rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments deposition of volcanic ash into aqueous environments leads to dissolution of adsorbed metal salts and aerosols increasing the bioavailability of key nutrients volcanogenic fertilization events could increase marine primary productivity leading to a drawdown of atmospheric co2 here we conduct flow through experiments on unhydrated volcanic ash samples from a variety of locations and sources measuring the concentrations and fluxes of elements into de ionized water and two contrasting ocean surface waters comparisons of element fluxes show that dissolution of adsorbed surface salts and aerosols dominates over glass dissolution even in sustained low ph conditions these surface ash leachates appear unstable decaying in situ even if kept unhydrated volcanic ash from recent eruptions is shown to have a large fertilization potential in both fresh and saline water fluorine concentrations are integral to bulk dissolution rates and samples with high f concentrations display elevated fluxes of some nutrients particularly fe si and p bio limiting micronutrients are released in large quantities suggesting that subsequent biological growth will be limited by macronutrient availability importantly acidification of surface waters and high fluxes of toxic elements highlights the potential of volcanic ash leachates to poison aqueous environments in particular large ph changes can cause undersaturation of caco3 polymorphs damaging populations of calcifying organisms deposition of volcanic ash can both fertilize and or poison aqueous environments causing significant changes to surface water chemistry and biogeochemical cycles

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

understanding the environmental impacts of large fissure eruptions aerosol and gas emissions from the 2014 2015 holuhraun eruption iceland abstract the 2014 2015 holuhraun eruption in iceland emitted 11 tg of so2 into the troposphere over 6 months and caused one of the most intense and widespread volcanogenic air pollution events in centuries this study provides a number of source terms for characterisation of plumes in large fissure eruptions in iceland and elsewhere we characterised the chemistry of aerosol particle matter pm and gas in the holuhraun plume and its evolution as the plume dispersed both via measurements and modelling the plume was sampled at the eruptive vent and in two populated areas in iceland the plume caused repeated air pollution events exceeding hourly air quality standards 350 g m3 for so2 on 88 occasions in reykjahli town 100 km distance and 34 occasions in reykjavik capital area 250 km distance average daily concentration of volcanogenic pm sulphate exceeded 5 g m3 on 30 days in reykjavik capital area which is the maximum concentration measured during non eruptive background interval there are currently no established air quality standards for sulphate combining the results from direct sampling and dispersion modelling we identified two types of plume impacting the downwind populated areas the first type was characterised by high concentrations of both so2 and s bearing pm with a high sgas spm mass ratio so2 g so 4 2 pm 10 the second type had a low sgas spm ratio

measuring volcanic plume and ash properties from space the remote sensing of volcanic ash plumes from space can provide a warning of an aviation hazard and knowledge on eruption processes and radiative effects in this paper new algorithms are presented to provide volcanic plume properties from measurements by the michelson interferometer for passive atmospheric sounding mipas the advanced along track scanning radiometer aatsr and spinning enhanced visible and infrared imager seviri a challenge of remote sensing is to provide near real time methods to identify and so warn of the presence of volcanic ash to achieve this a singular vector decomposition method has been developed for the mipas instrument on board the environmental satellite envisat this method has been applied to observations of the ash clouds from the eruptions of nabro and the puyehue cordon caulle in 2011 and lead to a more sensitive volcanic signal flag which was capable of tracking changes in the volcanic signal spectra as the plume evolved a second challenge for remote sensing is to identify the ash plume height this is a critical parameter for the initialisation of algorithms that numerically model the evolution and transport of a volcanic plume as mipas is a limb sounder the identification of ash also provides an estimate of height provided the plume is above about 6 km this is complemented by a new algorithm stereo ash plume height retrieval algorithm saphra that identifies plume height using the parallax between images provided by along track scanning radiometer type instruments the algorithm was tested on an image taken at 14 01 gmt on 6 june 2011 of the puyehue cordon caulle eruption plume and gives a height of 11 9 1 4 km which agreed with the value derived from the location of the plume shadow 12 7 1 8 km this plume height was similar to the height observed by mipas 12 1 5 km at 02 56 gmt on 6 june the quantitative use of satellite imagery and the full exploitation of high resolution spectral measurements of ash depends upon knowing the optical properties of the observed ash laboratory measurements of ash from the 1993 eruption of mt aso japan have been used to determine the refractive indices from 1 to 20 m these preliminary measurements have spectral features similar to ash values that have been used to date albeit with slightly different positions and strengths of the absorption bands the refractive indices have been used to retrieve ash properties plume height optical depth and ash effective radius from aatsr and seviri instruments using two versions of oxford ral retrieval of aerosol and cloud orac algorithm for aatsr a new ash cloud type was used in orac for the analysis of the plume from the 2011 eyjafjallajokull eruption for the first 500 km of the plume orac gave values of plume height 2 5 6 5 km optical depth 1 2 5 and effective radius 3 7 m which are in agreement with other observations a weakness of the algorithm occurs when underlying cloud invalidates the

the sediments of lake logurinn a unique proxy record of holocene glacial meltwater variability in eastern iceland the full holocene development of the large 8100 km 2 vatnajokull ice cap in iceland with its many outlet glaciers is poorly known the idea of an early deglaciation leading to a glacier free period in mid holocene followed by the neoglaciation is still the main concept for the glacial history in the north atlantic region including iceland we have examined a continuous sediment record from the glacier fed lake logurinn in eastern iceland to infer holocene meltwater variability of eyjabakkajokull which is a surge type outlet glacier of the vatnajokull ice cap we focus on the early and mid holocene and our data show that eyjabakkajokull receded rapidly during the final phase of the last deglaciation and did not deliver glacial meltwater to lake logurinn by 9000 years bp suggesting that eyjabakkajokull was significantly smaller than today at that time the return of glacial meltwater transport to lake logurinn and thus a return of eyjabakkajokull is dated to ca 4400 years bp suggesting an almost 5000 years long glacier free period during early and mid holocene during this time period we infer that the 8 2 ka cold event did not cause a significant expansion of eyjabakkajokull however we note a marked decrease in the aquatic productivity in lake logurinn which is suggested to be the result of shorter ice free seasons of lake logurinn the holocene thermal maximum is inferred by a period of maximum holocene aquatic productivity and dated to ca 7900 7000 years bp following the re formation of eyjabakkajokull ca 4400 years bp we suggest that the glacier reached stable conditions ca 1700 years bp and remained fairly stable until the later part of the little ice age when eyjabakkajokull reached its maximum holocene extent c 2012 elsevier ltd all rights reserved less

