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  • 04.08. Volcanology  (13)
  • Climate change  (5)
  • Archean atmosphere  (2)
  • Elsevier  (20)
  • Annual Reviews
  • De Gruyter
  • 2020-2023  (20)
  • 1935-1939
  • 1
    Publication Date: 2022-04-01
    Description: Volcanic hazard assessment relies on the accurate knowledge of the eruptive style and recurrence of volcanic eruptions in the past. At El Hierro (Canary Islands) historical and prehistorical records are still poorly defined, and although the island was the location of one of the most recent eruptions (La Restinga, 2011 CE) of the Canarian archipelago, the recent subaerial volcanism is still poorly studied. Information about the age of Holocene volcanic activity as well as the stratigraphy of the deposits is scarce: few eruptions are dated so far, whereas the others are classified as pre-or Holocene events considering lava flow characteristics along the coast. Here, we report on the dating of eleven (M˜na Chamuscada, M˜na del Tesoro, Orchilla, Las Calcosas, M˜na Negra, Lomo Negro, Below Lomo Negro, Cuchillo del Roque, Malpaso Member, and M˜na del Guanche) Holocene subaerial eruptions, distributed along the three rift zones, combining paleomagnetic and 14C methods. We also provide geochemical analyses for nine of them. Results indicate that M˜na Chamuscada and M˜na del Tesoro occurred more recently than previously considered, setting them within the last two thousand years. Conversely, paleomagnetic and 14C ages found for Lomo Negro eruption are consistent with literature data (Villasante- Marcos and Pav´on-Carrasco, 2014) and constrain the occurrence of this event in the XVI century CE. Finally, for Malpaso Member deposits, the two 14C datings obtained by charcoals found below and above the trachytic layer set the eruption during the Holocene epoch, between ~7300 BCE and ~4700 BCE. For the other eruptions, in two cases (Orchilla and Las Calcosas) many possible time windows during the last 14 ka have been found, whereas a few possible ages have been obtained for the others. On the whole, the resulting chronological reconstruction of the recent activity of El Hierro indicates that eruptions occurred unevenly along the three main rifts, with nine eruptions in the WNW rift, six in the NE rift, and four in the SSE rift. We document at least two periods characterized by high eruptive frequency: an old one, between 8000 BCE and 1000 BCE, with eight eruptions, three of which characterized by more evolved compositions (phonotephrite and trachyte), and a recent one, between 1000 BCE and present day, with at least seven eruptions, mainly showing basanite compositions. The new data yield a significant improvement of Holocene eruption chronology, thus are instrumental for a correct evaluation of the volcanic hazard at El Hierro.
    Description: Published
    Description: 107526
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Keywords: Paleomagnetism ; El Hierro ; 04.05. Geomagnetism ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2022-03-07
    Description: The investigation of the role played by CO2 circulating within the mantle during partial melting and metasomatic/refertilization processes, together with a re-consideration of its storage capability and re-cycling in the lithospheric mantle, is crucial to unravel the Earth's main geodynamic processes. In this study, the combination of petrology, CO2 content trapped in bulk rock- and mineral-hosted fluid inclusions (FI), and 3D textural and volumetric characterization of intra- and inter-granular microstructures was used to investigate the extent and modality of CO2 storage in depleted and fertile (or refertilized) Sub-Continental Lithospheric Mantle (SCLM) beneath northern Victoria Land (NVL, Antarctica). Prior to xenoliths entrainment by the host basalt, the Antarctic SCLM may have stored 0.2 vol% melt and 1.1 vol% fluids, mostly as FI trails inside mineral phases but also as inter-granular fluids. The amount of CO2 stored in FI varies from 0.1 μg(CO2)/g(sample) in olivine from the anhydrous mantle xenoliths at Greene Point and Handler Ridge, up to 187.3 μg/g in orthopyroxene from the highly metasomatized amphibole-bearing lherzolites at Baker Rocks, while the corresponding bulk CO2 contents range from 0.3 to 57.2 μg/g. Irrespective of the lithology, CO2 partitioning is favoured in orthopyroxene and clinopyroxene-hosted FI (olivine: orthopyroxene = 0.10 ± 0.06 to 0.26 ± 0.09; olivine: clinopyroxene = 0.10 ± 0.05 to 0.27 ± 0.14). The H2O/(H2O + CO2) molar ratios obtained by comparing the CO2 contents of FI to the H2O amount retained in pyroxene lattices vary between 0.72 ± 0.17 and 0.97 ± 0.03, which is well comparable with the values measured in olivine-hosted melt inclusions from Antarctic primary lavas and assumed as representative of the partition of volatiles at the local mantle conditions. From the relationships between mineral chemistry, thermo-, oxybarometric results and CO2 contents in mantle xenoliths, we speculate that relicts of CO2-depleted mantle are present at Greene Point, representing memory of a CO2-poor tholeiitic refertilization related to the development of the Jurassic Ferrar large magmatic event. On the other hand, a massive mobilization of CO2 took place before the (melt-related) formation of amphibole veins during the alkaline metasomatic event associated with the Cenozoic rift-related magmatism, in response to the storage and recycling of CO2-bearing materials into the Antarctica mantle likely induced by the prolonged Ross subduction.
