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  • ddc:550.724  (15)
  • GPS  (9)
  • Additives
  • perovskiteferroelectricpowder neutron diffraction
  • Springer Berlin Heidelberg  (25)
  • American Chemical Society
  • International Union of Crystallography (IUCr)
  • 1
    Publication Date: 2020-10-14
    Description: We present an up-to-date high resolution picture of the ongoing crustal deformation field of Iberian region, based on an extensive combination of permanent and non-permanent GPS observations carried out since 1999. We detected appreciable deformation along the NW and SE margins of the Iberian Peninsula and along the Gibraltar arc, while on the inner parts of the peninsula, the crustal deformation occurs locally at rate 〈 15 nanostrain/year.
    Description: Published
    Description: 369-372
    Description: 1T. Geodinamica e interno della Terra
    Description: restricted
    Keywords: GPS ; Strain-rate ; Plate motion ; Iberia ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 2
    Publication Date: 2019-12-05
    Description: The analysis of Global Positioning System (GPS) coordinates time series is a valuable tool in quantifying crustal deformations. The longer continuous GPS time series allow estimation of nonlinear signatures. As a matter of fact, besides the linear and periodic behaviors, other relevant signals are present in such time series as the so-called transient deformations. They can be related to, e.g., slow slip events, which play a crucial role in studying fault mechanisms. To give reliable estimates of these signals, an appropriate and rigorous approach for defining the deterministic and the stochastic models of the data is needed. We prove that the theory of the second order stationary random process (SOSRP) can be used to describe the stochastic behavior of the daily GPS time series. In particular, the second order stationarity condition has to be verified for the daily GPS coordinate time series to be described as a SOSRP. This method has been already used for modeling the gravity field of the earth and in predicting/filtering problems, and this work shows that it can also be useful for characterizing the colored noise in the GPS time series.
    Description: Published
    Description: id 86
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: GPS ; time series ; Stationary stochastic process ; Auto-covariance function ; Power law spectrum ; 04.03. Geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2022-10-26
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Walsh, A. N., Reddy, C. M., Niles, S. F., McKenna, A. M., Hansel, C. M., & Ward, C. P. Plastic formulation is an emerging control of its photochemical fate in the ocean. Environmental Science & Technology, 55(18), (2021): 12383–12392, https://doi.org/10.1021/acs.est.1c02272.
    Description: Sunlight exposure is a control of long-term plastic fate in the environment that converts plastic into oxygenated products spanning the polymer, dissolved, and gas phases. However, our understanding of how plastic formulation influences the amount and composition of these photoproducts remains incomplete. Here, we characterized the initial formulations and resulting dissolved photoproducts of four single-use consumer polyethylene (PE) bags from major retailers and one pure PE film. Consumer PE bags contained 15–36% inorganic additives, primarily calcium carbonate (13–34%) and titanium dioxide (TiO2; 1–2%). Sunlight exposure consistently increased production of dissolved organic carbon (DOC) relative to leaching in the dark (3- to 80-fold). All consumer PE bags produced more DOC during sunlight exposure than the pure PE (1.2- to 2.0-fold). The DOC leached after sunlight exposure increasingly reflected the 13C and 14C isotopic composition of the plastic. Ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry revealed that sunlight exposure substantially increased the number of DOC formulas detected (1.1- to 50-fold). TiO2-containing bags photochemically degraded into the most compositionally similar DOC, with 68–94% of photoproduced formulas in common with at least one other TiO2-containing bag. Conversely, only 28% of photoproduced formulas from the pure PE were detected in photoproduced DOC from the consumer PE. Overall, these findings suggest that plastic formulation, especially TiO2, plays a determining role in the amount and composition of DOC generated by sunlight. Consequently, studies on pure, unweathered polymers may not accurately represent the fates and impacts of the plastics entering the ocean.
