however, has proven to be a challenging task especially in the Arctic realm.In this work we analyze the sodium, bromine and iodine records in the RECAP ice core, coastal eastern Greenland, to investigate the sea ice variability in the northern North Atlantic Ocean through the last 11,000 years of the current interglacial, i.e. the Holocene. We compare the RECAP records with marine sea ice proxy records available from the northern North Atlantic.We suggest that RECAP sodium concentrations can be associated with variability of sea ice extent, while the bromine-to-sodium ratios and iodine are associated respectively with seasonal sea ice and bioproductivity from open ocean and fresh sea ice surfaces.According to our interpretation, we find that sea ice was at its lowest extent and seasonal in nature during the early Holocene in all regions of the North Atlantic. Increasing sea ice signals are seen from ca. 8-9 ka b2k, in line with long-term Holocene cooling. The increasing sea ice trend appears uninterrupted in the Fram Strait and North Iceland while reaching a maximum ca. 5 ka b2k in the East Greenland region. Sea ice modifications during the last 5000 years display great variability in East Greenland with intermediate conditions between the early and mid Holocene, possibly associated with local fjord dynamics. The last sea ice maximum was reached across all regions 1000 y

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (similar to 1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since similar to 1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.The Antarctic ozone hole has had far-reaching impacts, but effects on geochemical cycles in polar regions is still unknown. Iodine records from the interior of Antarctica provide evidence for human alteration of the natural geochemical cycle of this essential element.

As the intricacies of paleoclimate dynamics are explored, it is becoming understood that sea-ice variability can instigate, or contribute to, climate change instabilities commonly described as "tipping points". Compared to ice sheets and circulating ocean currents, sea-ice is ephemeral and continentalscale changes to sea ice cover occur seasonally. Sea-ice greatly influences polar albedo, atmosphere-ocean gas exchange and vertical mixing of polar ocean masses. Major changes in sea ice distribution and thickness have been invoked as drivers of deglaciations as well as stadial climate variability described in Greenland climate records as "Dansgaard-Oeschger" cycles and described in Antarctic climate records as "Antarctic Isotopic Maxima".The role of halogens in polar atmospheric chemistry has been studied intensively over the past few decades. This research has been driven by the role of bromine, primarily as gas-phase bromine monoxide (BrO), which exerts a key control on polar tropospheric ozone concentrations. Initial findings led to the discovery of boundary-layer self-catalyzing heterogeneous bromine reactions fed by sunlight and ozone, known as bromine explosions. First-year sea-ice and blowing snow have been identified as key components for this heterogeneous bromine recycling in the polar boundary layer. This understanding of polar halogen chemistry - supported by an expanding body of observations and modeling - has formed the basis for investigating quantitative links between halogen concentrations in the polar atmospheric boundary layer and sea-ice presence and/or extent.Despite the clear importance of sea-ice in paleoclimate research, the ice core community lacks a conservative and quantitative proxy for sea-ice extent. The most commonly applied proxy, methanesulphonic acid (MSA), is volatile and has not been demonstrated reliably for ice core records extending beyond the last few centuries. Sodium has also been applied to reconstruct sea-ic

The aug-cc-pVTZ-J basis set family is extended to include the fourth row p-block elements \ce{Ga}, \ce{Ge}, \ce{As}, \ce{Se} and \ce{Br}. We use the established approach outlined by Sauer and co-workers [J. Chem. Phys. 115, 1324 (2001), J. Chem. Phys. 133, 054308 (2010), J. Chem. Theory Comput. 7, 4070 (2011), J. Chem. Theory Comput. 7, 4077 (2011)] where the completely uncontracted aug-cc-pVTZ basis set is saturated with tight \emph{s}-, \emph{p}-, \emph{d}- and \emph{f}-functions to form the aug-cc-pVTZ-Juc basis set for the tested elements. The saturation is carried out on the simplest hydrides possible for the tested elements \ce{GaH}, \ce{GeH4}, \ce{AsH3}, \ce{H2Se} and \ce{HBr} until an improvement is less than 0.01 \% for all \emph{s}-, \emph{p}- and \emph{d}-functions added. \emph{f}-functions are added to an improvement less than or equal to 1.0 \% due to the computational expense these functions add. The saturated aug-cc-pVTZ-Juc is (26s16p12d5f) is then recontracted using the molecular orbital coefficients from self-consistent field calculations on the simple hydrides to improve computational efficiency. During contraction of the basis set, we observe that the linear hydrogen bromide molecule has a slower convergence than the other tested molecules which sets a limit on the accuracy obtained. All calculations with the contracted aug-cc-pVTZ-J [17s10p7d5f] gives results that are within 1.0 \% of the uncontracted results at considerable computational savings.

