Subterranean calcite dissolution and precipitation are often considered as strictly geochemical processes. The active involvement of microbes in these processes is commonly underestimated in the ...literature due to general oligotrophic conditions in caves, except in particular cave conditions, such as sulfidic caves and moonmilk deposits, where the presence of microbes likely plays a key role in mineral deposition. Here, we study the possible involvement of microbes from Postojna Cave, Slovenia, in carbonate dissolution (litholysis) and precipitation (lithogenesis). Microbes were sampled from small pools below hydrologically diverse drip sites and incubated on polished limestone tablets at 10 and 20°C for 2 and 14 weeks under cave-analogue conditions. The tablets were then observed under scanning electron microscope to investigate microbe–rock interactions. Our experiments showed the presence of various microbial morphotypes, often associated with extracellular polymeric substances, firmly attached on the surfaces. Unfortunately, our surface sterilization method using 96% and 70% ethanol could not establish the complete aseptic conditions in deep natural cracks in the experimental limestone tablets. Nonetheless, our results emulate the interaction of environmental microbes with limestone rock. Conspicuous calcite dissolution and precipitation were observed in association with these microbes. Furthermore, we show evidence of entombment of microbes in a Si-rich precipitate during nutrient-depleted growth conditions and we suggest that microbial involvement in silica mobilization under ambient conditions may be a widespread and often overlooked phenomenon. Our findings have important implications for microbial-mediation of cave carbonate dissolution and precipitation, including the preservation of past climate proxy signals in speleothems and prehistoric cave art. Improvements to the methodology and further work are suggested to enable more robust
ex-situ
cultivation experiments in the future, facilitating better and more detailed research into this topic.
Cave carbonate mineral deposits (speleothems) contain trace elements that are intensively investigated for their significance as palaeoclimate and environmental proxies. However, chlorine, which is ...abundant in marine and meteoric waters, has been overlooked as a potential palaeo-proxy, while cosmogenic 36Cl could, in principle, provide a solar irradiance proxy. Here, total Cl concentrations analysed from various speleothems were low (3–14 mg/kg), with variations linked to crystal fabrics. High-resolution synchrotron radiation micro X-ray fluorescence (μ-XRF) trace element mapping showed Cl often associated with Na, Si, and Al. We propose that speleothems incorporate Cl in two fractions: (1) water soluble (e.g., fluid inclusions) and (2) water insoluble and strongly bound (e.g., associated with detrital particulates). However, disparities indicated that alternate unidentified mechanisms for Cl incorporation were present, raising important questions regarding incorporation of many trace elements into speleothems. Our first measurements of 36Cl/Cl ratios in speleothems required large samples due to low Cl concentrations, limiting the potential of 36Cl as a solar irradiance proxy. Critically, our findings highlight a knowledge gap into how Cl and other trace elements are incorporated into speleothems, how the incorporation mechanisms and final elemental concentrations are related to speleothem fabrics, and the significance this may have for how trace elements in speleothems are interpreted as palaeoclimate proxies.
Carbonate dissolution and precipitation are important geological processes whose rates often require quantification. In natural settings, these processes may be taking place at a slow rate, and thus, ...it may not be easily visible which of these processes is occurring. Alternatively, if the effects of precipitation/dissolution are visible, it may not be clear if they are still underway or an artefact of past conditions. Moreover, these two opposing processes may flip states depending on the environmental conditions, such as, on a seasonal basis. Here, we present the technical details and preliminary results of a method using carbonate tablets and Scanning Electron Microscopy (SEM) to evaluate which process (carbonate dissolution or precipitation) is occurring, using as an example, a cave environment. Our method involves making tablets by encasing blocks of carbonate rock into resin and polishing these to form a completely flat and smooth “zero surface”. These tablets are observed under SEM in exactly the same points both before and after exposure to the field environment, using a system of marking lines at specific locations on the resin. Our results show significant differences in the before and after images of the tablet surface after just six weeks in the cave. Furthermore, the use of the insoluble resin zero surface permits a comparison of the starting height with the new dissolved/precipitated surface that can be used to quantitatively estimate the rate of dissolution/precipitation happening at a field location in a relatively short time-frame (weeks/months). This method could be used in numerous natural and industrial settings to identify these processes that can be caused purely geochemically, but also through microbialmediation and physical weathering.
