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Objective: Despite considerable research examining the efficacy of psychedelic-assisted therapies (PATs) for treating psychiatric disorders, assessment of adverse events (AEs) in PAT research has lagged. Current AE reporting standards in PAT trials are poorly calibrated to features of PAT that distinguish it from other treatments, leaving many potential AEs unassessed., Methods: A multidisciplinary working group of experts involved in PAT pooled formally and informally documented AEs observed through research experience and published literature. This information was integrated with (a) current standards and practices for AE reporting in pharmacotherapy and psychotherapy trials and (b) published findings documenting post-acute dosing impacts of psychedelics on subjective states, meaning, and psychosocial health variables, to produce a set of AE constructs important to evaluate in PAT as well as recommended methods and time frames for their assessment and monitoring. Correspondence between identified potential AEs and current standards for AE assessment was examined, including the extent of coverage of identified AE constructs by 25 existing measures used in relevant research., Results: Fifty-four potential AE terms warranting systematized assessment in PAT were identified, defined, and categorized. Existing measures demonstrated substantial gaps in their coverage of identified AE constructs. Recommendations were developed for how to assess PAT AEs (including patient, clinician, and informant reports), and when to assess over preparation, dosing session, integration, and follow-up. Application of this framework is demonstrated in a preliminary assessment protocol (available in the supplement)., Conclusions: This assessment framework addresses the need to capture post-acute dosing AEs in PAT, accounting for its pharmacotherapy and psychotherapy components, as well as documented impacts of psychedelics on worldviews and spirituality., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Jessica L Maples-Keller has received research funding and consulting payments from COMPASS Pathways, and receives support from the Wounded Warrior Project (WWP), and Multidisciplinary Association of Psychedelic Studies. Barbara O Rothbaum has recently had funding from the Wounded Warrior Project, NIMH, National Science Foundation, and the Bob Woodruff Foundation. Barbara O Rothbaum receives royalties from Oxford University Press, Guilford, APPI, Psych Campus, and Emory University and received advisory board payments from Jazz Pharmaceuticals, Bioserenity, Cerebral Therapeutics, Otsuka, Psychwire, and Senseye. Barbara O Rothbaum owns equity in Virtually Better, Inc. that creates virtual environments. The terms of these arrangements have been reviewed and approved by Emory University in accordance with its conflict of interest policies. Boadie W Dunlop has received research support from Boehringer-Ingelheim, Compass Pathways, NIMH, and Usona, and has received consulting fees from Biohaven, The Department of Defense, Myriad Neuroscience, Otsuka, and Sage. Charles L Raison has received personal fees from Usona Institute and grants to Usona Institute from Dr. Bronner’s All-One, Fournier Family Foundation, Good Ventures, Steven and Alexandra Cohen Foundation, Tiny Blue Dot Foundation, Turnbull Family Foundation, William A Linton, Novartis, Sage/Biogen, Emory Healthcare, and Vail Health. Roman Palitsky, Deanna M Kaplan, John Perna, Zacchary Bosshardt, Holly F Levin-Aspenson, Ali John Zarrabi, Caroline Peacock, and George H Grant all report no disclosures. Tanja Mletzko reports no disclosures.

Background: Psychedelic-assisted therapies hold early promise for treating multiple psychiatric conditions. However, absent standards for the care, teams providing psychedelic-assisted therapy pose a major roadblock to safe administration. Psychedelics often produce spiritually and existentially meaningful experiences, and spiritual health practitioners have been involved in administering psychedelic-assisted therapies in multiple settings, suggesting important qualifications for delivering these therapies. However, the roles and competencies of spiritual health practitioners in psychedelic-assisted therapies have not been described in research., Method: This study examined interviews with 15 spiritual health practitioners who have facilitated psychedelic-assisted therapy. Thematic analyses focused on their contributions, application of expertise and professional background, and roles in administering these therapies., Results: Seven themes emerged, comprising two domains: unique and general contributions. Unique contributions included: competency to work with spiritual material, awareness of power dynamics, familiarity with non-ordinary states of consciousness, holding space, and offer a counterbalance to biomedical perspectives. General contributions included use of generalizable therapeutic repertoire when conducting PAT, and contributing to interdisciplinary collaboration., Implications: Spiritual health practitioners bring unique and specific expertise to psychedelic-assisted therapy based on their training and professional experience. They are skilled at interprofessional collaboration in a way that complements other clinical team members. Psychedelic-assisted therapy teams may benefit from including spiritual health practitioners. In order to ensure rigorous standards and quality care, further efforts to delineate the roles and necessary qualifications and training of spiritual health clinicians for psychedelic-assisted therapy are needed., Competing Interests: Dr. Dunlop has received research support from Boehringer Ingelheim, Compass Pathways, NIMH, Usona Institute, and has served as a consultant for Biohaven, Cerebral Therapeutics, Myriad Neuroscience, NRx Pharmaceuticals, and Otsuka. Dr Raison has received research support from the Tiny Blue Dot Foundation and has served as a consultant for Usona Institute, Emory Healthcare, Vail Health, Novartis and Sage/Biogen. Dr. Peacock has received convening support for the Transforming Chaplaincy Psychedelic Care Network from the Riverstyx Foundation. Dr. Maples-Keller has received research support from Wounded Warrior Project and Compass Pathways and has served as a consultant of Compass Pathways. This does not alter our adherence to PLOS One policies on sharing data and materials., (Copyright: © 2024 Peacock et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The mobility of chromium (Cr) is controlled by minerals, especially iron (oxyhydr)oxides. The influence of organic carbon (OC) on the mobility and fate of Cr(VI) during Fe(II)-induced transformation of iron (oxyhydr)oxide, however, is still unclear. We investigate how low-weight carboxyl-rich OC influences the transformation of ferrihydrite (Fh) and controls the mobility of Cr(VI/III) in reducing environments and how Cr influences the formation of secondary Fe minerals and the stabilization of OC. With respect to the transformation of Fe minerals, the presence of low-weight carboxyl-rich OC retards the growth of goethite crystals and stabilizes lepidocrocite for a longer time. With respect to the mobility of Cr, low-weight carboxyl-rich OC suppresses the Cr(III) non-extractable associated with Fe minerals, and this suppression is enhanced with increasing carboxyl-richness of OC and decreasing pH. The presence of Cr(III) mitigates the decrease in total C associated with Fe minerals and increases the C non-extractable especially for Fh organominerals made with carboxyl-rich OC. Our study sheds new light on the mobility and fate of Cr in reducing environments and suggests that there is a potential synergy between Cr(VI) remediation and OC stabilization.