    Description: Published
    Description: 106643
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: 4V. Processi pre-eruttivi
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: CO2 storage ; Sub-Continental Lithospheric Mantle ; Alkaline metasomatism ; Fluid inclusions ; Synchrotron X-ray microtomography ; Inter-granular fluids ; 04.01. Earth Interior ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2022-03-15
    Description: The origin of magmatic fluids along the East African Rift System (EARS) is a long-lived field of debate in the scientific community. Here, we investigate the chemical composition of the volcanic gas plume and fumaroles at Nyiragongo and Nyamulagira (Democratic Republic of Congo), the only two currently erupting volcanoes set on the Western Branch of the rift. Our results are in line with earlier conceptual models proposing that volcanic gas emissions along the EARS mainly reflect variable contributions of either a Sub-Continental Lithospheric Mantle (SCLM) component or a Depleted Morb Mantle (DMM) component, and deeper fluid. At Nyiragongo and Nyamulagira, our study discards a major contribution of a high 3He/4He mantle plume component in the genesis of volcanic fluids beneath the area. High CO2/3He in fumaroles of both volcanoes is thought to reflect carbonate metasomatism in the lithospheric mantle source. As inferred by previous results obtained on the lava chemistry, this carbonate metasomatism would be more pronounced beneath Nyiragongo. This supports the idea of the presence of distinct metasomes within the lithospheric mantle beneath the Western Branch of the rift.
    Description: Published
    Description: 120811
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: East African Rift System ; Volcano ; Gas chemistry ; 04.08. Volcanology ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2022-03-21
    Description: Changbaishan, an intraplate volcano, is characterized by an approximately 6 km wide summit caldera and last erupted in 1903. Changbaishan experienced a period of unrest between 2002 and 2006. The activity developed in three main stages, including shield volcano (basalts), cone-construction (trachyandesites to trachytes with minor basalts), and caldera-forming stages (trachytes to comendites). This last stage is associated with one of the more energetic eruptions of the last millennium on Earth, the 946 CE, VEI 7 Millennium Eruption (ME), which emitted over 100 km3 of pyroclastics. Compared to other active calderas, the plumbing system of Changbaishan and its evolution mechanisms remain poorly constrained. Here, we merge new whole-rock, glass, mineral, isotopic, and geobarometry data with geophysical data and present a model of the plumbing system. The results show that the volcano is characterized by at least three main magma reservoirs at different depths: a basaltic reservoir at the Moho/lower crust depth, an intermediate reservoir at 10–15 km depth, and a shallower reservoir at 0.5–3 km depth. The shallower reservoir was involved in the ME eruption, which was triggered by a fresh trachytic melt entering a shallower reservoir where a comenditic magma was stored. The trachytes and comendites originate from fractional crystallization processes and minor assimilation of upper crust material, while the less evolved melts assimilate lower crust material. Syn-eruptive magma mingling occurred during the ME eruption phase. The magma reservoirs of the caldera-forming stage partly reactivate those of the cone-construction stage. The depth of the magma storage zones is controlled by the layering of the crust. The plumbing system of Changbaishan is vertically extensive, with crystal mush reservoirs renewed by the replenishment of new trachytic to trachyandesitic magma from depth. Unlike other volcanoes, evidence of a basaltic recharge is lacking. The interpretation of the signals preceding possible future eruptions should consider the multi-level nature of the Changbaishan plumbing system. A new arrival of magma may destabilize a part of or the entire system, thus triggering eruptions of different sizes and styles. The reference model proposed here for Changbaishan represents a prerequisite to properly understand periods of unrest to potentially anticipate future volcanic eruptions and to identify the mechanisms controlling the evolution of the crust below volcanoes.
    Description: National Natural Science Foundation of China (Grant Nos. 41972313 and 41790453), Engineering Research Center of Geothermal Resources Development Technology and Equipment, Ministry of Education, Jilin University, China, INGV Ricerca Libera.
    Description: Published
    Description: 101171
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Elsevier
    Publication Date: 2022-02-10
    Description: The airborne magnetic method was established a few decades ago, as a strong tool in mining and petroleum exploration. Several economically relevant discoveries are often credited to aeromagnetism. Geological reconnaissance and mapping, deep crustal and upper mantle studies, environmental characterization, and national and international security issues can greatly benefit from the aeromagnetic method, as compared with other geophysical prospecting schemes. The rapid rate of coverage and the low cost per unit area explored represent just a few among the many advantages of the technique. Consequently, large-scale airborne magnetic surveys have been carried out in various parts of the globe. The amount of direct discoveries of ore bodies by means of aeromagnetism is impressive. Large magnetic iron deposits found in the early 1960s are in Southern California, Missouri, Nevada, Pennsylvania, Quebec, Ontario, and elsewhere. In the field of petroleum exploration, the method has also been used, although with less direct application. Depth to magnetic basement estimation in sedimentary basins narrows down areas of interest where to conduct exploration surveys in detail by means of more costly methods. The most relevant use of airborne magnetic results is crustal imaging and characterization. Nowadays, geology is interpreted in three dimensions using a digital aeromagnetic map.
