genesis of fumarolic emissions as inferred by isotope mass balances co2 and water at vulcano island italy we have developed a quantitative model of co2 and h2o isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the la fossa crater vulcano island italy on the basis of isotope balance equations the model takes into account the isotope equilibrium between h2o and co2 and extends the recent model of chemical and energy two end member mixing by nuccio et al 1999 as a result the h2o and co2 content and the d 18o and 13c isotope compositions for both magmatic and hydrothermal end members have been assessed low contributions of meteoric steam added at a shallow depth have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998 nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits the 13cco2 of the magmatic gases varies around 3 to 1 vs peedee belemnite pdb following a perfect synchronism with the variations of the co2 concentration in the magmatic gases this suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization the hydrogen isotopes in the magmatic gases 1 to vs standard mean ocean water smow as well as the above 13cco2 value are coherent with a convergent tectonic setting of magma generation where the local mantle is widely contaminated by fluids released from the subducted slab magma contamination in the crust probably amplifies this effect the computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the d and 13c of the entire hydrothermal system including mixed h2o co2 vapor liquid water and dissolved carbon we have computed values of about 10 vs smow for water and 2 to 6 5 vs pdb for co2 on these grounds we think that mediterranean marine water dh2o 10 feeds the hydrothermal system it infiltrates at depth throughout the local rocks reaching oxygen isotope equilibrium at high temperatures interaction processes between magmatic gases and the evolving seawater also seem to occur causing the dissolution of isotopically fractionated aqueous co2 and providing the source for hydrothermal carbon these results have important implications concerning fluid circulation beneath vulcano and address the more convenient routine of geochemical surveillance

on the onset of the gulf of cadiz coastal countercurrent 1 we investigate the onset of the warm counterflow recurrent in summer periods along the shelf of the gulf of cadiz and southwest of iberia fully realistic and idealized numerical configurations are used with the aim of partitioning the different processes at play in the complex circulation of the gulf of cadiz the realistic model simulates in great detail an event of warm counterflow in august 2000 the analysis of the idealized and sensitivity experiments allow us to conclude that the counterflow is mainly wind driven in response to short but strong levanter episodes recurrent after periods of persistent upwelling favorable situations

total co2 output from vulcano island aeolian islands italy 1 total co2 output from fumaroles soil gas bubbling gas discharges and water dissolved gases discharged from the island was estimated for vulcano island italy the co2 emission from fumaroles from the la fossa summit crater was estimated from the so2 crater output while co2 discharged through diffuse soil emission was quantified on the basis of 730 measurements of co2 fluxes from the soil of the island performed by using the accumulation chamber method the results indicate an overall output of 500 t day 1 of co2 from the island the main contribution to the total co2 output comes from the summit area of the la fossa cone 453 t day 1 with 362 t day 1 from crater fumaroles and 91 t day 1 from crater soil degassing the release of co2 from peripheral areas is 20 t day 1 by soil degassing palizzi and istmo areas mainly an amount comparable to both the contribution of water dissolved co2 6 t day 1 as well as to seawater bubbling co2 4 t day 1 measured in the istmo area presented data september 2007 refer to a period of moderate solphataric activity when the fumaroles temperature were 450 c and gas water molar ratio of fumaroles was up to 0 16 the calculated total co2emission allows the estimation of the mass release and related thermal energy from the volcanic hydrothermal system

co2 output and δ13c co2 from mount etna as indicators of degassing of shallow asthenosphere an estimated average co2 output from etna s summit craters in the range of 13 3 mt a has recently been determined from the measured so2 output and measured co2 so2 molar ratios to this amount the co2 output emitted diffusely from the soil 1 mt a and the amount of co2 dissolved in etna s aquifers 0 25 mt a must be added data on the solubility of co2 in etnean magmas at high temperature and pressure allow the volume of magma involved in the release of such an amount of this gas to be estimated this volume of magma 0 7 km3 a is approximately 20 times greater than the volume of magma erupted annually during the period 1971 1995 on the basis of c isotopic data of co2 collected in the etna area and of new hypotheses on the source of mediterranean magmas significant contributions of co2 from non magmatic sources to the total output from etna are unlikely such large outputs of co2 and also of so2 from etna could be due to an anomalously shallow asthenosphere beneath the volcano that allows a continuous escape of gases toward the surface even without migration of magma

