Rhenium (Re) has been proposed as a tracer of petrogenic organic carbon (OCpetro) oxidation, also known as georespiration, but information regarding the solid phases hosting Re in rocks and Re weathering behavior is limited. Examining grey shale rocks from two small mountainous river basins in the Pacific Northwest, USA, we found that the majority of parent material (bedrock) Re in both basins is associated with OCpetro (average 71 %, range 50 to 93 %), with minimal Re hosted in sulfide minerals. In soil and weathered rock profiles, mass transfer calculations (tau) reveal a clear distinction between the weathering behavior of Re and that of other elements, indicating that Re weathering in these siliclastic rocks and soils does not primarily trace sulfide oxidation or dissolution of primary minerals. We find evidence that Re likely traces OCpetro oxidation, although patterns of Re and OC weathering are influenced by heterogeneity in bedrock composition and inputs of modern OC near the surface. In some cases Re loss exceeds that of OC during weathering, suggesting that the kinetics of Re oxidation are sometimes faster than those of OC oxidation. We observe greater Re loss in systems with slower erosion rate, which implies that systems subject to faster erosion export more unoxidized particulate Re. Our observations of Re phase associations and weathering behavior in soil and rock weathering profiles support the use of the Re proxy for georespiration, but also provide qualifications on its application in future work quantifying georespiration fluxes at regional and global scales.

The search for suitable cathode materials for aqueous zinc metal batteries is key to achieving the full potential of this promising energy storage system. This work reports the performance of a vanadium hexacyanoferrate (VHCF) cathode in a ZnCl2-based water-in-salt electrolyte, which unveils a chlorine-storage phenomenon. Characterization results suggest that the cycling of VHCF stores not only Zn2+ but also chlorine species, which contributes extra capacity. The results show that VHCF experiences a conditioning process, previously deemed detrimental for this class of structures, where a cathode-electrolyte interphase is formed, extending cycle life. The hosting of chlorine species renders the VHCF electrode a double-ion cathode, delivering a discharge capacity of up to 231 mA h g-1 at a current rate of 0.1 C, where the capacity per unit mass of vanadium is the highest among those of vanadium-based cathodes. At 0.5 C, the electrode exhibits a capacity of 204 mA h g-1 at an average potential of 0.96 V and retains 88% of its capacity over 440 cycles, while holding 85.9% its capacity over 930 cycles at 2.0 C with a discharge capacity of 177 mA h g-1. Pouch cells with a limited zinc metal anode (N/P ratio of 5:1) demonstrate promising performance of this cathode material for aqueous energy storage systems.

The role of suspended particulate matter in the biogeochemical cycling of neodymium (Nd) in the ocean is not well understood. This study reports the measurement of dissolved Nd concentrations and isotopes (<0.2 um), and particulate Nd concentrations along the Eastern Pacific Zonal Transect (EPZT, GP16) as part of the GEOTRACES program. The western part of the EPZT cruise track is influenced by a hydrothermal plume, observed between 2200 and 2800 m, originating at the southern East Pacific Rise. This setting allows for the investigation of the role of particulate matter in Nd biogeochemical cycling and its contribution in modifying the distribution of dissolved Nd. Results show that the highest removal of dissolved Nd (∼ 21 %) was observed near the hydrothermal ridge crest, decreasing to ∼ 8 % at the westernmost station. Here, we report the partition coefficient (Kd) of each particle constituent (e.g., lithics, CaCO3, POM, Opal, Fe-phase, Mn-phase) to show that particle composition plays an important role in Nd removal alongside particle mass. Along the plume, both particulate Mn and Fe contributed to the removal of Nd, with Mn playing the dominant role in sites closest to the vent. At the western stations, below the plume, the concentration of both dissolved and particulate Nd increased with depth, with particulate Nd one to two orders of magnitude lower than measured in the dissolved phase. The increase in dissolved Nd with depth in the interval below the plume could result either from the continuing remineralization of raining particles or the influx of dissolved Nd from bottom sediments. Close to the ridge crest, where the hydrothermal Nd input is at its highest, there is a hint of local modification of dissolved εNd signature, however not large enough to affect the use of εNd as a water mass tracer.