The balance between degradation and preservation of sedimentary organic carbon (OC) is important for global carbon and oxygen cycles 1 . The relative importance of different mechanisms and environmental conditions contributing to marine sedimentary OC preservation, however, remains unclear 2-8 . Simple organic molecules can be geopolymerized into recalcitrant forms by means of the Maillard reaction 5 , although reaction kinetics at marine sedimentary temperatures are thought to be slow 9,10 . More recent work in terrestrial systems suggests that the reaction can be catalysed by manganese minerals 11-13 , but the potential for the promotion of geopolymerized OC formation at marine sedimentary temperatures is uncertain. Here we present incubation experiments and find that iron and manganese ions and minerals abiotically catalyse the Maillard reaction by up to two orders of magnitude at temperatures relevant to continental margins where most preservation occurs 4 . Furthermore, the chemical signature of the reaction products closely resembles dissolved and total OC found in continental margin sediments globally. With the aid of a pore-water model 14 , we estimate that iron- and manganese-catalysed transformation of simple organic molecules into complex macromolecules might generate on the order of approximately 4.1 Tg C yr -1 for preservation in marine sediments. In the context of perhaps only about 63 Tg C yr -1 variation in sedimentary organic preservation over the past 300 million years 6 , we propose that variable iron and manganese inputs to the ocean could exert a substantial but hitherto unexplored impact on global OC preservation over geological time., (© 2023. The Author(s).)

The role of microbial interactions and the underlying mechanisms that shape complex biofilm communities are poorly understood. Here we employ a microfluidic chip to represent porous subsurface environments and show that cooperative microbial interactions between free-living and biofilm-forming bacteria trigger active spatial segregation to promote their respective dominance in segregated microhabitats. During initial colonization, free-living and biofilm-forming microbes are segregated from the mixed planktonic inoculum to occupy the ambient fluid and grain surface. Contrary to spatial exclusion through competition, the active spatial segregation is induced by cooperative interactions which improves the fitness of both biofilm and planktonic populations. We further show that free-living Arthrobacter induces the surface colonization by scavenging the biofilm inhibitor, D-amino acids and receives benefits from the public goods secreted by the biofilm-forming strains. Collectively, our results reveal how cooperative microbial interactions may contribute to microbial coexistence in segregated microhabitats and drive subsurface biofilm community succession., (© 2023. The Author(s).)

Importance: Mounting evidence supports the role of spiritual, existential, religious, and theological components in mediating psychedelic-assisted therapy, yet integration of these elements into the clinical setting is lagging., Observations: Although psychedelic-assisted therapy commonly produces spiritually, existentially, religiously, or theologically relevant experiences for patients, these have not been systematically integrated into the psychotherapies that accompany therapeutic uses of psychedelics. As a key feature and potential mediator of therapeutic effects, evidence-based psychedelic-assisted therapies should include these topics in the treatment model. Research across multiple diagnostic targets and treatment contexts suggests that spiritually integrated psychotherapies are effective, feasible, and produce add-on benefits in spiritually, existentially, religiously, and theologically relevant outcomes, which are particularly germane to psychedelics. Established standards in spiritually integrated psychotherapy may be fruitfully applied to psychedelic-assisted therapy. Objectives for spiritually, existentially, religiously, and theologically integrated psychedelic-assisted therapy based on these standards and informed by considerations specific to psychedelics are recommended., Conclusions and Relevance: Spiritual, existential, religious, and theological topics' integration in psychedelic-assisted therapy is needed to ensure culturally competent, evidence-based treatment aligned with the highest standards of clinical care. Neglecting to address these topics can detract from cultural competence, contribute to risks for patients, and potentially undermine treatment success.

