carbon dioxide and carbon monoxide emission rates from an alkaline intra plate volcano mt erebus antarctica abstract this is the first report of co and co 2 flux from mt erebus antarctica an alkaline intra plate volcano with a convecting lava lake the co 2 flux from the mt erebus plume was measured by in plume infrared analysis during december 1997 december 1999 and january 2001 the co 2 emission rates were consistently close to the average of 22 3 kg s 1930 mg day for the three measurements conducted over a 4 year period even though the third measurement january 2001 was conducted at a time of elevated activity as co 2 is considered a good indicator of eruptive activity a more frequent type of monitoring system may be necessary to detect changes related to activity at mt erebus increased co 2 emissions lost via strombolian eruptions in the lava lake were not accounted for in our airborne measurements carbon monoxide flux determined by fourier transform infrared spectroscopy in december 1995 yielded a rate of 1 74 kg s 150 mg day and a high co co 2 ratio of 0 12

sulfur dioxide from nevado del ruiz volcano colombia total flux and isotopic constraints on its origin abstract nevado del ruiz volcano has been releasing extraordinarily large volumes of sulfur dioxide gas from its arenas crater since september 1985 and probably since the renewal of volcanic activity began in late 1984 the combined release from eruptive and passive flux has been approximately 3 4 1 0 10 6 metric tons in the four years after november 1984 this value combined with data of others on pre eruption sulfur content of the magma allows the calculation of a minimum required volume of magma of 0 92 km 3 consideration of the continued high flux and typical ratios of erupted to degassed magma indicate that the true minimum volume of magma involved is probably at least 4 6 9 2 km 3 a systematic study of the various species of sulfur in the volcanic plume and the hydrothermal system has provided a characterization of the geochemistry and sulfur isotopic variation consideration has been given to five potential sources of the sulfur dioxide dissolution of subvolcanic evaporites remobilization and oxidation of native sulfur within summit crater fumaroles large scale release from the hydrothermal system by reduction of sulfate or water rock interaction assimilation and oxidation of a pre existing sulfide deposit and magmatic volatiles the data are most realistically explained by the passage of magmatic gas through the hydrothermal system with some disproportionation of sulfur dioxide to produce the high sulfate content and low ph of the waters this model is also most consistent with the distribution of acid sulfate chloride hot springs high chloride and fluoride content of the hydrothermal waters sulfide deposition within the volcanic pile and the transient increase in sulfate content of the acid sulfate chloride hot springs that reached a maximum approximately one year after the november 1985 eruption the magmatic model is in apparent conflict with the absence of general deformation from the time that data began to be collected about one week before the eruption until the time this manuscript was finalized september 1989 although this conflict cannot be resolved with certainty it is noted that the absence of deformation is only an indication of the lack of magma movement not of the absence of magma an alternative magmatic model considers the available geological data and proposes that the system is related to a large scale caldera in this model the degassing is related to a long term process of exsolution of magmatic volatiles from a large volume of crystallizing magma left from the construction of modern ruiz this model can better explain the combined geological and geophysical data as well as the geochemical and isotopic data the nature of the degassing data at ruiz is interesting because it is an example of an explosive eruption cycle in which the gas flux is actually dominated by passive release the nature of the degassing allows us to hypothesize that some major change in the system occurred in april may 1986 and to predict that the present high flux can be expected to last for another decade

selenium in volcanic environments a review abstract selenium is a chemical element with major environmental implications due to the extremely narrow range between essential and toxic concentrations volcanoes emit significant amounts of se which has an enormous impact on the se cycle and potentially human and animal health this paper presents a broad overview of the current state of knowledge of major aspects of volcanic derived se focussing on the processes in soils and aquifers volcanic soils formed when volcanic products weather rapidly display peculiar characteristics selenium contents can be relatively high 1 2 orders of magnitude higher compared to the worldwide average 0 4 mg kg but often with low mobility the soils can be impacted by local deposition of volcanic emissions which are enriched in se due to volatilization in the magma chamber it seems that the chemical fate of se in volcanic soils is controlled by sorption processes on poorly crystalline phases which presence depends on the parental materials and weathering these sorption processes also determine leaching to groundwaters some volcanic aquifers have se concentrations above the who guideline of 10 g l this might also be related to geothermal activity in spite of the well documented interest on se during the last decades a significant number of uncertainties exist on the behavior of this fascinating element a preliminary model of the se cycle around volcanoes can be constructed but the well known analytical problems associated with se determinations have produced a lack of reliable information on some processes involved in the chemical interaction between soils and water this review therefore also aims to identify the processes where new efforts are needed to produce good quality data to be compared and integrated in global models

very long period oscillations of mount erebus volcano as the signal decays vlp scalar moments up to 5 10 11 n m exceed sp moments by an order of magnitude or more suggesting distinct though genetically related sp and vlp source mechanisms we conclude that vlp signals arise from excitation of a quasi linear resonator that is intimately associated with the conduit system and is excited by gravity and inertial forces associated with gas slug ascent eruption and magma recharge vlp signal stability across hundreds of eruptions spanning 5 years the persistence of the lava lake and the rapid posteruptive lava lake recovery indicate a stable near summit magma reservoir and vlp source process index terms 4544 oceanography physical internal and inertial waves 7280 seismology volcano seismology 8419 8414 volcanology eruption mechanisms 8419 volcanology eruption monitoring 7280 keywords strombolian very long period volcano seismology

