ALBERT

Description: The South Sandwich Volcanic Arc is one of the most remote and enigmatic arcs on Earth. Sporadic observations from rare cloudfree satellite images—and even rarer in situ reports—provide glimpses into a dynamic arc system characterised by persistent gas emissions and frequent eruptive activity. Our understanding of the state of volcanic activity along this arc is incomplete compared to arcs globally. To fill this gap, we present here detailed geological and volcanological observations made during an expedition to the South Sandwich Islands in January 2020.We report the first in situ measurements of gas chemistry, emission rate and carbon isotope composition from along the arc. We show that Mt. Michael on Saunders Island is a persistent source of gas emissions, releasing 145±59 t day−1 SO2 in a plume characterised by a CO2/SO2 molar ratio of 1.8 ± 0.2. Combining this CO2/SO2 ratio with our independent SO2 emission rate measured near simultaneously, we derive a CO2 flux of 179 ± 76 t day−1. Outgassing from low temperature (90–100 °C) fumaroles is pervasive at the active centres of Candlemas and Bellingshausen, with measured gas compositions indicative of interaction between magmatic fluids and hydrothermal systems. Carbon isotope measurements of dilute plume and fumarole gases from along the arc indicate a magmatic δ13C of − 4.5 ± 2.0‰. Interpreted most simply, this result suggests a carbon source dominated by mantle-derived carbon. However, based on a carbon mass balance from sediment core ODP 701, we show that mixing between depleted upper mantle and a subduction component composed of sediment and altered crust is also permissible.We conclude that, although remote, the South Sandwich Volcanic Arc is an ideal tectonic setting in which to explore geochemical processes in a young, developing arc.

Description: This expedition was funded by public donations raised by Quark Expeditions Ltd., by the Government of South Georgia and the South Sandwich Islands (GSGSSI) and by individual contributions. This work was carried out under RAP 2019/025 issued by GSGSSI. EJL was supported by a Leverhulme Early Career Fellowship. A.A. and M.B. acknowledge funding from Miur (Grant N. 2017LMNLAW). K.W. acknowledges support from the Mount Everest Foundation (20-06)

Description: Published

Description: id 3

Description: 4V. Processi pre-eruttivi

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: JCR Journal

Description: Volcanic emissions are a critical pathway in Earth's carbon cycle. Here, we show that aerial measurements of volcanic gases using unoccupied aerial systems (UAS) transform our ability to measure and monitor plumes remotely and to constrain global volatile fluxes from volcanoes. Combining multi-scale measurements from ground-based remote sensing, long-range aerial sampling, and satellites, we present comprehensive gas fluxes-3760 ± [600, 310] tons day-1 CO2 and 5150 ± [730, 340] tons day-1 SO2-for a strong yet previously uncharacterized volcanic emitter: Manam, Papua New Guinea. The CO2/ST ratio of 1.07 ± 0.06 suggests a modest slab sediment contribution to the sub-arc mantle. We find that aerial strategies reduce uncertainties associated with ground-based remote sensing of SO2 flux and enable near-real-time measurements of plume chemistry and carbon isotope composition. Our data emphasize the need to account for time averaging of temporal variability in volcanic gas emissions in global flux estimates.

Description: This research was enabled through the Alfred P. Sloan Foundation's support of the Deep Carbon Observatory Deep Earth Carbon Degassing program (DECADE). Part funding also came from the EPSRC CASCADE programme grant (EP/R009953/1). EJL was supported by a Leverhulme Trust Early Career Fellowship. KW was supported by the National Center for Nuclear Robotics (NCNR) EPSRC grant (EP/R02572X/1).

Description: Published

Description: eabb9103

Description: 7TM.Sviluppo e Trasferimento Tecnologico

Description: JCR Journal

Description: Stratospheric aerosol and ozone profiles obtained simoultaneosly from the lidar station at the university of L'Aquila during the first 6 months following the eruption of Mount Pinatubo are compared with corresponding nearby Stratosperic Aerosol and Gas Experiment (SAGE) II profiles. The agreement between the two data stes is found to be reasonably good. The temporal change of aerosol profiles obtained by both technique showed the intrusion and growth of Pinatubo aerosols. In addition, ozone concntration profiles derivide from an empirical time-series model based on SAGE II ozone data obtained bifore the Pinatubo eruption are compared with measured profiles. Good agreement is shown in the 1991 profiles, but ozone concentration measured in January 1992 were reduced relative ti time-series model estimates. Possible reasons for the diffrences between measured and model-based ozone profiles are discussed.