The Zn isotope fingerprint is widely used as a proxy of various environmental geochemical processes, so it is crucial to determine which are the mechanisms responsible for isotopic fractionation. Iron (Fe) (hydr)oxides greatly control the cycling and fate and thus isotope fractionation factors of Zn in terrestrial environments. Here, Zn isotope fractionation and related mechanisms during adsorption on and substitution in three FeOOH polymorphs are explored. Results demonstrate that heavy Zn isotopes are preferentially enriched onto solids, with almost similar isotopic offsets (Δ 66/64 Zn solid-solution = 0.25-0.36‰) for goethite, lepidocrocite, and feroxyhyte. This is consistent with the same average Zn-O bond lengths for adsorbed Zn on these solids as revealed by Zn K-edge X-ray absorption fine structure spectroscopy. In contrast, at an initial Zn/Fe molar ratio of 0.02, incorporation of Zn into goethite and lepidocrocite by substituting for lattice Fe preferentially sequesters light Zn isotopes with Δ 66/64 Zn substituted-stock solution of -1.52 ± 0.09‰ and -1.18 ± 0.15‰, while Zn-substituted feroxyhyte (0.06 ± 0.11‰) indicates almost no isotope fractionation. This is closely related to the different crystal nucleation and growth rates during the Zn-doped FeOOH formation processes. These results provide direct experimental evidence of incorporation of isotopically light Zn into Fe (hydr)oxides and improve our understanding of Zn isotope fractionation mechanisms during mineral-solution interface processes.

Artificial ocean fertilization (AOF) aims to safely stimulate phytoplankton growth in the ocean and enhance carbon sequestration. AOF carbon sequestration efficiency appears lower than natural ocean fertilization processes due mainly to the low bioavailability of added nutrients, along with low export rates of AOF-produced biomass to the deep ocean. Here we explore the potential application of engineered nanoparticles (ENPs) to overcome these issues. Data from 123 studies show that some ENPs may enhance phytoplankton growth at concentrations below those likely to be toxic in marine ecosystems. ENPs may also increase bloom lifetime, boost phytoplankton aggregation and carbon export, and address secondary limiting factors in AOF. Life-cycle assessment and cost analyses suggest that net CO 2 capture is possible for iron, SiO 2 and Al 2 O 3 ENPs with costs of 2-5 times that of conventional AOF, whereas boosting AOF efficiency by ENPs should substantially enhance net CO 2 capture and reduce these costs. Therefore, ENP-based AOF can be an important component of the mitigation strategy to limit global warming., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Minerals are widely proposed to protect organic carbon from degradation and thus promote the persistence of organic carbon in soils and sediments, yet a direct link between mineral adsorption and retardation of microbial remineralisation is often presumed and a mechanistic understanding of the protective preservation hypothesis is lacking. We find that methylamines, the major substrates for cryptic methane production in marine surface sediment, are strongly adsorbed by marine sediment clays, and that this adsorption significantly reduces their concentrations in the dissolved pool (up to 40.2 ± 0.2%). Moreover, the presence of clay minerals slows methane production and reduces final methane produced (up to 24.9 ± 0.3%) by a typical methylotrophic methanogen-Methanococcoides methylutens TMA-10. Near edge X-ray absorption fine structure spectroscopy shows that reversible adsorption and occlusive protection of methylamines in clay interlayers are responsible for the slow-down and reduction in methane production. Here we show that mineral-OC interactions strongly control methylotrophic methanogenesis and potentially cryptic methane cycling in marine surface sediments., (© 2022. The Author(s).)

Burnout is endemic among oncology clinicians and impacts quality of care. In order to develop institutional strategies to address burnout, psychometrically sensitive measurement within local cancer organizations is necessary to identify embedded causes of burnout and resulting effects. The authors administered the Mini-Z burnout survey to clinicians and staff (n = 160) at a National Cancer Institute-designated comprehensive cancer center. Structural equation modeling was used to examine workplace stressors that predicted burnout, and the pathway between burnout and 2 meaningful quality outcomes was tested: (1) lack of compassion and (2) thoughts of leaving one's job or specialty. Females and advanced practice practitioners had the highest prevalence of burnout. The structural equation model achieved excellent model fit, and indicated that workplace atmosphere, control over workload, values alignment, time for documentation, and team efficiency underlie burnout in this sample. The pathways from burnout to lack of compassion and to thoughts of leaving one's job were significant., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.)

While oncology clinical research coordinators (CRCs) experience a combination of factors that are thought to put them at increased risk for burnout, very little research has been conducted to understand the risk factors associated with burnout among CRCs. We used a mixed-method approach, including self-report questionnaires to assess burnout and compassion satisfaction, as well as individual and interpersonal variables hypothesized to impact CRC well-being. We also conducted a focus group to gain a more nuanced understanding of coordinators' experiences around burnout, teamwork, resilience, and incivility. Coordinators reported relatively moderate levels of burnout and compassion satisfaction. Resilience, sleep dysfunction, stress, and incivility experienced from patients/family were significant predictors of burnout. Resilience and incivility from patients/family were significant predictors of compassion satisfaction. Themes that emerged from the focus group included that burnout is triggered by feeling overwhelmed from the workload, which is buffered by what was described as a supportive work culture based in teamwork. This study identified variables at the individual and interpersonal level that are associated with burnout and compassion satisfaction among oncology CRCs. Addressing these variables is of critical importance given that oncology CRCs and team-based coordinator care are vital to the success of clinical trials.

