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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Deep-freeze graph training for latent learning

Scientific and engineering advances are primarily driven by multi-tier conceptual constructs and conditional theoretical frameworks. The theories allow predictions of hypothetical system responses, given a set of approximate conditions (ranges of applicability) imposed on latent parameters that cannot be measured directly. Learning to estimate the latent variables (Latent Learning) helps to pinpoint the anticipated range-edge anomalies and improves the confidence in interpretation, interpolation and extrapolation of limited experimental data. Due to high dimensionality and extreme non-linearity of the materials science problems, very large datasets are typically required for conventional data-driven model development. The vital experimental data collection, particularly on microstructural phases, is very challenging, which makes it difficult to compile a high-quality database. Incorporation of the domain knowledge into the computational graph structure, initialization and optimization processes presents a viable mechanism for developing accurate models, with limited datasets. Furthermore, this study successfully utilized the approach to build the Deep Freeze Graph (DeepFreG) by mapping known causality relationships and by digitizing empirical domain knowledge for Latent Learning (LL), with specific applications in materials science.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Frequency-Dependent Enhancement of Fluid Intelligence Induced by Transcranial Oscillatory Potentials

Everyday problem solving requires the ability to go beyond experience by efficiently encoding and manipulating new information, i.e., fluid intelligence (Gf) [1]. Performance in tasks involving Gf, such as logical and abstract reasoning, has been shown to rely on distributed neural networks, with a crucial role played by prefrontal regions [2]. Synchronization of neuronal activity in the gamma band is a ubiquitous phenomenon within the brain; however, no evidence of its causal involvement in cognition exists to date [3]. Here, we show an enhancement of Gf ability in a cognitive task induced by exogenous rhythmic stimulation within the gamma band. Imperceptible alternating current [4] delivered through the scalp over the left middle frontal gyrus resulted in a frequency-specific shortening of the time required to find the correct solution in a visuospatial abstract reasoning task classically employed to measure Gf abilities (i.e., Raven’s matrices) [5]. Crucially, gamma-band stimulation (γ-tACS) selectively enhanced performance only on more complex trials involving conditional/logical reasoning. The finding presented here supports a direct involvement of gamma oscillatory activity in the mechanisms underlying higher-order human cognition.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

BrainXcan identifies brain features associated with behavioral and psychiatric traits using large-scale genetic and imaging data

Advances in brain MRI have enabled many discoveries in neuroscience. Case-control comparisons of brain MRI features have highlighted potential causes of psychiatric and behavioral disorders. However, due to the cost and difficulty of collecting MRI data, most studies have small sample sizes, limiting their reliability. Furthermore, reverse causality complicates interpretation because many observed brain differences are the result rather than the cause of the disease. Here we propose a method (BrainXcan) that leverages the power of large-scale genomewide association studies (GWAS) and reference brain MRI data to discover new mechanisms of disease etiology and validate existing ones. BrainXcan tests the association with genetic predictors of brain MRI-derived features and complex traits to pinpoint relevant brain-wide and region-specific features. Requiring only genetic data, BrainXcan allows us to test a host of hypotheses on mental illness, across many MRI modalities, using public data resources. For example, our method shows that reduced axonal density across the brain is associated with schizophrenia risk, consistent with the disconnectivity hypothesis. We also find that the hippocampus volume is associated with schizophrenia risk, highlighting the potential of our approach. Taken together, our results show the promise of BrainXcan to provide insights into the biology of GWAS traits.