contribution of icelandic ice caps to sea level rise trends and variability since the little ice age 1 in total icelandic ice caps contain 3600 km3 of ice which if melted would raise sea level by 1 cm here we present an overview of mass changes of icelandic ice masses since the end of the 19th century they have both gained and lost mass during this period changes in ice volume have been estimated both through surface mass balance measurements performed annually since 1990 and differencing of digital elevation models derived from various satellite and airborne observations while the glaciers showed little mass loss as the 20th century began losses increased rapidly after 1925 peaked in the 1930s and 1940s and remained significant until the 1960s after being near zero or even positive during the 1980s and early 1990s glacier mass budgets declined considerably and have since the mid 1990s shown an average annual loss of 9 5 1 5 gt a 1 contributing 0 03 mm a 1 to sea level rise since 1995 interannual variability in mass loss is high ranging from 2 7 to 25 3 1 5 gt a 1 corresponding to surface mass balances of 0 2 to 2 2 0 15 m we a 1 this variability is driven by climate fluctuations and also by transient reduction of albedo due to volcanic eruptions

emission of bromine and iodine from mount etna volcano 1 constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion however very few such measurements have been made hitherto such that global volcanic fluxes are poorly constrained here we extend the data set of volcanic br and i degassing by reporting the first measurements of bromine and iodine emissions from mount etna these data were obtained using filter packs and contemporaneous ultraviolet spectroscopic so2 flux measurements resulting in time averaged emission rates of 0 7 kt yr 1 and 0 01 kt yr 1 for br and i respectively from april to october 2004 from which we estimate global br and i fluxes of order 13 range 3 40 and 0 11 range 0 04 6 6 kt yr 1 observed changes in plume composition highlight the coherent geochemical behavior of hcl hf hbr and hi during magmatic degassing and strong fractionation of these species with respect to so2

metal emissions from kilauea and a suggested revision of the estimated worldwide metal output by quiescent degassing of volcanoes abstract measurements of a large suite of metals pb cd cu zn and several others and sulfur at kilauea volcano over an extended period of time has yielded a detailed record of the atmospheric injection of ordinarily rare metals from this quiescently degassing volcano representative of an important type we have combined the kilauea data with data of recent studies by others emissions from volcanoes in the indonesian arc the large laki eruption of two centuries ago etna estimates of total volcanic emissions of sulfur to form the basis for a new working estimate of the rate of worldwide injection of metals to the atmosphere by volcanoes the new estimate is that volcanoes inject a substantially smaller mass of ordinarily rare metals into the atmosphere than was stated in a widely cited previous estimate j o nriagu a global assessment of natural sources of atmospheric trace metals nature 338 1989 47 49 our estimate which is an upper limit is an annual injection mass of about 10 000 tons of the metals considered versus the earlier estimate of about 23 000 tons also the proportions of the metals are substantially different in our new estimate

volcanic source for fixed nitrogen in the early earth s atmosphere hot volcanic vents promote the thermal fixation of atmospheric n2 into biologically available forms the importance of this process for the global nitrogen cycle is poorly understood at masaya volcano nicaragua no and no2 are intimately associated with volcanic aerosol such that nox levels reach as much as an order of magnitude above local background in plume hno3 concentrations are elevated above background to an even greater extent 50 mmol m 23 we estimate the production efficiency of fixed nitrogen at hot vents to be 3 3 10 28 mol j 21 implying present day global production of 10 9 mol of fixed n per year although conversion efficiency would have been lower in a preoxygenated atmosphere we suggest that subaerial volcanoes potentially constituted an important source of fixed nitrogen in the early earth producing as much as 10 11 mol yr 21 of fixed n during major episodes of volcanism these fluxes are comparable to estimated nitrogen fixation rates in the prebiotic earth from other major sources such as bolide impacts and thunderstorm and volcanic lightning

controls on the lifespans of icelandic ice caps abstract the increasingly common disappearance of glaciers is striking and it is often used to highlight the effects of anthropogenic climate change to the public this approach is more effective when modern glacier and climate change is placed within a frame of reference here we present a new efficient method to assess the timing of glacier birth and death we model equilibrium line altitudes elas of 22 icelandic glaciers through time and in doing so produce the first regional estimates of glacier lifespans we force the model with three holocene temperature reconstructions and five future climate projections while also exploring the effects of glacial isostatic adjustment and variable precipitation mass balance parameters are tuned for each ice cap using modern data geologically constrained inception ages are used to validate individual simulations the timing of icelandic glacier inception likely ranged from before the holocene to as late as the little ice age anthropogenic warming is expected to cut short the lifespans of glaciers that have existed for thousands of years by quantifying the controlling factors we show that topography and the rate of summer temperature change are the primary controls of glacier lifespans in iceland topography represented by the difference between the modern ela and the highest local topography is ten times as important as ela sensitivity to temperature this easy to measure topographic metric exerts a first order control on the timing of inception and the future loss of accumulation area and it can be used to contextualize ongoing glacier disappearance

atmospheric chemistry of an antarctic volcanic plume 1 we report measurements of the atmospheric plume emitted by erebus volcano antarctica renowned for its persistent lava lake the observations were made in december 2005 both at source with an infrared spectrometer sited on the crater rim and up to 56 km downwind using a twin otter aircraft with the two different measurement platforms plume ages were sampled ranging from 1 min to as long as 9 h three species co carbonyl sulfide ocs and so2 were measured from both air and ground while co and ocs were conserved in the plume consistent with their long atmospheric lifetimes the downwind measurements indicate a so2 co ratio about 20 of that observed at the crater rim suggesting rapid chemical conversion of so2 the aircraft measurements also identify volcanogenic h2so4 hno3 and recognized for the first time in a volcanic plume ho2no2 we did not find nox in the downwind plume despite previous detection of no2 above the crater this suggests that near source nox was quickly oxidized to hno3 and ho2no2 and probably no3 aq possibly in tandem with the conversion of so2 to sulfate these fast processes may have been facilitated by cloud processing in the dense plume immediately downwind from the crater a further striking observation was o3 depletion of up to 35 in parts of the downwind plume this is likely to be due to the presence of reactive halogens bro and clo formedthrough heterogeneous processes in the young plume our analysis adds to the growing evidence for the tropospheric reactivity of volcanic plumes and shows that erebus volcano has a significant impact on antarctic atmospheric chemistry at least locally in the southern ross sea area

spatial patterns of glaciers in response to spatial patterns in regional climate abstract glaciers are direct recorders of climate history and have come to be regarded as emblematic of climate change they respond to variations in both accumulation and ablation which can have separate atmospheric controls leading to some ambiguity in interpreting the causes of glacier changes both climate change and climate variability have characteristic spatial patterns and time scales the focus of this study is the regional scale response of glaciers to natural patterns of climate variability using the pacific northwest of north america as the setting the authors employ a simple linear glacier model to study how the combination of patterns of melt season temperature and patterns of annual accumulation produce patterns of glacier length variations regional scale spatial correlations in glacier length variations reflect three factors the spatial correlations in precipitation and melt season temperature the geometry of a glacier and how it determines the relative importance of temperature and