Sea ice plays a pivotal role in Earth's climate and its past reconstruction is crucial to investigate the connections and feedbacks with the other components of the climate system. Among the available archives that store information of past sea ice are marine and ice cores. Recent studies on the IP biomarker extracted from marine sediments has shown great skill to infer past changes of Arctic sea ice. In ice matrixes, sodium, bromine and iodine have shown potential to store the fingerprint of sea ice presence. The development of an unambiguous sea ice proxy from ice cores, however, has proven to be a challenging task especially in the Arctic realm. In this work we analyze the sodium, bromine and iodine records in the RECAP ice core, coastal eastern Greenland, to investigate the sea ice variability in the northern North Atlantic Ocean through the last 11,000 years of the current interglacial, i.e. the Holocene. We compare the RECAP records with marine sea ice proxy records available from the northern North Atlantic. We suggest that RECAP sodium concentrations can be associated with variability of sea ice extent, while the bromine-to-sodium ratios and iodine are associated respectively with seasonal sea ice and bioproductivity from open ocean and fresh sea ice surfaces. According to our interpretation, we find that sea ice was at its lowest extent and seasonal in nature during the early Holocene in all regions of the North Atlantic. Increasing sea ice signals are seen from ca. 8–9 ka b2k, in line with long-term Holocene cooling. The increasing sea ice trend appears uninterrupted in the Fram Strait and North Iceland while reaching a maximum ca. 5 ka b2k in the East Greenland region. Sea ice modifications during the last 5000 years display great variability in East Greenland with intermediate conditions between the early and mid Holocene, possibly associated with local fjord dynamics. The last sea ice maximum was reached across all regions 1000 years b2k.

Of the reactive halogens, those containing reactive bromine are of particular scientific interest as they play a key role in the chemistry and oxidising capacity of the polar troposphere (Simpson et al., 2015). In early spring, bromine molecules (as Br2) are rapidly released from the sea ice via heterogenous reactions on sea salt surfaces, both in the sea ice itself and on blowing snow (Simpson et al., 2015; Huang et al., 2018; Peterson et al., 2019). This rapid bromine release can initiate a chemical reaction, known as a bromine explosion, which oxidises gaseous elemental mercury, resulting in the subsequent deposition of toxic water-soluble mercury into the polar environment (Prados-Roman et al., 2018). However, reactive bromine and mercury measurements in coastal Antarctica are mostly limited to a handful of short-term campaigns, limiting current understanding of the sources and drivers controlling variability. To further investigate these processes, observations of bromine monoxide (BrO) were acquired via Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) during six resupply voyages of the Aurora Australis to the coast of east Antarctica during the CAMMPCAN 2017-19 campaign, along with in situ measurements of gaseous elemental mercury (Hg0) and reactive mercury (RM). These were analysed along with meteorological measurements from the Aurora Australis, satellite observations of sea ice cover and modelled air mass back trajectories.

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (similar to 1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since similar to 1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.The Antarctic ozone hole has had far-reaching impacts, but effects on geochemical cycles in polar regions is still unknown. Iodine records from the interior of Antarctica provide evidence for human alteration of the natural geochemical cycle of this essential element.