Association study↗
DOE OSTI2020

A dataset of eco-evidence tools to inform early-stage environmental impact assessments of hydropower development

The datasets described herein provide the foundation for a decision support prototype (DSP) toolkit aimed at assisting stakeholders in determining evidence of which aspects of river ecosystems have been impacted by hydropower. The DSP toolkit and its application are presented and described in the article “Evidence-based indicator approach to guide preliminary environmental impact assessments of hydropower development” [1]. Development of the DSP and the output for decision support centralize around 42 river function indicators describing the dimensionality of river ecosystems through six main categories: biota and biodiversity, water quality, hydrology, geomorphology, land cover, and river connectivity. Three main tools are represented in the DSP: A science-based questionnaire (SBQ), an environmental envelope model (EEM), and a river function linkage assessment tool (RFLAT). The SBQ is a structured survey-style questionnaire whose objective is to provide evidence of which indicators have been impacted by hydropower. Based on a global literature review, 140 questions were developed from general hypotheses regarding the impacts of dams on rivers. The EEM is a model to predict the likelihood of hydropower impacting indicators based on a several variables. The intended use of the EEM is for situations of new hydropower development where results of the SBQ are incomplete or highly uncertain. The EEM was developed through the compilation of a dataset containing attributes of dams, reservoirs, and geospatial information on environmental concerns, which was combined with data on ecological indicators documented at those sites through literature review. The model operates through 247 “envelopes” and weighting factors, representing the individual effect of each variable on each indicator, all available through spreadsheets. Finally, the RFLAT is a tool to examine causal relationships amongst indicators. Inter-indicator relationships were hypothesized based on literature review and summarized into node and edge datasets to represent the structure of a graphical network. Bayes theorem was used estimate conditional probabilities of inter-indicator relationships based on the output of the SBQ. Nodes and edges were imported into R programming environment to visualize ecological indicator networks. The datasets can be expanded upon and enriched with more detailed questions for the SBQ, building upon the EEM with to develop more sophisticated models, and identifying new relationships for the RFALT. Additionally, once the tools are applied to numerous hydropower developments, the output of the tools (e.g. evidence of impacted indicators) becomes a very useful dataset for meta-analyses of hydropower impacts.

13 HYDRO ENERGY↗
DOE OSTI2014

Impact assessment: Eroding benefits through streamlining?

This paper argues that Governments have sought to streamline impact assessment in recent years (defined as the last five years) to counter concerns over the costs and potential for delays to economic development. We hypothesise that this has had some adverse consequences on the benefits that subsequently accrue from the assessments. This hypothesis is tested using a framework developed from arguments for the benefits brought by Environmental Impact Assessment made in 1982 in the face of the UK Government opposition to its implementation in a time of economic recession. The particular benefits investigated are ‘consistency and fairness’, ‘early warning’, ‘environment and development’, and ‘public involvement’. Canada, South Africa, the United Kingdom and Western Australia are the jurisdictions tested using this framework. The conclusions indicate that significant streamlining has been undertaken which has had direct adverse effects on some of the benefits that impact assessment should deliver, particularly in Canada and the UK. The research has not examined whether streamlining has had implications for the effectiveness of impact assessment, but the causal link between streamlining and benefits does sound warning bells that merit further investigation. -- Highlights: • Investigation of the extent to which government has streamlined IA. • Evaluation framework was developed based on benefits of impact assessment. • Canada, South Africa, the United Kingdom, and Western Australia were examined. • Trajectory in last five years is attrition of benefits of impact assessment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

The paradox of strategic environmental assessment

Strategic Environmental Assessment (SEA) is a tool that can facilitate sustainable development and improve decision-making by introducing environmental concern early in planning processes. However, various international studies conclude that current planning practice is not taking full advantage of the tool, and we therefore define the paradox of SEA as the methodological ambiguity of non-strategic SEA. This article explores causality through at three-step case study on aggregates extraction planning in Denmark, which consists of a document analysis; a questionnaire survey and follow-up communication with key planners. Though the environmental reports on one hand largely lack strategic considerations, practitioners express an inherent will for strategy and reveal that their SEAs in fact have been an integrated part of the planning process. Institutional context is found to be the most significant barrier for a strategy and this suggests that non-strategic planning setups can prove more important than non-strategic planning in SEA practice. Planners may try to execute strategy within the confinements of SEA-restricted planning contexts; however, such efforts can be overlooked if evaluated by a narrow criterion for strategy formation. Consequently, the paradox may also spark from challenged documentation. These findings contribute to the common understanding of SEA quality; however, further research is needed on how to communicate and influence the strategic options which arguably remain inside non-strategic planning realities. - Highlights: • International studies conclude that SEAs are not strategic. = The paradox of SEA. • Even on the highest managerial level, some contexts do not leave room for strategy. • Non-strategic SEA can derive from challenged documentation. • Descriptive and emergent strategy formation can, in practice, be deemed non-strategic.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Assessment of health risks of policies

