Uranium and Radon in Private Bedrock Well Water in Maine: Geospatial Analysis at Two Scales

In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km² contained [U] > 30 μg/L, the U.S. Environmental Protection Agency’s (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km² showed [Rn] > 4,000 pCi/L (148 Bq/L), the U.S. EPA’s Alternative MCL. Groundwater pH, calcite dissolution and redox condition are factors controlling the distribution of groundwater U but not Rn due to their divergent chemical and hydrological properties. Groundwater U is associated with incompatible elements (S, As, Mo, F, and Cs) in water samples within granitic intrusions. Elevated [U] and [Rn] are located within 5–10 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (10⁰−10¹ km). This spatial association is confirmed by a high-density sampling (n = 331, 5–40 samples per km²) at local scales (≤10–1 km) and the statewide sampling (n = 5857, 1 sample per 16 km²) at regional scales (10²–103 km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48 800–63 900 and 324 000 people in Maine are estimated at risk of exposure to U (> 30 μg/L) and Rn (> 4000 pCi/L) in well water, respectively

Searching for dark matter with plasma haloscopes

We summarize the recent progress of the Axion Longitudinal Plasma Haloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space

Grass-fed vs. grain-fed beef systems: performance, economic, and environmental trade-offs.

Between increasing public concerns over climate change and heightened interest of niche market beef on social media, the demand for grass-fed beef has increased considerably. However, the demand increase for grass-fed beef has raised many producers' and consumers' concerns regarding product quality, economic viability, and environmental impacts that have thus far gone unanswered. Therefore, using a holistic approach, we investigated the performance, carcass quality, financial outcomes, and environmental impacts of four grass-fed and grain-fed beef systems currently being performed by ranchers in California. The treatments included 1) steers stocked on pasture and feedyard finished for 128 d (CON); 2) steers grass-fed for 20 mo (GF20); 3) steers grass-fed for 20 mo with a 45-d grain finish (GR45); and 4) steers grass-fed for 25 mo (GF25). The data were analyzed using a mixed model procedure in R with differences between treatments determined by Tukey HSD. Using carcass and performance data from these systems, a weaning-to-harvest life cycle assessment was developed in the Scalable, Process-based, Agronomically Responsive Cropping Systems model framework, to determine global warming potential (GWP), consumable water use, energy, smog, and land occupation footprints. Final body weight varied significantly between treatments (P < 0.001) with the CON cattle finishing at 632 kg, followed by GF25 at 570 kg, GR45 at 551 kg, and GF20 478 kg. Dressing percentage differed significantly between all treatments (P < 0.001). The DP was 61.8% for CON followed by GR45 at 57.5%, GF25 at 53.4%, and GF20 had the lowest DP of 50.3%. Marbling scores were significantly greater for CON compared to all other treatments (P < 0.001) with CON marbling score averaging 421 (low-choice ≥ 400). Breakeven costs with harvesting and marketing for the CON, GF20, GR45, and GF25 were $6.01,$8.98, $8.02, and$8.33 per kg hot carcass weight (HCW), respectively. The GWP for the CON, GF20, GR45, and GF25 were 4.79, 6.74, 6.65, and 8.31 CO2e/kg HCW, respectively. Water consumptive use for CON, GF20, GR45, and GF25 were 933, 465, 678, and 1,250 L/kg HCW, respectively. Energy use for CON, GF20, GR45, and GF25 were 18.7, 7.65, 13.8, and 8.85 MJ/kg HCW, respectively. Our results indicated that grass-fed beef systems differ in both animal performance and carcass quality resulting in environmental and economic sustainability trade-offs with no system having absolute superiority