    Description: Funding was provided by the Seaver Institute, the Gerstner Family Foundation, Woods Hole Oceanographic Institution, and the National Science Foundation Graduate Research Fellowship Program (A.N.W.). The Ion Cyclotron Resonance user facility at the National High Magnetic Field Laboratory is supported by the National Science Foundation Division of Chemistry and Division of Materials Research through DMR-1644779 and the State of Florida.
    Keywords: Plastic pollution ; Marine debris ; Additives ; Dissolved organic carbon ; Photochemical oxidation ; FT-ICR-MS ; Titanium dioxide
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-12-07
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in James, B., de Vos, A., Aluwihare, L., Youngs, S., Ward, C., Nelson, R., Michel, A., Hahn, M., & Reddy, C. Divergent forms of pyroplastic: lessons learned from the M/V X-Press Pearl ship fire. ACS Environmental Au, 2(5), (2022): 467–479, https://doi.org/10.1021/acsenvironau.2c00020.
    Description: In late May 2021, the M/V X-Press Pearl container ship caught fire while anchored 18 km off the coast of Colombo, Sri Lanka and spilled upward of 70 billion pieces of plastic or “nurdles” (∼1680 tons), littering the country’s coastline. Exposure to combustion, heat, chemicals, and petroleum products led to an apparent continuum of changes from no obvious effects to pieces consistent with previous reports of melted and burned plastic (pyroplastic) found on beaches. At the middle of this continuum, nurdles were discolored but appeared to retain their prefire morphology, resembling nurdles that had been weathered in the environment. We performed a detailed investigation of the physical and surface properties of discolored nurdles collected on a beach 5 days after the ship caught fire and within 24 h of their arrival onshore. The color was the most striking trait of the plastic: white for nurdles with minimal alteration from the accident, orange for nurdles containing antioxidant degradation products formed by exposure to heat, and gray for partially combusted nurdles. Our color analyses indicate that this fraction of the plastic released from the ship was not a continuum but instead diverged into distinct groups. Fire left the gray nurdles scorched, with entrained particles and pools of melted plastic, and covered in soot, representing partial pyroplastics, a new subtype of pyroplastic. Cross sections showed that the heat- and fire-induced changes were superficial, leaving the surfaces more hydrophilic but the interior relatively untouched. These results provide timely and actionable information to responders to reevaluate cleanup end points, monitor the recurrence of these spilled nurdles, gauge short- and long-term effects of the spilled nurdles to the local ecosystem, and manage the recovery of the spill. These findings underscore partially combusted plastic (pyroplastic) as a type of plastic pollution that has yet to be fully explored despite the frequency at which plastic is burned globally.
    Description: This work was supported by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution (WHOI), with funding provided by the Weston Howland Jr. Postdoctoral Scholarship. Additional support was provided by the WHOI Marine Microplastics Catalyst Program, the WHOI Marine Microplastics Innovation Accelerator Program, the WHOI Investment in Science Fund, the March Marine Initiative (a program of March Limited, Bermuda), The Seaver Institute, Gerstner Philanthropies, the Wallace Research Foundation, the Richard Saltonstall Charitable Foundation, the Harrison Foundation, Hollis and Ermine Lovell Charitable Foundation, and the Richard Grand Foundation. AdV was supported by funding from the Schmidt Foundation.
    Keywords: Microplastic ; Resin pellets ; Pollution ; Additives ; Open burning ; Weathering ; Maritime accident
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2023-06-21
    Description: Currently, many commercial airline aircraft cannot perform three-dimensionally guided approaches based on satellite-based augmentation systems. We propose a system to rebroadcast the correction and integrity data via a data link as provided by the ground-based augmentation system such that aircraft equipped with a GPS landing system (GLS) can use the wide-area corrections and perform localizer performance with vertical guidance (LPV) approaches while maintaining the same level of integrity. In consequence, the system loses some availability and the time to alert is slightly increased. We build a prototype system and present data collected for one week, confirming technical feasibility. There is a loss of 5.3 percent of availability during a 1-week data collection cycle in which we compared our system to standalone LPV service. We tested our prototype with two commercially available GLS receivers with positive results and successfully demonstrated the functionality with a conventional Airbus 319 equipped with a standard GLS receiver.
