Offsetting of CO₂ emissions by air capture in mine tailings at the Mount Keith Nickel Mine, Western Australia: Rates, controls and prospects for carbon neutral mining

The hydrated Mg-carbonate mineral, hydromagnesite [Mg₅(CO₃)₄(OH)₂•4H₂O], precipitates within mine tailings at the Mount Keith Nickel Mine, Western Australia as a direct result of mining operations. We have used quantitative mineralogical data and δ¹³C, δ¹⁸O and F¹⁴C isotopic data to quantify the amount of CO₂fixation and identify carbon sources. Our radiocarbon results indicate that at least 80% of carbon stored in hydromagnesite has been captured from the modern atmosphere. Stable isotopic results indicate that dissolution of atmospheric CO₂ into mine tailings water is kinetically limited, which suggests that the current rate of carbon mineralization could be accelerated. Reactive transport modeling is used to describe the observed variation in tailings mineralogy and to estimate rates of CO₂ fixation. Based on our assessment, approximately 39,800 t/yr of atmospheric CO₂ are being trapped and stored in tailings at Mount Keith. This represents an offsetting of approximately 11% of the mine's annual greenhouse gas emissions. Thus, passive sequestration via enhanced weathering of mineral waste can capture and store a significant amount of CO₂. Recommendations are made for changes to tailings management and ore processing practices that have potential to accelerate carbonation of tailings and further reduce or completely offset the net greenhouse gas emissions at Mount Keith and many other mines

Microbial Populations of Stony Meteorites: Substrate Controls on First Colonizers

Finding fresh, sterilized rocks provides ecologists with a clean slate to test ideas about first colonization and the evolution of soils de novo. Lava has been used previously in first colonizer studies due to the sterilizing heat required for its formation. However, fresh lava typically falls upon older volcanic successions of similar chemistry and modal mineral abundance. Given enough time, this results in the development of similar microbial communities in the newly erupted lava due to a lack of contrast between the new and old substrates. Meteorites, which are sterile when they fall to Earth, provide such contrast because their reduced and mafic chemistry commonly differs to the surfaces on which they land; thus allowing investigation of how community membership and structure respond to this new substrate over time. We conducted 16S rRNA gene analysis on meteorites and soil from the Nullarbor Plain, Australia. We found that the meteorites have low species richness and evenness compared to soil sampled from directly beneath each meteorite. Despite the meteorites being found kilometers apart, the community structure of each meteorite bore more similarity to those of other meteorites (of similar composition) than to the community structure of the soil on which it resided. Meteorites were dominated by sequences that affiliated with the Actinobacteria with the major Operational Taxonomic Unit (OTU) classified as Rubrobacter radiotolerans. Proteobacteria and Bacteroidetes were the next most abundant phyla. The soils were also dominated by Actinobacteria but to a lesser extent than the meteorites. We also found OTUs affiliated with iron/sulfur cycling organisms Geobacter spp. and Desulfovibrio spp. This is an important finding as meteorites contain abundant metal and sulfur for use as energy sources. These ecological findings demonstrate that the structure of the microbial community in these meteorites is controlled by the substrate, and will not reach homeostasis with the Nullarbor community, even after ca. 35,000 years. Our findings show that meteorites provide a unique, sterile substrate with which to test ideas relating to first-colonizers. Although meteorites are colonized by microorganisms, the microbial population is unlikely to match the community of the surrounding soil on which they fall

First non-destructive internal imaging of Rangea, an icon of complex Ediacaran life

The origins of multicellular life have remained enigmatic due to the paucity of high-quality, three-dimensionally preserved fossils. Rangea was a centimetre- to decimetre-scale frond characterised by a repetitive pattern of self-similar branches and a sessile benthic lifestyle. Fossils are typically preserved as moulds and casts exposing only a leafy petalodium, and the rarity and incompleteness of specimens has made it difficult to reconstruct the three-dimensional (3D) morphology of the entire organism. This, in turn, has led to many differing interpretations of its morphology and phylogenetic affinities. Here we use high resolution X-ray micro-computed tomography (microCT) to investigate the 3D internal morphology of rare, exceptionally preserved ironstone fossils of Rangea from the Nama Group in southern Namibia. Our investigation reveals a series of structures that represent boundaries between individual fronds or structural elements that divide into smaller secondary and tertiary elements, leading to a repetitive pattern of branches. These elements surround an internal core of a distinctly different texture and internal appearance. There is no distortion of the walls of the primary elements, thus we conclude that Rangea likely had a rigid or semi-rigid skeleton-like structure that prevented buckling or compression and maintained integrity during life. We compare these findings with previous interpretations of Rangea morphology and present new insights on the architecture of internal structures, such as the central core, and the overall appearance of this complex Ediacaran life form. Our insights based on microCT scans of these rare, uniquely-preserved specimens provide a more accurate interpretation of the 3D morphology essential for determining the true affinities and modes of life of the Ediacaran biota during this early stage in the evolution of complex macroscopic life