The assessment of health risks of policies is an inevitable, although challenging prerequisite for the inclusion of health considerations in political decision making. The aim of our project was to develop a so far missing methodological guide for the assessment of the complex impact structure of policies. The guide was developed in a consensual way based on experiences gathered during the assessment of specific national policies selected by the partners of an EU project. Methodological considerations were discussed and summarized in workshops and pilot tested on the EU Health Strategy for finalization. The combined tool, which includes a textual guidance and a checklist, follows the top-down approach, that is, it guides the analysis of causal chains from the policy through related health determinants and risk factors to health outcomes. The tool discusses the most important practical issues of assessment by impact level. It emphasises the transparent identification and prioritisation of factors, the consideration of the feasibility of exposure and outcome assessment with special focus on quantification. The developed guide provides useful methodological instructions for the comprehensive assessment of health risks of policies that can be effectively used in the health impact assessment of policy proposals. - Highlights: • Methodological guide for the assessment of health risks of policies is introduced. • The tool is developed based on the experiences from several case studies. • The combined tool consists of a textual guidance and a checklist. • The top-down approach is followed through the levels of the full impact chain. • The guide provides assistance for the health impact assessment of policy proposals.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Understanding the long-term influence of EIA on organisational learning and transformation

This research is an attempt to verify the notion postulated by Robert Bartlett and Lynton Caldwell that the full benefits of environmental impact assessment (EIA) would take decades to be realized. While EIA is intended to directly influence decision-making regarding new development proposals, the process is also expected to lead to organisational learning and transformation over time. Our aim was to examine the influence of EIA on a single Western Australian proponent with sustained experience in the process to understand how EIA is used within the organisation and to seek evidence of transformation of the organisation's purpose and mission. The research reviewed literature in order to identify key influences of EIA on organisations, along with semi-structured staff interviews and document analysis for the case study organisation. Ascertaining causality that involvement in EIA processes influences or effects organisational learning and transformation is a challenge in the face of other societal events. Document analysis and interviewee data indicates that the action-forcing nature of EIA did influence proponent behavior through the creation of internal processes seeking to ensure robust design of new projects that would satisfy environmental protection expectations, without the need to trigger formal EIA. Evidence of EIA values and thinking were apparent within internal documentation, including the evolving mission statement. Our research indicates that participation in the EIA process can positively influence organisational learning and transformation by guiding internal change for decision-making. - Highlights: • The long-term influence of EIA on a proponent organisation is investigated. • EIA promotes internal organisational learning and transformation. • Analysis of mission statements can indicate the influence of EIA on organisations. • Organisations aligned with EIA values can reduce the need to engage in formal EIA.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Mining project's economic impact on local communities, as a social determinant of health: A documentary analysis of environmental impact statements