continuous gas monitoring at galeras volcano colombia first evidence abstract this paper describes a system of instruments for continuously monitoring fumarolic gases which is installed at galeras volcano colombia several parameters such as the concentration of co2 and rn in the fumarolic emissions as well as the temperature of the gases and their pressure are measured every 6 s we report variations in these parameters which were observed during a short flurry of seismic activity at the volcano at this stage it is uncertain whether the changes in the parameters are directly associated with volcanic processes from the data presented here we can conclude that ambient air can enter the fumarolic vent system in consequence the fumarole may be influenced by the direction and strength of the wind

importance of geochemical transformations in determining submarine groundwater discharge derived trace metal and nutrient fluxes abstract seasonal spring and summer 2002 concentrations of dissolved 3 po 4 si and doc were determined in groundwater samples from 5 wells aligned along a 30 m shore normal transect in west neck bay long island ny results show that significant systematic changes in groundwater trace metal and nutrient composition occur along the flowpath from land to sea while conservative mixing between west neck bay water and the groundwaters explains the behavior of si and doc non conservative inputs for co and ni were observed concentration increases of 10 and 2 fold respectively and removal of po 4 and no 3 decreases to about half along the transport pathway groundwater associated chemical fluxes from the aquifer to the embayment calculated for constituents not exhibiting conservative behavior can vary by orders of magnitude depending on sampling location and season e g co 3 4 10 2 8 2 10 3 mol d 1 using measured values from different wells as being representative of the true groundwater endmember chemical composition also results in calculation of very different fluxes e g cu 6 3 10 3 mol d 1 inland freshwater well vs 2 1 10 5 mol d 1 seaward well s 17 ppt this study suggests that seasonal variability and chemical changes occurring within the subterranean estuary must be taken into account when determining the groundwater flux of dissolved trace metals and nutrients to the coastal ocean

isotopic and geochemical characterization of salinization in the shallow aquifers of a reclaimed subsiding zone the southern venice lagoon coastland summary the coastal plain bordering the southern venice lagoon is a reclaimed lowland characterized by high subsidence rate and ground level and water table depth below sea level in this agricultural region where the surface hydrologic network is entirely artificially controlled by irrigation drainage canals salinization problems have long been encountered in soils and groundwaters here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi confined aquifer 0 40 m and the freshwater inputs to this hydrological system water samples have been collected at different seasons in the coastal adriatic sea lagoon rivers and irrigation canals as well as in the semi confined aquifer at depths between 12 and 35 m 14 boreholes and in the first confined aquifer three boreholes drilled between 40 and 80 m depth stable isotopes 18 o and d and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area fresh groundwaters are found only in the most western zone the sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer the border between these two regions also corresponds to the limits of the most strongly subsiding zone our results can be interpreted in terms of a four end member mixing scheme involving 1 marine water from the lagoon or the open sea 2 alpine and pre alpine regional recharge waters carried either by the main rivers adige bacchiglione and brenta irrigation waters or by the regional groundwater circulation 3 local precipitation and 4 evaporated waters infiltrated from the surface infiltration from the surface is also revealed by the stratification of the electrical conductivity profiles showing that the brackish groundwaters are overlain by a shallow layer of less saline water all over the central depression in the first confined aquifer the groundwaters have isotopic compositions similar to the deep groundwaters of the venetian confined aquifers 40 400 m depth the isotopic data and the br cl ratio show that the origin of the salinization of the phreatic aquifer can be ascribed to seawater intrusion alone with no indication of the involvement of deep brines identified at 450 m depth in the process the chemical composition of the saline and brackish groundwaters is characterized by an excess of sodium and a deficit of calcium compared to conservative mixing between fresh groundwaters and seawater this suggests that the phreatic aquifer is progressively freshening as a consequence of the beneficial influence of the extensive irrigation drainage network including raised canals acting as a hydraulic barrier along the coast this freshening tendency may have been lasting since the reclamation in the mid twentieth century and has probably been accelerated by the ban on groundwater abstraction since the 1970s