As the intricacies of paleoclimate dynamics are explored, it is becoming understood that sea-ice variability can instigate, or contribute to, climate change instabilities commonly described as "tipping points". Compared to ice sheets and circulating ocean currents, sea-ice is ephemeral and continentalscale changes to sea ice cover occur seasonally. Sea-ice greatly influences polar albedo, atmosphere-ocean gas exchange and vertical mixing of polar ocean masses. Major changes in sea ice distribution and thickness have been invoked as drivers of deglaciations as well as stadial climate variability described in Greenland climate records as "Dansgaard-Oeschger" cycles and described in Antarctic climate records as "Antarctic Isotopic Maxima".The role of halogens in polar atmospheric chemistry has been studied intensively over the past few decades. This research has been driven by the role of bromine, primarily as gas-phase bromine monoxide (BrO), which exerts a key control on polar tropospheric ozone concentrations. Initial findings led to the discovery of boundary-layer self-catalyzing heterogeneous bromine reactions fed by sunlight and ozone, known as bromine explosions. First-year sea-ice and blowing snow have been identified as key components for this heterogeneous bromine recycling in the polar boundary layer. This understanding of polar halogen chemistry - supported by an expanding body of observations and modeling - has formed the basis for investigating quantitative links between halogen concentrations in the polar atmospheric boundary layer and sea-ice presence and/or extent.Despite the clear importance of sea-ice in paleoclimate research, the ice core community lacks a conservative and quantitative proxy for sea-ice extent. The most commonly applied proxy, methanesulphonic acid (MSA), is volatile and has not been demonstrated reliably for ice core records extending beyond the last few centuries. Sodium has also been applied to reconstruct sea-ic

Plastics (n = 3880) have been sampled from 39 beaches of ten Swiss lakes of varying sizes, hydrodynamics, and catchments, with a selection (n = 598) analysed for potentially hazardous (and regulated) chemical elements (As, Ba, Br, Cd, Cr, Hg, Pb, Sb, Se) by X-ray fluorescence spectrometry. Plastic objects and fragments with identifiable or unidentifiable origins were present on all beaches surveyed, and were often most abundant in proximity to major riverine inputs. Chemical elements were detected in between two (Hg) and 340 (Ba) samples with maximum concentrations exceeding 2% by weight for Ba, Cd, Cr, Pb, and Sb. Inter-element relationships and characteristics of the samples suggest that elements are largely present as various additives, including pigments (e.g., CdSSe, PbCrO), stabilizers (in polyvinyl chloride), and flame retardants (Br). Observations are similar to, and complement, those previously reported in Switzerland’s largest lake (Lake Geneva). Comparison of concentrations of targeted chemical elements in beached plastic with currently used plastics illustrate the interest of these types of measurements in providing an insight into the persistence of plastics in standing stocks and in lakes. This information could help to introduce management schemes that consider whether plastic pollution is new or old and act accordingly.

Antarctica exhibits near pristine conditions to study natural chemical processes that occur under extreme temperatures and radiation conditions. As such, Antarctica provides an ideal location to observe the long-term hemispheric-scale trends in atmospheric trace gases. Air mass observations at three coastal Antarctic stations (Casey, Davis, and Mawson) during 2018/19 resupply voyages aboard the RV Aurora Australis were classified according to their recent fetch history, and their degree of terrestrial influence characterised via radon-222 (radon) observations. Fetch classification categories were based on absolute water content, with oceanic being the wettest and katabatic being the driest (i.e., originating from the Antarctic interior). The fetch separation technique was most successful when a wide representation of meteorological conditions was present. Casey showed the clearest separation of air mass fetch categories, with each fetch category also having observable differences in trace gas composition. Casey corresponded to the longest study period (14 days) followed by Mawson (9 days) and Davis (8 Days). Davis showed the highest degree of mixing with most observed air masses correlating to mixed/coastal fetch. Air mass observations at Mawson were almost completely synoptically forced down slope winds/katabatic flow. Radon observations at all three sites was proven to be a reliable indicator of terrestrial influence, however all three sites could have benefited from a deeper understanding of (radon) source mechanisms and better-established baseline concentrations. The use of radon observations as a marker for terrestrial influence was also shown to be dependent on the success of the fetch classification technique.