Evaluation of meteorites as habitats for terrestrial microorganisms: results from the Nullarbor Plain, Australia, a Mars analogue site

Unambiguous identification of biosignatures on Mars requires access to well-characterized, long-lasting geochemical standards at the planet's surface that can be modified by theoretical martian life. Ordinary chondrites, which are ancient meteorites that commonly fall to the surface of Mars and Earth, have well-characterized, narrow ranges in trace element and isotope geochemistry compared to martian rocks. Given that their mineralogy is more attractive to known chemolithotrophic life than the basaltic rocks that dominate the martian surface, exogenic rocks (e.g., chondritic meteorites) may be good places to look for signs of prior life endemic to Mars. In this study, we show that ordinary chondrites, collected from the arid Australian Nullarbor Plain, are commonly colonized and inhabited by terrestrial microorganisms that are endemic to this Mars analogue site. These terrestrial endolithic and chasmolithic microbial contaminants are commonly found in close association with hygroscopic veins of gypsum and Mg-calcite, which have formed within cracks penetrating deep into the meteorites. Terrestrial bacteria are observed within corrosion cavities, where troilite (FeS) oxidation has produced jarosite [KFe(SO)(OH)]. Where terrestrial microorganisms have colonized primary silicate minerals and secondary calcite, these mineral surfaces are heavily etched. Our results show that inhabitation of meteorites by terrestrial microorganisms in arid environments relies upon humidity and pH regulation by minerals. Furthermore, microbial colonization affects the weathering of meteorites and production of sulfate, carbonate, Fe-oxide and smectite minerals that can preserve chemical and isotopic biosignatures for thousands to millions of years on Earth. Meteorites are thus habitable by terrestrial microorganisms, even under highly desiccating environmental conditions of relevance to Mars. They may therefore be useful as chemical and isotopic “standards” that preserve evidence of life, thereby providing the possibility of universal context for recognition of microbial biosignatures on Earth, Mars and throughout the solar system

The crystal structure of stichtite, re-examination of barbertonite, and the nature of polytypism in MgCr hydrotalcites

abStraCt Stichtite, ideally Mg 6 Cr 2 CO 3 (OH) 16 •4H 2 O, from Stichtite Hill, Tasmania, Australia, and barbertonite, also ideally Mg 6 Cr 2 CO 3 (OH) 16 •4H 2 O, from the Kaapsehoop asbestos mine, South Africa, have been studied by powder X-ray diffraction and their structures have been refined using the Rietveld method. Stichtite from Stichtite Hill crystallizes in the rhombohedral space group R3m, with unitcell parameters a = 3.09575(3) and c = 23.5069(6) Å, V = 195.099(6) Å 3 , with Z = 3/8. Barbertonite from the Kaapsehoop asbestos mine crystallizes in the hexagonal space group P6 3 /mmc. The co-type specimens of barbertonite were found to be intergrown mixtures consisting of barbertonite and stichtite. Unit-cell parameters of barbertonite from the co-type specimens were a = 3.09689(6), c = 15.6193(8) Å, and V = 129.731(8) Å 3 and a = 3.09646(6), c = 15.627(1) Å V = 129.76(1) Å 3 , and Z = ¼. Rietveld refinements of both stichtite and barbertonite show that they are polytypes rather than polymorphs and do not represent distinct mineral species. Several possible nomenclature systems are discussed for the naming of hydrotalcite minerals and groups. Raman band assignments are also presented for stichtite from Stichtite Hill. Stichtite and hydrotalcite minerals make up a large proportion of the ore at the Mount Keith nickel mine in Western Australia. Bulk powder diffraction shows the ore contains 6.1 wt% stichtite and 5.6 wt% iowaite. Hydrotalcite group minerals provide an important potential reservoir of CO 2 . At Mount Keith, the amount of CO 2 mined as stichtite could exceed 45 000 metric tons per year, while exchange of Cl for CO 3 could fix in excess of 40 000 metric tons CO 2 per year if end-member iowaite is reacted to form pyaroaurite