passive infrared remote sensing evidence for large intermittent co2 emissions at popocatepetl volcano mexico abstract passive infrared ftir and correlation spectrometer cospec measurements were conducted at popocatepetl volcano during february 10 to 26 1998 from sites 4 to 17 km distant from the summit volcano behavior was relatively quiet and so 2 flux averaged 1670 1420 t day 51 measurements relatively small for popocatepetl concurrent hcl so 2 and hf so 2 ratios were 0 17 0 01 and 0 031 0 003 respectively about the same as ratios measured from 1994 to 1997 the amount of co 2 in the volcanic plume was quantified using fascode in which atmospheric co 2 is numerically subtracted from the total infrared spectrum to obtain the residual magmatic co 2 surprisingly co 2 so 2 mass ratios rose dramatically to values as high as 140 about 30 times higher than typical values of 2 to 8 measured from 1994 to 1996 these excursions in high co 2 so 2 ratios were short lived lasting no longer than about 0 5 to 3 0 h but co 2 flux occasionally exceeded 100 000 t day we estimate that the average co 2 so 2 ratio for the period was about 23 yielding an average co 2 flux of roughly 38 000 t day chemical and petrographic analyses of lava and pumice erupted during explosions on june 30 1997 and january 1 1998 show conclusively that popocatepetl produces mixed products formed by injection of mafic magma into a more silicic chamber at temperatures and pressures of roughly 1040 c and 5 kbar in addition popocatepetl eruptive products include xenoliths of metamorphosed carbonate rocks containing wollastonite and other calc silicate minerals indicating reaction of magma with cretaceous limestone underlying the volcano using a normal co 2 so 2 ratio of 4 for reference we calculate an average excess co 2 production of 32 000 t day for 17 days this would require assimilation of only 5 10 4 km 3 of limestone an amount easily accessible in the 3 km thick cretaceous section beneath the volcano we also examine two scenarios in which excess co 2 is produced by degassing of subjacent basalt magma but these explanations seem less plausible to us because many other volcanoes are underlain by carbonate sequences short duration bursts of co 2 flux and increased co 2 so 2 ratio might be observed at other sites if simultaneous real time measurements of major gas species are made

source and distribution of dissolved radium in the bega river estuary southeastern australia abstract measurements of the activities of the four naturally occurring radium isotopes in the surface water and porewater of an estuary have yielded information on the release of radium from sediments and on the extent of surface water porewater interaction in the estuary under low flow conditions the non conservative behaviour of dissolved radium in the estuary is almost entirely due to the flux of radium from estuarine bed sediments radium accumulates in bottom sediment porewater and is then mixed with estuarine surface water probably as a result of tidal action it is shown experimentally that the enrichment of the short lived isotopes 224ra and 223ra relative to 226ra in estuarine porewater can be explained by the repeated leaching of radium from bottom sediments by saline water and the rapid regeneration of the short lived isotope activity from their sediment bound parent nuclides the leaching of radium from bottom sediments is apparently occurring on a time scale which is long weeks months compared with the 224ra and 223ra half lives indicating that the amount of ion exchangeable radium adsorbed to the sediments is large compared with the amount dissolved in porewater by applying a simple 2 d steady state multi box model 224ra and 223ra surface water and porewater concentrations have been used to estimate the daily flux of porewater crossing the sediment water interface in the bega estuary this flux is found to be about 15 of the estuary volume

geochemical evidence of the renewal of volcanic activity inferred from co2 soil and so2 plume fluxes the 2007 stromboli eruption italy on 27 february 2007 a new eruption occurred on stromboli which lasted until 2 april it was characterized by effusive activity on the sciara del fuoco and by a paroxysmal event 15 march this crisis represented an opportunity for us to refine the model that had been developed previously 2002 2003 eruption and to improve our understanding of the relationship between the magmatic dynamics of the volcano and the geochemical variations in the fluids in particular the evaluation of the dynamic equilibrium between the volatiles co2 and so2 released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of criticality of the volcanic activity one of the major accomplishments of this study is a 4 year database of summit soil co2 flux on the basis of which we define the thresholds low medium high for this parameter that are empirically based on the natural volcanological evolution of stromboli the so2 fluxes of the degassing plume and the co2 fluxes emitted from the soil at pizzo sopra la fossa are also presented it is noteworthy that geochemical signals of volcanic unrest have been clearly identified before during and after the effusive activity these signals were found almost simultaneously in the degassing plume so2 flux and in soil degassing co2 flux at the summit although the two degassing processes are shown to be clearly different the interpretation of the results will be useful for future volcanic surveillance at stromboli