    Description: Published
    Description: 675-688
    Description: 1T. Struttura della Terra
    Description: 4T. Sismicità dell'Italia
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare
    Description: 5A. Ricerche polari e paleoclima
    Description: 7A. Geofisica per il monitoraggio ambientale
    Description: 1TR. Georisorse
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: 6SR VULCANI – Servizi e ricerca per la società
    Description: 7SR AMBIENTE – Servizi e ricerca per la società
    Keywords: aeromagnetism ; potential fields ; magnetic anomaly ; 04.02. Exploration geophysics ; 04.05. Geomagnetism ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 6
    Publication Date: 2022-02-11
    Description: Fluids supplied by stored magma at depth are causal factors of volcanic unrest, as they can cause pressurization/ heating of hydrothermal systems. However, evidence for links between hydrothermal pressurization, CO2 emission and volcano seismicity have remained elusive. Here, we use recent (2010−2020) observations at Campi Flegrei caldera (CFc) to show hydrothermal pressure, gas emission and seismicity at CFc share common source areas and well-matching temporal evolutions. We interpret the recent escalation in seismicity and surface gas emissions as caused by pressure-temperature increase at the top of a vertically elongated (0.3–2 km deep) gas front. Using mass (steam) balance considerations,we showhydrothermal pressurization is causing energy transfer from the fluids to the host rocks, ultimately triggering low magnitude earthquakes within a seismogenetic volume containing the hydrothermal system. This mechanism is probably common to other worldwide calderas in similar hydrothermal activity state.
    Description: MIUR project n. PRIN2017-2017LMNLAW“Connect4Carbon”
    Description: Published
    Description: 107245
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: CO2 emission ; Campi Flegrei ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2022-02-11
    Description: The evolution of volcanic activity observed at the New South East Crater (NSEC) and Voragine (VOR) between July 2019 and January 2020 has been deciphered by taking into account the changes of textures and chemical zoning of plagioclase and olivine crystals from the erupted lavas and tephra. The petrological observations have been integrated with analyses of the amplitude and source location of volcanic tremor and infrasound data. Characteristics of crystals erupted on July 2019 at the NSEC reflect protracted intrusions of magma into the mid-upper section of the plumbing system, approximately within 290–120 MPa, which acted as the main zone of magma accumulation and crystallization before the beginning of the eruptive activity. Textures and compositions of crystals erupted at VOR emphasize the beginning of volcanic activity driven by recharge/discharge phases that mostly affect the shallowest portion of the Mt. Etna plumbing system (〈40 MPa). At the end of 2019, mineral compositions and zoning patterns changed again in accordance with eruption dynamics. The observed changes reflect the transition from an early phase, between November and December 2019, characterized by substantial equilibrium during magma storage and transport toward higher disequilibrium conditions and eruptive frequency, in January 2020. This has been associated to episodes of deep replenishment of mafic magmas displacing the resident one. Diffusion chronometry applied to zoned olivines shows that most of the episodes of magma intrusion correlate temporally with changes in the features of both volcanic tremor and infrasonic events in terms of amplitude and source location, providing evidence that such geophysical signals are directly related to the magma dynamics in the upper plumbing system.
    Description: Published
    Description: 107350
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Keywords: 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2022-02-14
    Description: Shallow water equations are widely used in the simulation of those geophysical flows for which the flow horizontal length scale is much greater than the vertical one. Inspired by the example of lava flows, we consider here a modified model with an additional transport equation for a scalar quantity (e.g., temperature), and the derivation of the shallow water equations from depth-averaging the Navier-Stokes equations is presented. The assumption of constant vertical profiles for some of the model variables is relaxed allowing the presence of vertical profiles, and it follows that the non-linearity of the flux terms results in the introduction of appropriate shape coefficients. The space discretization of the resulting system of hyperbolic partial differential equations is obtained with a modified version of the finite volume central-upwind scheme introduced by Kurganov and Petrova in 2007. The time discretization is based on an implicit-explicit Runge-Kutta method which couples properly the hyperbolic part and the stiff source terms, avoiding the use of a very small time step; the use of complex arithmetic increases accuracy in the implicit treatment of stiff terms. The whole scheme is proved to preserve the positivity of flow thickness and the stationary steady-states. Some numerical experiments are performed to validate the proposed method and to show the incidence on the numerical solutions of shape coefficients introduced in the model.
    Description: Published
    Description: 482-505
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: Shallow water equations ; Viscous fluids ; Finite Volume ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2022-07-14
    Description: Forest destruction by ‘a‘ ̄a lava flow is common. However, mechanical and thermal interactions between the invading lava and the invaded forest are poorly constrained. We complete mapping, thermal image and sample analyses of a channel-fed ‘a‘a ̄ lava flow system that invaded forest on the NE flank of Mt. Etna (Italy) in 2002. These lava flows destroyed 231,000 trees, only 2% of which are still visible as felled trunks on the levees or at the channel-levee contact. The remaining 98% were first felled by the flow front, with the trunks then buried by the flow. Rare tree molds can be found at the rubble levee base where trees were buried by avalanching hot breccia and then burnt through, with a time scale for total combustion being a few days. Protruding trunks fell away from the flow, if felled by blocks avalanching down the levee flank, or became aligned with the flow if falling onto the moving stream. Estimated cooling rates (0.1–5.5 ◦C km− 1) are normal for well-insulated ‘a‘a ̄ flow, suggesting no thermal interaction. We find the highest phenocryst concentrations (of 50–60%, above an expected value of 30–40%) in low velocity (〈0.5 m s− 1) locations. These low velocity zones are also characterized by high trunk concentrations. Thus, the common factor behind crystal and trunk deposition is velocity. That is, when the lava slows down, crystal settling occurs and trunks are preferentially deposited. Thus, although we find no thermal or textural effects due to the presence of the forest, we do find mechanical and environmental in- teractions where the trees are consumed to become part of the flow.
