bluuebunny/crossref_metadata_2025_split huggingface dataset:
Present‐Day Activity of the Anninghe Fault and Zemuhe Fault, Southeastern Tibetan Plateau, Derived From Soil Gas CO2Emissions and Locking Degree
Authors: Yang Yao , Li Ying , Li Youguo , Ji Lingyun , Gong Yue , Du Fang , Zhang Lei , Chen Zhi 
Published: August 2021

AbstractThe Anninghe fault (ANHF) and the Zemuhe fault (ZMHF), located in the southeast of the Tibetan Plateau, have a high level of seismic hazard and are among the most active faults in China. This study performed the first measurements of soil gas CO2at three sites across the ANHF and the ZMHF. The fault locking (FL) depth and extent of different segments of the ANHF and the ZMHF were inverted using the negative dislocation model based on global positioning system velocity data acquired during 2009–2015. Results showed that the degassing intensity of CO2in the ZMHF is substantially higher than in the ANHF, which is spatially consistent with the degree of inverted FL. The inversion results revealed that the level of coupling, including the locking depth and extent, along the southern segment of the ANHF is markedly greater than in the northern segment of the ZMHF. Soil gas CO2geochemistry yielded different spatially anomalous features, indicating that the faults have different properties and permeability. The intensive locking of the ANHF and ZMHF segments has reduced permeability through self‐sealing processes, which has restricted the escape of gas from the deep crust. Correspondingly, a creeping fault with a low level of coupling could maintain high permeability, which would be favorable for CO2migration.
Radio Frequency Characteristics of Volcanic Lightning and Vent Discharges
Authors: Behnke Sonja A. , Edens Harald , Senay Seda , Iguchi Masato , Miki Daisuke 
Published: August 2021

AbstractIn this study, we analyze the pulse width and spectral content of vent discharges and volcanic lightning flashes. We made measurements of electrical activity with a broadband very high frequency antenna (20–80 MHz) during an explosive eruption of Sakurajima volcano on November 8, 2019. The individual impulses that comprise vent discharges and volcanic lightning were analyzed to determine the fundamental width of the impulses and the rate of fall‐off of their energy spectral density. The results show that vent discharges are more similar to volcanic lightning than they are different. The mean pulse width for both vent discharges and volcanic lightning was 50 ns. Both types of electrical activity had similar spectral content; the average slope of the amplitude spectra was −3.4 for both. Further, examination of the pulse width and spectral slope distributions showed that while the distributions of volcanic lightning and vent discharges are statistically distinct from each other, the distribution of vent discharges is a subset of the distribution of volcanic lightning.
Reconciling the Infrared and Microwave Observations of the Lunar South Pole: A Study on Subsurface Temperature and Regolith Density
Authors: Feng Jianqing , Siegler Matthew A. 
Published: August 2021

AbstractThe Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter and the Microwave Radiometer (MRM) onboard Chang'e‐2 (CE‐2) orbiter performed nearly coincident measurements of the lunar south polar region in 2010–2011. In this study, we reconcile infrared data from Diviner and microwave data from MRM to reveal thermal behavior of lunar regolith at very low temperatures. Assuming a uniform density structure and dielectric properties across the polar region, we retrieve a relative apparent thermal‐gradient map based on radiative transfer model. The result shows apparent thermal gradients in the permanently shadowed regions (PSRs) are much larger than that in non‐PSRs, which implies a systematic difference in thermal conductivity and/or density of lunar regolith in PSRs. We also model surface temperature and microwave brightness temperature over time in PSR and non‐PSR locations. The modeling results at these representative locations and the thermal gradient map confirm that the regolith in the PSRs is consistent with a much lower thermal conductivity and higher porosity than non‐PSRs.
Impacts of Drying and Rewetting on the Radiocarbon Signature of Respired CO2 and Implications for Incubating Archived Soils
Authors: Beem‐Miller Jeffrey , Schrumpf Marion , Hoyt Alison M. , Guggenberger Georg , Trumbore Susan 
Published: August 2021