ra 226 and rn 222 in saline water compartments of the aral sea region abstract the aral sea has been shrinking since 1963 due to extensive irrigation and the corresponding decline in the river water inflow understanding of the current hydrological situation demands an improved understanding of the surface water groundwater dynamics in the region 222 rn and 226 ra measurements can be used to trace groundwater discharge into surface waters data of these radiometric parameters were not previously available for the study region we determined 222 rn activities after liquid phase extraction using liquid scintillation counting lsc with peak length discrimination and analyzed 226 ra concentrations in different water compartments of the amu darya delta surface waters unconfined groundwater artesian water and water profiles from the closed large aral sea western basin the water samples comprise a salinity range between 1 and 263 g l the seasonal dynamics of solid water interaction under an arid climate regime force the hydrochemical evolution of the unconfined groundwater in the amu darya delta to high salinity na mg cl so 4 water types the dissolved radium concentrations in the waters were mostly very low due to mineral over saturation extensive co precipitation of radium and adsorption of radium on coexisting solid substrates the analysis of very low 226 ra concentrations 226 ra after solid phase extraction of radium using 3m empore high performance extraction disks purkl 2002 for the analysis of the radionuclide using an icp sector field mass spectrometer the 226 ra concentration of 17 unconfined groundwater samples ranged between 0 2 and 5 ppq and that of 28 artesian waters between 222 rn ingrowth after purging and trapping on super cooled charcoal the 226 ra concentrations were positively correlated with the salinity and the dissolved nacl concentrations the occurrence of unusually high 226 ra activities is explained by radium release from adsorption sites with increasing salinity the inferred spatial variability of 222 rn in the aral sea and of 222 rn and 226 ra in the groundwater of the amu darya delta is discussed in the context of our own previous hydrochemical studies in the study sites relatively low 222 rn activities in the unconfined gw 1 9 5 bq l indicate the alluvial sediments hosting the gw to be a low 238 u 226 ra substrate positive correlations between u and 226 ra and u and 222 rn are likely related to locally deposited fe mn ooh precipitates the 222 rn activity of the gw however distinctly exceeds the 222 rn concentration in the aral sea 10 mbq l in principle making 222 rn a sensitive tracer for the inflow of gw the high water volume of the large aral sea and wind induced mixing of its water body however hamper the detection of local groundwater inflow

did deepwater horizon hydrocarbons transit to the west florida continental shelf abstract hydrocarbons that originated from deepwater horizon were observed at the surface along west florida s northern coastline in june 2010 the farthest eastward advance nearly to cape san blas occurred during the last week of june before the surface oil retreated back westward and dissipated surface oil was not observed on the portion of the west florida continental shelf wfs situated to the southeast of cape san blas nevertheless there were numerous anecdotal occurrences of reef fish caught on the wfs with lesions and other deformities subsequent systematic sampling of wfs reef fish provided additional evidence for damage that extended as far south as the dry tortugas here we examine the possibility that hydrocarbons of deepwater horizon origin transited to the wfs beneath the surface we use a numerical circulation model simulation run for the entirety of 2010 and quantitatively gauged against in situ observations a passive tracer is introduced into the model to mimic the movement of subsurface hydrocarbons either dissolved or of sufficiently small particle size to effectively be dissolved the tracer driven primarily by an anomalously strong and persistent upwelling circulation eventually covered most of the wfs using reasonable estimates of what the initial tracer concentration may have been with respect to hydrocarbons we conclude that the transport of subsurface hydrocarbons to the wfs is both plausible and consistent with the observed distribution of fish lesions fish liver chemistry and other chemical and ecological evidence