    Description: This research was financed by the Agence National de la Recherche through the project LAVA (Program: DS0902 2016; Project: ANR-16 CE39-0009). We very much thank Sean I. Peters and an anonymous reviewer for their extremely constructive advice and support. This is ANR-LAVA contribution no. 23 and Laboratory of Excellence ClerVolc contribution no. 552.
    Description: Published
    Description: 107621
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Channelized ‘a‘ ̄a lava flow ; thermal imagery ; lava flows ; 2002-03 eruption ; forest destruction ; tree molds ; Etna volcano ; cooling rates ; Interaction lava and trees ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2022-09-05
    Description: The chemical composition of gases emitted by active volcanoes reflects both magma degassing and shallower processes, such as fluid-rock hydrothermal interaction and mixing with atmospheric-derived fluids. Untangling the magmatic fluid endmember within surface gas emission is therefore challenging, even with the use of well-known magma degassing tracers such as noble gases. Here, we investigate the deep magmatic fluid composition at the Nisyros caldera (Aegean Arc, Greece) by measuring nitrogen and noble gas abundances and isotopes in naturally degassing fumaroles. Gas samples were collected from 32 fumarolic vents at water-boiling temperature between 2018 and 2021. These fumaroles are admixtures of magmatic fluids typical of subduction zones, groundwater (or air saturated water, ASW), and air. The N2, He, and Ar composition of the magmatic endmember is calculated by reverse mixing modeling and shows N2/He = 31.8 ± 4.5, N2/Ar = 281.6, d15N = +7 ± 3 ‰, 3He/4He = 6.2 Ra (where Ra is air 3He/4He), and 40Ar/36Ar = 551.6 ± 19.8. Although N2/He is significantly low with respect to typical values for arc volcanoes (1,000–10,000), the contribution of subducted sediments to the Aegean Arc magma generation is reflected by the positive d15N values of Nisyros fumaroles. The low N2/He ratio indicates N2-depletion due to solubility-controlled differential degassing of an upper-crustal silicic (dacitic/rhyodacitic) melt in a high-crystallinity reservoir. We compare our 2018–2021 data with N2, He, and Ar values collected from the same fumaroles during a hydrothermal unrest following the seismic crisis in 1996–1997. Results show additions of both magmatic fluid and ASW during this unrest. In the same period, fumarolic vents display an increase in magmatic species relative to hydrothermal gas, such as CO2/CH4 and He/CH4 ratios, an increase of 50 C in the equilibrium temperature of the hydrothermal system (up to 325 C), and greater amounts of vapor separation. These variations reflect an episode of magmatic fluid expulsion during the seismic crisis. The excess of heat and mass supplied by the magmatic fluid injection is then dissipated through boiling of deeper and peripheral parts of the hydrothermal system. Reverse mixing modeling of fumarolic N2-He-Ar has therefore important ramifications not only to disentangle the magmatic signature from gases emitted during periods of dormancy, but also to trace episodes of magmatic outgassing and better understand the state of the upper crustal reservoir.
    Description: Published
    Description: 68-84
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Noble gases ; Nitrogen isotope ; Mixing modeling ; Magmatic degassing ; High-crystallinity mush ; Caldera ; Unrest ; CO2 ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2022-10-18
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pold, G., Kwiatkowski, B. L., Rastetter, E. B., & Sistla, S. A. Sporadic P limitation constrains microbial growth and facilitates SOM accumulation in the stoichiometrically coupled, acclimating microbe-plant-soil model. Soil Biology & Biochemistry, 165, (2022): 108489, https://doi.org/10.1016/j.soilbio.2021.108489.
    Description: Requirements for biomass carbon (C), nitrogen (N), and phosphorus (P) constrain organism growth and are important agents for structuring ecosystems. Arctic tundra habitats are strongly nutrient limited as decomposition and recycling of nutrients are slowed by low temperature. Modeling interactions among these elemental cycles affords an opportunity to explore how disturbances such as climate change might differentially affect these nutrient cycles. Here we introduce a C–N–P-coupled version of the Stoichiometrically Coupled Acclimating Microbe-Plant-Soil (SCAMPS) model, “SCAMPS-CNP”, and a corresponding modified CN-only model, “SCAMPS-CN”. We compared how SCAMPS-CNP and the modified SCAMPS-CN models project a moderate (RCP 6.0) air warming scenario will impact tussock tundra nutrient availability and ecosystem C stocks. SCAMPS-CNP was characterized by larger SOM and smaller organism C stocks compared to SCAMPS-CN, and a greater reduction in ecosystem C stocks under warming. This difference can largely be attributed to a smaller microbial biomass in the CNP model, which, instead of being driven by direct costs of P acquisition, was driven by variable resource limitation due to asynchronous C, N, and P availability and demand. Warming facilitated a greater relative increase in plant and microbial biomass in SCAMPS-CNP, however, facilitated by increased extracellular enzyme pools and activity, which more than offset the metabolic costs associated with their production. Although the microbial community was able to flexibly adapt its stoichiometry and become more bacteria-like (N-rich) in both models, its stoichiometry deviated further from its target value in the CNP model because of the need to balance cellular NP ratio. Our results indicate that seasonality and asynchrony in resources affect predicted changes in ecosystem C storage under warming in these models, and therefore build on a growing body of literature indicating stoichiometry should be considered in carbon cycling projections.