AbstractThe radiocarbon signature of respired CO2 (∆14C‐CO2) measured in laboratory soil incubations integrates contributions from soil carbon pools with a wide range of ages, making it a powerful model constraint. Incubating archived soils enriched by “bomb‐C” from mid‐20th century nuclear weapons testing would be even more powerful as it would enable us to trace this pulse over time. However, air‐drying and subsequent rewetting of archived soils, as well as storage duration, may alter the relative contribution to respiration from soil carbon pools with different cycling rates. We designed three experiments to assess air‐drying and rewetting effects on ∆14C‐CO2 with constant storage duration (Experiment 1), without storage (Experiment 2), and with variable storage duration (Experiment 3). We found that air‐drying and rewetting led to small but significant (α < 0.05) shifts in ∆14C‐CO2 relative to undried controls in all experiments, with grassland soils responding more strongly than forest soils. Storage duration (4–14 y) did not have a substantial effect. Mean differences (95% CIs) for experiments 1, 2, and 3 were: 23.3‰ (±6.6), 19.6‰ (±10.3), and 29.3‰ (±29.1) for grassland soils, versus −11.6‰ (±4.1), 12.7‰ (±8.5), and −24.2‰ (±13.2) for forest soils. Our results indicate that air‐drying and rewetting soils mobilizes a slightly older pool of carbon that would otherwise be inaccessible to microbes, an effect that persists throughout the incubation. However, as the bias in ∆14C‐CO2 from air‐drying and rewetting is small, measuring ∆14C‐CO2 in incubations of archived soils appears to be a promising technique for constraining soil carbon models.
Phosphorus Regulation of Methane Oxidation in Water From Ice‐Covered Lakes
Authors: Sawakuchi Henrique O. , Martin Gaëtan , Peura Sari , Bertilsson Stefan , Karlsson Jan , Bastviken David 
Published: August 2021

AbstractWinter methane (CH4) accumulation in seasonally ice‐covered lakes can contribute to large episodic emissions to the atmosphere during spring ice melt. Biological methane oxidation can significantly mitigate such CH4 emissions, but despite favorable CH4 and O2 concentrations, CH4 oxidation appears constrained in some lakes for unknown reasons. Here we experimentally test the hypothesis that phosphorus (P) availability is limiting CH4 oxidation, resulting in differences in ice‐out emissions among lakes. We observed a positive relationship between potential CH4 oxidation and P concentration across 12 studied lakes and found an increase in CH4 oxidation in response to P amendment, without any parallel change in the methanotrophic community composition. Hence, while an increase in sedimentary CH4 production and ebullitive emissions may happen with eutrophication, our study indicates that the increase in P associated with eutrophication may also enhance CH4 oxidation. The increase in CH4 oxidation may hence play an important role in nutrient‐rich ice‐covered lakes where bubbles trapped under the ice may to a greater extent be oxidized, reducing the ice‐out emissions of CH4. This may be an important factor regulating CH4 emissions from high latitude lakes.
Quantifying the Health Benefits of Face Masks and Respirators to Mitigate Exposure to Severe Air Pollution
Authors: Kodros John K. , O’Dell Katelyn , Samet Jonathan M. , L’Orange Christian , Pierce Jeffrey R. , Volckens John 
Published: August 2021

AbstractFamiliarity with the use of face coverings to reduce the risk of respiratory disease has increased during the coronavirus pandemic; however, recommendations for their use outside of the pandemic remains limited. Here, we develop a modeling framework to quantify the potential health benefits of wearing a face covering or respirator to mitigate exposure to particulate air pollution. This framework accounts for the wide range of available face coverings and respirators, fit factors and efficacy, air pollution characteristics, and exposure‐response data. Our modeling shows that N95 respirators offer robust protection against different sources of particulate matter, reducing exposure by more than a factor of 14 when worn with a leak rate of 5%. Synthetic‐fiber masks offer less protection with a strong dependence on aerosol size distribution (protection factors ranging from 4.4 to 2.2), while natural‐fiber and surgical masks offer reductions in the exposure of 1.9 and 1.7, respectively. To assess the ability of face coverings to provide population‐level health benefits to wildfire smoke, we perform a case study for the 2012 Washington state fire season. Our models suggest that although natural‐fiber masks offer minor reductions in respiratory hospitalizations attributable to smoke (2%–11%) due to limited filtration efficiency, N95 respirators and to a lesser extent surgical and synthetic‐fiber masks may lead to notable reductions in smoke‐attributable hospitalizations (22%–39%, 9%–24%, and 7%–18%, respectively). The filtration efficiency, bypass rate, and compliance rate (fraction of time and population wearing the device) are the key factors governing exposure reduction potential and health benefits during severe wildfire smoke events.
Melting of Bridgmanite Under Hydrous Shallow Lower Mantle Conditions
Authors: Amulele George , Karato Shun‐ichiro , Girard Jennifer 
Published: August 2021