estimation of submarine groundwater discharge and associated nutrient fluxes in eastern laizhou bay china using 222 rn summary there is increasing evidence that the inputs of nutrients to the bohai sea are closely related to submarine groundwater discharge sgd in this study the naturally occurring isotope of radon 222 rn was used as a tracer to assess sgd in eastern laizhou bay the 222 rn concentration during a tidal period was measured continuously and a mass balance model that included atmospheric loss tidal effects mixing loss diffusion from sediments and sgd was established the model budget indicated that 222 rn flux attributed to sgd accounted for 58 3 of the total tracer input to the study area the time series of 222 rn revealed that the sgd flux ranged from 6 64 to 7 21 cm d 1 with an average of 6 93 cm d 1 in september 2014 the estimated sgd flux is reasonable compared with those previously estimated in other studies by direct measurement methods hydrogeological simulation and geochemical tracers this result as well as the current understanding of nutrients dissolved in groundwater confirms the importance of sgd in delivering nutrients to laizhou bay and possible impact on marine ecological environment

carbon dioxide degassing from the albani hills volcanic region central italy the albani hills are affected by strong co2 degassing processes the amount of co2 which rises from the depths and subsequently dissolves into shallow groundwater has been estimated to be more than 4 2 109 mol year 1 most of the gas is released in localised anomalous spots lavinio solforata and ciampino albano nemi areas generated by fluid leakage processes from buried pressurized reservoirs hosted by structural highs of the calcareous siliceous marly basement the groundwater circulating in the anomalous areas becomes co2 oversaturated generating observable gas manifestations whose composition is mainly controlled by gas liquid separation processes a gas flow rate of 6 1 108 mol year 1 has been measured from the two larger manifestations using the accumulation chamber technique the presence at shallow level of co2 oversaturated groundwater can explain several episodes of sudden release of gas which was documented by historical chronicles from roman times until now

an in situ method for measuring co2 flux from volcanic hydrothermal fumaroles abstract the theory of an in situ method to measure co 2 flux from hydrothermal fumarolic vents using a tracer gas technique is established and applied to vents and wells at three sites izu oshima japan kirishima japan and teide canary islands spain volcanoes the method is done by releasing the tracer gas into the vent at known flux and by measuring co 2 to the tracer gas ratio in situ in izu oshima we carried out flux measurements at a low temperature steam well 90 c with three different tracer gas species h 2 ch 4 and sf 6 and three methods gc portable analyzers ftir to evaluate this method the calculated co 2 flux showed an average of 2 3 t day in the case of kirishima volcanic area the flux measurement was tested at two low temperature fumaroles on iwoyama cone 2 fluxes were 9 10 2 and 2 10 0 kg day respectively the total co 2 flux from the cone including both fumarolic and ground co 2 discharges was estimated to be less than several tons per day in teide volcano co 2 flux measurements were performed in the fumarolic system of the summit crater 85 c co 2 flux from one fumarole reached levels up to 30 2 kg day we estimated that the co 2 discharge from all fumaroles is roughly 30 t day or less at maximum these results imply that the total output of co 2 flux from teide s fumarolic activity is much lower than the observed levels of co 2 diffuse degassing from the summit crater

estimating groundwater discharge into the northeastern gulf of mexico using radon 222 abstract submarine groundwater discharge sgd may provide important chemical constituents to the ocean but the dispersed nature of this process makes locating and quantifying its input extremely difficult since groundwater contains 3 4 orders of magnitude greater radon than seawater 222rn may be a useful tracer of this process if all other sources of radon to bottom waters can be evaluated we report development of a sgd tracing tool based on radon inventories in a coastal area of the northeastern gulf of mexico we evaluated factors that influence the concentration of radon in the water column i e production decay horizontal transport and loss across the pycnocline using a linked benthic exchange horizontal transport model total 222rn benthic fluxes 2420 dpm m 2 day 1 measured with in situ chambers are of the magnitude required to support measured sub pycnocline 222rn inventories while estimates of molecular diffusion show that this input is relatively small 230 dpm m 2 day 1 using this model approach together with measurements of the radon inventory we estimated a regional subsurface fluid flow ranging from 180 to 710 m3 sec 1 into the 620 km2 study area this discharge equivalent to an upward advective velocity of approximately 2 10 cm day 1 dispersed over this entire study area is equivalent to approximately 20 first magnitude springs