    Description: This work was funded by the National Science Foundation Signals in the Soil grant number 1841610 to SAS and EBR.
    Keywords: Stoichiometry ; Modeling ; Microbial physiology ; Tundra ; Climate change
    Repository Name: Woods Hole Open Access Server
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  • 12
    Publication Date: 2022-10-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Broadley, M., Byrne, D., Ardoin, L., Almayrac, M., Bekaert, D., & Marty, B. High precision noble gas measurements of hydrothermal quartz reveal variable loss rate of Xe from the Archean atmosphere. Earth and Planetary Science Letters, 588, (2022): 117577, https://doi.org/10.1016/j.epsl.2022.117577.
    Description: Determining the composition of the Archean atmosphere and oceans is vital to understanding the environmental conditions that existed on the surface of the early Earth. The analysis of atmospheric remnants in fluid inclusions trapped in Archean-aged samples has shown that the Xe isotopic signature of the Archean atmosphere progressively evolved via mass-dependent fractionation, arriving at a modern atmospheric composition around the Archean-Proterozoic transition. The mechanisms driving this evolution are however not well constrained, and it is not yet clear whether the evolution proceeded continuously or via episodic bursts. Providing further constraints on the evolution of Xe in the Archean atmosphere is hampered by the limited amounts of atmospheric gas trapped within fluid inclusions during mineral formation, which impacts the precision at which the Archean atmosphere can be determined. Here, we develop a new crush-and-accumulate extraction technique that enables the heavy noble gases (Ar, Kr and Xe) released from crushing large quantities of hydrothermal quartz to be accumulated and analysed to a higher precision than was previously possible. Using this new technique, we re-evaluate the composition of atmospheric gases trapped within fluid inclusions of 3.3 Ga quartz samples from Barberton, South Africa. We find that the Xe isotopic signature is fractionated by +10.3 ± 1.0‰u−1 (2 SE) relative to modern atmosphere, which is within uncertainty of, but slightly lower than, the previous determination of 12.9 ± 2.4‰u−1 for this sample (Avice et al., 2017). We show for the first time that the Kr/Xe ratio measured within Archean quartz samples is enriched in Xe compared to the modern atmosphere, demonstrating that the atmosphere has lost Xe since the Archean. This further reinforces the proposal of atmospheric escape as the primary mechanism for Earth's Xe loss. We further show that the atmospheric Kr/Xe and Xe isotope fractionation recorded in the Barberton quartz at 3.3 Ga is incompatible with a model describing atmospheric loss at a continuous rate under a constant fractionation factor. This gives credence to numerical models of hydrodynamic escape, which suggest that Xe was lost from the Archean atmosphere in episodic bursts rather than at a constant rate. Refining the evolution curve of atmospheric Xe isotopes using the new technique presented here has the potential to shed light on discrete atmospheric events that punctuated the evolution of the Archean Earth and accompanied the evolution of life.
    Description: This study was supported by the European Research Council (PHOTONIS project, grant agreement No. 695618). This is CRPG contribution #2820.
    Keywords: Archean atmosphere ; Noble gases ; Xenon ; Atmospheric escape
    Repository Name: Woods Hole Open Access Server
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  • 13
    Publication Date: 2022-05-27
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Burnham, K. A., Nowicki, R. J., Hall, E. R., Pi, J., & Page, H. N. Effects of ocean acidification on the performance and interaction of fleshy macroalgae and a grazing sea urchin. Journal of Experimental Marine Biology and Ecology, 547, (2022): 151662, https://doi.org/10.1016/j.jembe.2021.151662.