Chlorine (Cl) and bromine (Br) are rare elements when considering the whole Earth. However, being highly volatile elements, their delivery and retention processes during planetary accretion and chemical differentiation provide important clues about the formation of the Earth. Variations in Cl and Br isotopic systems (37 Cl/35 Cl or d37 Cl and81 Br/79 Br or d81 Br) among terrestrial reservoirs could trace these processes. While the Br isotopic value of the mantle remains entirely unknown, the measurement of mantle Cl isotopic values is a controversial subject, with measured d37 Cl values ranging from À3 to 0‰ in midocean-ridge basalts (MORBs) and from À2 to +3‰ in oceanic island basalts (OIBs). Here, we report newly-determined d81 Br and d37 Cl values, together with noble gas 3 He/4 He (R) ratios, measured in geothermal fluids from production wells of three Mexican fields: Cerro Prieto, Las Tres Vı´rgenes, and Los Azufres. Relationships between3 He/4 He ratios and both d37 Cl and d81 Br suggest that geothermal fluid volatiles have three distinct sources: (1) a local crustal source, enriched in radiogenic4 He (R = 1.7–1.9Ra, where Ra is the atmospheric 3 He/4 He ratio), and halogens from brines with d37 Cl and d81 Br of +0.1 and +0.3‰ respectively; (2) the mantle wedge, with 3 He/4 He ratios of 6–6.5Ra, typical of arc volcanism, and d37 Cl and d81 Br of À0.4 and À1.0‰ respectively, typical (for Cl) of fluids derived from the dehydration of serpentinite in the subducting slab; and (3) a mantle source, with 3 He/4 He ratios of 7.7–8.2Ra, typical of MORBs, and d37 Cl and d81 Br of +0.9 and +0.7‰ respectively. These results suggest that the primitive mantle Cl isotopic composition was positive – possibly !+3‰, as measured in some OIBs – and inherited during the Moon forming impact. The progressive subduction of isotopically lighter halogens over the last 2–3 Ga could have progressively lowered this initial value to those currently measured in the depleted mantle beneath Mexico

The efficient production of energy from low-temperature heat sources (below 100 °C) would open the doors to the exploitation of a huge amount of heat sources such as solar, geothermal, and industrial waste heat. Thermal regenerable redox-flow batteries (TRBs) are flow batteries that store energy in concentration cells that can be recharged by distillation at temperature <100 °C, exploiting low-temperature heat sources. Using a single membrane cell setup and a suitable redox couple (LiBr/Br2), a TRB has been developed that is able to store a maximum volumetric energy of 25.5 Wh dm−3, which can be delivered at a power density of 8 W m−2. After discharging 30 % of the volumetric energy, a total heat-to-electrical energy conversion efficiency of 4 % is calculated, the highest value reported so far in harvesting of low-temperature heat.

Efficiency in charge-transport is a fundamental but demanding prerequisite to allow better exploitation of molecular functionalities in organic electronics and energy-conversion systems. Here, we report on a mechanism that enables a one-dimensional conductance structure by connecting discrete molecular states at 2.1 eV through the pores of a metal–organic network on Cu(110). Two adjacent, periodic and isoenergetic contributions, namely a molecular resonance and the confined surface-state, add-up leading to anisotropic structures, as channels, observable in real-space conductance images. The adsorption configurations of Br atoms, inorganic byproduct of the redox-reacted 4,7-dibromobenzo[c]-1,2,5-thiadiazole (2Br-BTD) molecules on the copper surface, drive the confinement of the Cu surface state within the pores and critically control the channel continuity. Small displacements of the Br atoms change the local surface potential misaligning the energy levels. This work visualizes the effect of order-disorder transitions caused by the movement of single atoms in the electronic properties of two-dimensional organic networks.

Bromine and iodine chemistry has been updated in the Community Multiscale Air Quality (CMAQ) model to better capture the influence of natural emissions from the oceans on ozone concentrations. Annual simulations were performed using the hemispheric CMAQ model without and with bromine and iodine chemistry. Model results over the Northern Hemisphere show that including bromine and iodine chemistry in CMAQ not only reduces ozone concentrations within the marine boundary layer but also aloft and inland. Bromine and iodine chemistry reduces annual mean surface ozone over seawater by 25%, with lesser ozone reductions over land. The bromine and iodine chemistry decreases ozone concentration without changing the diurnal profile and is active throughout the year. However, it does not have a strong seasonal influence on ozone over the Northern Hemisphere. Model performance of CMAQ is improved by the bromine and iodine chemistry when compared to observations, especially at coastal sites and over seawater. Relative to bromine, iodine chemistry is approximately four times more effective in reducing ozone over seawater over the Northern Hemisphere (on an annual basis). Model results suggest that the chemistry modulates intercontinental transport and lowers the background ozone imported to the United States.