Potential for critical mineral deposits in Maine, USA

An analysis of the potential for deposits of critical minerals and elements in Maine presented here includes data and discussions for antimony, beryllium, cesium, chromium, cobalt, graphite, lithium, manganese, niobium, platinum group elements, rhenium, rare earth elements, tin, tantalum, tellurium, titanium, uranium, vanadium, tungsten, and zirconium. Deposits are divided into two groups based on geological settings and common ore-deposit terminology. One group consists of known deposits (sediment-hosted manganese, volcanogenic massive sulphide, porphyry copper-molybdenum, mafic- and ultramafic-hosted nickel-copper [-cobalt-platinum group elements], pegmatitic lithium-cesium-tantalum) that are in most cases relatively large, well-documented, and have been explored extensively in the past. The second, and much larger group of different minerals and elements, comprises small deposits, prospects, and occurrences that are minimally explored or unexplored. The qualitative assessment used in this study relies on three key criteria: (1) the presence of known deposits, prospects, or mineral occurrences; (2) favourable geologic settings for having certain deposit types based on current ore deposit models; and (3) geochemical anomalies in rocks or stream sediments, including panned concentrates. Among 20 different deposit types considered herein, a high resource potential is assigned only to three: (1) sediment-hosted manganese, (2) mafic- and ultramafic-hosted nickel-copper(-cobalt-platinum group elements), and (3) pegmatitic lithium-cesium-tantalum. Moderate potential is assigned to 11 other deposit types, including: (1) porphyry copper-molybdenum (-rhenium, selenium, tellurium, bismuth, platinum group elements); (2) chromium in ophiolites; (3) platinum group elements in ophiolitic ultramafic rocks; (4) granite-hosted uranium-thorium; (5) tin in granitic plutons and veins; (6) niobium, tantalum, and rare earth elements in alkaline intrusions; (7) tungsten and bismuth in polymetallic veins; (8) vanadium in black shales; (9) antimony in orogenic veins and replacements; (10) tellurium in epithermal deposits; and (11) uranium in peat.L’analyse du potentiel de gîtes de minéraux et d’éléments critiques au Maine exposée aux présentes comporte des données et des examens concernant l’antimoine, le béryllium, le césium, le chrome, le cobalt, le graphite, le lithium, le manganèse, le niobium, les éléments du groupe du platine, le rhénium, les éléments des terres rares, l’étain, le tantale, le tellure, le titane, l’uranium, le vanadium, le tungstène et le zirconium. Les gîtes sont répartis en deux groupes selon les cadres géologiques et la terminologie des minéraux métallifères communs. Un groupe est constitué de gîtes connus [manganèse dans des roches sédimentaires, sulfures massifs volcanogènes, gîtes porphyriques de cuivre-molybdène nickel-cuivre (-cobalt-éléments du groupe du platine) dans des roches mafiques et ultramafiques ainsi que gisements pegmatitiques de lithium-césium-tantale] qui sont dans la majorité des cas relativement vastes, qui sont bien documentés et qui ont fait l’objet d’une exploration poussée par le passé. Le second groupe, beaucoup plus nombreux, de minéraux et d’éléments différents, est composé de petits gîtes, de zones prometteuses et de venues ayant été peu explorées ou inexplorées. L’évaluation qualitative utilisée dans le cadre de l’étude repose sur trois critères clés : 1) la présence de gîtes, de zones prometteuses ou de venues minérales connus; 2) les cadres géologiques favorables en raison de la présence de certains types de gîtes basés sur les modèles de dépôts de minerai courants; et 3) les anomalies géochimiques dans les roches ou les sédiments fluviatiles, notamment les concentrés lavés à la batée. Parmi les 20 différents types de gîtes considérés aux présentes, seuls trois se voient conférer un potentiel de ressources élevé : 1) les gîtes de manganèse dans des roches sédimentaires, 2) le nickel-cuivre (-cobalt-éléments du groupe du platine) dans des roches mafiques et ultramafiques, et 3) les gîtes pegmatitiques de lithium-césium-tantale. Un potentiel moyen est attribué à 11 autres types de gîtes, notamment : les gîtes porphyriques de cuivre-molybdène (-rhénium, sélénium, tellure, bismuth, éléments du groupe du platine); 2) le chrome dans des ophiolites; 3) les éléments du groupe du platine dans des roches ultramafiques ophiolitiques; 4) l’uranium-thorium dans du granite; 5) l’étain dans des plutons et filons granitiques; 6) le niobium, le tantale et les éléments des terres rares dans des intrusions alcalines; 7) le tungstène et le bismuth dans des filons polymétalliques; 8) le vanadium dans des schistes noirs; 9) des filons orogéniques et des substitutions; 10) le tellure dans des gîtes épithermaux et 11) l’uranium dans la tourbe