arsenic in volcanic gases total arsenic contents were determined in volcanic gases by analysis of fumarolic condensates collected in the period 1984 1992 from different volcanoes around the world arsenic concentrations range from 0 006 to 30 g g the highest values 1 2 30 g g were found at vulcano aeolian islands southern italy the analytical data show that volcanic gases have a large variability of arsenic contents possibly related to both the different physicochemical features of magma source and rock properties within the volcanic system

vapor phase cristobalite as a durable indicator of magmatic pore structure and halogen degassing an example from white island volcano new zealand vesicles in volcanic rocks are physical records of magmatic degassing however the interpretation of their textures is complicated by resorption coalescence and collapse we discuss the textural significance of vesicle hosted vapor phase cristobalite high t low p sio2 polymorph and its utility as a complement to textural assessments of magmatic degassing using a representative dacite bomb erupted from white island volcano new zealand in 1999 imaging in 2d sem and 3d ct shows the bomb to have 56 bulk porosity almost all of which is connected 99 and devoid of sio2 phases the remaining 1 of porosity is in isolated sub spherical vesicles that have corroded walls and contain small 30 m across prismatic vapor phase cristobalite crystals 98 4 0 4 wt sio2 with diagnostic laser raman spectra halogen degassing models show vapor phase cristobalite to be indicative of closed system chlorine and fluorine partitioning into h2o rich fluid in isolated pores at white island this occurred during shallow 100s of meters ascent and extensive 50 groundmass crystallization associated with slow cooling in a volcanic plug pristine textures in this white island bomb demonstrate the link between pore isolation and vapor phase cristobalite deposition we suggest that because these crystals have higher preservation potential than the bubbles in which they form they can serve as durable qualitative textural indicators of halogen degassing and pre quench bubble morphologies in slowly cooled volcanic rocks e g lava flows and domes even where emplacement mechanisms have overprinted original bubble textures

distribution of metals between particulate and gaseous forms in a volcanic plume in order to gain information on the distribution of metals between particles and gaseous forms in the plume of kilauea volcano a filter designed to collect metals associated with particles was followed in series by two other collectors intended to trap metals present in gaseous atomic molecular or complexed form first an acid bubbler bath and then a cold trap of the six metals measured all of the in tl and bi and almost all of the cd pb and cu were found on the filter none of any of the metals was detected in the acid bubbler bath masses equivalent to 0 3 of the amount of cd on the filter 0 4 of the amount of pb and 9 3 of the cu were measured in the cold trap the results indicate that all or nearly all of the six metals were partitioned to the particulate portion of the physical mixture of gases and particles that constitutes a volcanic plume but that there may be systematic differences between chalcophile metals in the ways they are partitioned between particulate and gaseous phases in a cooled plume and possibly differences in the acidity or other chemical properties of the molecular phases

metal transport in volcanic plumes a case study at white island and yasur volcanoes abstract we report new data on trace metal emissions at white island volcano 2015 2016 the first estimates from yasur volcano 2016 and a brief review of global volcanic metal fluxes bi cd tl se sb te and au are the most enriched metals and metalloids in the particulate phase of volcanic plumes observations of the particulate phase from the volcanic plumes of white island yasur and etna reveal abundant silicates and sulfates sulfuric acid and more interestingly zn oxide containing variable amounts of cu thermodynamic speciation calculations show chloride species to be very important in terms of gaseous metal transport complexation with sulfur in contrast appears significant only in s rich and cl poor gases at high 700 c temperature bromine despite being a minor component of volcanic gases is very efficient at complexing with metals and especially with cu pb bi zn and cr metal emission rates in the study period at white island are one to two orders of magnitude lower than reported previously with 6 10 kg d of cu as se and zn and

ionospheric characteristics above martian crustal magnetic anomalies 1 we studied several thousand electron density profiles from the mars global surveyor radio science experiment electron densities in some of these profiles change significantly over vertical distances as short as 1 2 km often causing localized bite outs these anomalous profiles are preferentially located above crustal magnetic anomalies anomalous features and their association with strong magnetic fields are also seen in profiles from mariner 9 the probability of a profile being anomalous depends on the orientation of the magnetic field suggesting localized electrodynamic effects upon otherwise global photochemical ionospheric processes on mars unlike most other planets the magnetic field has a short characteristic lengthscale so its effects on the ionosphere will vary over short horizontal distances we discuss possible ionospheric dynamo processes and encourage additional ionospheric observations over regions of strong crustal magnetic field

radioactive isotopes and trace elements in gaseous emissions from white island new zealand abstract measurements of the radioactivity of gases released by white island volcano show variations in 210 po concentrations with temperature in fumarolic gases and this is interpreted to be due to dilution of magmatic gases with vapours derived from an envelope of acid brines surrounding the vent system the degassing model derived for mount etna emissions is tested on white island magmatic gases the results are a short degassing time 2 days small degassing magma volume 5 10 6 m 3 and the following estimations of emanation coefficients pb 1 bi 2 7 cd 0 05 and cu 0 07 the initial content of s in the magma is estimated to be within the range 300 600 mg kg fluxes of trace metals kg day emitted by the volcano are estimated to be pb 125 bi 6 cu 300 and cd 9