composition resolved size distributions of volcanic aerosols in the mt etna plumes 1 particle size distributions for soluble and insoluble species in mt etna s summit plumes were measured across an extended size range 10 nm d 100 m using a combination of techniques automated scanning electron microscopy qemscan was used to chemically analyze many thousands of insoluble particles collected on pumped filters allowing the relationships between particle size shape and composition to be investigated the size distribution of fine silicate particles d 10 m was found to be lognormal consistent with formation by bursting of gas bubbles at the surface of the magma the compositions of fine silicate particles were found to vary between magmatic and nearly pure silica this is consistent with depletion of metal ions by reactions in the acidic environment of the gas plume and vent measurements of the size shape and composition of fine silicate particles may potentially offer insights into preemission synemission and postemission processes the mass flux of fine silicate particles from mt etna released during noneruptive volcanic degassing in 2004 and 2005 was estimated to be 7000 kg d 1 analysis of particles in the range 0 1 d m 100 by ion chromatography shows that there are persistent differences in the size distributions of sulfate aerosols between the two main summit plumes analysis of particles in the range 0 01 m d 0 1 m by scanning transmission electron microscopy stem shows that there are significant levels of nanoparticles in the mt etna plumes although their compositions remain uncertain

abrupt holocene climate transitions in the northern north atlantic region recorded by synchronized lacustrine records in iceland abstract two high sediment accumulation rate icelandic lakes the glacial lake hvitarvatn and the non glacial lake haukadalsvatn contain numerous tephra layers of known age which together with high resolution paleomagnetic secular variations allow synchronization with a well dated marine core from the shelf north of iceland a composite standardized climate record from the two lakes provides a single time series that efficiently integrates multi proxy data that reflect the evolution of summer temperatures through the holocene the first order trends in biogenic silica bsi 13c and c n rise relatively abruptly following deglaciation reaching maximum values shortly after 8 ka following a complex minimum between 8 7 and 8 0 ka the holocene thermal maximum htm in the lakes is marked by all proxies with a sharp transition out of the 8 ka cold event into peak summer warmth by 7 9 ka and continuing warm with some fluctuations until 5 5 ka decreasing summer insolation after the htm is reflected by incremental cooling initially 5 5 ka with subsequent cold perturbations recorded by all proxies 4 3 to 4 0 ka and 3 1 to 2 8 ka the strongest disturbance occurred after 2 ka with initial summer cooling occurring between 1 4 and 1 0 ka followed by a more severe drop in summer temperatures after 0 7 ka culminating between 0 5 and 0 2 ka following each late holocene cold departure bsi re equilibrated at a lower value independent of the sediment accumulation rate some of the abrupt shifts may be related to icelandic volcanism influencing catchment stability but the lack of a full recovery to pre existing values after the perturbation suggests increased periglacial activity decreased vegetation cover and glacier growth in the highlands of iceland the similarity in timing direction and magnitude of our multi proxy records from glacial and non glacial lakes and from the adjacent marine shelf suggests that our composite record reflects large scale shifts in ocean atmosphere circulation throughout the northern north atlantic

sensitivity of vatnajokull ice cap hydrology and dynamics to climate warming over the next 2 centuries 1 the sensitivity of vatnajokull ice cap to future climate change is examined using spatially distributed coupled models of ice dynamics and hydrology we simulate the evolving ice cap geometry mass balance velocity structure subglacial water pressures and fluxes and basin runoff in response to perturbations to a 1961 1990 reference climatology for a prescribed warming rate of 2 c per century simulated ice cap area and volume are reduced by 12 15 and 18 25 within 100 years respectively individual outlet glaciers experience 3 6 km of retreat in the first 100 years and a total retreat of 10 30 km over 200 years for the same applied warming our results suggest a maximum increase in glacier derived runoff of 25 after 130 years ice cap thinning and retreat alters vatnajokull s subglacial hydraulic catchment structure in the simulations with up to several kilometers of local hydraulic divide migration this serves to redistribute water among the major outlet rivers and in extreme cases to isolate river basins from glacially derived runoff glacier discharge from northern and northwestern vatnajokull distal from the coast appears to be the most robust to climate warming while discharge from vatnajokull s southern margin proximal to the coast is particularly vulnerable the latter reflects pronounced changes in the geometry of the southern outlet glaciers and has implications for glacier flood routing and frequency

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

holocene thinning of the greenland ice sheet the nature of the response of the greenland ice sheet gis to climate change is a fundamental question in climate science but the details remain unclear during the holocene climate optimum 6 000 to 9 000 years ago for example many locations in the northern hemisphere showed unusual warmth yet changes in greenland appeared inconsistent vinther et al now standardize the previously disparate seeming ice core records of climate history on the gis during the holocene and find consistent evidence for a stronger climate optimum than was previously recognized together with elevation reduction and marginal ice sheet thinning the response of the greenland ice sheet gis to changes in climate remains uncertain during the holocene climatic optimum an unusually warm period from about 9 000 to 6 000 years ago changes in greenland appear inconsistent with the rest of the northern hemisphere here the greenland holocene temperature history and the evolution of gis surface elevation are extracted from four gis locations the results may resolve this disparity on entering an era of global warming the stability of the greenland ice sheet gis is an important concern1 especially in the light of new evidence of rapidly changing flow and melt conditions at the gis margins2 studying the response of the gis to past climatic change may help to advance our understanding of gis dynamics the previous interpretation of evidence from stable isotopes 18o in water from gis ice cores was that holocene climate variability on the gis differed spatially3 and that a consistent holocene climate optimum the unusually warm period from about 9 000 to 6 000 years ago found in many northern latitude palaeoclimate records4 did not exist here we extract both the greenland holocene temperature history and the evolution of gis surface elevation at four gis locations we achieve this by comparing 18o from gis ice cores3 5 with 18o from ice cores from small marginal icecaps contrary to the earlier interpretation of 18o evidence from ice cores3 6 our new temperature history reveals a pronounced holocene climatic optimum in greenland coinciding with maximum thinning near the gis margins our 18o based results are corroborated by the air content of ice cores a proxy for surface elevation7 state of the art ice sheet models are generally found to be underestimating the extent and changes in gis elevation and area our findings may help to improve the ability of models to reproduce the gis response to holocene climate

oxygen and sulfur isotopic composition of volcanic sulfate aerosol at the point of emission volcanic sulfate aerosol is emitted from the vents of many active volcanoes but its origin has not yet been explained we report the first measurements of the isotopic compositions of near vent volcanic aerosol sulfate and use the combined sulfur and oxygen isotope systematics of the aerosol and magma at masaya volcano nicaragua to draw preliminary conclusions about the production mechanism of near source volcanic sulfate the sulfate aerosol does not display a significant mass independent oxygen or sulfur isotopic signature which suggests that primary volcanic aerosol does not contribute to the larger mass independent anomalies found in some ambient atmospheric aerosols and as preserved in ice cores the oxygen isotope composition of the sulfate appeared to become heavier on the particle filters with increasing amount of sample collected and suggests that the 18o value of the sulfate aerosol is 8 the sulfur isotopic composition of the sulfate did not vary with sample loading on the filters and had a mean 34s value of 7 7 0 8 similar to that of the magma 6 6 0 2 the low 17o value the 18o value of the magma 6 6 0 3 and the high 18o value of atmospheric oxygen 23 5 suggest that known atmospheric oxidation pathways at ambient temperatures are not the major routes of production for this sulfate instead the isotopic systematics of aerosol and magma are consistent with sulfate production either by high temperature equilibration of the magmatic gas mixture with small amounts of atmospheric oxygen or by direct emission of so4 2 from the magma