AbstractHigh pressure and temperature experiments were carried out on the oxide mixtures corresponding to the bridgmanite stoichiometry under the hydrous shallow lower mantle conditions (24–25 GPa and 1673–1873 K with 5–10 wt. % of water in the starting material). Oxide mixtures investigated correspond to MgSiO3, (Mg, Fe)SiO3, (Mg, Al, Si)O3, and (Mg, Fe, Al, Si)O3. Melting was observed in all runs. Partitioning of various elements, including Mg, Fe, Si, and H is investigated. Melting under hydrous lower mantle conditions leads to increased (Mg + Fe)O/SiO2in the melt compared to the residual solids. The residual solids often contain a large amount of stishovite, and the melt contains higher (Mg,Fe)O/SiO2ratio than the initial material. (Mg + Fe)O‐rich hydrous melt could explain the low‐velocity anomalies observed in the shallow lower mantle and a large amount of stishovite in the residual solid may be responsible for the scattering of seismic waves in the mid‐lower mantle and may explain the “stishovite paradox." Since stishovite‐rich materials are formed only when silica‐rich source rock (MORB) is melted (not a typical peridotitic rock [bulk silicate Earth]), seismic scattering in the lower mantle provides a clue on the circulation of subducted MORB materials. To estimate hydrogen content, we use a new method of estimating the water content of unquenchable melts, and also propose a new interpretation of the significance of superhydrous phase B inclusions in bridgmanite. The results provide revised values of water partitioning between solid minerals and hydrous melts that are substantially higher than previous estimates.
Tidal Triggering of Microseismicity at the Equatorial Mid‐Atlantic Ridge, Inferred From the PI‐LAB Experiment
Authors: Leptokaropoulos K. , Harmon N. , Hicks S. P. , Rychert C. A. , Schlaphorst D. , Kendall J. M. 
Published: August 2021

AbstractThe gravitational pulls from the moon and the sun result in tidal forces which influence both Earth's solid and water mass. These stresses are periodically added to the tectonic ones and may become sufficient for initiating rupture in fault systems critically close to failure. Previous research indicates correlations between increased seismicity rates and low tides for fast‐ and intermediate‐spreading mid‐ocean ridges in the Pacific Ocean. Here, we present a microseismicity data set (4,719 events) recorded by an ocean bottom seismometer deployment at the equatorial Mid‐Atlantic Ridge. We show that low, as well as decreasing ocean water level, result in relatively elevated seismicity rates at higher magnitudes (lower b‐values), translated into increased probabilities of stronger event occurrence at or towards low tides. Moreover, seismic bursts (enhanced activity rate clusters), occurring at rates well above the reference seismicity, are exclusively present during values of either high tidally induced extensional stresses or high extensional stress rates. Although the b‐value differences are not significant enough to be conclusive, the seismicity rate variations exhibit statistical significance, supporting the previous findings for tidal triggering at low tides within normal‐faulting regimes and extending the range of observations to slow‐spreading ridges. Observed triggering of slip on low angle faults at low tides is predicted by Coulomb stress modeling. The triggering of slip on high angle faults observed here, is not easily explained without another factor. It may be related to the presence of a shallow magma body beneath the ridge, as supported by previous seismic imaging in the region.
Is the Grain Size Distribution a Key Parameter for Explaining the Long Runout of Granular Avalanches?
Authors: Cabrera Miguel , Estrada Nicolas 
Published: August 2021