    Keywords: ddc:526 ; SBAS ; Satellite ; Navigation ; Augmentation ; Aviation ; GPS ; GNSS
    Language: English
    Type: doc-type:article
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  • 6
    Publication Date: 2023-06-20
    Description: Aufgrund deutlich erhöhter Wärmebedarfsdichten urbaner Räume besteht in besonderem Maße hier die Möglichkeit und Erfordernis, durch eine nachhaltige Wärmeversorgung und saisonale Wärmespeicherung im geologischen Untergrund einen wesentlichen Beitrag zu den national und international gesetzten Klimaschutzzielen zu liefern. Eine effiziente Möglichkeit zur Wärmegewinnung und -speicherung bieten hierfür Erdwärmesonden, die jedoch aus Gründen des vorbeugenden Grundwasserschutzes in Bereichen der Trinkwassernutzung heutzutage meist nicht oder nur beschränkt genehmigt werden. Numerische Simulationen einer Erdwärmesondenleckage für Randbedingungen eines zur Trinkwassergewinnung genutzten norddeutschen Aquifers auf Grundlage von aufgearbeiteten stoffspezifischen Abbauratenkonstanten zeigen, dass Grenzwerte für die meisten handelsüblichen Wärmeträgerfluid-Inhaltsstoffe bereits bei einem Abstand von nur 100 m zwischen Erdwärmesonde und Trinkwasserentnahme aufgrund starker Verdünnung und mikrobiellen Abbaus mit einem Faktor 〉 10 unterschritten werden. Vor dem Hintergrund dieser Ergebnisse und angesichts der Zielsetzung einer Reduktion fossiler Primärenergiequellen um 80–95 % bis 2050, erscheinen pauschale Abstandsvorgaben (von zurzeit 〉 1000 m) daher zumindest hinsichtlich der Trinkwassergefährdung durch Erdwärmesondenleckagen diskussionswürdig.
    Description: Christian-Albrechts-Universität zu Kiel (3094)
    Keywords: ddc:549 ; Borehole heat exchanger ; Heat transfer fluids ; Additives ; Groundwater ; Risk assessment
    Language: German
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  • 7
    Publication Date: 2023-06-22
    Description: The Sentinel-6 (or Jason-CS) altimetry mission provides a long-term extension of the Topex and Jason-1/2/3 missions for ocean surface topography monitoring. Analysis of altimeter data relies on highly-accurate knowledge of the orbital position and requires radial RMS orbit errors of less than 1.5 cm. For precise orbit determination (POD), the Sentinel-6A spacecraft is equipped with a dual-constellation GNSS receiver. We present the results of Sentinel-6A POD solutions for the first 6 months since launch and demonstrate a 1-cm consistency of ambiguity-fixed GPS-only and Galileo-only solutions with the dual-constellation product. A similar performance (1.3 cm 3D RMS) is achieved in the comparison of kinematic and reduced-dynamic orbits. While Galileo measurements exhibit 30–50% smaller RMS errors than those of GPS, the POD benefits most from the availability of an increased number of satellites in the combined dual-frequency solution. Considering obvious uncertainties in the pre-mission calibration of the GNSS receiver antenna, an independent inflight calibration of the phase centers for GPS and Galileo signal frequencies is required. As such, Galileo observations cannot provide independent scale information and the estimated orbital height is ultimately driven by the employed forces models and knowledge of the center-of-mass location within the spacecraft. Using satellite laser ranging (SLR) from selected high-performance stations, a better than 1 cm RMS consistency of SLR normal points with the GNSS-based orbits is obtained, which further improves to 6 mm RMS when adjusting site-specific corrections to station positions and ranging biases. For the radial orbit component, a bias of less than 1 mm is found from the SLR analysis relative to the mean height of 13 high-performance SLR stations. Overall, the reduced-dynamic orbit determination based on GPS and Galileo tracking is considered to readily meet the altimetry-related Sentinel-6 mission needs for RMS height errors of less than 1.5 cm.