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

iceland rising solid earth response to ice retreat inferred from satellite radar interferometry and visocelastic modeling a broad uplift occurs in iceland in response to the retreat of ice caps which began circa 1890 until now this deformation signal has been measured primarily using gps at points some distance away from the ice caps here for the first time we use satellite radar interferometry interferometric synthetic aperture radar to constrain uplift of the ground all the way up to the edge of the largest ice cap vatnajokull this allows for improved constraints on the earth rheology both the thickness of the uppermost earth layer that responds only in an elastic manner and the viscosity below it the interferometric synthetic aperture radar velocities indicate a maximum displacement rate of 24 4 and 31 4 mm yr at the edge of vatnajokull during 1995 2002 and 2004 2009 respectively the fastest rates occur at outlet glaciers of low elevation where ice retreat is high we compare the observations with glacial isostatic adjustment models that include the deglaciation history of the icelandic ice caps since 1890 and two earth layers using a bayesian approach we derived probability density functions for the average earth model parameters for three satellite tracks based on our assumptions the three best fit models give elastic thicknesses in the range of 15 40 km and viscosities ranging from 4 10 1018 pa s

modelling reactive halogen formation and ozone depletion in volcanic plumes in this paper we present a purpose built model plumechem to simulate the reactive halogen chemistry in plumes from persistently degassing volcanoes the model includes photolytic gas phase and aqueous phase chemical reactions and dispersion of the plume into the background atmosphere we investigate how high temperature chemistry close to the vent believed to enhance plume nox hox brox and clox affects bro formation in the downwind plume plumechem simulations initialised using output from thermodynamic calculations at 1000 c with atmospheric magmatic gas ratio 0 1 above the compositional discontinuity are in good quantitative agreement with observations of bro so2 and also provide a mechanism whereby clo and oclo may be formed in the plume the model reproduces the observed magnitudes and rates of increase of bro so2 at several volcanoes the hbr content of the initial plume is shown to be an important control in determining the bro so2 ratio and ozone depletion in the downwind plume the model simulates conversion of nox to hno3 and destruction of ozone in the plume providing an explanation for observed elevated hno3 in volcanic plumes and in agreement with an in plume observation of depleted ozone the predicted ozone depletion was locally and regionally significant for three different volcanic plume compositions therefore we present a new model of volcanic plume chemistry supported by observations of volcanic bro and hno3 which identifies hbr emission as a key determinant in ozone depletion by volcanoes

responses of mountain ice caps in central iceland to holocene climate change abstract a chronology of holocene fluctuations of small outlet glaciers from the regnabu ajokull ice cap on hrutfell central iceland allows comparison of their sensitivity with the margin of the nearby langjokull icefield to ascertain which frequencies of climatic variability are recorded by adjacent glaciers of different size dating utilised tephra layers in aeolian soils lying on between and beneath moraine ridges key marker isochrones dating from the hekla 4 tephra c 3 8 ka bp to katla a d 1918 provide unequivocal bracketing ages the stratigraphy and geochemical fingerprinting of tephras on younger moraines allows subdivision of little ice age moraines five groups of moraines are identified at c 4 5 5 0 c 3 0 3 5 ka bp c 2 0 2 5 ka bp and from the little ice age at c a d 1700 and in the late 19th early 20th century these represent a neoglacial sequence in which steep small glaciers readvanced to similar positions during what are here termed little ice age type periods liatps in contrast the nearby margins of langjokull show evidence of a late nineteenth century advance only suggesting that this was the holocene maximum for this glacier the contrasting responses of local glaciers and the large icefield are explained by their different sizes and response times so that the preserved moraine record is largely pre conditioned by the glacier type in general the forefields of steep fast responding glaciers contain more complete archives of holocene climatic changes than do the margins of the large icefields

lead ba and bi in antarctic law dome ice corresponding to the 1815 ad tambora eruption an assessment of emission sources using pb isotopes lead ba and bi concentrations and pb isotopic compositions have been measured in antarctic law dome 66 8 s 112 4 e ice dated from 1814 ad to 1819 ad by thermal ionisation mass spectrometry to investigate the possible deposition of heavy metals from the 1815 ad eruption of tambora volcano 8 5 s 117 4 e in indonesia although volcanic s emissions from tambora observed as so42 are present in the antarctic ice core record there are grounds to question the origin of the pb and bi also deposited at law dome from late 1817 as the pb isotope data suggest this pb originated from mount erebus 77 5 s 167 2 e on ross island antarctica it is shown that at least 97 of any pb and bi emitted from tambora was removed from the atmosphere within the 1 6 year period required to transport aerosols from indonesia to antarctica consequently increased pb and bi concentrations observed in law dome ice about 1818 ad are attributed to either increased heavy metal emissions from mount erebus or increased fluxes of heavy metals to the antarctic ice sheet resulting from climate and meteorological modifications following the tambora eruption elevated ba concentrations observed from mid 1816 to mid 1818 indicate increased atmospheric loading of rock and soil dust also occurred at the time

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

environmental effects of ashfall in argentina from the 2008 chaiten volcanic eruption analyses of air water and vegetation samples collected in june 2008 offer new insights into the environmental effects of the may 2008 chaiten eruption on argentina which was subject to significant ashfall between 42 s and 46 s results from air filtration in the ash affected town of esquel with samples analysed by gravimetry and scanning electron microscopy show the total mass of resuspended ash in the air is well correlated with traffic activity however this variation is primarily related to varying amounts of the largest particles with little variation in the amounts of fine ash particles i e d results from water and vegetation sampling with samples analysed by inductively coupled plasma mass spectrometry and ion chromatography indicate that ashfall resulted in significant compositional changes in ephemeral lakes and coiron grass festuca pallescens for b cd zn tl cu and ni there are strong linear correlations between concentrations and ash thickness where 2 mm in both datasets these results suggest that the eruption of chaiten led to significant changes in the concentrations of trace volatile elements within the environment analysis of vegetation samples collected in january 2009 indicates that the elevated element concentrations in coiron grass persisted for 8 months these results offer insights into the environmental fate of volatile trace elements emitted during volcanic eruptions