Australian mining developments cause indirect economic impacts on nearby communities leading to poor health and wellbeing of local residents. Economic instability is a recognised social determinant of health (SDoH); however, SDoHs are rarely considered adequately in Environmental Impact Assessments (EIAs). This research aimed to determine the extent economic impacts as a SDoH are considered in three Environmental Impact Statements (EISs) of mining projects in the New South Wales, Australia. We adopted an exploratory case study design following Yin (2012). Three cases in New South Wales, Australia, were purposively sampled as being of concern to the local community who had sought legal advice about the content of the EIS (although not necessarily for health reasons). Two were open cut mines: Watermark located in the Liverpool Plains and Warkworth Continuation in the Hunter Valley Region. The third is a comparative case – the underground Mandalong Southern Extension located in Lake Macquarie. We adapted a health-focused EIA coding framework to investigate how economic indicators as SDoH were explicitly mentioned in EISs and applied this to the three cases. Economic indicators as SDoH were rarely considered. There was a greater focus on population characteristics rather than the potential economic impacts of the mining projects on the communities. Causal association of economic determinants and health outcomes were insufficiently reported compared to best practice, and health data were not used to inform assessments. Despite two EISs – Warkworth Continuation and Watermark – associating some economic indicators to health outcomes, impacts were not adequately discussed when compared to the known literature on economic impacts of mines. Our findings show that the three EISs were inadequately utilised to determine economic impacts of mining projects on the health and wellbeing of local communities. The evidence base linking economic impacts of mines to health is underdeveloped, which compromises assessing the quality of economic coverage in EISs. EIA scoping should enable sufficient inclusion of broader determinants of health using appropriate methodology, and the economic-focused content of EISs should be subject to rigorous peer-review process to fully inform government approvals for projects. Our methods lend themselves to research in other contexts to investigate the quality of EIAs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Advocating for view and daylight in buildings: Next steps

With the exponential growth in population and commensurate increased density in urban cities, access to daylight and views to nature is being severely curtailed in buildings. In parallel, increasingly urgent demands to sharply reduce building energy use and associated greenhouse gas emissions are being made to mitigate climate change. There are many challenges and performance tradeoffs associated with the building facade (i.e., daylight and view versus solar and glare control); increased prioritization of health and well-being as a fundamental human requirement could adversely affect building energy-efficiency. Given the current state of knowledge on the effects of daylight and view on health and well-being in buildings, we identify critical needs in research, tools and technologies that if satisfied may enable more effective use of daylight and view in buildings within the constraints of climate change. Lack of knowledge regarding the complex causal mechanisms of window views on human factors is a severely limiting factor in forward progress. Current models and methods to derive bidirectional scattering distribution functions (BSDFs) will need to be modified. Developers of energy-efficient window technologies will need more guidance to shape product development. Advanced window technologies and integrated design can enable attainment of both health and well-being and net zero energy goals, but considerable work will be needed to make such options turnkey and broadly available.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2011

Exposure to airborne metals and particulate matter and risk for youth adjudicated for criminal activity

Antisocial behavior is a product of multiple interacting sociohereditary variables, yet there is increasing evidence that metal exposure, particularly, manganese and lead, play a role in its epigenesis. Other metals, such as arsenic, cadmium, chromium, and mercury, and exposure to traffic-related air pollution, such as fine particulate matter ({<=}2.5 {mu}m) have been associated with neurological deficits, yet largely unexplored with respect to their relationship with delinquent behavior. The purpose of this study is to evaluate the ecological relationship between county-wide reported airborne emissions of air metals, particulate matter, and youth adjudicated for criminal activity. Metal exposure data were collected from the Environmental Protection Agency AirData. Population statistics were obtained from the United States Census 2000 and adjudication data was obtained from the Courts of Common Pleases from each Ohio County. Simple correlations were calculated with the percentage of adjudications, all covariates, and estimated metal air emissions. Separate negative binomial regression models for each pollutant were used to provide an estimated risk ratio of pollutant emissions on the risk of adjudication for all Ohio counties adjusting for urban-rural residence, percentage of African Americans, median family income, percentage of family below poverty, percentage of high school graduation in 25 years and older populations, and population density. Metal emissions and PM in 1999 were all correlated with adjudication rate (2003-2005 average). Metal emissions were associated with slightly higher risk of adjudication, with about 3-4% increased risk per natural log unit of metal emission except chromium. The associations achieved statistical significance for manganese and mercury. The particulate matter {<=}2.5 and {<=}10 {mu}m emissions had a higher risk estimate, with 12% and 19% increase per natural log unit emission, respectively, and also achieved statistical significance. In summary, airborne exposure to manganese, mercury, and particulate matter are associated with increased risk of adjudication. Causality cannot be proven in observational studies such as this one, but the association warrants further examination in other research studies. Comprehensive epidemiologic investigations of metal exposure in pediatric populations should include social health outcomes, including measures of delinquent or criminal activity. Furthermore, the influence of metals on the neurotoxic pathway leading to delinquent activity should be further explored. - Highlights: Black-Right-Pointing-Pointer We evaluate the relationship between air pollutants and adjudication. Black-Right-Pointing-Pointer Manganese, mercury, and particulate matter are associated with risk of adjudication. Black-Right-Pointing-Pointer Further research of metal exposure should include social health outcomes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Self-rated health and chronic conditions are associated with blood concentrations of persistent organic pollutants in the general population of Catalonia, Spain