Cadmium (Cd) isotopes have great potential for understanding Cd geochemical cycling in soil and aquatic systems. Iron (oxyhydr)oxides can sequester Cd via adsorption and isomorphous substitution, but how these interactions affect Cd isotope fractionation remains unknown. Here, we show that adsorption preferentially enriches lighter Cd isotopes on iron (oxyhydr)oxide surfaces through equilibrium fractionation, with a similar fractionation magnitude (Δ 114/110 Cd solid-solution ) for goethite (Goe) (-0.51 ± 0.04‰), hematite (Hem) (-0.54 ± 0.10‰), and ferrihydrite (Fh) (-0.55 ± 0.03‰). Neither the initial Cd 2+ concentration or ionic strength nor the pH influence the fractionation magnitude. The enrichment of the light isotope is attributed to the adsorption of highly distorted [CdO 6 ] on solids, as indicated by Cd K-edge extended X-ray absorption fine-structure analysis. In contrast, Cd incorporation into Goe by substitution for lattice Fe at a Cd/Fe molar ratio of 0.05 preferentially sequesters heavy Cd isotopes, with a Δ 114/110 Cd solid-solution of 0.22 ± 0.01‰. The fractionation probably occurs during the transformation of Fh into Goe via dissolution and reprecipitation. These results improve the understanding of the Cd isotope fractionation behavior being affected by iron (oxyhydr)oxides in Earth's critical zone and demonstrate that interactions with minerals can obscure anthropogenic and natural Cd isotope characteristics, which should be carefully considered when applying Cd isotopes as environmental tracers.

Purpose: Oncology clinical research coordinators (CRCs) and team-based coordinator care are critical for the success of clinical trials. However, CRCs typically report elevated anxiety and burnout and many oncology centers have high levels of coordinator attrition. To address the need for a team-based intervention to reduce burnout and promote resilience and cohesion among CRCs, we developed a compassion-centered, team-based intervention, Compassion-Centered Spiritual Health Team Intervention (CCSH-TI)., Methods: Participants were CRCs working in disease-specific teams within a comprehensive cancer center. CRCs were randomly assigned by team to either participate in four 60-minute sessions of CCSH-TI or receive the intervention after the study. To evaluate whether CCSH-TI is feasible and acceptable, we used a mixed-method approach including self-report questionnaires and a focus group. To evaluate the impact of CCSH-TI, we assessed self-reported resilience, well-being, burnout, and team civility before and immediately after the intervention period (ClinicalTrials.gov identifier: NCT04060901)., Results: Attendance varied by team, but all teams had rates more than 60%. Coordinators rated high levels of credibility of CCSH-TI to improve burnout, and the majority reported that they received benefits, particularly in resilience and stress management, indicating acceptability. Coordinators randomly assigned to CCSH-TI reported an increase in resilience compared with coordinators randomly assigned to the wait-list group (F(41) = 4.53, P = .039)., Conclusion: Data from this pilot study indicate that CCSH-TI may be a feasible, credible, acceptable, and effective intervention to augment individual resilience among CRCs. However, the quantitative and qualitative data suggest that more comprehensive and systematic programming is necessary to truly mitigate burnout., Competing Interests: Charles RaisonConsulting or Advisory Role: Novartis, Otsuka, Alfasigma, MindMed, Inmune BioNo other potential conflicts of interest were reported.