A full cell chemistry of aqueous dual-ion battery (DIB) was reported, comprising the graphite cathode and 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) as the anode. This DIB employed a mixture aqueous electrolyte: 5 m tributylmethylammonium (TBMA) chloride plus 5 m MgCl2 , where [MgCl3 ]- and TBMA+ serve as the charge carriers for cathode and anode of the DIB, respectively. This novel full cell exhibited a specific capacity of around 41 mAh g-1 based on the total active mass of both electrodes with an average operation voltage of 1.45 V and stable cycling for 400 cycles.

New acceptor‐type graphite intercalation compounds (GICs) offer candidates of cathode materials for dual‐ion batteries (DIBs), where superhalides represent the emerging anion charge carriers for such batteries. Here, the reversible insertion of [LiCl 2 ] − into graphite from an aqueous deep eutectic solvent electrolyte of 20 m LiCl + 20 m choline chloride is reported. [LiCl 2 ] − is the primary anion species in this electrolyte as revealed by the femtosecond stimulated Raman spectroscopy results, particularly through the rarely observed H–O–H bending mode. The insertion of Li–Cl anionic species is suggested by 7 Li magic angle spinning nuclear magnetic resonance results that describe a unique chemical environment of Li + ions with electron donors around. 2 H nuclear magnetic resonance results suggest that water molecules are co‐inserted into graphite. Density functional theory calculations reveal that the anionic insertion of hydrated [LiCl 2 ] − takes place at a lower potential, being more favorable. X‐ray diffraction and the Raman results show that the insertion of [LiCl 2 ] − creates turbostratic structure in graphite instead of forming long‐range ordered GICs. The storage of [LiCl 2 ] − in graphite as a cathode for DIBs offers a capacity of 114 mAh g −1 that is stable over 440 cycles.

This study examines dissolved rhenium (Re) concentrations as a function of water runoff using river samples from two contrasting mountainous watersheds, the Eel and Umpqua Rivers in the Pacific Northwest, USA. These watersheds share many key characteristics in terms of size, discharge, climate, and vegetation, but they have a 15-fold difference in sediment yield due to differences in their tectonic setting and uplift and erosion rates. We evaluate concentration-runoff (C-R) relationships and ratios of coeffi-cients of variation (CVC/CVR) for major cations, anions, dissolved inorganic carbon, selected trace ele-ments including Re, and 87Sr/Sr-86 ratios. Recent research outlines the potential of Re to serve as a tracer for the oxidation of ancient/fossil organic matter because of its close association with petrogenic carbon (OCpetro) in rocks. In both the Eel and Umpqua Rivers, our measurements show that Re behaves similarly to major weathering derived-solutes corrected for atmospheric input, such as Ca2+*, Mg2+*, and Na+* with modest dilution across all tributaries with increasing runoff. Rhenium behaves dissimilarly from other trace elements, such as Mo and U, and is also dissimilar to biologically-cycled nutrients, such as NO3 -, PO43-, and K+*, suggesting differences in sources, solute generation mechanisms, and flowpaths. Rhenium behavior is also distinct from that of colloids, which have increasing concentrations with increasing runoff. We find that Re and sulfate corrected for atmospheric input (SO42-*) have distinct C-R relationships, in which SO42-* undergoes greater dilution with increasing runoff. This implies that Re is not dominantly sourced from sulfide weathering, which leaves primary bedrock minerals and OCpetro hosted in bedrock of these watersheds as the likely dominant sources of dissolved Re release. At mean discharge, Re concentration in the Eel river (3.5 pmol L-1) is more than two times greater than Re concentrations in the Umpqua River (1.5 pmol L-1). Furthermore, comparison of two tributary watersheds with similar bedrock but marked differences in erosion rates show higher Re concentrations in Bull Creek (erosion rate of 0.5 mm yr(-1)) relative to Elder Creek (erosion rate of 0.2 mm yr(-1)). The results of this study suggest that dissolved Re in the Eel and Umpqua River basins is likely derived from primary mineral dis-solution or OCpetro oxidation, and Re fluxes are higher in areas with higher erosion rates, suggesting that tectonic setting is one factor that controls Re release and therefore OCpetro oxidation.(C) 2022 Elsevier Ltd. All rights reserved.