    Description: Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (4202)
    Keywords: ddc:526 ; Sentinel-6 ; Jason-CS ; Single-receiver ambiguity fixing ; Precise orbit determination ; GPS ; Galileo ; SLR ; Altimetry
    Language: English
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  • 8
    Publication Date: 2023-06-23
    Description: Magmas vesiculate during ascent, producing complex interconnected pore networks, which can act as outgassing pathways and then deflate or compact to volcanic plugs. Similarly, in-conduit fragmentation events during dome-forming eruptions create open systems transiently, before welding causes pore sealing. The percolation threshold is the first-order transition between closed- and open-system degassing dynamics. Here, we use time-resolved, synchrotron-source X-ray tomography to image synthetic magmas that go through cycles of opening and closing, to constrain the percolation threshold ΦC at a range of melt crystallinity, viscosity and overpressure pertinent to shallow magma ascent. During vesiculation, we observed different percolative regimes for the same initial bulk crystallinity depending on melt viscosity and gas overpressure. At high viscosity (〉 106 Pa s) and high overpressure (~ 1–4 MPa), we found that a brittle-viscous regime dominates in which brittle rupture allows system-spanning coalescence at a low percolation threshold (ΦC~0.17) via the formation of fracture-like bubble chains. Percolation was followed by outgassing and bubble collapse causing densification and isolation of the bubble network, resulting in a hysteresis in the evolution of connectivity with porosity. At low melt viscosity and overpressure, we observed a viscous regime with much higher percolation threshold (ΦC 〉 0.37) due to spherical bubble growth and lower degree of crystal connection. Finally, our results also show that sintering of crystal-free and crystal-bearing magma analogues is characterised by low percolation thresholds (ΦC = 0.04 – 0.10). We conclude that the presence of crystals lowers the percolation threshold during vesiculation and may promote outgassing in shallow, crystal-rich magma at initial stages of Vulcanian and Strombolian eruptions.
    Description: Paul Scherrer Institut http://dx.doi.org/10.13039/501100004219
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: NERC
    Description: Deutsche Forschungsgemeinschaft
    Keywords: ddc:550.724 ; Effusive-explosive transition ; Percolation threshold ; Outgassing ; Crystal-rich magma ; Magma viscosity ; Gas overpressure ; Porosity ; Pore connectivity ; Hysteresis ; Strombolian/Vulcanian eruptions ; Dome-forming eruptions
    Language: English
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  • 9
    Publication Date: 2023-06-23
    Description: Magma ascent during silicic dome-forming eruptions is characterized by significant changes in magma viscosity, permeability, and gas overpressure in the conduit. These changes depend on a set of parameters such as ascent rate, outgassing and crystallization efficiency, and magma viscosity, which in turn may influence the prevailing conditions for effusive versus explosive activity. Here, we combine chemical and textural analyses of tephra with viscosity models to provide a better understanding of the effusive-explosive transitions during Vulcanian phases of the 9.4 ka eruption of Kilian Volcano, Chaîne des Puys, France. Our results suggest that effusive activity at the onset of Vulcanian episodes at Kilian Volcano was promoted by (i) rapid ascent of initially crystal-poor and volatile-rich trachytic magma, (ii) a substantial bulk and melt viscosity increase driven by extensive volatile loss and crystallization, and (iii) efficient degassing/outgassing in a crystal-rich magma at shallow depths. Trachytic magma repeatedly replenished the upper conduit, and variations in the amount of decompression and cooling caused vertical textural stratification, leading to variable degrees of crystallization and outgassing. Outgassing promoted effusive dome growth and occurred via gas percolation through large interconnected