Speleothems have proven to be one of the most reliable terrestrial archives for palaeoclimate research. However, due to the complexity of karst systems, long-term monitoring and high-resolution ...analyses of the cave atmosphere and water geochemistry have become essential to better constrain the factors that control calcite growth and how geochemical palaeoclimate proxies are encoded into speleothems. While calcite precipitation incorporates the palaeoclimate signals into the speleothem fabric, certain conditions in caves can favour dissolution, which may form hiatuses or even destroy these signals. In extreme cases, in-cave dissolution by dripwater can form cup-shaped features (i.e., corrosion cups), which were the main focus of this study. The study site in Postojna Cave, Slovenia was investigated through cave climate monitoring and drip and cup water sampling, which took place during 2017–2021. We found that the cups are fed by low-calcium drips as the consequence of the thin rock overburden above the cave. Due to the specific configuration of the airflow pathways, the study site accumulates high levels of CO2 (>10,000 ppm), which shifts low-calcium dripwater into undersaturation. This causes dissolution on the rock surfaces and speleothems on the cave floor. The results of this study have broader significance in addressing the suitability of cave environments and speleothems used in paleoclimate research.
Lack of community engagement in road safety issues has been a difficult barrier to achieving greater road safety outcomes. In this project, our aim was to develop a road safety campaign that ...humanises cyclists. We devised a four-step approach to develop and implement the campaign to engage the community and achieve positive outcomes. The four steps were: 1) key stakeholder engagement, 2) community consultation, 3) campaign creation and delivery and, 4) evaluation. As this project was conducted in 2020/2021, we address how we managed disruptions caused by COVID-19. Key findings show the campaign was successful and increased understanding of safe behaviours and positive influence on attitudes about cyclists. The frameworks used for this project are provided and while the insights from this project apply to cyclist safety, the steps can be applied to improve collaborative projects to include community engagement in any area of road safety.
A key challenge to providing quality developmental care in remote Aboriginal primary health care (PHC) centers has been the absence of culturally appropriate developmental screening instruments. This ...study focused on the cross-cultural adaptation of the Ages and Stages Questionnaires, 3rd edition (ASQ-3), with careful attention to language and culture. We aimed to adapt the ASQ-3 for use with remote dwelling Australian Aboriginal children, and to investigate the cultural appropriateness and feasibility of the adapted ASQ-3 for use in this context. We undertook a qualitative study in two remote Australian Aboriginal communities, using a six-step collaborative adaptation process. Aboriginal Health Workers (AHWs) were trained to use the adapted ASQ-3, and follow-up interviews examined participants' views of the cultural acceptability and usefulness of the adapted instrument. The adapted ASQ-3 was found to have high face validity and to be culturally acceptable and relevant to parents, AHWs, and early childhood development experts. Author abstract
Adult smoking has its roots in adolescence. If individuals do not initiate smoking during this period it is unlikely they ever will. In high income countries, smoking rates among Indigenous youth are ...disproportionately high. However, despite a wealth of literature in other populations, there is less evidence on the determinants of smoking initiation among Indigenous youth. The aim of this study was to explore the determinants of smoking among Australian Indigenous young people with a particular emphasis on the social and cultural processes that underlie tobacco use patterns among this group.
This project was undertaken in northern Australia. We undertook group interviews with 65 participants and individual in-depth interviews with 11 youth aged 13-20 years led by trained youth 'peer researchers.' We also used visual methods (photo-elicitation) with individual interviewees to investigate the social context in which young people do or do not smoke. Included in the sample were a smaller number of non-Indigenous youth to explore any significant differences between ethnic groups in determinants of early smoking experiences. The theory of triadic influence, an ecological model of health behaviour, was used as an organising theory for analysis.
Family and peer influences play a central role in smoking uptake among Indigenous youth. Social influences to smoke are similar between Indigenous and non-Indigenous youth but are more pervasive (especially in the family domain) among Indigenous youth. While Indigenous youth report high levels of exposure to smoking role models and smoking socialisation practices among their family and social networks, this study provides some indication of a progressive denormalisation of smoking among some Indigenous youth.