    Description: When predicting the response of marine ecosystems to climate change, it is increasingly recognized that understanding the indirect effects of ocean acidification on trophic interactions is as important as studying direct effects on organism physiology. Furthermore, comprehensive studies that examine these effects simultaneously are needed to identify and link the underlying mechanisms driving changes in species interactions. Using an onshore ocean acidification simulator system, we investigated the direct and indirect effects of elevated seawater pCO2 on the physiology and trophic interaction of fleshy macroalgae and the grazing sea urchin Lytechinus variegatus. Macroalgal (Dictyota spp.) biomass increased despite decreased photosynthetic rates after two-week exposure to elevated pCO2. Algal tissue carbon content remained constant, suggesting the use of alternative carbon acquisition pathways beneficial to growth under acidification. Higher C:N ratios driven by a slight reduction in N content in algae exposed to elevated pCO2 suggest a decrease in nutritional content under acidification. Urchin (L. variegatus) respiration, biomass, and righting time did not change significantly after six-week exposure to elevated pCO2, indicating that physiological stress and changes in metabolism are not mechanisms through which the trophic interaction was impacted. Correspondingly, urchin consumption rates of untreated macroalgae (Caulerpa racemosa) were not significantly affected by pCO2. In contrast, exposure of urchins to elevated pCO2 significantly reduced the number of correct foraging choices for ambient macroalgae (Dictyota spp.), indicating impairment of urchin chemical sensing under acidification. However, exposure of algae to elevated pCO2 returned the number of correct foraging choices in similarly exposed urchins to ambient levels, suggesting alongside higher C:N ratios that algal nutritional content was altered in a way detectable by the urchins under acidification. These results highlight the importance of studying the indirect effects of acidification on trophic interactions simultaneously with direct effects on physiology. Together, these results suggest that changes to urchin chemical sensing and algal nutritional quality are the driving mechanisms behind surprisingly unaltered urchin foraging behavior for fleshy macroalgae under joint exposure to ocean acidification. Consistent foraging behavior and consumption rates suggest that the trophic interaction between L. variegatus and fleshy macroalgae may be sustained under future acidification. However, increases in fleshy macroalgal biomass driven by opportunistic carbon acquisition strategies have the potential to cause ecological change, depending on how grazer populations respond. Additional field research is needed to determine the outcome of these results over time and under a wider range of environmental conditions.
    Description: This work was supported by Mote Marine Laboratory Postdoctoral Fellowships (RJN and HNP), Becker Internship Funding, and philanthropic funds to ERH.
    Keywords: Climate change ; Elevated pCO2 ; Direct effects ; Physiology ; Indirect effects ; Herbivory
    Repository Name: Woods Hole Open Access Server
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  • 14
    Publication Date: 2022-07-20
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Clark, S., Hubbard, K., Ralston, D., McGillicuddy, D., Stock, C., Alexander, M., & Curchitser, E. Projected effects of climate change on Pseudo-nitzschia bloom dynamics in the Gulf of Maine. Journal of Marine Systems, 230, (2022): 103737, https://doi.org/10.1016/j.jmarsys.2022.103737.
    Description: Worldwide, warming ocean temperatures have contributed to extreme harmful algal bloom events and shifts in phytoplankton species composition. In 2016 in the Gulf of Maine (GOM), an unprecedented Pseudo-nitzschia bloom led to the first domoic-acid induced shellfishery closures in the region. Potential links between climate change, warming temperatures, and the GOM Pseudo-nitzschia assemblage, however, remain unexplored. In this study, a global climate change projection previously downscaled to 7-km resolution for the Northwest Atlantic was further refined with a 1–3-km resolution simulation of the GOM to investigate the effects of climate change on HAB dynamics. A 25-year time slice of projected conditions at the end of the 21st century (2073–2097) was compared to a 25-year hindcast of contemporary ocean conditions (1994–2018) and analyzed for changes to GOM inflows, transport, and Pseudo-nitzschia australis growth potential. On average, climate change is predicted to lead to increased temperatures, decreased salinity, and increased stratification in the GOM, with the largest changes occurring in the late summer. Inflows from the Scotian Shelf are projected to increase, and alongshore transport in the Eastern Maine Coastal Current is projected to intensify. Increasing ocean temperatures will likely make P. australis growth conditions less favorable in the southern and western GOM but improve P. australis growth conditions in the eastern GOM, including a later growing season in the fall, and a longer growing season in the spring. Combined, these changes suggest that P. australis blooms in the eastern GOM could intensify in the 21st century, and that the overall Pseudo-nitzschia species assemblage might shift to warmer-adapted species such as P. plurisecta or other Pseudo-nitzschia species that may be introduced.
    Description: This research was funded by the National Science Foundation (Grant Number OCE-1840381), the National Institute of Environmental Health Sciences (Grant Number 1P01ES028938), the Woods Hole Center for Oceans and Human Health, and the Academic Programs Office of the Woods Hole Oceanographic Institution.
    Keywords: Gulf of Maine ; ROMS ; Pseudo-nitzschia ; Climate change ; Harmful algal blooms
    Repository Name: Woods Hole Open Access Server
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  • 15
    Publication Date: 2022-05-26
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Pirotta, E., Thomas, L., Costa, D., Hall, A., Harris, C., Harwood, J., Kraus, S., Miller, P., Moore, M., Photopoulou, T., Rolland, R., Schwacke, L., Simmons, S., Southall, B., & Tyack, P. Understanding the combined effects of multiple stressors: a new perspective on a longstanding challenge. Science of The Total Environment, 821, (2022): 153322, https://doi.org/10.1016/j.scitotenv.2022.153322.