acid gas emissions from galeras volcano colombia 1989 1994 abstract characterization of acid gases discharged by galeras volcano have allowed us to define a clear change in the pattern of degassing during 1989 through 1994 probably associated with pressure buildup that ended with the destruction of the dome by an explosive eruption on july 16 1992 using japanese boxes for sampling it was possible to establish characteristic discharge absorption levels for the period of study and to conclude that the absolute discharge of acid gases was declining at least until the middle of 1991 a staggered temporal response in gas compositions particularly co 2 and st for the different fumaroles suggests at least three possibilities 1 magma resurgence which would increase relative co 2 discharge as a result of new gas contribution and its relatively low solubility in magma 2 solidification and or crystallization of magma first in a zone of higher thermal gradient where there is a greater interaction with the hydrothermal system calvache fumarole and second toward the volcanic magmatic fumaroles deformes and besolima and 3 contribution of the hydrothermal system produced by water saturation and or temperature increase that would reduce co 2 solubility in water the similar behavior of the calvache fumarole and japanese box 3 as well as the existence of la trucha lake in the northeastern moat between the active cone and the amphitheater margin help us to define the location of the principal hydrothermal system the abrupt change toward a hydrothermal component in deformes fumaroles in august 1990 and the variations in chloride concentrations and other cation concentrations in condensate samples allow us to observe very large changes over short periods in the composition of the fluid phase of the volcanic system this suggests that the density of sampling should be increased together with the development of alternative techniques that could reduce risks and augment the resolution in the observation of the chemical changes on the other hand the dependence of gas absorption e g co 2 on the sampling period seen at the japanese boxes suggests that fixed sampling intervals would improve this method by reduction of sampling variables

interlinked barrier chain and delta lobe development northern gulf of mexico abstract a wealth of new data provides a well constrained chronology of mid to late holocene coastal development in the louisiana mississippi borderland that may also be utilized in a globally applicable sedimentation model barrier sand and deltaic mud sequences illustrate a process by which potential ground water and hydrocarbon reservoir rocks accumulated unusually rapidly and were preserved set against decelerating holocene sea level rise and locally variable subsidence rates the study provides an example of the interplay between an emerging prograding and partially stranded barrier island chain a sizable estuary and several extensive delta lobes utilizing microfossil fauna based depositional facies information and archaeological data absolute dates helped to reconstruct the history of the alabama louisiana barrier chain and deltas between ca 5 7 and ca 1 5 14c ka bp protected by the substantial dune cover that prevented island submersion the regional eustastic transgression paradoxically was synchronous with significant progradational barrier and deltaic regression the earliest barrier islands emerged ca 4 6 4 4 14c ka bp ca 5 7 5 0 cal years when sea level stood at ca 1 0 to 1 5 m these islands isolated mississippi sound from the greater gulf of mexico the absence of a lagoonal inshore sediment interval beneath the islands and the 3 15 m thick basal nearshore marine muddy sandy unit that blankets the pleistocene surface refutes the transgressive history of barrier initiation the islands aggraded on a 3 0 16 5 m thick fine sandy shallow marine regressive platform lithosome that in turn overlies a transgressive muddy sandy nearshore marine lower sediment interval avulsion of the mississippi river had abruptly reduced nearshore salinities by ca 3 9 3 7 ka 14c bp renewed mississippi delta growth induced rapid aggradation and progradation on the opposite pearl river delta mainland shore as well gulf influences have rapidly diminished in areas so affected a new absolute chronology of the mississippi st bernard delta lobes constrains these events delta growth and mainland progradation first isolated then severely constricted the lake borgne embayment accompanied by ongoing subsidence the western barriers were stranded then buried shoaling related to st bernard delta progradation interfered with westward littoral drift to maintain cat island archaeology provided important supplementary data for dating environmental changes refuting earlier suggestions that native colonization rapidly followed delta complex formation the earliest known indian sites postdated the start of the associated st bernard delta lobe by 1 9 3 1 14c ka