The open dump in the city of Portoviejo is in the technical closure stage and there are domestic and industrial waste. These wastes can generate contamination by the various toxic chemical elements they contain. The objective of this work was to characterize soils through physical and chemical parameters such as pH, humidity, electrical conductivity, Dry Evaporated Residue (RSE), Calcined Dry Residue (RSC), real and apparent density and measure Cr (VI), Ni, Br and Fe for proposing a zoning of possible spread of contaminants, in relation to leaching curves. We proceeded to analyse several sampling techniques, in terms of feasibility and applicability to the study area, so was used methodology proposed by the Ecuadorian Environmental Technical Standard, the Secretariat of the Environment of Mexico and the proposal based on the publication of Research of the Soil Pollution of the Basque Government of Spain, it was decided to use the last one, which resulted in a total of 20 samples in the study area. The physical-chemical characterization of the soil allowed to obtain information about its properties, which served as input for the elaboration of spatial distribution maps, with the purpose of applying algebra of maps, depending on the variation of these properties, for the determination of two zones, where, greater and less vulnerability of pollution was identified in terms of the mobility of these elements. The values ​​shown by the pH and electrical conductivity, determined that they are soils that behave neutrally and slightly alkaline, and significantly saline soils. The percentage of moisture obtained in each of the extracts determined sandy loam soils. As a result, the highest concentration of the measured elements was oriented to the southwest of the dump, and after analysing the relationship between zoning and leaching, it was possible to determine how the mobility of these elements is, where special attention should be paid to the vulnerable zone that presents, El botadero de basura a cielo abierto de la ciudad de Portoviejo se encuentra en etapa de cierre técnico y en este existen desechos de origen doméstico e industrial. Estos desechos pueden generar contaminación por los diversos elementos químicos tóxicos que contienen. El objetivo de este trabajo fue caracterizar los suelos mediante parámetros físicos y químicos como pH, humedad, conductividad eléctrica, Residuo Seco Evaporado (RSE), Residuo Seco Calcinado (RSC), densidad real y aparente y medir Cr (VI), Ni, Br y Fe para proponer una zonificación de posible propagación de los contaminantes, con relación a las curvas de lixiviación. Se procedió a analizar varias técnicas de muestreo, en cuanto a factibilidad y aplicabilidad a la zona de estudio, por ello se empleó metodología propuesta por la Norma Técnica Ambiental Ecuatoriana, la Secretaría de Medio Ambiente de México y la propuesta basada en la publicación de Investigación de la Contaminación de Suelos del Gobierno Vasco de España, se optó por utilizar esta última, que dio como resultado un total de 20 muestras en la zona de estudio. La caracterización fisicoquímica del suelo permitió obtener información de sus propiedades, las mismas que sirvieron como insumo para la elaboración de mapas de distribución espacial, con la finalidad de aplicar algebra de mapas, en función de la variación de estas propiedades, para la determinación de dos zonas, donde, se identificó mayor y menor vulnerabilidad de contaminación en cuanto a la movilidad de estos elementos. Los valores mostrados por el pH y conductividad eléctrica determinaron que son suelos que se comportan de manera neutral y ligeramente alcalino, y suelos significativamente salinos. El porcentaje de humedad obtenido en cada uno de los extractos determinó suelos franco arenosos. Como resultado se tuvo que la mayor concentración de los elementos medidos está orientada al suroccidente del botadero, y tras analizar la relación entre la zonificación y lixiviación, se pudo