vesicles, fractures, and tuffisite veins, fostering the formation of cristobalite in the carapace and talus regions. Build-up of overpressure was likely caused by closing of pore space (bubbles and fractures) in the dome through a combination of pore collapse, cristobalite formation, sintering in tuffisite veins, and limited pre-fragmentation coalescence in the dome or underlying hot vesicular magma. Sealing of the carapace may have caused a transition from open- to closed- system degassing and to renewed explosive activity. We generalize our findings to propose that the broad spectrum of eruptive styles for trachytic magmas may be inherited from a combination of characteristics of trachytic melts that include high water solubility and diffusivity, rapid microlite growth, and low melt viscosity compared to their more evolved subalkaline dacitic and rhyolitic equivalents. We show that trachytes may erupt with a similar style (e.g., Vulcanian) but at significantly higher ascent rates than their andesitic, dacitic, and rhyolitic counterparts. This suggests that the periodicity of effusive-explosive transitions at trachytic volcanoes may differ from that observed at the well-monitored andesitic, dacitic, and rhyolitic volcanoes, which has implications for hazard assessment associated with trachytic eruptions.
    Description: ERC ADV 2018
    Keywords: ddc:550.724 ; Effusive-explosive transitions ; Trachytic magma ; Vulcanian eruption ; Magma Viscosity ; Crystallization ; Degassing ; Nanolites ; Cristobalite
    Language: English
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  • 10
    Publication Date: 2023-06-23
    Description: Subsurface magmatic–hydrothermal systems are often associated with elevated electrical conductivities in the Earthʼs crust. To facilitate the interpretation of these data and to allow distinguishing between the effects of silicate melts and fluids, the electrical conductivity of aqueous fluids in the system H 2 O–HCl was measured in an externally heated diamond anvil cell. Data were collected to 700 °C and 1 GPa, for HCl concentrations equivalent to 0.01, 0.1, and 1 mol/l at ambient conditions. The data, therefore, more than double the pressure range of previous measurements and extend them to geologically realistic HCl concentrations. The conductivities 𝜎 (in S/m) are well reproduced by a numerical model log 𝜎 = −2.032 + 205.8 T−1 + 0.895 log c + 3.888 log 𝜌 + logΛ0(T,𝜌), where T is the temperature in K, c is the HCl concentration in wt. %, and 𝜌 is the density of pure water at the corresponding pressure and temperature conditions. Λ0(T,𝜌) is the limiting molar conductivity (in S cm2 mol −1 ) at infinite dilution, Λ0(T,𝜌) = 2550.14 − 505.10𝜌 − 429,437 T−1 . A regression fit of more than 800 data points to this model yielded R2 = 0.95. Conductivities increase with pressure and fluid densities due to an enhanced dissociation of HCl. However, at constant pressures, conductivities decrease with temperature because of reduced dissociation. This effect is particularly strong at shallow crustal pressures of 100–200 MPa and can reduce conductivities by two orders of magnitude. We, therefore, suggest that the low conductivities sometimes observed at shallow depths below the volcanic centers in magmatic–hydrothermal systems may simply reflect elevated temperatures. The strong negative temperature effect on fluid conductivities may offer a possibility for the remote sensing of temperature variations in such systems and may allow distinguishing the effects of magma intrusions from changes in hydrothermal circulation. The generally very high conductivities of HCl–NaCl–H 2 O fluids at deep crustal pressures (500 MPa–1 GPa) imply that electrical conductors in the deep crust, as in the Altiplano magmatic province and elsewhere, may at least partially be due to hydrothermal activity.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Universität Bayreuth (3145)
    Keywords: ddc:550.724 ; Electrical conductivity ; Fluid ; HCl ; Hydrothermal systems ; Magnetotelluric data
    Language: English
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