The challenges of soil degradation and climate change have led to the emergence of Conservation Agriculture (CA) as a sustainable alternative to tillage-based agriculture systems. Despite the recognition of positive impacts on soil health, CA adoption in Africa has remained low. Previous soil health studies have mainly focused on 'scientific' measurements, without consideration of local knowledge, which influences how farmers interpret CA impacts and future land management decisions. This study, based in Malawi, aims to 1) combine local knowledge and conventional soil science approaches to develop a contextualised understanding of the impact of CA on soil health; and 2) understand how an integrated approach can contribute to explaining farmer decision-making on land management. Key farmers' indicators of soil health were crop performance, soil consistence, moisture content, erosion, colour, and structure. These local indicators were consistent with conventional soil health indicators. By combining farmers' observations with soil measurements, we observed that CA improved soil structure, moisture (Mwansambo 7.54%-38.15% lower for CP; Lemu 1.57%-47.39% lower for CP) and infiltration (Lemu CAM/CAML 0.15 cms -1 , CP 0.09 cms -1 ; Mwansambo CP/CAM 0.14 cms -1 , CAML 0.18 cms -1 ). In the conventional practice, farmers perceived ridges to redistribute nutrients, which corresponded with recorded higher exchangeable ammonium (Lemu CP 76.0 mgkg -1 , CAM 49.4 mgkg -1 , CAML 51.7 mgkg -1 ), nitrate/nitrite values (Mwansambo CP 200.7 mgkg -1 , CAM 171.9 mgkg -1 , CAML 103.3 mgkg -1 ). This perception contributes to the popularity of ridges, despite the higher yield measurements under CA (Mwansambo CP 3225 kgha -1 , CAML 5067 kgha -1 , CAM 5160 kgha -1 ; Lemu CP 2886 kgha -1 , CAM 2872 kgha -1 , CAML 3454 kgha -1  ). The perceived carbon benefits of residues and ridge preference has promoted burying residues in ridges. Integrated approaches contribute to more nuanced and localized perceptions about land management. We propose that the stepwise integrated soil assessment framework developed in this study can be applied more widely in understanding the role of soil health in farmer-decision making, providing a learning process for downscaling technologies and widening the evidence base on sustainable land management practices., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Autotrophic carbon dioxide (CO 2 ) fixation by microbes is ubiquitous in the environment and potentially contributes to the soil organic carbon (SOC) pool. However, the multiple autotrophic pathways of microbial carbon assimilation and fixation in paddy soils remain poorly characterized. In this study, we combine metagenomic analysis with 14 C-labelling to investigate all known autotrophic pathways and CO 2 assimilation mechanisms in five typical paddy soils from southern China. Marker genes of six autotrophic pathways are detected in all soil samples, which are dominated by the cbbL genes (67%-82%) coding the ribulose-bisphosphate carboxylase large chain in the Calvin cycle. These marker genes are associated with a broad range of phototrophic and chemotrophic genera. Significant amounts of 14 C-CO 2 are assimilated into SOC (74.3-175.8 mg 14 C kg -1 ) and microbial biomass (5.2-24.1 mg 14 C kg -1 ) after 45 days incubation, where more than 70% of 14 C-SOC was concentrated in the relatively stable humin fractions. These results show that paddy soil microbes contain the genetic potential for autotrophic carbon fixation spreading over broad taxonomic ranges, and can incorporate atmospheric carbon into organic components, which ultimately contribute to the stable SOC pool., (© 2020 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Pb contamination of soils is a global problem. This paper discusses the ability of an Fe-rich waste, water treatment residual (WTR), to adsorb Pb(II). This was investigated using batch sorption experiments, X-ray diffraction, electron microprobe microanalysis, PHREEQC modeling and Extended X-ray Absorption Fine Structure (EXAFS) analysis. The WTR is composed of approximately 23 wt. % natural organic matter (NOM), 70 wt. % ferrihydrite and <10 wt. % silicate material. Pb(II) sorption to WTR was dependent on initial Pb(II) load, particle size, time and pH, but not on ionic strength. EXAFS analysis at the Pb L III -edge confirmed that Pb(II) sorbed to WTR by co-existing bidentate edge-sharing and monodentate or corner-sharing complexes, with 2 O at ∼2.31-2.34 Å, 1 Fe at ∼3.32-3.34 Å, 2 Fe at ∼3.97-3.99 Å and 1 Pb at ∼3.82-3.85 Å. Linear combination showed that the Pb(II)-sorbed spectra were best fit with a ∼0.9 ± 0.1 and 0.1 ± 0.1 contribution from Pb(II)-sorbed ferrihydrite and Pb(II)-sorbed humic acid end members, respectively. Overall, we show that Pb(II) sorbs via strong inner-sphere complexation of Pb(II) to the ferrihydrite component of the WTR, which itself is stable over a wide pH range. Therefore, we suggest that Fe-rich WTR wastes could be used as effective adsorbents in Pb(II)-contaminated soils to help ensure sustainable terrestrial ecosystems., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The outer membrane c -type cytochromes ( c -Cyts) OmcA and MtrC in Shewanella are key terminal reductases that bind and transfer electrons directly to iron (hydr)oxides. Although the amounts of OmcA and MtrC at the cell surface and their molecular structures are largely comparable, MtrC is known to play a more important role in dissimilatory iron reduction. To explore the roles of these outer membrane c -Cyts in the interaction of Shewanella oneidensis MR-1 with iron oxides, the processes of attachment of S. oneidensis MR-1 wild type and c -type cytochrome-deficient mutants (the Δ omcA, Δ mtrC , and Δ omcA Δ mtrC mutants) to goethite are compared via quartz crystal microbalance with dissipation monitoring (QCM-D). Strains with OmcA exhibit a rapid initial attachment. The quantitative model for QCM-D responses reveals that MtrC enhances the contact area and contact elasticity of cells with goethite by more than one and two times, respectively. In situ attenuated total reflectance Fourier transform infrared two-dimensional correlation spectroscopic (ATR-FTIR 2D-CoS) analysis shows that MtrC promotes the initial interfacial reaction via an inner-sphere coordination. Atomic force microscopy (AFM) analysis demonstrates that OmcA enhances the attractive force between cells and goethite by about 60%. As a result, OmcA contributes to a higher attractive force with goethite and induces a rapid short-term attachment, while MtrC is more important in the longer-term interaction through an enhanced contact area, which promotes interfacial reactions. These results reveal that c -Cyts OmcA and MtrC adopt different mechanisms for enhancing the attachment of S. oneidensis MR-1 cells to goethite. It improves our understanding of the function of outer membrane c -Cyts and the influence of cell surface macromolecules in cell-mineral interactions. IMPORTANCE Shewanella species are one group of versatile and widespread dissimilatory iron-reducing bacteria, which are capable of respiring insoluble iron minerals via six multiheme c -type cytochromes. Outer membrane c -type cytochromes ( c -Cyts) OmcA and MtrC are the terminal reductases in this pathway and have comparable protein structures. In this study, we elucidate the different roles of OmcA and MtrC in the interaction of S. oneidensis MR-1 with goethite at the whole-cell level. OmcA confers enhanced affinity toward goethite and results in rapid attachment. Meanwhile, MtrC significantly increases the contact area of bacterial cells with goethite and promotes the interfacial reaction, which may explain its central role in extracellular electron transfer. This study provides novel insights into the role of bacterial surface macromolecules in the interfacial interaction of bacteria with minerals, which is critical to the development of a comprehensive understanding of cell-mineral interactions., (Copyright © 2020 American Society for Microbiology.)