trace elements in the gas emissions from the erta ale volcano afar ethiopia high temperature 1084 c fumarolic emissions from a spatter cone at the erta ale north pit crater granted a rare opportunity to collect giggenbach bottles condensates and sublimates from the fumarolic gases of a rift plume volcano in the immediate proximity of degassing lava these results represent the highest temperature gases sampled directly for trace elements and the first high t fumarolic samples for a rift plume volcano sixty seven metals and metalloids were measured quantitatively by icp aes and icp ms in liquid gas condensates and solid sublimates the total amount of trace elements in the gas without si exceeded 170 ppm the ten most abundant elements transported in nonsilicate modes were na 61 ppm fe 41 ppm k 32 ppm br 12 4 ppm cd 3 0 ppm se 2 3 ppm cu 2 0 ppm zn 2 0 ppm te 1 7 ppm and as 1 2 ppm the gases contained 27 ppb re 1 5 ppb au 0 5 ppb pt and 0 27 ppb os rh and pd containing phases were observed in solid sublimates the only metal not detected by all analytical methods was ruthenium chalcophile elements cd cu zn se te as were transported primarily in the gaseous form alkali metals were emitted at least partially as liquid micron size sulfate droplets whereas alkali earths aluminum and ree had a high affinity to silicate aerosol in the form of basaltic microspheres the silicate aerosol content was evaluated at 59 ppm on average but varied within a 7 5 fold range during sampling because of the extremely high temperature refractory elements ca ba ta u and lree showed evidence of transport in the form of gaseous species the so2 flux in january 2011 was evaluated at 91 24 t d for the entire volcano including 31 t d from the north crater and 60 t d from the lava lake the daily output of trace elements from both erta ale craters without si was estimated at 53 kg d including 20 kg of na 13 5 kg of fe 10 5 kg of k 4 5 kg of chalcophile elements 9 g of re 0 5 g of au and 0 17 g of pt the trace element pattern of erta ale fumarolic gases do not possess any distinct geochemical specialization and resemble te patterns from fumarolic emissions of studied arc and plume volcanoes

rates of sulfur dioxide and particle emissions from white island volcano new zealand and an estimate of the total flux of major gaseous species airborne correlation spectrometry cospec was used to measure the rate of so2 emission at white island on three dates i e november 1983 1230 300 t d november 1984 320 120 t d and january 1985 350 150 t d t metric tons the lower emission rates are likely to reflect the long term emission rates whereas the november 1983 rate probably reflects conditions prior to the eruption of december 1983 the particle flux in the white island plume as determined with a quartz crystal microbalance cascade in november 1983 was 1 3 t d unusually low for volcanic plumes the observed plume particles as shown from scanning electron microscopy include halite native sulfur and silicates and are broadly similar to other volcanic plumes

size resolved chemical composition of aerosol emitted by erebus volcano antarctica 1 persistent open vent degassing of erebus volcano antarctica is a significant point source of gases and aerosol to the austral polar troposphere we report here on the chemical composition and size distribution of the erebus aerosol focusing on the water soluble fraction the aerosol was sampled at the rim of the active crater using a cascade impactor which collected and sized particles in 14 size bins from 10 to 0 01 m the soluble fraction of the erebus aerosol is distinct from other volcanic sources in several respects it is dominated by chloride bearing particles over 30 of total mass and has an unusually high cl so42 molar ratio of 3 5 coarse particles contribute little to the total mass of the soluble fraction elevated concentrations of f cl br and so42 are found in a narrow particle size fraction of 0 1 0 25 m the detection of particulate br reinforces our understanding of the potential for quiescent volcanic emissions to deplete tropospheric ozone the small aerosol size reflects the low atmospheric temperature and humidity which inhibit particle growth halide alkali metal salts na k cl f appear to be the most abundant species in the aerosol the concentration of pb is high compared to other volcanoes its exsolution may be promoted by the high abundance of halogens in erebus magma despite the previously reported high nox content in the plume we did not detect significant quantities of nitrate in the near vent aerosol our findings emphasize the potential regional significance of emissions from erebus for understanding the antarctic atmospheric composition and glaciochemical records

volcanic emissions of metals and halogens from white island new zealand and erebus volcano antarctica determined with chemical traps abstract volcanic emission rates of as sb pb hg se cl and f were determined at erebus volcano antarctica and white island new zealand using chemical traps the trace metal fluxes were determined by combining the species to s ratios in the solutions with so2 emission rates measured by correlation spectrometry at the two volcanoes at erebus volcano fluxes for the metals pb and hg were 2 0 10 4 and 8 1 10 6 kg s 11 respectively fluxes for cl f as sb and se 0 35 0 15 2 5 10 4 1 2 10 5 and 4 5 10 6 kg s 1 respectively agreed within error limits for values determined previously by the lioh impregnated filter method zreda gostynska g kyle p finnegan d prestbo k 1997 volcanic gas emissions from mount erebus and their impact on the antarctic environment journal of geophysical research 102 b7 15039 15055 demonstrating the utility of the chemical trap method a fall in the as s ratio from 7 10 4 in 1997 1999 to 3 10 4 in 2000 at erebus coincided with a change in the frequency and style of eruptive activity that may have been due to injection of magma into the system at white island chemical trap data indicated fluxes of cl 0 90 f 0 0079 pb 2 7 10 4 hg 1 1 10 5 as 1 3 10 4 sb 1 9 10 5 and se 1 5 10 5 kg s 1 samples collected 600 m downwind of the active crater were comparable to samples collected adjacent to the main gas vent showing that this method can still be used at some distance from a degassing vent

control of the topside martian ionosphere by crustal magnetic fields we present observations from the mars advanced radar for subsurface and ionospheric sounding marsis instrument onboard mars express of the thermal electron plasma density of the martian ionosphere and investigate the extent to which it is influenced by the presence of mars s remnant crustal magnetic fields we use locally measured electron densities derived when marsis is operating in active ionospheric sounding ais mode covering an altitude range from 300 km to 1200 km we compare these measured densities to an empirical model of the dayside ionospheric plasma density in this diffusive transport dominated regime we show that small spatial scale departures from the averaged values are strongly correlated with the pattern of the crustal fields persistently elevated densities are seen in regions of relatively stronger crustal fields across the whole altitude range comparing these results with measurements of the scalar magnetic field also obtained by marsis ais we characterize the dayside strength of the draped magnetic fields in the same regions finally we provide a revised empirical model of the plasma density in the martian ionosphere including parameterizations for both the crustal field dominated and draping dominated regimes