Chemically tuned inorganic–organic hybrid halide perovskites based on bromide and chloride anions CH3NH3Pb(Br1–xClx)3 have been crystallized and investigated by synchrotron X-ray diffraction (SXRD), scanning electron microscopy, and UV–vis spectroscopy. CH3NH3PbBr3 and CH3NH3PbCl3 experience successive phase transitions upon cooling, which are suppressed for intermediate compositions probably due to compositional disorder. For CH3NH3PbCl3, a transient phase, formerly described as tetragonal, was identified at 167.5 K; the analysis of SXRD data demonstrated that it is indeed orthorhombic, with space group Pnma, and a ≈ √2ap; b ≈ 2ap; c ≈ √2ap (ap is the ideal cubic perovskite unit-cell parameter). The band gap engineering brought about by the chemical management of CH3NH3Pb(Br1–xClx)3 perovskites can be controllably tuned: the gap progressively increases with the concentration of Cl ions from 2.2 to 2.9 eV, and shows a concomitant variation with the unit-cell parameters of the cubic phases at 295 K. This study provides an improved understanding of the structural and optical properties of the mixed CH3NH3Pb(Br1–xClx)3 perovskites.

Electrochemical energy storage is increasingly important as the world decarbonizes and electrifies. Research in this area requires compromise between properties that are often mutually exclusive, including power, energy, lifetime, efficiency, operating temperature, safety, and cost. Electric double layer capacitors (EDLCs) exhibit high power and outstanding cycle life compared to secondary batteries, but have low specific energy, limiting applications. Redox-enhanced electrochemical capacitors (redox ECs) are a class of augmented electric double-layer capacitors utilizing reversible redox reactions of soluble redox couples in the electrolyte to add faradaic charge storage. These systems offer increased energy density, efficient power delivery, and simple construction. We study a range of redox-active electrolytes to clarify operating mechanisms and formalize design rules for high-performance. Our investigations focus on dual-redox ECs, which attain higher energy density by employing a pair of distinct redox couples, with each operating at a different electrode. Simplicity is important both in terms of the mechanistic aspects of the electrochemical redox chemistry and for system cost considerations. A single ionic molecular entity that intrinsically delivers both distinct redox couples is preferable over two separate redox-active electrolytes. In this context, we have identified specific viologen bromide salts as particularly promising aqueous redox-active electrolytes for dual-redox ECs. While charging, Br– is oxidized to Br3– at the positive electrode and the viologen dication (V2+) is reduced to the stable monocation radical (V+•) at the negative electrode. The reverse processes occur during discharge, providing a high-capacity faradaic discharge plateau and attaining an energy density of ~20 Wh/L. The viologen bromide system shows unusually high Coulombic efficiency and low self-discharge rates for an aqueous redox-EC. This was initially attributed to strong adso

Electrochemical energy storage is increasingly important as the world decarbonizes and electrifies. Research in this area requires compromise between properties that are often mutually exclusive, including power, energy, lifetime, efficiency, operating temperature, safety, and cost. Electric double layer capacitors (EDLCs) exhibit high power and outstanding cycle life compared to secondary batteries, but have low specific energy, limiting applications. Redox-enhanced electrochemical capacitors (redox ECs) are a class of augmented electric double-layer capacitors utilizing reversible redox reactions of soluble redox couples in the electrolyte to add faradaic charge storage. These systems offer increased energy density, efficient power delivery, and simple construction. We study a range of redox-active electrolytes to clarify operating mechanisms and formalize design rules for high-performance. Our investigations focus on dual-redox ECs, which attain higher energy density by employing a pair of distinct redox couples, with each operating at a different electrode. Simplicity is important both in terms of the mechanistic aspects of the electrochemical redox chemistry and for system cost considerations. A single ionic molecular entity that intrinsically delivers both distinct redox couples is preferable over two separate redox-active electrolytes. In this context, we have identified specific viologen bromide salts as particularly promising aqueous redox-active electrolytes for dual-redox ECs. While charging, Br– is oxidized to Br3– at the positive electrode and the viologen dication (V2+) is reduced to the stable monocation radical (V+•) at the negative electrode. The reverse processes occur during discharge, providing a high-capacity faradaic discharge plateau and attaining an energy density of ~20 Wh/L. The viologen bromide system shows unusually high Coulombic efficiency and low self-discharge rates for an aqueous redox-EC. This was initially attributed to strong adso