Future initiatives aimed at preventing smoking uptake in this population need to focus on changing social normative beliefs around smoking, both at a population level and within young peoples' immediate social environment. Such interventions could be effectively delivered in both the school and family environments. Specifically, health practitioners in contact with Indigenous families should be promoting smoke free homes and other anti-smoking socialisation behaviours.
This article considers what Australian responses to climate change may teach us about the concept of ownership. Through a close analysis of laws aimed at encouraging specific land uses in order to ...mitigate emissions, it argues that these laws support the increasingly uncontroversial claim that ownership of estates or interests in land places obligations and responsibilities on owners to exercise the resulting rights for the benefit of others. However, although land ownership is flexible enough to support the environmental objectives of these laws, their failure to adequately accommodate the practicalities of ownership, such as anticipating the position of successors in title, increases the risk of conflict between owners of estates and interests in land, and compromises the ability of both environmental and property law regimes to achieve their intended objectives.
Health system strengthening is needed to improve delivery of secondary prophylaxis against rheumatic heart disease.
We undertook a stepped-wedge, randomized trial in northern Australia. Five pairs of ...Indigenous community clinics entered the study at 3-month steps. Study phases comprised a 12 month baseline phase, 3 month transition phase, 12 month intensive phase and a 3- to 12-month maintenance phase. Clinics received a multicomponent intervention supporting activities to improve penicillin delivery, aligned with the chronic care model, with continuous quality-improvement feedback on adherence. The primary outcome was the proportion receiving ≥80% of scheduled penicillin injections. Secondary outcomes included "days at risk" of acute rheumatic fever recurrence related to late penicillin and acute rheumatic fever recurrence rates. Overall, 304 patients requiring prophylaxis were eligible. The proportion receiving ≥80% of scheduled injections during baseline was 141 of 304 (46%)-higher than anticipated. No effect attributable to the study was evident: in the intensive phase, 126 of 304 (41%) received ≥80% of scheduled injections (odds ratio compared with baseline: 0.78; 95% confidence interval, 0.54-1.11). There was modest improvement in the maintenance phase among high-adhering patients (43% received ≥90% of injections versus 30% baseline and 28% intensive,
<0.001). Also, the proportion of days at risk in the whole cohort decreased in the maintenance phase (0.28 versus 0.32 baseline and 0.34 intensive,
=0.001). Acute rheumatic fever recurrence rates did not differ between study sites during the intensive phase and the whole jurisdiction (3.0 versus 3.5 recurrences per 100 patient-years,
=0.65).
This strategy did not improve adherence to rheumatic heart disease secondary prophylaxis within the study time frame. Longer term primary care strengthening strategies are needed.
URL: www.anzctr.org.au. Unique identifier: ACTRN12613000223730.
To explore young Aboriginal people's and clinicians’ experiences of injection pain for the 10 years of penicillin injections children are prescribed to prevent rheumatic fever recurrences.
Aboriginal ...children on the penicillin regimen and clinicians were purposively recruited from four remote sites in Australia. Semi‐structured interviews and participant observations were conducted. Views were synthesised and thematically analysed.
A total of 29 Aboriginal children and 59 clinicians were interviewed. Sixteen participants appeared to become accustomed to the injection pain, eight did not find pain an issue, and five found injection pain difficult. A further five believed the injections made them unwell. Patients expressed varying abilities to negotiate with clinicians about the use of pain reduction measures. Clinicians revealed good knowledge of pain reduction measures, but offered them inconsistently. All clinicians found administering the injections distressing.
Repeated painful procedures in children necessitate well‐planned and child‐focused care. Current practices are not in line with guidance from the Royal Australasian College of Physicians about effects of repeated painful procedures on children. Initiating the long‐term injection regimen for rheumatic fever is a special event requiring expert input. A newly reported finding of a subset of young people feeling unwell after receiving the injection requires further investigation.
Improvement of local and jurisdictional guidelines on use of pain reduction measures for children who have been prescribed repeated painful injections for rheumatic fever is needed.
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