seismic and acoustic observations at mount erebus volcano ross island antarctica 1994 1998 volcanic activity at mount erebus is dominated by eruptive activity within a phonolitic summit lava lake common eruption styles range from passive degassing to strombolian explosions which typically occur several times daily and occasionally in swarms of up to 900 per day shallow explosions although generally the result of steady exsolution of volatiles from depth can be triggered by surficial input of h 2o through mass wasting of rock snow and ice from the crater walls broadband observations of strombolian explosions document very long period vlp signals with strong spectral peaks near 20 12 and 7 s which are polarized in the vertical radial plane these signals precede lava lake surface explosions by 1 5 s are highly repeatable and persist for up to 200 s first motions indicate a deflationary source with any precursory inflation being below the 30 s passband of our instruments particle motions suggest a vlp source residing up to 800 m below the lava lake surface however this depth could be exaggerated by near field radial tilt seismic and acoustic signals associated with lava lake explosions commonly show evidence for multiple bubble bursts in corresponding complexity features resulting from varying time delays and relative sizes of superimposed bursts a systematic decrease in seismic acoustic ratio for smaller surface explosions suggests that either the seismic energy from the smallest shallowest bubble bursts experiences much greater seismic attenuation than energy arising from larger events which may involve a deeper less attenuative portion of the magma column and or that the shallowest layer is seismically isolated from deeper parts of a stratified magma column which are not excited by the smallest explosions due to sharp impedance contrasts across distinct layers tremor at erebus is uncommon with only a few isolated instances identified in five years of monitoring some tremor events are nearly monochromatic and some exhibit numerous gliding harmonic spectral lines q 2000 elsevier science b v all rights reserved

characterizing average electron densities in the martian dayside upper ionosphere we use more than 10years of the martian topside ionospheric data measured by the mars advanced radar for subsurface and ionosphere sounding radar sounder on board the mars express spacecraft to der

maven observations of the effects of crustal magnetic fields on electron density and temperature in the martian dayside ionosphere mars lacks a global magnetic field but possesses concentrated regions of crustal magnetic field that influence the planet s interaction with the solar wind and the structure of the martian ionosphere in this study we survey 17 months of maven langmuir probe and waves dayside electron density and temperature measurements to study how these quantities are affected in regions with strong crustal magnetic fields above 200 km altitude we find that regions of strong crustal magnetic fields feature cooler electron temperatures and enhanced electron densities compared to regions with little or no crustal magnetic field neutral densities and temperatures are not significantly affected closed field lines on which electrons can be trapped are more prevalent in strong crustal field regions than elsewhere trapped on closed field lines electrons are protected against loss processes involving the solar wind this would lead to longer plasma lifetimes higher densities and lower temperatures

trace metal suites in antarctic pre industrial ice are consistent with emissions from quiescent degassing of volcanoes worldwide abstract trace metals are more abundant in atmospheric load and deposition material than can be due to rock and soil dusts and ocean salt in pre industrial ice from coastal west antarctica dust and salt account for only a few percent of the lead cadmium and indium that is present in most samples less than half in any sample for these trace metals the deposition rate to the pre industrial ice is approximately matched by the output rate to the atmosphere by quiescent non explosive degassing of volcanoes worldwide according to a new estimate the basis of the match is the masses and proportions of the metals and the proportions of pb isotopes in ice and in volcano emissions the isotopic compositions of pb in ice are similar to those of a suite of ocean island volcanoes mostly in the southern hemisphere the natural baseline values for pre industrial atmospheric deposition fluxes of trace metal suites at taylor dome and the worldwide quiescent volcano emissions fluxes to which they are linked constitute a reasonably well constrained baseline component for deposition fluxes of metals in modern times

anthropogenic lead isotopes in antarctica we report the first measurements of pb isotopes in antarctic snow which show that even recent snow containing 2 3 pg g is highly polluted with anthropogenic pb this follows from a comparison of isotope abundances of pb in surface snow and terrestrial dust extracted from ancient antarctic ice dome c depth 308 m approximate age 7 500 a bp the latter being distinctly more radiogenic this result is independent of geochemical arguments based on measurements of al na and so 4 south america is suggested as a likely source of this anthropogenic pb the presence of significantly less radiogenic pb in the snow adjacent to two antarctic base stations indicates that there is contamination from station emissions although emission from australia is an alternative explanation for a site 33 km from dumont d urville