Aluminum substitution is common in iron (hydr)oxides in subsurface environments, and can significantly modify mineral interactions with contaminants. However, few studies investigate Cr(VI) adsorption and its subsequent mobility on Al-substituted iron (hydr)oxide surfaces. Here shows that Al substitution gradually modifies hematite crystals from {101}, {112}, {110} and {104} faceted rhombohedra to {001} faceted plates, resulting in a general decrease in Cr(VI) adsorption density and favoring of monodentate mononuclear over bidentate binuclear Cr(VI) adsorption complexes. Consequently, the mobility of Cr(VI) might be increased in environments with an abundance of Al-containing iron (hydr)oxides. However, pre-adsorption of Fe 2+ on hematite promotes Cr(VI) adsorption, reduction and fixation, and Al-substituted hematite removes more Cr(VI) than pure hematite. Similarly, although addition of Fe 2+ to Cr(VI)-adsorbed hematite remobilizes a small proportion of Cr, it greatly increases the proportion of Cr fixed. As the coexistence of Fe 2+ and iron (hydr)oxides is common in subsurface environments, Al-containing iron (hydr)oxides will promote Cr(VI) uptake and retention, with a significant proportion fixed as Cr(III), limiting Cr mobility and toxicity. These results offer new insights into how iron (hydr)oxides might control the behaviors of other high-valence redox-sensitive contaminants, and provide a platform for modeling such processes in complex soil and sediment systems., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Arsenic mobility in soils, sediments and groundwater systems is strongly controlled by adsorption occurring at iron oxide/water interfaces, and the extent of this adsorption may be influenced by the presence of natural organic matter (NOM). This study aims to investigate the adsorption of As(III) and As(V) onto coprecipitates made with ferrihydrite (Fh) and humic acid (HA) with two organic carbon (OC) loadings of 5 and 15 wt% OC. We show that the coprecipitation of HA with Fh can significantly reduce the retention of both As(III) and As(V) over a wide pH range (4-11), and with increased OC loading, there is reduced arsenic adsorption. On pure Fh, As(III) is adsorbed to a greater extent than As(V) at pH > 6.5 (the crossover pH), whereas the crossover pH shifts to more acidic pH in the presence of HA, implying that the binding of As(III) is more favorable than As(V) in the presence of NOM. Both As(III) and As(V) are complexed with the ferric hydroxyl functional groups, and no ternary Fh-HA-As complexes are detected. We observe that ∼40% of the adsorbed As(III) is oxidized to As(V) on pure Fh, compared to only ∼29% of As(III) oxidation on the Fh-HA coprecipitate, indicating that NOM hinders As(III) oxidation on iron (hydr)oxide. The results of this study suggest that NOM interacts with arsenic in ways that promote arsenic mobility and especially promote the mobility of arsenate relative to arsenite, which is of great significance for evaluating the migration and bioavailability of arsenic in both natural and contaminated environments., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Extracellular polymeric substances (EPS) are ubiquitous in the soil and water environment and interact strongly with mineral surfaces. However, these interactions and their impacts on the behavior and fate of minerals remain poorly understood. Here, for a better understanding of the colloidal stability of minerals in the environment, we investigated the aggregation of goethite (α-FeOOH) nanoparticles (NPs) in the presence of EPS from Bacillus subtilis under different environmental conditions (pH, ionic strength and ionic valence). Results showed that the aggregation processes of goethite NPs are determined by the solution chemistry, and the colloidal stability of goethite NPs is strongly influenced by the addition of EPS. In the absence of ionic strength, the addition of EPS promotes the aggregation of goethite NPs only when the pH (pH = 6) is less than the point of zero charge for the goethite nanoparticles (pH pzc  ≈ 8). In the presence of ionic strength, the aggregation rate of goethite NPs increases with increasing concentration of NaCl, NaNO 3 and Na 2 SO 4 solutions, and after the addition of EPS solution, the critical coagulation concentrations (CCC) of goethite NPs are increased from 43.0, 56.7 and 0.39 mM to 168.0, 304.9 and 126.2 mM in the three electrolyte solutions, indicating that the addition of EPS inhibits the aggregation of goethite NPs. While in Na 3 PO 4 solution, when the concentration of Na 3 PO 4 solution ranged from 0 to 1 mM, the aggregation rate of goethite NPs increases first, followed by a decrease, and with the concentration of Na 3 PO 4 solution exceeding 1 mM, the aggregation rate of goethite NPs increases again, due to the charge screening by sodium counter ions. This study provides a fundamental understanding of the behavior of goethite NPs in natural soil and water environments., (Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.)