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

non linear holocene climate evolution in the north atlantic a high resolution multi proxy record of glacier activity and environmental change from hvitarvatn central iceland abstract iceland is well situated to monitor north atlantic holocene climate variability terrestrial sites there offer the potential for well dated high resolution continuous records of environmental change and or glacier activity laminated sediments from the proglacial lake hvitarvatn provide a continuous record of environmental change and the development of the adjacent langjokull ice cap for the past 10 2 ka replicate lake sediment cores collected from multiple locations in the basin are placed in a secure geochronology by splicing a varve chronology for the past 3 ka with a tephra constrained paleomagnetic secular variation derived chronology for older sediments multiple proxies including sedimentation rate bulk density ice rafted debris sediment organic matter biogenic silica and diatom abundance allow annual to multi decadal resolution and reveal a dynamic holocene terrestrial climate following regional deglaciation of the main iceland ice sheet summer temperatures were high enough that mountain ice caps had already melted or were contributing insignificant sediment to the lake pronounced increases in sedimentation rate sediment density and the influx of terrestrial organic matter between 8 7 and 7 9 ka suggest early holocene warmth was interrupted by two distinct pulses of cold summers leading to widespread landscape destabilization and possibly glacier growth the holocene thermal maximum htm 7 9 to 5 5 ka was characterized by high within lake productivity and ice free conditions in the watershed neoglaciation is recorded as a non linear transition toward cooler summers landscape destabilization and the inception and expansion of langjokull beginning ca 5 5 ka with notable increases in ice cap size and landscape instability at 4 2 and 3 0 ka the past two millennia are characterized by the abrupt onset of sustained cold periods at ca 550 and 1250 ad separated by an interval of relative warmth from ca 950 to 1150 ad the greatest holocene extent of langjokull occurred in the nineteenth century and is coincident with peak landscape instability followed by ice recession throughout the twentieth century

solar forcing of holocene summer sea surface temperatures in the northern north atlantic mounting evidence from proxy records suggests that variations in solar activity have played a significant role in triggering past climate changes however the mechanisms for sun climate links remain a topic of debate here we present a high resolution summer sea surface temperature sst record covering the past 9300 yr from a site located at the present day boundary between polar and atlantic surface water masses the record is age constrained via the identification of 15 independently dated tephra markers from terrestrial archives circumventing marine reservoir age variability problems our results indicate a close link between solar activity and ssts in the northern north atlantic during the past 4000 yr they suggest that the climate system in this area is more susceptible to the influence of solar variations during cool periods with less vigorous ocean circulation furthermore the high resolution sst record indicates that climate in the north atlantic regions follows solar activity variations on multidecadal to centennial time scales

satellite observations of the impact of weak volcanic activity on marine clouds 1 because emissions from weak volcanic eruptions tend to remain in the low troposphere they may have a significant radiative impact through the indirect effect on clouds however this type of volcanic activity is underreported and its global impact has been assessed only by model simulations constrained with very limited observations first observations of the impact of high latitude active volcanoes on marine boundary layer clouds are reported here these observations were made using a combination of standard derived products and visible images from the modis amsr e and goes detectors two distinctive effects are identified when there is an existing boundary layer cloud deck an increase in cloud brightness and a decrease in both cloud effective radius and liquid water content were observed immediately downwind of the volcanoes the visible appearance of these volcano tracks resembles the effect of man made ship tracks when synoptic conditions favor low cloudiness the volcano plume or volcano cloud increases significantly the cloud cover downwind the volcano cloud can extend for hundreds of kilometers until mixing with background clouds unlike violent eruptions the volcano clouds reported here the aleutian islands in the north pacific and the south sandwich islands in the south atlantic have retrieved microphysical properties similar to those observed in ship tracks however when comparing the volcano clouds from these two regions liquid water content can decrease increase or remain unchanged with respect to nearby unperturbed clouds these differences suggest that composition at the source type of eruption and meteorological conditions influence the evolution of the cloud

degree day glacier mass balance modelling with applications to glaciers in iceland norway and greenland a degree day glacier mass balance model is applied to three glaciers in iceland norway and greenland for which detailed mass balance measurements are available over a period of several years model results are in good agreement with measured variations in the mass balance with elevation over the time periods considered for each glacier in addition the model explains 60 80 of the year to year variance in the elevation averaged summer season mass balance measurements on the glaciers using a single parameter set for each glacier the increase in ablation on the glaciers due to a warming of 2 c is predicted to range from about 1 m w e year 1 at the highest elevations to about 2 5 m w e year 1 at the lowest elevations predicted changes in the winter balance measured between fixed date are relatively small except at the lowest elevations on the icelandic and norwegian glaciers where the winter balance is significantly reduced equilibrium line altitudes are raised by 200 300 m on the icelandic and norwegian glaciers except at the highest elevations the winter balance of the icelandic and norwegian glaciers is predicted to decrease even if the warming is accompanied by a 10 increase in the precipitation no firm evidence of a climate related variation in the degree day factors or in the temperature lapse rate on the same glacier could be found the model furthermore reproduces large variations in the mass balance with elevation and from year to year on each glacier using the same parameter set we assume therefore that these parameters will not change significantly for the climate scenarios considered here

aerosol formation in basaltic lava fountaining eyjafjallajokull volcano iceland 1 a short lived episode of basaltic lava fountaining at eyjafjallajokull volcano march april 2010 produced a low altitude ash poor plume we measured the composition of aerosol particles sampled using a cascade impactor and filter packs gases sampled using filter packs and volatile species scavenged by scoria and external water in order to investigate the formation and speciation of near source aerosol 0 4 m and its composition was dominated by chloride rather than sulfate we used two thermodynamic equilibrium models e aim and hsc chemistry v5 1 to show that the formation of particulate cl by condensation of hcl gas is more responsive to changes in ambient temperature than the oxidation of so2 to so42 so that a low so42 cl ratio in aerosol particles is characteristic of volcanic emissions in cold climates field measurements suggested that the efficiency of so2 to so42 conversion inside the vent increased with lower explosivity volatiles adsorbed on the surface of scoria had significantly higher so42 halogen molar ratios than the aerosol samples several potential explanations for these differences are discussed

modeled patterns of late pleistocene glacier inception and growth in the southern and central rocky mountains usa sensitivity to climate change and paleoclimatic implications abstract high resolution modern climate data for the southern and central rocky mountains provide a starting point for analysis of climate changes necessary to produce regional late pleistocene glaciation a gis based model was used to assess the sensitivity of glaciation in different ranges to climatic change and the combinations of temperature and precipitation change necessary to sustain the last glacial maximum lgm extent of glaciation in each range extensive glaciation initiates first in the wind river range of wyoming under every climate change scenario tested in absence of precipitation change a summer temperature depression of 6 8 c would be necessary to maintain lgm ice extents in colorado and wyoming if precipitation was halved necessary summer temperature depression would be 8 10 c if precipitation was doubled a depression of 3 5 5 5 c would suffice given model uncertainties these values may underestimate necessary temperature depression by as much as 2 c under all scenarios tested lgm glaciation in utah particularly the wasatch range requires either more temperature depression for given precipitation change or more precipitation for a given temperature depression than is required in the colorado wyoming rockies a summer temperature depression of 7 c which would suffice to sustain lgm ice extent with little change from modern precipitation in the colorado wyoming rockies would need to be coupled with a near doubling of precipitation to maintain lgm ice extent in the wasatch range this difference appears to reflect lgm precipitation enhancement in the wasatch range and to a lesser degree the uinta mountains resulting from the presence of lake bonneville immediately upwind of these ranges