mars global surveyor radio science electron density profiles neutral atmosphere implications the mars global surveyor mgs radio sci ence rs experiment permits retrieval of electron density prof iles versus height 90 200 km from occultation mea surements an initial set of electron profiles is examined spanning high northern latitudes early morning solar local times and high solar zenith angles 78 to 81 near aphelion sampling for these 32 profiles is well distributed over longi tude the height of the photochemically driven ionospheric peak is observed to respond to the background neutral den sity structure with a mean height during this season at this location of 134 4 km strong wave 3 oscillations about this mean are clearly observed as a function of longitude and correspond to neutral density variations measured by the mgs accelerometer acc experiment the wave 3 tidal pattern implicated by both the rs and acc datasets is consistent with a semi diurnal wave frequency clearly the height of the martian dayside ionospheric peak is a sensitive indicator of the state of the underlying mars atmosphere this ionospheric peak height can be used as a proxy of the longitude specific non migrating tidal variations present in the mars lower thermosphere

acid gas and metal emission rates during long lived basalt degassing at stromboli volcano the discharge of acid gases and metals from stromboli is determined from airborne and ground based filter sampling of particulate matter in the volcanic plume combined with cospec measurements of so2 fluxes smaller particle sizes and high enrichment factors distinguish the most volatile elements by order s se br cl cd bi in as sb sn f au pb cr cu from those strictly fe mn ree sc sr th ti v or mainly al ba ca co k na u derived from volcanic ash time averaged volatile fluxes show that stromboli is a representative arc emittor producing 1 2 of the global volcanic budget of sulfur halogens and several trace metals while 15 25 of volcanic emissions of bi cd cs pb and sn in southern italy subaerial degassing of its s cl rich shoshonitic magma over the last 2 ky of similar activity may have released as much copper and gold as is encountered in magma derived high sulfidation ore deposits

atmospheric sources and sinks of volcanogenic elements in a basaltic volcano etna italy abstract this study reports on the first quantitative assessment of the geochemical cycling of volcanogenic elements from their atmospheric release to their deposition back to the ground etna s emissions and atmospheric depositions were characterised for more than 2 years providing data on major and trace element abundance in both volcanic aerosols and bulk depositions volcanic aerosols were collected from 2004 to 2007 at the summit vents by conventional filtration techniques precipitation was collected from 2006 to 2007 in five rain gauges at various altitudes around the summit craters analytical results for volcanic aerosols showed that the dominant anions were s cl and f and that the most abundant metals were k ca mg al fe and ti 1 5 50 g m 3 minor and trace element concentrations ranged from about 0 001 to 1 g m 3 from such analysis we derived an aerosol mass flux ranging from 3000 to 8000 t a 1 most analysed elements had higher concentrations close to the emission vent confirming the prevailing volcanic contribution to bulk deposition calculated deposition rates were integrated over the whole etna area to provide a first estimate of the total deposition fluxes for several major and trace elements these calculated deposition fluxes ranged from 20 to 80 t a 1 al fe si to 0 01 0 1 t a 1 bi cs sc th tl and u comparison between volcanic emissions and atmospheric deposition showed that the amount of trace elements scavenged from the plume in the surrounding of the volcano ranged from 0 1 to 1 for volatile elements such as as bi cd cs cu tl and from 1 to 5 for refractory elements such as al ba co fe ti th u and v consequently more than 90 of volcanogenic trace elements were dispersed further away and may cause a regional scale impact such a large difference between deposition and emission fluxes at mt etna pointed to relatively high stability and long residence time of aerosols in the plume

magnitude of lead flux to the atmosphere from volcanoes pb s tl s and bi s ratios were measured in eruptive and fumarolic volcanic gases and indexed to the global flux of volcanic s to characterize approximate global volcanic emissions of these three metals to the atmosphere which are about 1200 tons pb yr 600 tons tl yr and 4000 tons bi yr this volcanic pb input is similar to the magnitude of natural soil dust pb input which is about 1400 tons pb yr during the holocene interglacial both are negligible compared to annual industrial inputs of 300 000 tons pb yr which maintain the present tropospheric reservoir of pb however polar ice records indicate that thousands of years ago the atmospheric pb reservoir was only 1 of its present size which means that volcanic pb was the source of about half the pb in the atmosphere during preindustrial holocene times

synchronous volcanic eruptions and abrupt climate change 17 7 ka plausibly linked by stratospheric ozone depletion glacial state greenhouse gas concentrations and southern hemisphere climate conditions persisted until 17 7 ka when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the southern hemisphere with many changes ascribed to a sudden poleward shift in the southern hemisphere westerlies and subsequent climate impacts we used high resolution chemical measurements in the west antarctic ice sheet divide byrd and other ice cores to document a unique 192 y series of halogen rich volcanic eruptions exactly at the start of accelerated deglaciation with tephra identifying the nearby mount takahe volcano as the source extensive fallout from these massive eruptions has been found 2 800 km from mount takahe sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface uv radiation indicate that the eruptions led to stratospheric ozone depletion rather than a highly improbable coincidence circulation and climate changes extending from the antarctic peninsula to the subtropics similar to those associated with modern stratospheric ozone depletion over antarctica plausibly link the mount takahe eruptions to the onset of accelerated southern hemisphere deglaciation 17 7 ka