Potentiel de gîtes de minéraux critiques au Maine, États-Unis

An analysis of the potential for deposits of critical minerals and elements in Maine presented here includes data and discussions for antimony, beryllium, cesium, chromium, cobalt, graphite, lithium, manganese, niobium, platinum group elements, rhenium, rare earth elements, tin, tantalum, tellurium, titanium, uranium, vanadium, tungsten, and zirconium. Deposits are divided into two groups based on geological settings and common ore-deposit terminology. One group consists of known deposits (sediment-hosted manganese, volcanogenic massive sulphide, porphyry copper-molybdenum, mafic- and ultramafic-hosted nickel-copper [-cobalt-platinum group elements], pegmatitic lithium-cesium-tantalum) that are in most cases relatively large, well-documented, and have been explored extensively in the past. The second, and much larger group of different minerals and elements, comprises small deposits, prospects, and occurrences that are minimally explored or unexplored. The qualitative assessment used in this study relies on three key criteria: (1) the presence of known deposits, prospects, or mineral occurrences; (2) favourable geologic settings for having certain deposit types based on current ore deposit models; and (3) geochemical anomalies in rocks or stream sediments, including panned concentrates. Among 20 different deposit types considered herein, a high resource potential is assigned only to three: (1) sediment-hosted manganese, (2) mafic- and ultramafic-hosted nickel-copper(-cobalt-platinum group elements), and (3) pegmatitic lithium-cesium-tantalum. Moderate potential is assigned to 11 other deposit types, including: (1) porphyry copper-molybdenum (-rhenium, selenium, tellurium, bismuth, platinum group elements); (2) chromium in ophiolites; (3) platinum group elements in ophiolitic ultramafic rocks; (4) granite-hosted uranium-thorium; (5) tin in granitic plutons and veins; (6) niobium, tantalum, and rare earth elements in alkaline intrusions; (7) tungsten and bismuth in polymetallic veins; (8) vanadium in black shales; (9) antimony in orogenic veins and replacements; (10) tellurium in epithermal deposits; and (11) uranium in peat.L’analyse du potentiel de gîtes de minéraux et d’éléments critiques au Maine exposée aux présentes comporte des données et des examens concernant l’antimoine, le béryllium, le césium, le chrome, le cobalt, le graphite, le lithium, le manganèse, le niobium, les éléments du groupe du platine, le rhénium, les éléments des terres rares, l’étain, le tantale, le tellure, le titane, l’uranium, le vanadium, le tungstène et le zirconium. Les gîtes sont répartis en deux groupes selon les cadres géologiques et la terminologie des minéraux métallifères communs. Un groupe est constitué de gîtes connus [manganèse dans des roches sédimentaires, sulfures massifs volcanogènes, gîtes porphyriques de cuivre-molybdène nickel-cuivre (-cobalt-éléments du groupe du platine) dans des roches mafiques et ultramafiques ainsi que gisements pegmatitiques de lithium-césium-tantale] qui sont dans la majorité des cas relativement vastes, qui sont bien documentés et qui ont fait l’objet d’une exploration poussée par le passé. Le second groupe, beaucoup plus nombreux, de minéraux et d’éléments différents, est composé de petits gîtes, de zones prometteuses et de venues ayant été peu explorées ou inexplorées. L’évaluation qualitative utilisée dans le cadre de l’étude repose sur trois critères clés : 1) la présence de gîtes, de zones prometteuses ou de venues minérales connus; 2) les cadres géologiques favorables en raison de la présence de certains types de gîtes basés sur les modèles de dépôts de minerai courants; et 3) les anomalies géochimiques dans les roches ou les sédiments fluviatiles, notamment les concentrés lavés à la batée. Parmi les 20 différents types de gîtes considérés aux présentes, seuls trois se voient conférer un potentiel de ressources élevé : 1) les gîtes de manganèse dans des roches sédimentaires, 2) le nickel-cuivre (-cobalt-éléments du groupe du platine) dans des roches mafiques et ultramafiques, et 3) les gîtes pegmatitiques de lithium-césium-tantale. Un potentiel moyen est attribué à 11 autres types de gîtes, notamment : les gîtes porphyriques de cuivre-molybdène (-rhénium, sélénium, tellure, bismuth, éléments du groupe du platine); 2) le chrome dans des ophiolites; 3) les éléments du groupe du platine dans des roches ultramafiques ophiolitiques; 4) l’uranium-thorium dans du granite; 5) l’étain dans des plutons et filons granitiques; 6) le niobium, le tantale et les éléments des terres rares dans des intrusions alcalines; 7) le tungstène et le bismuth dans des filons polymétalliques; 8) le vanadium dans des schistes noirs; 9) des filons orogéniques et des substitutions; 10) le tellure dans des gîtes épithermaux et 11) l’uranium dans la tourbe

Effect of Material Structure on Photoluminescence of ZnO/MgO Core-Shell Nanowires

Zinc oxide (ZnO) nanowires are widely studied for use in ultraviolet optoelectronic devices, such as nanolasers and sensors. Nanowires (NWs) with an MgO shell exhibit enhanced band-edge photoluminescence (PL), a result previously attributed to passivation of ZnO defects. However, we find that processing the ZnO NWs under low oxygen partial pressure leads to an MgO-thickness-dependent PL enhancement owing to the formation of optical cavity modes. Conversely, processing under higher oxygen partial pressure leads to NWs that support neither mode formation nor band-edge PL enhancement. High-resolution electron microscopy and density-functional calculations implicate the ZnO m-plane surface morphology as the key determinant of core-shell structure and cavity-mode optics. A ZnO surface with atomic steps along the m-plane in the c-axis direction stimulates the growth of a smooth MgO shell that supports guided-wave optical modes and enhanced UV PL. On the other hand, a smoother ZnO surface leads to nucleation of a rough cladding layer which supports neither enhanced UV PL nor optical cavity modes. Finite-element analysis shows a clear correlation between allowed Fabry-Perot and whispering gallery modes and enhanced UV-PL. These results point the way to fabricating ZnO/MgO core-shell nanowires for more efficient UV nanolasers, scintillators, and sensors