Description: NASA ING

Description: Published

Description: 1881-1884

Description: 1.8. Osservazioni di geofisica ambientale

Description: JCR Journal

Description: open

Description: The long-term evolution of upper stratospheric ozone has been recorded by lidars and microwave radiometers within the ground-based Network for the Detection of Stratospheric Change (NDSC), and by the space-borne Solar Backscatter Ultra-Violet instruments (SBUV), Stratospheric Aerosol and Gas Experiment (SAGE), and Halogen Occultation Experiment (HALOE). Climatological mean differences between these instruments are typically smaller than 5% between 25 and 50 km. Ozone anomaly time series from all instruments, averaged from 35 to 45 km altitude, track each other very well and typically agree within 3 to 5%. SBUV seems to have a slight positive drift against the other instruments. The corresponding 1979 to 1999 period from a transient simulation by the fully coupled MAECHAM4-CHEM chemistry climate model reproduces many features of the observed anomalies. However, in the upper stratosphere the model shows too low ozone values and too negative ozone trends, probably due to an underestimation of methane and a consequent overestimation of ClO. The combination of all observational data sets provides a very consistent picture, with a long-term stability of 2% or better. Upper stratospheric ozone shows three main features: (1) a decline by 10 to 15% since 1980, due to chemical destruction by chlorine; (2) two to three year fluctuations by 5 to 10%, due to the Quasi-Biennial Oscillation (QBO); (3) an 11-year oscillation by about 5%, due to the 11-year solar cycle. The 1979 to 1997 ozone trends are larger at the southern mid-latitude station Lauder (45 S), reaching 8%/decade, compared to only about 6%/decade at Table Mountain (35 N), Haute Provence/Bordeaux ( 45 N), and Hohenpeissenberg/Bern( 47 N). At Lauder, Hawaii (20 N), Table Mountain, and Haute Provence, ozone residuals after subtraction of QBO- and solar cycle effects have levelled off in recent years, or are even increasing. Assuming a turning point in January 1997, the change of trend is largest at southern mid-latitude Lauder, +11%/decade, compared to +7%/decade at northern mid-latitudes. This points to a beginning recovery of upper stratospheric ozone. However, chlorine levels are still very high and ozone will remain vulnerable. At this point the most northerly mid-latitude station, Hohenpeissenberg/Bern differs from the other stations, and shows much less clear evidence for a beginning recovery, with a change of trend in 1997 by only +3%/decade. In fact, record low upper stratospheric ozone values were observed at Hohenpeissenberg/Bern, and to a lesser degree at Table Mountain and Haute Provence, in the winters 2003/2004 and 2004/2005.

Description: Published

Description: D10308

Description: open

Description: This paper presents extensive {bias determination} analyses of ozone observations from the Atmospheric Chemistry Experiment (ACE) satellite instruments: the ACE Fourier Transform Spectrometer (ACE-FTS) and the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (ACE-MAESTRO) instrument. Here we compare the latest ozone data products from ACE-FTS and ACE-MAESTRO with coincident observations from nearly 20 satellite-borne, airborne, balloon-borne and ground-based instruments, by analysing volume mixing ratio profiles and partial column densities. The ACE-FTS version 2.2 Ozone Update product reports more ozone than most correlative measurements from the upper troposphere to the lower mesosphere. At altitude levels from 16 to 44 km, the average values of the mean relative differences are nearly all within +1 to +8%. At higher altitudes (4560 km), the ACE-FTS ozone amounts are significantly larger than those of the comparison instruments, with mean relative differences of up to +40% (about +20% on average). For the ACE-MAESTRO version 1.2 ozone data product, mean relative differences are within ±10% (average values within ±6%) between 18 and 40 km for both the sunrise and sunset measurements. At higher altitudes (~3555 km), systematic biases of opposite sign are found between the ACE-MAESTRO sunrise and sunset observations. While ozone amounts derived from the ACE-MAESTRO sunrise occultation data are often smaller than the coincident observations (with mean relative differences down to −10%), the sunset occultation profiles for ACE-MAESTRO show results that are qualitatively similar to ACE-FTS, indicating a large positive bias (mean relative differences within +10 to +30%) in the 4555 km altitude range. In contrast, there is no significant systematic difference in bias found for the ACE-FTS sunrise and sunset measurements.