Electrochemical energy storage is increasingly important as the world decarbonizes and electrifies. Research in this area requires compromise between properties that are often mutually exclusive, including power, energy, lifetime, efficiency, operating temperature, safety, and cost. Electric double layer capacitors (EDLCs) exhibit high power and outstanding cycle life compared to secondary batteries, but have low specific energy, limiting applications. Redox-enhanced electrochemical capacitors (redox ECs) are a class of augmented electric double-layer capacitors utilizing reversible redox reactions of soluble redox couples in the electrolyte to add faradaic charge storage. These systems offer increased energy density, efficient power delivery, and simple construction. We study a range of redox-active electrolytes to clarify operating mechanisms and formalize design rules for high-performance. Our investigations focus on dual-redox ECs, which attain higher energy density by employing a pair of distinct redox couples, with each operating at a different electrode. Simplicity is important both in terms of the mechanistic aspects of the electrochemical redox chemistry and for system cost considerations. A single ionic molecular entity that intrinsically delivers both distinct redox couples is preferable over two separate redox-active electrolytes. In this context, we have identified specific viologen bromide salts as particularly promising aqueous redox-active electrolytes for dual-redox ECs. While charging, Br– is oxidized to Br3– at the positive electrode and the viologen dication (V2+) is reduced to the stable monocation radical (V+•) at the negative electrode. The reverse processes occur during discharge, providing a high-capacity faradaic discharge plateau and attaining an energy density of ~20 Wh/L. The viologen bromide system shows unusually high Coulombic efficiency and low self-discharge rates for an aqueous redox-EC. This was initially attributed to strong adso

Organic matter degradation is the engine behind the biogeochemical evolution of sediments during burial. Previous research has shown that eogenesis is the seat of a complex interplay between organic matter, microbes and the most reactive part of inorganic compounds, such as clay minerals. To explore the variability and stability of bromine and clay minerals as geochemical and mineral tracers, we selected an eastern Mediterranean core that has a high degree of stability in the quality and quantity of organic matter through time at a one-million-year scale and great variability in organic matter content at a 10 ky scale. According to the very low maximal burial depth reached by these sediments (the core length is only 36.5 m), physical parameters, such as temperature and pressure, did not significantly influence the evolution of the studied parameters during the burial history. The bulk clay mineralogy of organic-rich and organic-poor sediments is similar all along the investigated core material; smectite predominates over kaolinite. The only identified authigenic minerals are biogenetic framboidal pyrite and manganese oxides. The X-ray data and the chemical compositions of the smectite are characteristic of a montmorillonite which is representative of a detrital Nile source. At a one-million-year scale, the organic matter content has no significant influence on clay eogenesis, and detrital smectite and kaolinite remain unchanged. Bromine is present in marine organic matter as organobromine compounds. During eogenesis, bromine is released from organic matter as bromide ion, resulting in an increase in the bromide concentration in the pore water with depth. Dissolved bromide can be used as a conservative tracer of the debromination of sedimentary organic matter. For the first time, we established that solid-phase BrOrg is a reliable tracer of debromination rates in marine sediments. The rate of debromination depends on the organic matter content. The rate increases fro, La dégradation de la matière organique est le moteur de l'évolution biogéochimique des sédiments au cours de l'enfouissement. Les recherches précédentes ont montré que l'éogenèse est le siège d'interférences complexes entre la matière organique, les microorganismes et la partie la plus réactive des composés inorganiques comme les minéraux argileux. Pour étudier la variabilité et la stabilité du brome et des minéraux argileux comme traceurs géochimiques et minéralogiques, nous avons choisi une carotte de Méditerranée orientale qui présente une grande stabilité de la qualité et de la quantité de la matière organique à l'échelle de 1 million d'années et une grande variabilité de cette quantité à une échelle de 10 ka. Considérant le faible enfouissement de ces dépôts (la carotte ne fait que 36,5 m de long), les paramètres physiques comme la température et la pression, n'influencent pas significativement l'évolution des paramètres étudiés. La minéralogie des argiles demeure semblable dans toute la carotte, que les sédiments soient riches ou pauvres en matière organique ; la smectite domine sur la kaolinite. Les seuls minéraux authigéniques identifiés sont la pyrite framboïdale biogénique et des oxydes de manganèse. Les données de diffraction de rayons X et la composition chimique de la smectite correspondent à celles d'une montmorillonite représentative des apports détritiques du Nil. À l'échelle de 1 million d'années, la quantité de matière organique n'influence pas l'éogenèse des minéraux argileux, la kaolinite et la smectite détritique demeurent inchangées. Le brome est dans la matière organique marine sous forme de composés organobromés. Pendant l'éogenèse, le brome est libéré de la matière organique sous forme d'ion bromure, il en résulte une augmentation avec l'enfouissement de la concentration en bromure dans l'eau interstitielle. Le bromure dissous peut être utilisé comme un traceur conservatif de la débromination de la matière organique sédimentaire. Pour la pre