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

holocene palaeoclimatic reconstruction in northern iceland approaches and results abstract the period since the mid 19th century when instrumental meteorological recording first started in iceland has shown climate conditions close to or even at both holocene minimum and optimum levels the 19th century part of the little ice age represents a thermal minimum whilst the warmest decades of the 20th century are close to the estimated holocene thermal maximum a model describing sea ice climate ela relationships in northern iceland for this period has been developed providing a calibrated proxy climate record as a basis for palaeoclimatic reconstruction for the holocene as a whole glacier advances in the periods around 4700 bp around 4200 bp ca 3200 3000 bp around 2000 bp around 1500 bp and around 1000 bp based on radiocarbon dating and tephrochronology mark climatic minima of the post preboreal holocene when conditions were comparable to the extremes in the second half of the 19th century compared to optimal holocene thermal conditions with temperatures at least as high as in the 1930s the range of holocene temperature variation was ca 3 k this was accompanied by a doubling in precipitation from the thermal minima to the maxima

high resolution size distributions and emission fluxes of trace elements from masaya volcano nicaragua active volcanoes are significant natural sources of trace elements to the atmosphere yet the processes of emission and the impacts of deposition into terrestrial and aquatic environments remain poorly understood the varying contributions of volatile degassing and magma ejection i e spattering spraying extrusion and fragmentation to the emission of trace elements from masaya volcano nicaragua are investigated through measurement of high resolution trace element size distributions using cascade impactors in 2009 and 2010 the volatile elements e g as cd tl cu pb zn are strongly correlated across the size distribution and exist in the plume primarily as fine sulfate 0 6 m diameter with lesser amounts transported as coarse sulfates 3 5 m diameter and coarse chlorides 11 m diameter these results suggest that trace elements released from the magma as chlorides react rapidly with h2so4 in the plume to form sulfates in contrast the non volatile elements e g alkali earth and rare earth exist primarily as particles in the 1 10 m range and show no correlation with sulfate chloride or the volatile elements suggesting that they are emitted primarily by magma ejection trace element emission fluxes from masaya in 2010 were estimated using filter pack measurements with emissions of cu zn as tl rb and cd each in excess of 10 kg d 1 these emission fluxes are similar to those measured in 2000 2001 suggesting notable decadal stability in the emission of trace elements from masaya

nitric acid from volcanoes abstract atmospheric cycling of nitric acid and other nitrogen bearing compounds is an important biogeochemical process with significant implications for ecosystems and human health volcanoes are rarely considered as part of the global nitrogen cycle but here we show that they release a previously unconsidered flux of hno3 vapour to the atmosphere we report the first measurements of nitric acid vapour in the persistent plumes from four volcanoes masaya nicaragua etna italy and villarrica and lascar chile mean near source volcanic plume concentrations of hno3 range from 1 8 to 5 6 mol m 3 an enrichment of one to two orders of magnitude over background 0 1 1 5 mol m 3 using mean molar hno3 so2 ratios of 0 01 0 02 0 05 and 0 07 for villarrica masaya etna and lascar respectively combined with so2 flux measurements we calculate gaseous hno3 fluxes from each of these volcanic systems and extend this to estimate the global flux from high temperature non explosive volcanism to be 0 02 0 06 tg n yr 1 while comparatively small on the global scale this flux could have important implications for regional fixed n budgets the precise mechanism for the emission of this hno3 remains unclear but we suggest that thermal nitrogen fixation followed by rapid oxidation of the product no is most likely in explosive ash rich plumes no may result from or at least be supplemented by production from volcanic lightning rather than thermal n fixation we have calculated no production via this route to be of the order of 0 02 tg n yr 1

halogen oxide measurements at masaya volcano nicaragua using active long path differential optical absorption spectroscopy active long path differential optical absorption spectroscopy lp doas measurements of halogen oxides were conducted at masaya volcano in nicaragua from april 14 to 26 2007 the active lp doas system allowed night time halogen measurements and reduced the clo detection limit by an order of magnitude when compared to previous passive doas measurements as wavelengths below 300 nm could be used for the doas retrievals bro was detected with an average bro so2 molecular ratio of approximately 3 10 5 during the day however bro values were below the detection limit of the instrument for all night time measurements a strong indication that bro is not directly emitted but rather the result of photochemical formation in the plume itself according to the autocatalytic bromine explosion mechanism despite the increased sensitivity both clo and oclo could not be detected the achieved upper limits for the x so2 ratios were 5 10 3 and 7 10 6 respectively a rough calculation suggests that clo and oclo should be present at similar abundances in volcanic plumes since the doas technique is orders of magnitude more sensitive for oclo than for clo this indicates that oclo should always be detectable in plumes in which clo is found however further lp doas studies are needed to conclusively clarify the role of chlorine oxides in volcanic plumes

the effects of interannual climate variability on the moraine record valley glacier moraines are commonly used to infer past mean annual precipitation and mean melt season temperature however recent research has demonstrated that even in steady climates multi decadal kilometer scale fluctuations in glacier length occur in response to stochastic year to year variability in mass balance when interpreting moraine sequences it is important to include the effect of interannual weather variability on glacier length moraines record advances that are forced either by interannual variability or by a combination of climate change and interannual variability we address this issue for the last glacial maximum lgm glaciers of the colorado front range united states using a linear glacier model that allows thorough exploration of parameter uncertainties supplemented by a shallow ice flowline model our analyses suggest that 1 glacial standstills longer than 50 years were unlikely 2 mean glacier lengths are 10 15 up valley from maximum glacier lengths and 3 individual lgm terminal moraines were formed by a combination of a climate change and interannual variability forced advances

high temperature mixtures of magmatic and atmospheric gases recent measurements of bro nox and near source sulfate in volcanic plumes suggest that volcanic vents might not simply act as point sources of emissions into the troposphere but may also act as high temperature reaction sites where mixtures of magmatic and ambient atmospheric gases may combine giving new and previously unexpected reaction products the detection of such species demands that a more complex model be developed for the interaction of volcanoes and atmospheres we show that general thermodynamic models can be applied successfully to volcanic gas equilibria by comparing the results from hsc chemistry with those from two volcanic gas equilibrium models solvgas and gasmix using a thermodynamic model optimized for volcanic gas chemistry c o s h f cl br i n ar speciation we show that the volume ratio of atmospheric gas to magmatic gas in a high temperature mixture is an important parameter of the volcanic plume chemistry and our results suggest that even small amounts of air a few for an h2o rich magmatic gas in the high temperature mixture are sufficient to yield elevated levels of reactive nitrogen halogen cl br and i and sulfur species within the volcanic plume further modifications of the plume chemistry may also occur due to low temperature reactions and chemical schemes for the modification of halogen cl br i nitrogen and sulfur chemistry are suggested within the constraints imposed by recent measurements