Description: The persistent open-vent activity of basaltic volcanoes is periodically interrupted by spectacular but hazardous paroxysmal explosions. The rapid transition from quiescence to explosive eruption poses a significant challenge for volcanic hazard assessment and mitigation, and improving our understanding of the processes that trigger these paroxysmal events is critical. Although magmatic gas is unquestionably the driver, direct measurements of a paroxysm's gas flux budget have remained challenging, to date. A particularly violent paroxysmal sequence took place on Etna on December 2015, intermittently involving all summit craters, especially the Voragine (VOR) that had previously displayed no activity for several years. Here, we characterize the volcano's SO2 degassing budget prior to, during and after this paroxysmal sequence, using ground-based (UV-Camera) and satellite (OMI) observations, complemented with ground- and space-borne thermal measurements. We make use of the high spatial resolution of UV-cameras to resolve SO2 emissions from the erupting VOR crater for the first time, and to characterize temporal switches in degassing activity from VOR to the nearby New Southeast Crater (NSEC). Our data show that onset of paroxysmal activity on December 3–5 was marked by visible escalation in VOR SO2 fluxes (4,700–8,900 tons/day), in satellite-derived thermal emissions (2,000 MW vs. ~2–11 MW in July-November 2015), and in OMI-derived daily SO2 masses (5.4 ± 0.7 to 10.0 ± 1.3 kilotonnes, kt; 0.5 kt was the average in the pre-eruptive period). Switch in volcanic activity from VOR to NSEC on December 6 was detected by increasing SO2 fluxes at the NSEC crater, and by decaying SO2 emissions at VOR, until activity termination on December 19. Taken together, our observations infer the total degassed SO2 mass for the entire VOR paroxysmal sequence at 21,000 ± 2,730 t, corresponding to complete degassing of ~1.9 ± 0.3 Mm3 of magma, or significantly less than the measured erupted magma volumes (5.1–12 Mm3). From this mismatch we propose that only a small fraction of the erupted magma was actually emplaced in the shallow plumbing system during (or shortly prior) the paroxysmal sequence. Rather, the majority of the erupted magma was likely stored conduit magma, having gone through extensive degassing for days to weeks prior to the paroxysm.

Description: Published

Description: id 239

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: The aim of this study was to assess potential candidate gene regions and corresponding universal primer pairs as secondary DNA barcodes for the fungal kingdom, additional to ITS rDNA as primary barcode. Amplification efficiencies of 14 (partially) universal primer pairs targeting eight genetic markers were tested across 〉 1 500 species (1 931 strains or specimens) and the outcomes of almost twenty thousand (19 577) polymerase chain reactions were evaluated. We tested several well-known primer pairs that amplify: i) sections of the nuclear ribosomal RNA gene large subunit (D1–D2 domains of 26/28S); ii) the complete internal transcribed spacer region (ITS1/2); iii) partial β-tubulin II (TUB2); iv) γ-actin (ACT); v) translation elongation factor 1-α (TEF1α); and vi) the second largest subunit of RNA-polymerase II (partial RPB2, section 5–6). Their PCR efficiencies were compared with novel candidate primers corresponding to: i) the fungal-specific translation elongation factor 3 (TEF3); ii) a small ribosomal protein necessary for t-RNA docking; iii) the 60S L10 (L1) RP; iv) DNA topoisomerase I (TOPI); v) phosphoglycerate kinase (PGK); vi) hypothetical protein LNS2; and vii) alternative sections of TEF1α. Results showed that several gene sections are accessible to universal primers (or primers universal for phyla) yielding a single PCR-product. Barcode gap and multi-dimensional scaling analyses revealed that some of the tested candidate markers have universal properties providing adequate infra- and inter-specific variation that make them attractive barcodes for species identification. Among these gene sections, a novel high fidelity primer pair for TEF1α, already widely used as a phylogenetic marker in mycology, has potential as a supplementary DNA barcode with superior resolution to ITS. Both TOPI and PGK show promise for the Ascomycota, while TOPI and LNS2 are attractive for the Pucciniomycotina, for which universal primers for ribosomal subunits often fail.

Description: Rearing of anemonefishes is now relatively routine compared to the culture of cardinalfishes (Apogonidae) or angelfishes (Pomacanthidae). However, it is still a labor intensive, time intensive and expensive procedure. To reduce time and cost of rearing anemonefishes, experiments were undertaken to improve the methods for rearing Amphiprion melanopus. These experiments were conducted to determine the effect of the length of photoperiod on larval duration, growth to metamorphosis and early juvenile phase. Growth of larvae was significantly faster and the duration of the larval phase was significantly shorter, under a photoperiod of 16 hours light/8 hours dark, compared to the photoperiods of 12 hours light/12 hours dark and 24 hours light/0 hours dark.

Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 1983

Description: Brook trout (Salvelinus fontinalis) raised from eggs under two photoperiod and two feeding regimes were tested for physiological changes preparatory for transition from freshwater to seawater. Size, age, growth rate, photoperiod, and diel rhythms were examined for possible influences on plasma osmolarity, [Na+], [Cl-], [K+], [Mg2+], thyroxine concentration, hematocrit, and gill Na+,K+-ATPase activity of brook trout in freshwater. Significant diel cycles were found in plasma osmolarity, (Na+] and thyroxine concentration. Significant size and/or age related changes occurred for plasma osmolarity, [Na+], [K+] and hematocrit, but could explain little of their total variation (0.02 〈 r2 〈0.18). A sexually dimorphic response to photoperiod was observed in hematocrit for both mature and immature fish, with hematocrit of mature females declining in autumn and hematocrit of immature males increasing in autumn. Gill Na+,K+-ATPase activity did not respond to photoperiod or feeding treatment and showed no change with size or age. Plasma thyroxine levels responded to feeding and photoperiod treatment. There was a significant correlation between the percent mean difference in plasma thyroxine and the mean difference in growth rate between high and low feed fish (r2 = 0.51), suggesting a relationship between thyroxine and growth. In 11 experiments over 1.5 yrs, brook trout were gradually exposed to 32 ppt seawater for 20 d to investigate the ontogeny of salinity tolerance. A single experiment examined daily changes in plasma osmolarity, [Na+], [Cl-], [K+], [Mg2+], thyroxine, hematocrit and gill Na+,K+-ATPase during adaptation to 10 ppt, 20 ppt and 32 ppt. Size was the primary determinant of seawater survival (r2 = 0.77); the effect of size on seawater survival slowed after fish reached a fork length of 14 cm. The effect of age on seawater. survival (r2 = 0.65) was through its covariance with size. Photoperiod affected seawater survival only through its influence on the timing of male maturation, which decreased salinity tolerance. Hypoosmoregulation of plasma osmolarity, [Na+], [Cl-], [K+], [Mg2+] and hematocrit increased linearly with size over the entire range of sizes (6-32 cm). Gill Na+,K+-ATPase activity after 20 d in seawater decreased with increasing size of brook trout, possibly reflecting decreased demand for active ion transport in larger fish. Plasma thyroxine concentrations generally declined in seawater, but no definitive role of this hormone in seawater adaptation was found. Size dependent survival and osmoregulatory ability of brook trout is compared to other salmonids and a conceptual model is developed. Decreased salinity tolerance and hypoosmoregulatory ability was found in mature male brook trout and was not found in females or immature males. Lowered salinity tolerance of adult males becomes acute during autumn photoperiod when normal spawning occurs. Plasma [Cl-], [Mg2+], osmolarity and hematocrit are significantly higher in mature males after transfer to seawater, relative to mature females. It is postulated that reduced adult male hypoosmoregulatory ability explains skewed sex ratios in anadromous populations, limits the extent of anadromy, and was a significant phase in the evolution of extended salmonid migration. Anadromous brook trout of Riviere a la Truite, Quebec, were examined for physiological changes associated with salmonid smoltification, and compared to non-anadromous brook trout of the Matamek River. There were no significant differences in plasma thyroxine concentration, gill Na+,K+-ATPase activity, hematocrit or osmoregulatory ability of anadromous and non-anadromous brook trout. Moisture content was significantly different between fish from the two river systems, but had the same pattern of declining moisture content as summer progressed. Silver coloration of brook trout in Riviere a la Truite was significantly associated with larger fish and higher gill Na+,K+-ATPase activity, but not with changes in plasma thyroxine, moisture content, hematocrit or condition factor. Silver coloration was absent in Matamek River brook trout. Brook trout at high salinity estuarine sites had significantly greater gill Na+,K+-ATPase activity and hypoosmoregulatory ability than brook trout at low salinity sites. Atlantic salmon (Salmo salar) in high salinity estuarine sites had significantly higher plasma thyroxine and gill Na+,K+-ATPase activity than brook trout. The results indicate that smoltification is relatively undeveloped in brook trout and that estuarine residence is important in salinity adaptation and eventual seaward migration.

Description: I gratefully acknowledge the financial support of the W.H.O.I. education office, the Tai Ping foundation and the U.S. Department of Commerce Sea Grant Program.

Description: Offering a scientific perspective, this paper provides a rationale for the use of dispersants in oil spill remediation by discussing their formulations and modes of action and connecting their physics and chemistry to a their environmental fates and impacts. With the first use of dispersants at the source of the oil release during the Deepwater Horizon incident, there is a new great need for understanding the efficiency and the environmental impacts of their use. The paper concludes with some cautionary recommendations on dispersant research.

Description: Author Posting. © The Oceanography Society, 2016. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 29, no. 3 (2016): 108–117, doi:10.5670/oceanog.2016.75.