AbstractBy means of the Discrete Element Method, we investigate the relationship between the power‐law exponent of the grain size distribution (GSD) and the mobility of granular transitional flows. This is done with the aim of testing a recently posed hypothesis, suggesting that high power‐law exponents are related to the large mobility observed in natural mass flows (Lai et al., 2017, https://doi.org/10.1002/2017gl075689), as a consequence of a lubrication mechanism in which small grains act as rotational bearings reducing the shear strength of the flowing mass. We show that both the mobility of the flow and the shear strength of the material are independent of the GSD power‐law exponent, as long as the system‐to‐grain size ratio of the studied system is sufficiently large, as it is expected in natural granular flows. This confirms that the power‐law exponent, or the proportion of small and big grains, are not plausible origins of the large mobility of granular avalanches.
Geological History of Southeastern Gorgonum Chaos, Mars: A Story of Water and Wind
Authors: Haack David , Adeli Solmaz , Hauber Ernst 
Published: August 2021

AbstractGorgonum Chaos is part of the Eridania paleolake in Terra Sirenum and displays a number of prominent light‐toned morphological features that bear a record of the regional climatic conditions throughout most of Martian history. Based on an intergrated analysis of orbital data, we mapped a 1,500 km2 area in the southeast of Gorgonum Chaos. Morphologic, spectroscopic, and stratigraphic analyses were used to determine age and composition of the main geological units in the area. We identified four major geological units with decreasing content of hydrated minerals from the oldest to the youngest units, which were completely free of hydrated minerals. In the study area, phyllosilicate‐rich Noachian units compose the majority of the basin floor. Deposits enriched with evaporites were formed around the Noachian/Hesperian transition and erosion created prominent inverted morphologies. Loess‐like material without significant amounts of hydrated minerals was deposited until the late Hesperian. The youngest unit is an Amazonian layer free of hydrated minerals that originated from volcanic activities. This succession of minerals reflects the transition from more humid climatic conditions with the ability to sustain liquid water on the planet's surface during the Noachian to the hyper‐arid Amazonian environment we observe currently on Mars.
Gravity Wave Packets in the Venusian Atmosphere Observed by Radio Occultation Experiments: Comparison With Saturation Theory
Authors: Mori Ryota , Imamura Takeshi , Ando Hiroki , Häusler Bernd , Pätzold Martin , Tellmann Silvia 
Published: August 2021

AbstractThe characteristics of gravity wave packets in the Venusian atmosphere were studied using high‐vertical‐resolution temperature profiles obtained by ESA's Venus Express and JAXA's Akatsuki radio occultation experiments with radio holographic methods. Localized disturbances were detected by applying a wavelet transform to the temperature profiles. The packet lengths were found to be distributed over 0.6–10 km, in which typically 1.5–4.0 oscillations are included. The number of oscillations per wave packet was found to have only a slight dependence on the wavelength, which is consistent with the −3 power law dependence of the spectral density on the wavenumber in the saturation model. The spectral densities of the wave packets are roughly aligned with the power law of the saturation model, while the saturation ratio for each quasi‐monochromatic wave is low. This suggests that the saturated spectrum is produced by the superposition of individually unsaturated quasi‐monochromatic waves. Waves with short vertical wavelengths (<1.5 km) were found to be more prevalent at lower altitudes than at higher altitudes, implying an effect of radiative damping during upward propagation. The amplitude was found to be larger at higher latitudes, which might be attributed to an increase in background static stability at high latitudes, which allows larger saturation amplitudes.
Late Holocene Precipitation Fluctuations in South America Triggered by Variability of the North Atlantic Overturning Circulation
Authors: Bahr A. , Kaboth‐Bahr S. , Jaeschke A. , Chiessi C. , Cruz F. , Carvalho L. , Rethemeyer J. , Schefuß E. , Geppert P. , Albuquerque A. L. , Pross J. , Friedrich O. 
Published: August 2021