ice volume changes bias estimation of mass balance measurements and changes in subglacial lakes derived by lidar mapping of the surface of icelandic glaciers icelandic glaciers cover 11 000 km2 in area and store 3600 km3 of ice starting in 2008 during the international polar year accurate digital elevation models dems of the glaciers are being produced with airborne lidar more than 90 of the glaciers have been surveyed in this effort including vatnajokull hofsjokull myrdalsjokull drangajokull eyjafjallajokull and several smaller glaciers the publicly available dems are useful for glaciological and geological research including studies of ice volume changes estimation of bias in mass balance measurements studies of jokulhlaups and subglacial lakes formed by subglacial geothermal areas and for mapping of crevasses the lidar mapping includes a 500 1000 m wide ice free buffer zone around the ice margins which contains many glacio geomorphological features and therefore the new dems have proved useful in geological investigations of proglacial areas comparison of the lidar dems with older maps confirms the rapid ongoing volume changes of the icelandic ice caps which have been shown by mass balance measurements since 1995 96 in some cases ice volume changes derived by comparing the lidar measurements with older dems are in good agreement with accumulated ice volume changes derived from traditional mass balance measurements but in other cases such a comparison indicates substantial biases in the traditional mass balance records

holocene climate conditions and glacier variation in central iceland from physical modelling and empirical evidence abstract lacustrine sediment cores from proglacial lake hvitarvatn central iceland reveal a detailed chronology of holocene sedimentation from which environmental conditions and the attendant fluctuations of langjokull ice cap have been interpreted we apply a numerical ice sheet model to determine the climatic conditions under which the empirical reconstruction is glaciologically plausible modelling constraints are derived from core records of diatom concentration benthic diatom fraction and ice rafted debris occurrence as well as lake bottom morphology and the present day ice cap geometry holocene simulations driven by the ngrip 18 o record that are consistent with the empirical constraints show the most extensive advance of langjokull ice cap to be its most recent beginning somewhere between 5 and 3 ka bp ice advance in response to the 8 2 ka bp cold event is followed by several thousand years of nearly ice free conditions in the mid holocene all simulations suggest that the maximum holocene stand of the ice cap occurred during the little ice age lia those consistent with the constraints show little to no ice advance into hvitarvatn before 1 ka bp and indicate the lake area occupied by ice was much greater during the lia than at any previous time the most plausible simulation results were obtained for a maximum holocene warming of 3 4 c relative to the 1961 1990 reference twice the arctic average and for holocene thermal maximum htm precipitation amounts comparable to or slightly greater than the modern reconciling the simulated subglacial discharge record to the empirically derived sediment volumes and emplacement times requires mean holocene sediment concentrations of 0 8 1 6 kg m 3 these estimates increase to 1 4 2 0 kg m 3 when sedimentation rates are highest

timing and significance of mid holocene glacier advances in northern and central iceland tephrochronology is used to date mid holocene moraines in iceland in the granavatn cirque trollaskagi peninsula the h 4 tephra ca 3830 yr bp lies within sediment accumulated against the distal slope of a lateral moraine providing a minimum age for glaciation and the absence of h 5 ca 5950 yr bp provides a maximum age by implication the cirque was glaciated in the early neoglacial period a large rock glacier the development of which post dates the moraine probably formed within the little ice age lia of the sixteenth to nineteenth centuries ad at eystri lo mundarjokull in central iceland frozen colluvium containing the h 3 ca 2900 yr bp and h 4 tephras provides a minimum age of ca 3830 yr bp for two terminal moraines and a maximum age of ca 2900 yr bp for a third the older moraines are correlated with the vatnsdalur i drangagil advances ca 4700 yr bp and 4500 yr bp respectively and the begisardalur i advance ca 4200 yr bp they imply that early neoglacial advances throughout iceland were locally more extensive than those of the lia the apparent lia holocene glacial maximum may reflect i selective sampling of large ice cap outlet glaciers where the preservation potential of pre lia deposits is low and ii reliance on lichenometric dating which has a restriced temporal range copyright 2001 john wiley sons ltd

halogens and trace metal emissions from the ongoing 2008 summit eruption of kīlauea volcano hawai i volcanic plume samples taken in 2008 and 2009 from the halema uma u eruption at k lauea provide new insights into k lauea s degassing behaviour the cl f and s gas systematics are consistent with syn eruptive east rift zone measurements suggesting that the new halema uma u activity is fed by a convecting magma reservoir shallower than the main summit storage area comparison with degassing models suggests that plume halogen and s composition is controlled by very shallow 77 as gaseous elemental mercury at the point of emission sulphate is an important aerosol component modal particle diameter 0 44 m aerosol halide ion concentrations are low compared to other systems consistent with the lower proportion of gaseous hydrogen halides plume concentrations of many metallic elements rb cs be b cr ni cu mo cd w re ge as in sn sb te tl pb mg sr sc ti v mn fe co y zr hf ta al p ga th u la ce pr nd sm eu gd tb dy er tm are elevated above background air there is considerable variability in metal to so2 ratios but our ratios generally at the lower end of the range previously measured at k lauea support assertions that k lauea s emissions are metal poor compared to other volcanic settings our aerosol re and cd measurements are complementary to degassing trends observed in hawaiian rock suites although measured aerosol metal s ratios are about an order of magnitude lower than those calculated from degassing trends determined from glass chemistry plume enrichment factors with respect to hawaiian lavas are in broad agreement with those from previous studies allowing similar element classification schemes to be followed i e lithophile elements having lower volatility and chalcophile elements having higher volatility the proportion of metal associated with the largest particle size mode collected 2 5 m and that bound to silicate is significantly higher for lithophiles than chalcophiles many metals show higher solubility in ph 7 buffer solution than deionised water suggesting that acidity is not the sole driver in terms of solubility nonetheless many metals are largely water soluble when compared with the other sequential leachates suggesting that they are delivered to the environment in a bioavailable form preliminary analyses of environmental samples show that concentrations of metals are elevated in rainwater affected by the volcanic plume and even more so in fog however metal levels in grass samples showed no clear enrichment downwind of the active vents