Background: Self-rated health (SRH) is a powerful predictor of mortality, morbidity, and need for health services. SRH generally increases with educational level, and decreases with age, number of chronic conditions, and body mass index (BMI). Because human concentrations of most persistent organic pollutants (POPs) also vary by age, education, and BMI, and because of the physiological and clinical effects of POPs, we hypothesized that body concentrations of POPs are inversely associated with SRH. Objectives: To analyze the relation between serum concentrations of POPs and SRH in the general population of Catalonia, Spain, taking into account sociodemographic factors and BMI, as well as chronic health conditions and mental disorders, measured by the General Health Questionnaire-12 (GHQ-12). Methods: POP serum concentrations were measured by gas chromatography with electron-capture detection in 919 participants of the Catalan Health Interview Survey. Results: Individuals with higher concentrations of POPs had significantly poorer SRH; e.g., the median concentration of HCB in subjects with poor SRH was twice as high as in subjects with excellent SRH (366 ng/g vs. 169 ng/g, respectively; p-value<0.001). In crude models and in models adjusted for sex and BMI, the POPs-SRH association was often dose-dependent, and the likelihood of poor or regular SRH was 2 to 4-times higher in subjects with POP concentrations in the top quartile. In models adjusted for age or for chronic conditions virtually all ORs were near unity. No associations were found between POP levels and GHQ-12. Conclusions: Individuals with higher concentrations of POPs had significantly poorer SRH, an association likely due to age and chronic conditions, but not to sex, education, social class, BMI, or mental disorders. - Highlights: • The relation between POPs and self-rated and mental health has seldom been studied. • Subjects with higher POP levels had poorer self-rated health (SRH) (dose-dependent). • The number of chronic conditions was positively related to POP levels. • The POPs-SRH association was likely due to age (or birth cohort), and to chronic conditions. • Causal or not, the fact is that people with poorer SRH often have higher levels of POPs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Health effects of desalinated water: Role of electrolyte disturbance in cancer development