The impact of training non-physician clinicians in Malawi on maternal and perinatal mortality : a cluster randomised controlled evaluation of the enhancing training and appropriate technologies for mothers and babies in Africa (ETATMBA) project

Background: Maternal mortality in much of sub-Saharan Africa is very high whereas there has been a steady decline in over the past 60 years in Europe. Perinatal mortality is 12 times higher than maternal mortality accounting for about 7 million neonatal deaths; many of these in sub-Saharan countries. Many of these deaths are preventable. Countries, like Malawi, do not have the resources nor highly trained medical specialists using complex technologies within their healthcare system. Much of the burden falls on healthcare staff other than doctors including non-physician clinicians (NPCs) such as clinical officers, midwives and community health-workers. The aim of this trial is to evaluate a project which is training NPCs as advanced leaders by providing them with skills and knowledge in advanced neonatal and obstetric care. Training that will hopefully be cascaded to their colleagues (other NPCs, midwives, nurses). Methods/design: This is a cluster randomised controlled trial with the unit of randomisation being the 14 districts of central and northern Malawi (one large district was divided into two giving an overall total of 15). Eight districts will be randomly allocated the intervention. Within these eight districts 50 NPCs will be selected and will be enrolled on the training programme (the intervention). Primary outcome will be maternal and perinatal (defined as until discharge from health facility) mortality. Data will be harvested from all facilities in both intervention and control districts for the lifetime of the project (3–4 years) and comparisons made. In addition a process evaluation using both quantitative and qualitative (e.g. interviews) will be undertaken to evaluate the intervention implementation. Discussion: Education and training of NPCs is a key to improving healthcare for mothers and babies in countries like Malawi. Some of the challenges faced are discussed as are the potential limitations. It is hoped that the findings from this trial will lead to a sustainable improvement in healthcare and workforce development and training. Trial registration: ISRCTN6329415

High Survivability of Micrometeorites on Mars: Sites With Enhanced Availability of Limiting Nutrients

NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in these (e.g., P, S, Fe) become concentrated on the surface of Mars. We find that dense micrometeorites are abundant in a range of desert environments, becoming concentrated by aeolian processes into specific sites that would be easily investigated by a robotic rover. Our modeling suggests that micrometeorites are currently far more abundant on the surface of Mars than on Earth, and given the far greater abundance of water and warmer conditions on Earth and thus much more active weather system, this was likely true throughout the history of Mars. Because micrometeorites contain a variety of redox sensitive minerals including FeNi alloys, sulfide and phosphide minerals, and organic compounds, the sites where these become concentrated are far more nutrient rich, and thus more compatible with chemolithotrophic life than most of the Martian surface

Evidence-based consensus guidelines for the management of catatonia: Recommendations from the British Association for Psychopharmacology

The British Association for Psychopharmacology developed an evidence-based consensus guideline on the management of catatonia. A group of international experts from a wide range of disciplines was assembled. Evidence was gathered from existing systematic reviews and the primary literature. Recommendations were made on the basis of this evidence and were graded in terms of their strength. The guideline initially covers the diagnosis, aetiology, clinical features and descriptive epidemiology of catatonia. Clinical assessments, including history, physical examination and investigations are then considered. Treatment with benzodiazepines, electroconvulsive therapy and other pharmacological and neuromodulatory therapies is covered. Special regard is given to periodic catatonia, malignant catatonia, neuroleptic malignant syndrome and antipsychotic-induced catatonia. There is attention to the needs of particular groups, namely children and adolescents, older adults, women in the perinatal period, people with autism spectrum disorder and those with certain medical conditions. Clinical trials were uncommon, and the recommendations in this guideline are mainly informed by small observational studies, case series and case reports, which highlights the need for randomised controlled trials and prospective cohort studies in this area