year round record of size segregated aerosol composition in central antarctica concordia station implications for the degree of fractionation of sea salt particles the origin of sea salt aerosol that reaches the high antarctic plateau and is trapped in snow and ice cores remains still unclear in particular the respective role of emissions from the open ocean versus those from the sea ice surface is not yet quantified to progress on this question the composition of bulk and size segregated aerosol was studied in 2006 at the concordia station 75 s 123 e located on the high antarctic plateau a depletion of sulfate relative to sodium with respect to the seawater composition is observed on sea salt aerosol reaching concordia from april to september that suggests that in winter when the sea salt atmospheric load reaches a maximum emissions from the sea ice surface significantly contribute to the sea salt budget of inland antarctica citation jourdain b s preunkert o cerri h castebrunet r udisti and m legrand 2008 year round record of size segregated aerosol composition in central antarctica concordia station implications for the degree of fractionation of sea salt particles

variability of alkali and heavy metal fluxes released by mt etna volcano sicily between 1991 and 1995 abstract we regularly collected volcanic gases and aerosols at mt etna volcano over a long period 1991 1995 and measured their chemical composition by icp ms based on these data we present new evidence on the high volatility of both alkali and some heavy metals in contrast both lanthanides and actinides are not produced as significant gaseous compounds at magmatic temperatures and can be used as tracers of spattered materials all metals of each chemical family maintained systematic trends during the study period at both summit craters and effusive vents located in the valle del bove during the 1991 1993 eruption during the eruption we observed high metal enrichments at effusive vents these enrichments seem to be characteristic of the secondary degassing of a magma previously degassed under the summit area lower metal enrichments are recorded in aerosols sampled in summit crater plumes according to the primary degassing type occurring at these vents while a primary degassing type still occurs at both bocca nuova and voragine during the post eruptive period sud est crater exhibits a transition from primary to secondary type according to the variations of the volcanic activity level we confirm that the alkali metals fractionate systematically within their family as they cross the melt vapour interface the heavier members being always more enriched than the lighter ones in aerosols we also show that this fractionation is not related to the volcanic activity and the degassing type but seems to be a significant feature of the alkali family itself estimation of new emanation coefficients for rubidium caesium tin and thallium 0 07 0 15 0 50 and 21 respectively yields annual outputs around 1000 t yr 60 t yr 240 t yr and 1600 t yr respectively mount etna is a very important source of metals injected into the atmosphere contributing to the global volcanic budget about 16 for heavy metals and 19 for alkali metals in eruptive periods and only 2 and 4 respectively in quiet periods

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

post glacial rebound and asthenosphere viscosity in iceland during the weichselian glaciation iceland was covered with an ice cap which caused downward flexure of the earth s surface the post glacial rebound in iceland was very rapid being completed in about 1 000 years the length of this time interval constrains the maximum value of asthenosphere viscosity in iceland to be 1 times 10 sup 19 pa s or less further clarification of the ice retreat and uplift history may reveal lower viscosity current changes in the mass balance of icelandic glaciers must lead to measurable elevation changes considering this low viscosity expected current elevation changes around the vatnajoekull ice cap are of the order of 1 cm per year due to mass balance change in this century

hydrogen emissions from erebus volcano antarctica the continuous measurement of molecular hydrogen h2 emissions from passively degassing volcanoes has recently been made possible using a new generation of low cost electrochemical sensors we have used such sensors to measure h2 along with so2 h2o and co2 in the gas and aerosol plume emitted from the phonolite lava lake at erebus volcano antarctica the measurements were made at the crater rim between december 2010 and january 2011 combined with measurements of the long term so2 emission rate for erebus they indicate a characteristic h2 flux of 0 03 kg s 1 2 8 mg day 1 the observed h2 content in the plume is consistent with previous estimates of redox conditions in the lava lake inferred from mineral compositions and the observed co2 co ratio in the gas plume 0 9 log units below the quartz fayalite magnetite buffer these measurements suggest that h2 does not combust at the surface of the lake and that h2 is kinetically inert in the gas aerosol plume retaining the signature of the high temperature chemical equilibrium reached in the lava lake we also observe a cyclical variation in the h2 so2 ratio with a period of 10 min these cycles correspond to oscillatory patterns of surface motion of the lava lake that have been interpreted as signs of a pulsatory magma supply at the top of the magmatic conduit

glacio isostatic deformation around the vatnajokull ice cap iceland induced by recent climate warming gps observations and finite element modeling 1 glaciers in iceland began retreating around 1890 and since then the vatnajokull ice cap has lost over 400 km 3 of ice the associated unloading of the crust induces a glacio isostatic respo

sensitivities of the equilibrium line altitude to temperature and precipitation changes along the andes abstract equilibrium line altitudes elas of alpine glaciers are sensitive indicators of climate change and have been commonly used to reconstruct paleoclimates at different temporal and spatial scales however accurate interpretations of ela fluctuations rely on a quantitative understanding of the sensitivity of elas to changes in climate we applied a full surface energy and mass balance model to quantify ela sensitivity to temperature and precipitation changes across the range of climate conditions found in the andes model results show that ela response has a strong spatial variability across the glaciated regions of south america this spatial variability correlates with the distribution of the present day mean climate conditions observed along the andes we find that elas respond linearly to changes in temperature with the magnitude of the response being prescribed by the local lapse rates ela sensitivities to precipitation changes are nearly linear and are inversely correlated with the emissivity of the atmosphere temperature sensitivities are greatest in the inner tropics precipitation becomes more important in the subtropics and northernmost mid latitudes these results can be considered an important step towards developing a framework for understanding past episodes of glacial fluctuations and ultimately for predicting glacier response to future climate changes

mantle flow at oceanic spreading centers models derived from ophiolites abstract the internal structures of eleven ophiolite complexes have been structurally investigated the attitude of the foliation and the lineation in the peridotites is related to asthenospheric flow in the uppermost mantle at an oceanic spreading center from the orientation of these structures with respect to the paleohorizontal plane two oceanic situations are distinguished the horizontally spreading asthenosphere illustrated by the table mountain massif newfoundland is characterized by 1 a homogeneous regular and sub horizontal plastic flow pattern over large distances 2 b flat paleo mono and absence of large scale folding 3 c rare economical chromite deposits and depleted mantle the diapirically spreading asthenosphere illustrated by the acoje type philippines displays 1 a inhomogeneous and sub vertical plastic flow pattern 2 b deformed paleo moho and large scale folds 3 c important economical chromite deposits and less depleted mantle presumably due to secondary magmatic impregnation this leads to vogt s model of asthenospheric flow beneath an oceanic ridge the direction of which being equated with the dike swarm in this model the horizontally spreading asthenosphere is derived from the diapirically spreading one in the following way the vertical mantle flow at the diapir center diverges horizontally in every direction including that parallel to the ridge at about 50 km from the diapir center the mantle flow becomes progressively perpendicular to the ridge due to the damming effect of transform faults an important economical consequence of this model is that large chromite deposits are expected preferentially in the diapiric type of ophiolite because chromite is preferentially precipitated at the diapir center from pristine magma