This review contends that “healthy” water in terms of electrolyte balance is as important as “pure” water in promoting public health. It considers the growing use of desalination (demineralization) technologies in drinking water treatment which often results in tap water with very low concentrations of sodium, potassium, magnesium and calcium. Ingestion of such water can lead to electrolyte abnormalities marked by hyponatremia, hypokalemia, hypomagnesemia and hypocalcemia which are among the most common and recognizable features in cancer patients. The causal relationships between exposure to demineralized water and malignancies are poorly understood. This review highlights some of the epidemiological and in vivo evidence that link dysregulated electrolyte metabolism with carcinogenesis and the development of cancer hallmarks. It discusses how ingestion of demineralized water can have a procarcinogenic effect through mediating some of the critical pathways and processes in the cancer microenvironment such as angiogenesis, genomic instability, resistance to programmed cell death, sustained proliferative signaling, cell immortalization and tumorigenic inflammation. Evidence that hypoosmotic stress-response processes can upregulate a number of potential oncogenes is well supported by a number studies. In view of the rising production and consumption of demineralized water in most parts of the world, there is a strong need for further research on the biological importance and protean roles of electrolyte abnormalities in promoting, antagonizing or otherwise enabling the development of cancer. The countries of the Gulf Cooperative Council (GCC) where most people consume desalinated water would be a logical place to start this research. - Highlights: • Ingestion of low-mineral waters disrupts electrolyte homeostasis and cellular processes. • Electrolyte imbalance can affect the tumor microenvironment and many stages of tumorigenesis. • Electrolyte disturbance is frequently encountered in patients with malignancies. • Desalinated water consumption and cancer rates are rising in Persian Gulf countries “Balanced water” can be as important as balanced diet in safeguarding our health.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Symptoms and the use of wireless communication devices: A prospective cohort study in Swiss adolescents

Background: We investigated whether radiofrequency electromagnetic fields (RF-EMF) from mobile phones and other wireless devices or by the wireless device use itself due to non-radiation related factors in that context are associated with an increase in health symptom reports of adolescents in Central Switzerland. Methods: In a prospective cohort study, 439 study participants (participation rate: 36.8%) aged 12–17 years, completed questionnaires about their mobile and cordless phone use, their self-reported symptoms and possible confounding factors at baseline (2012/2013) and one year later (2013/2014). Operator recorded mobile phone data was obtained for a subgroup of 234 adolescents. RF-EMF dose measures considering various factors affecting RF-EMF exposure were computed for the brain and the whole body. Data were analysed using a mixed-logistic cross-sectional model and a cohort approach, where we investigated whether cumulative dose over one year was related to a new onset of a symptom between baseline and follow-up. All analyses were adjusted for relevant confounders. Results: Participation rate in the follow-up was 97% (425 participants). In both analyses, cross-sectional and cohort, various symptoms tended to be mostly associated with usage measures that are only marginally related to RF-EMF exposure such as the number of text messages sent per day (e.g. tiredness: OR:1.81; 95%CI:1.20–2.74 for cross-sectional analyses and OR:1.87; 95%CI:1.04–3.38 for cohort analyses). Outcomes were generally less strongly or not associated with mobile phone call duration and RF-EMF dose measures. Conclusions: Stronger associations between symptoms of ill health and wireless communication device use than for RF-EMF dose measures were observed. Such a result pattern does not support a causal association between RF-EMF exposure and health symptoms of adolescents but rather suggests that other aspects of extensive media use are related to symptoms. - Highlights: • This is a prospective cohort study with approximately one year of follow-up. • Self-reported and operator recorded mobile phone use data were collected. • The cumulative RF-EMF dose for the brain and for the whole body was calculated. • Associations were stronger for the use of wireless devices than for RF-EMF dose. • This suggests that rather aspects of extensive media use than RF-EMF are related to symptoms.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Environmental exposures and pediatric kidney function and disease: A systematic review

Background: Environmental chemical exposures have been implicated in pediatric kidney disease. No appraisal of the available evidence has been conducted on this topic. Methods: We performed a systematic review of the epidemiologic studies that assessed association of environmental exposures with measures of kidney function and disease in pediatric populations. The search period went through July 2016. Results: We found 50 studies that met the search criteria and were included in this systematic review. Environmental exposures reviewed herein included lead, cadmium, mercury, arsenic, fluoride, aflatoxin, melamine, environmental tobacco, bisphenol A, dental procedures, phthalates, ferfluorooctanoic acid, triclosan, and thallium/uranium. Most studies assessed environmental chemical exposure via biomarkers but four studies assessed exposure via proximity to emission source. There was mixed evidence of association between metal exposures, and other non-metal environmental exposures and pediatric kidney disease and other kidney disease biomarkers. The evaluation of causality is hampered by the small numbers of studies for each type of environmental exposure, as well as lack of study quality and limited prospective evidence. Conclusion: There is a need for well-designed epidemiologic studies of environmental chemical exposures and kidney disease outcomes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Fine particulate matters: The impact of air quality standards on cardiovascular mortality