geochemistry of metallic trace elements in fumarolic condensates from nicaraguan and costa rican volcanoes metallic trace element composition of volcanic gas from cerro negro momotombo san cristobal telica and masaya volcanoes in nicaragua and poas volcano in costa rica is indicated by analyses of fumarolic condensates for alkalis alkaline earths transition elements precious metals halogens and sulphate the temperatures of the fumaroles varied from 85 to 852 c element concentrations range from 104 to 10 3 ppm statistical tests indicate that the trace element constituents of the condensates are log normally distributed although there are variations in element concentrations in individual condensates the general order of decreasing elemental abundances in nicaraguan and costa rican fumarolic gas is cl so4 certain igneous rock forming elements si al fe ti f and alkalis li na k alkaline earths mg ca ba br and transition elements cr mn co ni cu zn other ore forming elements mo cd sn pb semi metals as sb sc hg and precious metals au ag li mn cr and pb were found to be near or below detection limits in many of the condensates analyzed so4 ti al k na zn sn cr and br all tend to decrease in abundance as mean fumarolic temperature between volcanoes decreases the remaining elements remain constant in abundance or behave erratically the metallic trace element composition of the nicaraguan and costa rican fumarolic condensates is very similar to condensates from subduction zone volcanoes around the pacific margin and the mediterranean metals in volcanic gas are postulated to have been transported as halogen sulphate and oxide compounds chloride and fluoride compounds are considered to be the primary transporters of metals in volcanic gas correlations between metal and halogen content vary considerably between volcanoes statistically significant correlations between metal content and both chlorine and bromine are found in the cerro negro and between metal content and bromine and fluorine in the momotombo condensates metal bearing compounds in volcanic gas are postulated from correlation matrices bromine though seldom reported in condensates is a minor but important constituent of volcanic gas with concentrations similar to those of fluorine metal bromide compounds have higher volatilities than fluoride compounds and volatilities similar to chloride compounds significant correlations between bromine content and metal concentration suggests that bromide compounds play a role in the transportation of metals in volcanic gas

geochemical surveillance of magmatic volatiles at popocatepetl volcano mexico surveillance of popocatepetl volcanic plume geochemistry and so 2 flux began in early 1994 after fumarolic and seismic activity increased significantly during 1993 volatile traps placed around the summit were collected at near monthly intervals until the volcano erupted on december 21 1994 additional trap samples were obtained in early 1996 before the volcano erupted again emplacing a small dacite dome in the summit crater abundances of volatile constituents ppm day of cl s total f co 2 hg and as varied but most constituents were relatively high in early and late 1994 however ratios of these constituents to cl were highest in mid 1994 34 s s total in trap solutions ranged from 1 5 to 6 4 lowest values generally occurred during late 1994 13 c co 2 of trap solutions were greatly contaminated with atmospheric co 2 and affected by absorption kinetics when trap data are combined with so 2 flux measurements made through november 1996 popocatepetl released about 3 9 mt so 2 16 mt co 2 0 75 mt hcl 0 075 mt hf 260 t as 2 6 t hg and roughly 200 mt h 2 o near vent gas concentrations in the volcanic plume measured by correlation spectrometer cospec and fourier transform infrared ftir commonly exceed human recommended exposure limits and may constitute a potential health hazard volatile geochemistry combined with petrologic observations and melt inclusion studies show that mafic magma injection into a preexisting silicic chamber has accompanied renewed volcanism at popocatepetl minor assimilation of cretaceous wall rocks probably occurred in mid 1994

sulfur dioxide emissions and degassing behavior of erebus volcano antarctica abstract emission rates of sulfur dioxide so 2 were measured at erebus volcano antarctica in december between 1992 and 2005 since 1992 so 2 emissions rates are normally distributed with a mean of 61 27 mg d 1 0 7 0 3 kg s 1 n 8064 the emission rates vary over minutes hours days and years hourly and daily variations often show systematic and cyclic trends long wavelength large amplitude trends appear related to lava lake area and both are likely controlled by processes occurring at depth time series analysis of continuous sequences of measurements obtained over periods of several hours reveals periodicity in so 2 output ranging from 10 to 360 min with a 10 min cycle being the most dominant closed and open system degassing models are considered to explain observed variable degassing rates closed system degassing is possible as rheological stiffening and stick slip may occur within the system however the timescales represented in these models do not fit observations made on erebus open system degassing and convection fits the observations collected as the presented models were developed for a system similar to erebus in terms of degassing eruptive activity and process repose time we show that with the observed emission rate 0 71 kg s 1 and a crystal content of 30 magma will cool 65 c to match observed heat fluxes this cooling is sufficient enough to drive convection

major and rare gases at white island volcano new zealand origin and flux of volatiles analyses of fumarolic gases at white island new zealand are reported with special emphasis on rare gases he ne ar kr and xe normalization of major species to rare gases have lead to the identification of several sources air saturated meteoric or marine water a magma body the crust and or sediments when compared to mid ocean ridge discharges the white island gas discharge represents about 3 0 7 0 1 and 0 05 of the global water carbon sulfur and helium 3 discharges respectively this balance shows that except for 3he which derives from the mantle practically all rare gases water and carbon and part of sulfur derive from originally superficial sources