    Description: Wildlife populations and their habitats are exposed to an expanding diversity and intensity of stressors caused by human activities, within the broader context of natural processes and increasing pressure from climate change. Estimating how these multiple stressors affect individuals, populations, and ecosystems is thus of growing importance. However, their combined effects often cannot be predicted reliably from the individual effects of each stressor, and we lack the mechanistic understanding and analytical tools to predict their joint outcomes. We review the science of multiple stressors and present a conceptual framework that captures and reconciles the variety of existing approaches for assessing combined effects. Specifically, we show that all approaches lie along a spectrum, reflecting increasing assumptions about the mechanisms that regulate the action of single stressors and their combined effects. An emphasis on mechanisms improves analytical precision and predictive power but could introduce bias if the underlying assumptions are incorrect. A purely empirical approach has less risk of bias but requires adequate data on the effects of the full range of anticipated combinations of stressor types and magnitudes. We illustrate how this spectrum can be formalised into specific analytical methods, using an example of North Atlantic right whales feeding on limited prey resources while simultaneously being affected by entanglement in fishing gear. In practice, case-specific management needs and data availability will guide the exploration of the stressor combinations of interest and the selection of a suitable trade-off between precision and bias. We argue that the primary goal for adaptive management should be to identify the most practical and effective ways to remove or reduce specific combinations of stressors, bringing the risk of adverse impacts on populations and ecosystems below acceptable thresholds.
    Description: This work was supported by the Office of Naval Research [grant numbers N000142012697, N000142112096]; and the Strategic Environmental Research and Development Program [grant numbers RC20-1097, RC20-7188, RC21-3091].
    Keywords: Adaptive management ; Climate change ; Combined effects ; Mechanistic modelling ; Multiple stressors ; Population consequences
    Repository Name: Woods Hole Open Access Server
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  • 16
    Publication Date: 2022-02-11
    Description: The resuspension of volcanic ash by wind is a significant source of hazard during and after volcanic eruptions. Parameterizing and modeling ash resuspension requires direct measurement of the minimum wind shear stress required to move particles, usually expressed as the threshold friction velocity U*th, a parameter that, for volcanic ash, has been measured only scarcely and always in the laboratory. Here, we report the first field measurements of U*th for volcanic ash, with a portable wind tunnel specifically developed, calibrated, and tested. Field measurements, performed on natural reworked ash deposits from Sakurajima (Japan) and Cordón Caulle (Chile) volcanoes, agree well with our laboratory determinations on ash from the same deposits, with values of U*th ranging from 0.13 to 0.38 m/s. Our results show that the median grain size of the deposit and particle shape have a stronger control on U*th than the local substratum nature and deposit texture.
    Description: Published
    Description: 116684
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: wind resuspension ; wind tunnel ; detachment threshold ; volcanic ash ; Sakurajima volcano ; Cordon Caulle volcano ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2021-12-09
    Description: Rome Capital City is located in a high heat flux area of central Italy, suitable for low-enthalpy geothermal exploitation. In the central-northern part of the city, near Tor di Quinto hippodrome close to Tiber River, a wide undeveloped area occurs, which is a possible future urban development site. We present the results of a geochemical and geophysical study aimed at assessing the presence in this zone of a low-enthalpy geothermal aquifer and at evaluating its depth, thickness and the physico-chemical characteristics of the geothermal water. Furthermore the natural CO2 output of this zone has been investigated. A soil CO2 flux survey with 551 measurements over a surface of 3.09 km2 revealed the presence of parallel NW-SE trending positive flux anomalies. The total CO2 output was estimated to 87.77 t*day-1, most of which (85 %) of endogenous or mixed origin. An Electrical Resistivity Tomography survey, consisting of five parallel 355 m long and 100 m spaced profiles, allowed the reconstruction of the stratigraphy of the underground sediments, which are fluvial deposits of the near Tiber River. The geothermal water is hosted in a low-resistivity layer, corresponding to the Tiber base gravels, which are here 20 m thick and whose top is 40 m below the surface. The water has a nearly constant temperature of 17.5 °C, a relatively high salinity and an appreciable content in dissolved gas. This low-enthalpy resource is suitable for direct uses, e.g. individual and district heating/cooling, sanitary hot water, spa facilities for swimming and bathing.
    Description: This work was partially supported by the INGV AMUSED research project (CUP D59C19000100005)
    Description: Published
    Description: 102298
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Low enthalpy geothermal aquifer Rome ; water chemistry ; diffuse soil CO2 output ; Electrical Resistivity Tomography ; 04.08. Volcanology ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2021-12-22
    Description: Despite Mt. Etna's long-standing reputation as an effusive volcano, since 1986 there has been an evident increase in mid-intensity explosive eruptions from its summit craters, with more than 240 episodes, better known as paroxysms (otherwise called paroxysmal episodes). These are characterized by strong Strombolian to lava fountaining activity that lasts from tens of minutes to a few days, producing some km-high volcanic plumes and tephra fallouts up to hundreds of km on the ground. Most paroxysms give life to sequences which are clustered like “episodic” eruptions for periods of a few days to a few months, their frequent recurrence causing hazard to air traffic and impacting densely inhabited areas. Nonetheless, a list containing the dates and data of these eruptions is lacking. In this paper, we tried to fill this gap by compiling a complete record, including master data (date, crater), eruption style and seismic parameters for identifying, characterizing and quantifying both the individual episodes and the entire period. This information comes from a critical review of surveillance reports, raw-data analysis and scientific literature. A retrieval of homogenous and comparable seismic data was possible only for episodes after 2006 following the renewal of seismic stations. The eruption list provides a complete picture of the 1986–2021 paroxysms, allowing to evaluate their temporal distribution, make a statistical analysis of their time-interval, and undertake a comprehensive investigation of the features of volcanic tremor. The results show a high probability (72%) of having a paroxysmal episode in the 10 days following the previous one. Moreover, a scaling relationship associated with the number-size distribution of the amplitude increases of volcanic tremor accompanying the explosive activities has been constrained. During sequences of paroxysms, combining these outputs can help improve the hazard assessment in terms of frequency of the associated tephra fallouts, and predict the duration of the entire sequence.