Soil is a heterogeneous porous media that is comprised of a variety of organo-mineral aggregates. Sorption of heavy metals onto these composite solids is a key process that controls heavy metal mobility and fate in the natural environment. Pollution from a combination of heavy metals is common in soil, therefore, understanding the competitive binding behavior of metal ions to organo-mineral composites is important in order to predict metal mobility and fate. In this study, batch experiments were paired with spectroscopic studies to probe the sorption characteristics of ternary CdNiCu sorbates to a binary organo-goethite composite made with Bacillus cereus cells. Scanning electron microscopy shows that goethite nano-sized crystals are closely associated with the bacterial surfaces. Sorption experiments show a larger adsorptivity and affinity for Cu than Cd/Ni on goethite and B. cereus, and the goethite-B. cereus composite. X-ray photoelectron spectroscopy reveals that carboxylate and phosphate functional moieties present on the bacterial cell walls are primarily responsible for metal sorption to the goethite-B. cereus composite. Synchrotron-based X-ray fluorescence shows that Cu and Ni are predominately associated with the bacterial fraction of the goethite-B. cereus composite, whereas Cd is mainly associated with the goethite fraction. The findings of this research have important implications for predicting the mobility and fate of heavy metals in soil multi-component systems., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Adsorption and coprecipitation of organic matter with iron (hydr)oxides can alter iron (hydr)oxide surface properties and their reactivity towards nutrient elements and heavy metals. Organo-mineral composites were synthesized using humic acid (HA) and iron oxide, during coprecipitation with ferrihydrite (Fh) and adsorption to pre-formed Fh with two C loadings. The Fh-HA coprecipitated composites have a higher C content and smaller surface area compared to the equivalent adsorbed composites. NanoSIMS shows there is a high degree of spatial correlation between Fe and C for both composites, but C distribution is more uniform in the coprecipitated composites. The C 1s NEXAFS reveals a similar C composition between the Fh-HA coprecipitated and adsorbed composites. However composites at high carbon loading are more enriched in aromatic C, likely due to preferential binding of carboxyl functional groups on aromatic rings in the HA. The amount of Cd sorbed is independent of the composite type, either coprecipitated or adsorbed, but is a function of the C loading. Composites with low C loading show Cd sorption that is almost identical to pure Fh, while composites with high C loading show Cd sorption that is intermediate between pure Fh and pure HA, with sorption significantly enhanced over pure Fh at pH < 6.5. A bidentate edge-sharing binding was identified for Cd on pure Fh and Cd-carboxyl binding on pure HA. These findings have significant implications not only for the sequestration of Cd in contaminated environments but also the coupled biogeochemical cycling of Cd, Fe and C in the critical zone., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

The ability of a Fe-Mn binary oxide waste to adsorb arsenic (As) in a historically contaminated soil was investigated. Initial laboratory sorption experiments indicated that arsenite [As(III)] was oxidized to arsenate [As(V)] by the Mn oxide component, with concurrent As(V) sorption to the Fe oxide. The binary oxide waste had As(III) and As(V) adsorption capacities of 70mgg -1 and 32mgg -1 respectively. X-ray Absorption Near-Edge Structure and Extended X-ray Absorption Fine Structure at the As K-edge confirmed that all binary oxide waste surface complexes were As(V) sorbed by mononuclear bidentate corner-sharing, with 2 Fe at ∼3.27Ǻ. The ability of the waste to perform this coupled oxidation-sorption reaction in real soils was investigated with a 10% by weight addition of the waste to an industrially As contaminated soil. Electron probe microanalysis showed As accumulation onto the Fe oxide component of the binary oxide waste, which had no As innately. The bioaccessibility of As was also significantly reduced by 7.80% (p<0.01) with binary oxide waste addition. The results indicate that Fe-Mn binary oxide wastes could provide a potential in situ remediation strategy for As and Pb immobilization in contaminated soils., (Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.)

Strontium is an important contaminant radionuclide at many former nuclear sites. This paper investigates the effect of changing pH and ionic strength on the sorption of Sr to a range of common soil minerals. Specifically it focuses on the sorption of Sr onto illite, chlorite, goethite, and a mixed sediment. The interplay between ionic strength and pH was determined by varying the background ionic strength of the system using both NaCl (for a constant pH) and NaOH (to also vary pH). Under conditions of moderate pH, Sr sorption decreased with increasing ionic strength, due to competition between the Na and Sr atoms for the outer-sphere complexes. However, where increasing ionic strength was accompanied by increasing pH, Sr sorption remained high. This suggested that Sr was sorbed to the minerals without competition from background Na ions. Extended X-ray absorption fine structure (EXAFS) spectra confirmed that at highly alkaline pH (>12.5) Sr was forming inner-sphere complexes on the surfaces of all minerals. This specific adsorption of the Sr (as SrOH(+)) explains why it was still adsorbed to the minerals under very high ionic strength conditions and was not out-competed by Na.

Soil components (e.g., clays, bacteria and humic substances) are known to produce mineral-organic composites in natural systems. Herein, batch sorption isotherms, isothermal titration calorimetry (ITC), and Cd K-edge EXAFS spectroscopy were applied to investigate the binding characteristics of Cd on montmorillonite(Mont)-humic acid(HA)-bacteria composites. Additive sorption and non-additive Cd(II) sorption behaviour is observed for the binary Mont-bacteria and ternary Mont-HA-bacteria composite, respectively. Specifically, in the ternary composite, the coexistence of HA and bacteria inhibits Cd adsorption, suggesting a "blocking effect" between humic acid and bacterial cells. Large positive entropies (68.1~114.4 J/mol/K), and linear combination fitting of the EXAFS spectra for Cd adsorbed onto Mont-bacteria and Mont-HA-bacteria composites, demonstrate that Cd is mostly bound to bacterial surface functional groups by forming inner-sphere complexes. All our results together support the assertion that there is a degree of site masking in the ternary clay mineral-humic acid-bacteria composite. Because of this, in the ternary composite, Cd preferentially binds to the higher affinity components-i.e., the bacteria.