steam output from fumaroles of an active volcano tectonic and magmatic hydrothermal controls on the degassing system at vulcano aeolian arc the results from measurements of extensive parameters steam output and exhaling surface area taken at the crater fumarolic field of vulcano island aeolian arc southern italy are reported along with a detailed description of the measuring method the steam emission rate increased by 1 order of magnitude during the observation time 1983 1995 while its concentration in the released gases was only slightly changed during the same period the total exhaling surface expanded from 50 m2 to more than 2400 m2 and evolved following preferential trends that coincide with the main tectonic structures of the island the observed peaks in steam output show a positive correlation with episodes of volcanic activity unrest the temporal increase of steam output and the observed development in the exhaling surface areas are consistent with a volcano tectonic triggering of the exhaling activity particularly the peaks in the steam output are interpreted as a consequence of degassing from an active magma slowly moving toward the surface

1989 1995 earthquake sequences in the galeras volcano region sw colombia and possible volcano earthquake interactions abstract the galeras volcanic complex located in the narino department sw colombia includes the most historically active volcano in the country galeras a 4276 m high stratovolcano located 9 km west of the city of san juan de pasto 400 000 inhabitants the area is also affected by the continental faulting represented by the buesaco aranda and pasto faults belonging to one of the most seismically active structures in colombia the romeral fault system several moderate to strong shallow earthquakes affected the city of san juan de pasto and its neighbouring region since the xvii century the coexistence of an active volcanic complex and an active fault system complicates the study and interpretation of the different processes taking place in the region as well as the identification of any connection or interaction among them the reactivation of the volcano in 1989 was characterized by three main magmatic events 1 a series of vulcanian eruptions during 4 9 may 1989 with semi continuous ash emissions from a secondary crater 2 the emplacement of an andesitic lava dome at the bottom of the main crater from september 1990 until december 1991 and 3 six vulcanian eruptions from the main crater during 1992 1993 with destruction of most of the dome during the first one on 16 july 1992 during the same period four earthquake sequences were located in a limited area n and ne of galeras volcano on august september 1989 aug1989 april june 1993 apr1993 november december 1993 nov1993 and march august 1995 mar1995 the last one included a ml4 7 main shock on 4 march 1995 producing moderate to high damage in the epicentral region msk maximum intensity viii and in the city of san juan de pasto vi vii the last damaging earthquake in the region was a msk intensity viii ix in 1947 a detailed analysis of the spatio temporal characteristics of the four earthquake sequences allowed identifying their different origin and suggesting some interrelationship between the reactivated eruptive process and the contemporaneous seismic activity the aug1989 sequence presents a typical volcanic swarm like pattern most probably related with the process of magma intrusion from depth at the beginning of the volcano s reactivation the apr1993 the nov1993 and the mar1995 sequences show a clear tectonic origin with events occurring on rupture planes almost vertical that can be associated to the active faults in the area the seismogenic process of these three sequences could have been activated or accelerated by the main eruptions during 1992 1993 these results suggest that constrains provided by improved relocations and the detailed analysis of the space time characteristics of earthquake sequences in galeras volcanic environment allow to establish the different generation mechanisms involved and to suggest feasible explanations on the possible interrelationships of the magmatic volcanic processes and the seismicity observed

the 2002 2003 eruption of stromboli italy evaluation of the volcanic activity by means of continuous monitoring of soil temperature co2 flux and meteorological parameters 1 from december 2002 to july 2003 stromboli volcano was characterized by a new effusive stage of eruption after a period of extraordinary strombolian activity signals recorded in two continuous monitoring stations during the eruption which have already been presented in very recent papers evidenced anomalies in the co2 flux just before the onset of the eruption a more detailed analysis carried out on the data subset acquired during the eruption integrated by daily field observations of the scientific personnel working at the volcanological observatory in stromboli showed that co2 flux and soil temperature are strictly related to volcanic events furthermore the relative minima and maxima of the two parameters showed a strong correlation with wind speed and direction this fact was especially true at the summit station whereas at the coastal sites seasonal and meteorological effects masked the volcanic signal the analysis of the wind data particularly the relationships between wind speed and direction air and soil temperature and local circulation of atmospheric air masses revealed that during the eruption in the summit area of stromboli air movements were not only related to atmospheric circulation but were also significantly affected and in certain cases caused by volcanic activity this conclusion was reached by observing several anomalies such as the discrepancies in the wind direction between the two stations higher air temperatures at the summit site and inversion of direction for wind before and after the reopening of the conduit in a major explosion on 5 april 2003 the relationships found between volcanic activity soil temperatures co2 fluxes and wind speed and direction indicate that soil temperature measurements in an open conduit volcano such as in this case could be used to monitor the level of volcanic activity along with co2 flux furthermore the possible volcanic origin of a peculiar type of air circulation identified in the summit area of stromboli suggests that the separation between volcanic and atmospheric signals might not be obvious requiring monitoring over a wide area rather than a single location