the behavior of metals pb zn as mo cu during crystallization and degassing of rhyolites from the okataina volcanic center taupo volcanic zone new zealand tthe taupo volcanic zone tvz new zealand is a region of voluminous and frequent rhyolitic volcanism and widespread geothermal activity additionally the hydrothermal systems of the tvz contain relatively high concentrations of base and precious metals here we present an extensive dataset of major element volatile and trace element including pb zn as mo cu abundances in melt inclusions pumice glasses and minerals from eight eruptions within the okataina volcanic center ovc of the tvz to investigate the behavior of metals during melt evolution the high sio2 rhyolites of the ovc contain high concentrations of volatiles 6 wt h2o 0 25 wt cl and underwent significant degassing prior to and during eruption the ovc melts contain moderate concentrations of metals 11 24 ppm pb 20 50 ppm zn 2 7 ppm as 2 5 ppm mo 5 ppm cu ferromagnesian minerals amphibole biotite and orthopyroxene in the ovc pumice have high concentrations of zn 1500 ppm and plagioclase and biotite contain moderate amounts of pb 11 ppm the melt inclusion and pumice glass trace element data reveal complex histories of magma mixing and mingling prior to eruption however discrete melt batches are easily identified based on trace element geochemistry variations in incompatible trace elements within these melt batches suggest that the ovc rhyolites underwent at least 20 25 fractional crystallization during quartz crystallization and melt inclusion entrapment at pressures of 100 200 mpa and little to no crystallization 5 during ascent and eruption comparison of melt inclusion metal and incompatible element e g u concentrations reveals that melt pb mo and as increase whereas melt zn decreases during fractional crystallization at depth 100 200 mpa these observations can be explained by minor partitioning of the metals pb mo and as into the fractionating minerals and stronger partitioning of zn into the ferromagnesian phases supported by calculated metal d values and analyzed metal concentrations in ovc minerals interestingly throughout both deep vapor saturated crystallization and during extensive degassing during magma ascent and eruption as recorded by pumice glasses the metals analyzed here do not appear to partition appreciably into the vapor we propose that the lack of volatility of the metals analyzed in this study can be attributed to a combination of several factors first vapor melt partitioning requires the presence of ligands commonly cl s and oh with which the metals may complex given the low cl h2o ratios in the ovc melts and the extensive degassing of h2o compared with cl it seems likely that the rhyolites would have exsolved h2o rich vapor with insufficient cl to transport metals in particular pb and zn into the vapor phase either at depth or during magma ascent second the overall small volumes of vapor present during crystallization at pressures of 100 200 mpa would have impeded significant vapor melt partitioning of the metals finally the estimated very rapid ascent of the ovc melts from depths of 4 8 km suggests that there was insufficient time at low pressure for diffusion of metals out of the melt these results imply that there may be an indirect connection between the rhyolites and the metals of the hydrothermal systems of the tvz as the metals and other species such as cl remain in the rhyolitic magmas upon eruption they are available in the large volumes of rhyolite emplaced in the upper crust of the tvz for leaching by heated meteoric waters

evaluation of gases condensates and so2 emissions from augustine volcano alaska the degassing of a cl rich volcanic system after the march april 1986 explosive eruption a comprehensive gas study at augustine was undertaken in the summers of 1986 and 1987 airborne cospec measurements indicate that passive so2 emission rates declined exponentially during this period from 380 45 metric tons day t d on 7 24 86 to 27 6 t d on 8 24 87 these data are consistent with the hypothesis that the augustine magma reservoir has become more degassed as volcanic activity decreased after the spring 1986 eruption gas samples collected in 1987 from an 870 c fumarole on the andesitic lava dome show various degrees of disequilibrium due to oxidation of reduced gas species and condensation and loss of h2o in the intake tube of the sampling apparatus thermochemical restoration of the data permits removal of these effects to infer an equilibrium composition of the gases although not conclusive this restoration is consistent with the idea that the gases were in equilibrium at 870 c with an oxygen fugacity near the ni nio buffer these restored gas compositions show that relative to other convergent plate volcanoes the augustine gases are very hcl rich 5 3 6 0 mol hcl s rich 7 1 mol total s and h2o poor 83 9 84 8 mol h2o values of d and 18o suggest that the h2o in the dome gases is a mixture of primary magmatic water pmw and local seawater part of the cl in the augustine volcanic gases probably comes from this shallow seawater source additional cl may come from subducted oceanic crust because data by johnston 1978 show that cl rich glass inclusions in olivine crystals contain hornblende which is evidence for a deep source 25km for part of the cl gas samples collected in 1986 from 390 642 c fumaroles on a ramp surrounding the inner summit crater have been oxidized so severely that restoration to an equilibrium composition is not possible h and o isotope data suggest that these gases are variable mixtures of seawater fmw and meteoric steam these samples are much more h2o rich 92 97 h2o than the dome gases possibly due to a larger meteoric steam component the 1986 samples also have higher cl s s c and f cl ratios which imply that the magmatic component in these gases is from the more degassed 1976 magma thus the 1987 samples from the lava dome are better indicators than the 1986 samples of degassing within the augustine magma reservoir even though they were collected a year later and contain a significant seawater component future gas studies at augustine should emphasize fumaroles on active lava domes condensates collected from the same lava dome fumarole have enrichments ot 107 102 in cl br f b cd as s bi pb sb mo zn cu k li na si and ni lower temperature 200 650 c fumaroles around the volcano are generally less enriched in highly volatile elements however these lower termperature fumaroles have higher concentration of rock forming elements probably derived from the wall rock