Enduring questions remain regarding the transition from relatively warm and stable pre‐ and early‐Pleistocene climate to that of the high amplitude glacial‐interglacial cycles later in the Quaternary. The main shift in glacial intensity and periodicity around 1 Ma is known as the Mid‐Pleistocene Transition (MPT). Here we analyze detrital strontium (Sr) and neodymium (Nd) isotopes in a western Arctic sediment core P23 previously investigated using several litho/biostratigraphic proxies. Based on an improved age framework combining lithostratigraphic cyclicity and Sr isotope stratigraphy, the P23 record extends to ∼3.3 Ma, thus providing a rare insight into the Quaternary Arctic climate change. The distinct pre‐MPT P23 record is dominated by Pacific‐sourced sediment inputs, with little to no intra‐Arctic glacial inputs, except for a sandy interval around ∼2.5 Ma. A consistent decrease of Nd isotopic values toward North American continental signatures started in both the Arctic and Bering Sea at ∼1.5 Ma and led to a major threshold shift in P23 proxies at ∼0.9 Ma. We argue that this threshold was associated with the first prolonged closure of the Bering Strait for an entire obliquity cycle. This shift marked the expansion of the North American ice sheets to the Arctic margin, with dramatic impacts on depositional and hydrographic environments in the Arctic Ocean. These impacts intensified in the subsequent glacial intervals indicating further ice‐sheet growth, probably fed back by continuing prolonged Bering Strait closures.

Dissolved rare earth element ([REE]) and neodymium isotopic (epsilon(Nd)) data from the US GEOTRACES Eastern Equatorial Pacific Transect (EPZT) are presented. These data are compared to watermass distributions (Peters etal., 2018), particulate data (Lam etal., 2018) and carbonate species data (Bates, 2018) to evaluate present theories of REE and epsilon(Nd) geochemistry, given that the Pacific has been notably intractable in relation to these ideas (Jones etal., 2008). The [REEs] have typical depth profile distributions (e.g., [La] ranges from similar to 5 to 15 pmol/kg in the surface, increasing with depth to values of similar to 40 pmol/kg), as does epsilon(Nd) (ranging from similar to-1 to -6 epsilon(Nd); similar to previous Pacific data). However, despite the unsurprising nature of these data, several apparent inconsistencies with respect to current models for REE/ epsilon(Nd) geochemistry arise. These are: (1) While eNdremarkably maintains watermass distribution information, there is a significant (+1.4 epsilon(Nd)) offset in the data compared to published end-member compositions, indicating a strong but largely consistent non-conservative component; (2) Reversiblescavenging seems an unlikely mechanism for redistribution of [REE] and epsilon(Nd) in the water column; (3) There does not appear to be any correlation of [REE] to carbonate ion concentration, and; (4) There are indications of influence from a benthic flux, but the evidence is ambiguous. (C) 2021 Elsevier B.V. All rights reserved.

The role of suspended particulate matter (SPM) in modulating dissolved Nd gains importance in hydrothermal settings where particle dynamics and scavenging play important roles in trace metal behaviors. Here we use seawater Nd isotopes and concentrations ([Nd]) from a Southern East Pacific Rise (SEPR) hydrothermal plume, sampled during the US-GEOTRACES GP16 Eastern Pacific Zonal Transect, to report how they are influenced by particles. Within the plume (2200-3000 m, identified by 3 He) dissolved Nd isotope ratios at both vent and distal stations are ~0.3-0.4 ε Nd - units more positive than shallower samples, approximately the analytical uncertainty. These results support previous conclusions that hydrothermal activity is not a significant source of seawater Nd [1]. In contrast, seawater [Nd] near vent stations exhibit a prominent decrease, which attenuates with increasing distance from the SEPR [2]. Within the SEPR plume there is a loss of 7-12% of the dissolved Nd inventory compared to proximal stations outside the plume, consistent with a 6-10% loss seen at the TAG site in the North Atlantic [3]. This cannot be explained by SPM concentration alone, possibly due to SPM