    Description: Published
    Description: 103686
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Keywords: Mt. Etna ; Summit craters ; Paroxysmal episodes ; Volcanic tremor ; Statistical analysis ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Almayrac, M. G., Broadley, M. W., Bekaert, D. V., Hofmann, A., & Marty, B. Possible discontinuous evolution of atmospheric xenon suggested by Archean barites. Chemical Geology, 581, (2021): 120405, https://doi.org/10.1016/j.chemgeo.2021.120405.
    Description: The Earth's atmosphere has continually evolved since its formation through interactions with the mantle as well as through loss of volatile species to space. Atmospheric xenon isotopes show a unique and progressive evolution during the Archean that stopped around the Archean-Proterozoic transition. The Xe isotope composition of the early atmosphere has been previously documented through the analysis of fluid inclusions trapped within quartz and barite. Whether this evolution was continuous or not is unclear, requiring additional analyses of ancient samples, which may potentially retain remnants of the ancient atmosphere. Here we present new argon, krypton and xenon isotopic data from a suite of Archean and Proterozoic barites ranging in age from 3.5 to 1.8 Ga, with the goal of providing further insights in to the evolution of atmospheric Xe, whilst also outlining the potential complications that can arise when using barites as a record of past atmospheres. Xenon released by low temperature pyrolysis and crushing of two samples which presumably formed around 2.8 and 2.6 Ga show Xe isotope mass dependent fractionation (MDF) of 11‰.u−1 and 3.4‰.u−1, respectively, relative to modern atmosphere. If trapped Xe is contemporaneous with the respective formation age, the significant difference in the degree of fractionation between the two samples provides supporting evidence for a plateau in the MDF-Xe evolution between 3.3 Ga and 2.8 Ga, followed by a rapid evolution at 2.8–2.6 Ga. This sharp decrease in MDF-Xe degree suggests the potential for a discontinuous temporal evolution of atmospheric Xe isotopes, which could have far reaching implications regarding current physical models of the early evolution of the Earth's atmosphere.
    Description: This work was funded by the ERC grant No. 695618 to B.M. We thank the S.A.R.M for providing elemental bulk analyses of the barites. We thank Laurent Zimmerman for technical mentorship and assistance.
    Keywords: Archean barite ; Noble gases ; Xenon anomalies ; Archean atmosphere
    Repository Name: Woods Hole Open Access Server
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  • 20
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Trathan, P. N., Wienecke, B., Barbraud, C., Jenouvrier, S., Kooyman, G., Le Bohec, C., Ainley, D. G., Ancel, A., Zitterbart, D. P., Chown, S. L., LaRue, M., Cristofari, R., Younger, J., Clucas, G., Bost, C., Brown, J. A., Gillett, H. J., & Fretwell, P. T. The emperor penguin - vulnerable to projected rates of warming and sea ice loss. Biological Conservation, 241, (2020): 108216, doi:10.1016/j.biocon.2019.108216.
    Description: We argue the need to improve climate change forecasting for ecology, and importantly, how to relate long-term projections to conservation. As an example, we discuss the need for effective management of one species, the emperor penguin, Aptenodytes forsteri. This species is unique amongst birds in that its breeding habit is critically dependent upon seasonal fast ice. Here, we review its vulnerability to ongoing and projected climate change, given that sea ice is susceptible to changes in winds and temperatures. We consider published projections of future emperor penguin population status in response to changing environments. Furthermore, we evaluate the current IUCN Red List status for the species, and recommend that its status be changed to Vulnerable, based on different modelling projections of population decrease of ≥50% over the current century, and the specific traits of the species. We conclude that current conservation measures are inadequate to protect the species under future projected scenarios. Only a reduction in anthropogenic greenhouse gas emissions will reduce threats to the emperor penguin from altered wind regimes, rising temperatures and melting sea ice; until such time, other conservation actions are necessary, including increased spatial protection at breeding sites and foraging locations. The designation of large-scale marine spatial protection across its range would benefit the species, particularly in areas that have a high probability of becoming future climate change refugia. We also recommend that the emperor penguin is listed by the Antarctic Treaty as an Antarctic Specially Protected Species, with development of a species Action Plan.
    Description: We thank Thomas J. Bracegirdle, Tony Phillips and Kevin Hughes for helpful comments on earlier drafts of this manuscript. PNT acknowledges the support of WWF-UK under GB095701 and SJ the support of NSF OPP1744794 and 1643901.
    Keywords: Antarctic ; Climate change ; Aptenodytes forsteri ; IUCN Red List threat status ; Protection ; Conservation
    Repository Name: Woods Hole Open Access Server
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