Highlights: • PM{sub 2.5} decreased following implementation of annual PM{sub 2.5} standard. • Cardiovascular mortality decreased with a decrease in PM{sub 2.5}. • Attainment counties had greater health benefit compared to nonattainment counties. • Associations were not statistically different. • Health benefits were shown even in counties below the current standard. In 1997 the U.S. Environmental Protection Agency set the first annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM{sub 2.5}). Although the weight of scientific evidence has determined that a causal relationship exists between PM{sub 2.5} exposures and cardiovascular effects, few studies have concluded whether NAAQS-related reductions in PM{sub 2.5} led to improvements in public health.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Large isotopic variability at the micron-scale in ‘Shuram’ excursion carbonates from South Australia

Ediacaran-aged (635–541 million years ago) marine sediments contain a large negative carbon isotope (δ 13 C) excursion, in which carbonate δ 13 C values reach -12‰ (VPDB). Known as the ‘Shuram’ excursion, many workers have interpreted this δ 13 C record as an unprecedented perturbation to the global carbon cycle, leading to speculation about a causal connection to the broadly contemporaneous rise of animal life. Others have interpreted the δ 13 C signal as a product of diagenesis, thereby minimizing its relevance for understanding the evolution of metazoans. In this work, we present SEM imaging and in-situ δ 13 C and δ 18 C values measured by secondary ion mass spectrometry (SIMS) to assess these competing hypotheses in the Wonoka Formation of South Australia. Our results from the minimum of the excursion show that rounded sedimentary grains of calcite have δ 13 C values between -12.8 to -10.6‰ and δ 18 C values between 17.8 to 15.5‰ (VPDB). Euhedral dolomite that appears to have grown unimpeded in open sedimentary pore spaces also is present. These early-stage dolomites are interpreted as early authigenic in origin and have δ 13 C values that reach +5‰, requiring a formation fluid with a substantially different δ 13 C composition from basin waters or bulk sediment. Together, these results provide little evidence for the hypothesis that a late diagenetic overprint has generated the ‘Shuram’ excursion in the Wonoka. Instead, they suggest the presence of a large carbon isotopic gradient in the surface environment, with shallow waters capable of precipitating carbonates with very low δ 13 C (down to 12‰) and deeper shelf and/or marine pore waters generating carbonates with positive carbon isotope values (up to +5‰). Because negative isotope excursions of similar magnitude are found in widely dispersed Ediacaran basins, it is likely that this gradient was characteristic of shelf environments of this period and that a still-unknown global process led to the ‘Shuram’ excursion in shallow water carbonates.

58 GEOSCIENCES↗
DOE OSTI2022

Supply sunspots and shadows: Business siting patterns and inequitable rooftop solar adoption in the United States

Entrepreneurs in certain industries tend to locate new businesses in relatively affluent areas. Preferences to site businesses in affluent areas can reduce low-income household access to certain products. Some argue that business siting patterns could explain inequitable consumption patterns, though such causal claims are often empirically weak. Here, we explore whether business siting patterns partly explain inequitable adoption of rooftop solar photovoltaics in California. We show that solar business formation drives an immediate and sustained increase in local solar adoption, including in low-income areas. However, solar business siting patterns have only weak impacts on solar adoption equity. The data show how solar businesses headquartered in low-income areas nonetheless install solar for relatively affluent customers. Customer-level adoption inequity partly offsets the potential equity gains of siting more businesses in low-income areas. We discuss how the emergent nature and unique business model of rooftop solar help explain these nuanced results.

14 SOLAR ENERGY↗