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Rare earth elements (REEs) are used as tracers for oceanic trace element cycling. However, the low (picomolar level) dissolved REE concentrations and time-consuming methods have so far hindered their extensive use in marine studies. This study reports the first application of the automated seaFAST-pico system (Elemental Scientific Inc.) in offline mode and using multi-element isotope dilution inductively coupled plasma-mass spectrometry (ID ICP-MS) for the robust and rapid pre-concentration, purification, and analysis of dissolved REEs from small volumes of seawater (11–12mL). Accuracy of our new method is checked with replicates of GEOTRACES intercalibration seawater from BATS (Bermuda Atlantic Time Series, North Atlantic) at 15m and 2000m water depths. Our results show excellent agreement (within the analytical uncertainty, 2σ SD) with the published intercalibrated values from the GEOTRACES intercalibration study. Replicates of GEOTRACES intercalibration seawater from SAFe at 3000m water depth (Sampling and Analysis of Iron, North Pacific) indicate a procedural long-term error of ≤3.9% 2σ RSD for all REEs, except for Ce and Gd. An international intercomparison from 4 labs using SAFe 3000m seawater aliquots, 2 of which also use the seaFAST-pico system in offline mode, and different pre-concentration, purification, and analytical methods shows excellent agreement between REE concentrations within 7% (2σ RSD) (except for Ce 71%, Gd 14%, Lu 12%). This is comparable to the agreement obtained for the BATS 15m and 2000m samples by six different labs for the international GEOTRACES intercalibration study (van de Flierdt et al., 2012). The REE intercomparison values of SAFe 3000m (i.e., the average of the values from the 4 labs) in this study agree within the analytical uncertainties (2σ SD) with published REE values of deep seawater from nearby stations. Our international intercomparison provides the first REE intercomparison values for the GEOTRACES intercalibration station SAFe at 3000m, and establishes the first reference seawater REE values for quality control of future REE studies in the Pacific Ocean as SAFe will remain a GEOTRACES baseline, and hence intercalibration station, for cruises in the North Pacific. Our method is easy to adopt and enables the extensive use of REEs, thereby opening the way to build a global seawater REE data set.

Biogenic particle flux was reconstructed using 230-Thorium normalization at two sites on the southern Chile margin. ODP Site 1233 at 41 degrees S, 838 m depth, is at the southern limit of the Peru-Chile upwelling system, where the northern extent of the Antarctic Circumpolar Current impinges on the South American continental margin. ODP Site 1234, at 36 degrees S, 1014 m depth, is located within the core of the coastal upwelling system near the mouths of the Bio Bio and Itata Rivers. At 41 degrees S, opal, lithogenic and carbonate fluxes are greatest during the Last Glacial interval (26-20 ka), carbonate has a secondary peak during the mid Holocene (similar to 8 ka) and organic carbon fluxes increase slightly from 17 ka to the present At 36 degrees S, large lithogenic fluxes are observed both during the Last Glacial interval and the Holocene, and a maximum in organic carbon flux is observed during the late Holocene (similar to 5 ka) without an accompanying peak in opal flux. These reconstructed fluxes at 36 degrees S and 41 degrees S fit within a larger latitudinal pattern of a poleward increase in the magnitude of opal flux during the glacial period. The pattern of normalized opal flux, opal mass accumulation rate and opal:carbonate ratios is consistent with either i) enhanced supply of Si from the Southern Ocean, as proposed by the Silicic Acid Leakage Hypothesis or ii) enhanced Si and Fe delivery from land, driven by glacial erosion. The pattern of reconstructed export production supports our view that the appearance of more reducing conditions in the sediments upon deglaciation was most likely driven by decreased ventilation, rather than increased local productivity. (C) 2014 Elsevier Ltd. All rights reserved.