AbstractHistoric droughts document the strong spatio‐temporal variability of the South American Monsoon System, which currently provides more than two thirds of the rainfall in tropical South America. The drivers of this variability have remained not well understood due to the lack of continuous, high‐resolution paleorecords, especially from the more arid regions of tropical South America. Here we present a novel record of moisture availability across eastern South America for the past ∼5,000 years from a sediment core retrieved off eastern Brazil. We document distinct decadal‐ to millennial‐scale spatial shifts of major atmospheric convection centers that caused increasingly pronounced droughts in eastern South America over the past ∼2,000 years. These fluctuations were triggered by climate anomalies in the high northern latitudes and propagated into equatorial latitudes via fluctuations in North Atlantic Overturning Circulation strength. As global warming is expected to decrease oceanic overturning due to enhanced meltwater input into the North Atlantic while at the same time reducing precipitation over eastern South America, an increasing risk for long‐lasting droughts can be expected for this region, posing severe socio‐economic challenges.
Pedestrian exposure to black carbon and PM2.5 emissions in urban hot spots: new findings using mobile measurement techniques and flexible Bayesian regression models
Authors: Alas Honey Dawn , Stöcker Almond , Umlauf Nikolaus , Senaweera Oshada , Pfeifer Sascha , Greven Sonja , Wiedensohler Alfred 
Published: August 2021

Abstract
Background
Data from extensive mobile measurements (MM) of air pollutants provide spatially resolved information on pedestrians’ exposure to particulate matter (black carbon (BC) and PM2.5 mass concentrations).

Objective
We present a distributional regression model in a Bayesian framework that estimates the effects of spatiotemporal factors on the pollutant concentrations influencing pedestrian exposure.

Methods
We modeled the mean and variance of the pollutant concentrations obtained from MM in two cities and extended commonly used lognormal models with a lognormal-normal convolution (logNNC) extension for BC to account for instrument measurement error.

Results
The logNNC extension significantly improved the BC model. From these model results, we found local sources and, hence, local mitigation efforts to improve air quality, have more impact on the ambient levels of BC mass concentrations than on the regulated PM2.5.

Significance
Firstly, this model (logNNC in bamlss package available in R) could be used for the statistical analysis of MM data from various study areas and pollutants with the potential for predicting pollutant concentrations in urban areas. Secondly, with respect to pedestrian exposure, it is crucial for BC mass concentration to be monitored and regulated in areas dominated by traffic-related air pollution.
Resilience and personality as predictors of the biological stress load during the first wave of the Covid-19 pandemic in Germany
Authors: Engert Veronika , Blasberg Jost U. , Köhne Sophie , Strauss Bernhard , Rosendahl Jenny 
Published: August 2021

AbstractSince the Covid-19 outbreak, pandemic-specific stressors have potentiated the—already severe—stress load across the world. However, stress is more than an adverse state, and chronic exposure is causally involved in the development of mental and physical disease. We ask the question whether resilience and the Big Five personality traits predict the biological stress response to the first lockdown in Germany. In a prospective, longitudinal, observational study, N = 80 adult volunteers completed an internet-based survey prior to the first Covid-19-related fatality in Germany (T0), during the first lockdown period (T1), and during the subsequent period of contact restrictions (T2). Hair strands for the assessment of systemic cortisol and cortisone levels were collected at T2. Higher neuroticism predicted higher hair cortisol, cortisone and subjective stress levels. Higher extraversion predicted higher hair cortisone levels. Resilience showed no effects on subjective or physiological stress markers. Our study provides longitudinal evidence that neuroticism and extraversion have predictive utility for the accumulation of biological stress over the course of the pandemic. While in pre-pandemic times individuals high in neuroticism are typically at risk for worse health outcomes, extraverted individuals tend to be protected. We conclude that, in the pandemic context, we cannot simply generalize from pre-pandemic knowledge. Neurotic individuals may currently suffer due to their general emotional lability. Extraverted individuals may primarily be socially stressed. Individualized stress management programs need to be developed, and offered in a lockdown-friendly format, to minimize the stress burden caused by Covid-19 or future pandemics and to protect the most severely affected individuals from the development of stress-associated disease.