Iron formations (IF) preserve a history of Precambrian oceanic elemental abundance that can be exploited to examine nutrient limitations on early biological productivity. However, in order for IF to be employed as paleomarine proxies, lumped-process distribution coefficients for the element of interest must be experimentally determined or assumed. This necessitates consideration of bulk ocean chemistry and which authigenic ferric iron minerals controlled the sorption reactions. It also requires an assessment of metal mobilization reactions that might have occurred in the water column during particle descent and during post-depositional burial. Here, we summarize recent developments pertaining to the interpretation and fidelity of the IF record in reconstructions of oceanic trace element evolution. Using an updated compilation, we reexamine and validate temporal trends previously reported for the nickel content in IF (see Konhauser et al., 2009 ). Finally, we reevaluate the consequences of methanogen Ni starvation in the context of evolving views of the Archean ocean-climate system and how the Ni famine may have ultimately facilitated the rise in atmospheric oxygen.

Minerals stabilize organic carbon (OC) in sediments, thereby directly affecting global climate at multiple scales, but how they do it is far from understood. Here we show that manganese oxide (Mn oxide) in a water treatment works filter bed traps dissolved OC as coatings build up in layers around clean sand grains at 3%w/wC. Using spectroscopic and thermogravimetric methods, we identify two main OC fractions. One is thermally refractory (>550 °C) and the other is thermally more labile (<550 °C). We postulate that the thermal stability of the trapped OC is due to carboxylate groups within it bonding to Mn oxide surfaces coupled with physical entrapment within the layers. We identify a significant difference in the nature of the surface-bound OC and bulk OC . We speculate that polymerization reactions may be occurring at depth within the layers. We also propose that these processes must be considered in future studies of OC in natural systems.

Diamond Light Source Ltd celebrated its 10th anniversary as a company in December 2012 and has now accepted user experiments for over 5 years. This paper describes the current facilities available at Diamond and future developments that enhance its capacities with respect to the Earth and environmental sciences. A review of relevant research conducted at Diamond thus far is provided. This highlights how synchrotron-based studies have brought about important advances in our understanding of the fundamental parameters controlling highly complex mineral-fluid-microbe interface reactions in the natural environment. This new knowledge not only enhances our understanding of global biogeochemical processes, but also provides the opportunity for interventions to be designed for environmental remediation and beneficial use.

The release of Se from shales is poorly understood because its occurrence, distribution, and speciation in the various components of shale are unknown. To address this gap we combined bulk characterization, sequential extractions, and spatially resolved μ-focus spectroscopic analyses and investigated the occurrence and distribution of Se and other associated elements (Fe, As, Cr, Ni, and Zn) and determined the Se speciation at the μ-scale in typical, low bulk Se containing shales. Our results revealed Se primarily correlated with the pyrite fraction with exact Se speciation highly dependent on pyrite morphology. In euhedral pyrites, we found Se(-II) substitutes for S in the mineral structure. However, we also demonstrate that Se is associated with framboidal pyrite grains as a discrete, independent FeSex phase. The presence of this FeSex species has major implications for Se release, because FeSex species oxidize much faster than Se substituted in the euhedral pyrite lattice. Thus, such an FeSex species will enhance and control the dynamics of Se weathering and release into the aqueous environment.

Red mud leachate (pH 13) collected from Ajka, Hungary is neutralized to < pH 10 by HCl, gypsum, or seawater addition. During acid neutralization >99% Al is removed from solution during the formation of an amorphous boehmite-like precipitate and dawsonite. Minor amounts of As (24%) are also removed from solution via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results in the precipitation of calcite, both in experiments and in field samples recovered from rivers treated with gypsum after the October 2010 red mud spill. Calcite precipitation results in 86% Al and 81% As removal from solution, and both are nonexchangeable with 0.1 mol L(-1) phosphate solution. Contrary to As associated with neoformed Al oxyhydroxides, EXAFS analysis of the calcite precipitates revealed only isolated arsenate tetrahedra with no evidence for surface adsorption or incorporation into the calcite structure, possibly as a result of very rapid As scavenging by the calcite precipitate. Seawater neutralization also resulted in carbonate precipitation, with >99% Al and 74% As removed from solution during the formation of a poorly ordered hydrotalcite phase and via surface adsorption to the neoformed precipitates, respectively. Half the bound As could be remobilized by phosphate addition, indicating that As was weakly bound, possibly in the hydrotalcite interlayer. Only 5-16% V was removed from solution during neutralization, demonstrating a lack of interaction with any of the neoformed precipitates. High V concentrations are therefore likely to be an intractable problem during the treatment of red mud leachates.

Results are presented from X-ray absorption spectroscopy based analysis of As, Cr, and V speciation within samples of bauxite ore processing residue (red mud) collected from the spill site at Ajka, Western Hungary. Cr K-edge XANES analysis found that Cr is present as Cr(3+) substituted into hematite, consistent with TEM analysis. V K-edge XANES spectra have E(1/2) position and pre-edge features consistent with the presence of V(5+) species, possibly associated with Ca-aluminosilicate phases. As K-edge XANES spectra identified As present as As(5+). EXAFS analysis reveals arsenate phases in red mud samples. When alkaline leachate from the spill site is neutralized with HCl, 94% As and 71% V are removed from solution during the formation of amorphous Al-oxyhydroxide. EXAFS analysis of As in this precipitate reveals the presence of arsenate Al-oxyhydroxide surface complexes. These results suggest that in the circumneutral pH, oxic conditions found in the Torna and Upper Marcal catchments, incorporation and sorption, respectively, will restrict the environmental mobility of Cr and As. V is inefficiently removed from solution by neutralization, therefore, the red mud may act as a source of mobile V(5+) where the red mud deposits are not removed from affected land.