Organic matter degradation is the engine behind the biogeochemical evolution of sediments during burial. Previous research has shown that eogenesis is the seat of a complex interplay between organic matter, microbes and the most reactive part of inorganic compounds, such as clay minerals. To explore the variability and stability of bromine and clay minerals as geochemical and mineral tracers, we selected an eastern Mediterranean core that has a high degree of stability in the quality and quantity of organic matter through time at a one-million-year scale and great variability in organic matter content at a 10 ky scale. According to the very low maximal burial depth reached by these sediments (the core length is only 36.5 m), physical parameters, such as temperature and pressure, did not significantly influence the evolution of the studied parameters during the burial history. The bulk clay mineralogy of organic-rich and organic-poor sediments is similar all along the investigated core material; smectite predominates over kaolinite. The only identified authigenic minerals are biogenetic framboidal pyrite and manganese oxides. The X-ray data and the chemical compositions of the smectite are characteristic of a montmorillonite which is representative of a detrital Nile source. At a one-million-year scale, the organic matter content has no significant influence on clay eogenesis, and detrital smectite and kaolinite remain unchanged. Bromine is present in marine organic matter as organobromine compounds. During eogenesis, bromine is released from organic matter as bromide ion, resulting in an increase in the bromide concentration in the pore water with depth. Dissolved bromide can be used as a conservative tracer of the debromination of sedimentary organic matter. For the first time, we established that solid-phase BrOrg is a reliable tracer of debromination rates in marine sediments. The rate of debromination depends on the organic matter content. The rate increases fro, La dégradation de la matière organique est le moteur de l'évolution biogéochimique des sédiments au cours de l'enfouissement. Les recherches précédentes ont montré que l'éogenèse est le siège d'interférences complexes entre la matière organique, les microorganismes et la partie la plus réactive des composés inorganiques comme les minéraux argileux. Pour étudier la variabilité et la stabilité du brome et des minéraux argileux comme traceurs géochimiques et minéralogiques, nous avons choisi une carotte de Méditerranée orientale qui présente une grande stabilité de la qualité et de la quantité de la matière organique à l'échelle de 1 million d'années et une grande variabilité de cette quantité à une échelle de 10 ka. Considérant le faible enfouissement de ces dépôts (la carotte ne fait que 36,5 m de long), les paramètres physiques comme la température et la pression, n'influencent pas significativement l'évolution des paramètres étudiés. La minéralogie des argiles demeure semblable dans toute la carotte, que les sédiments soient riches ou pauvres en matière organique ; la smectite domine sur la kaolinite. Les seuls minéraux authigéniques identifiés sont la pyrite framboïdale biogénique et des oxydes de manganèse. Les données de diffraction de rayons X et la composition chimique de la smectite correspondent à celles d'une montmorillonite représentative des apports détritiques du Nil. À l'échelle de 1 million d'années, la quantité de matière organique n'influence pas l'éogenèse des minéraux argileux, la kaolinite et la smectite détritique demeurent inchangées. Le brome est dans la matière organique marine sous forme de composés organobromés. Pendant l'éogenèse, le brome est libéré de la matière organique sous forme d'ion bromure, il en résulte une augmentation avec l'enfouissement de la concentration en bromure dans l'eau interstitielle. Le bromure dissous peut être utilisé comme un traceur conservatif de la débromination de la matière organique sédimentaire. Pour la pre