mixed convection and density dependent seawater circulation in coastal aquifers 1 density dependent circulation of seawater in coastal aquifers results in submarine groundwater discharge sgd across the seabed that is a mixture of terrestrial groundwater and former marine water in this study the controls of the relative amount of seawater to freshwater in sgd were investigated numerically using the feflow and sutra codes it was found that the key controls could be expressed in the form of a single nondimensional recirculation number that incorporates the combined effects of free convection forced convection and hydrodynamic dispersion on convective overturn within the coastal salt wedge anisotropy effects were incorporated into the recirculation number with limited success based on the principle of equivalent isotropic hydraulic conductivity the type of boundary condition employed along the seabed was shown to be important convective overturn was substantially increased if backward dispersion of salt into the aquifer from along the outflowing portion of the seabed boundary was prevented overall the results demonstrated a strong dependence of convective overturn on the aquifer dispersivities suggesting that results from numerical simulations are problematic to apply to real aquifer systems that typically exhibit uncertain scale dependent dispersion properties

evaluation of trajectory modeling in different dynamic regions using normalized cumulative lagrangian separation 1 the lagrangian separation distance between the endpoints of simulated and observed drifter trajectories is often used to assess the performance of numerical particle trajectory models however the separation distance fails to indicate relative model performance in weak and strong current regions such as a continental shelf and its adjacent deep ocean a new skill score is proposed based on the cumulative lagrangian separation distances normalized by the associated cumulative trajectory lengths this skill score is used to evaluate surface trajectories implied by global hycom hindcast surface currents as gauged against actual satellite tracked drifter trajectories in the eastern gulf of mexico during the 2010 deepwater horizon oil spill it is found that the new skill score correctly indicates the relative performance of the global hycom in modeling the strong currents of the gulf of mexico loop current and the gulf stream and the weaker currents of the west florida shelf in contrast the lagrangian separation distance alone gives a misleading result the proposed dimensionless skill score is particularly useful when the number of drifter trajectories is limited and neither a conventional eulerian based velocity nor a lagrangian based probability density function may be estimated

assimilation of high frequency radar currents in a nested model of the west florida shelf 1 high frequency radar currents are assimilated in a west florida shelf wfs model based on the regional ocean model system roms which is nested in the atlantic hybrid coordinate ocean model hycom for the purpose of including both local and deep ocean forcing particularly the gulf of mexico loop current tides are not included in this model an ensemble simulation of the wfs model is carried out under different wind forcings in order to estimate the error covariance of the model state vector and the covariance between ocean currents and winds radial currents measured by high frequency radar antennas near saint petersburg and venice florida usa are assimilated using this ensemble based error covariance different assimilation techniques using a time average ensemble a filter to reduce surface gravity waves and an extended state vector including wind stress were tested results of the wfs model assimilating surface currents show an improvement of the model currents not only at the surface but also at depth

ra isotopes and rn in brines and ground waters of the jordan dead sea rift valley enrichment retardation and mixing abstract thirty six springs and wells from the dead sea rift valley were periodically sampled and analyzed the latter included full chemical analyses 222 rn and 226 ra by counting emanometry as well as 228 ra 226 ra and 224 ra 228 ra activity ratios spectrometry sampling stretched over almost 2 yr several hundred rn ra analyses and close to a hundred isotopic ratios were measured most waters in the rift valley have both elevated ra several to 750 dpm l and rn a few hundred to almost 60 000 dpm l content in practically all samples 222 rn activity considerably exceeds that of its parent 226 ra the ra content is the result of all dead sea rift valley waters being mixtures of fresh water with saline brines ra is efficiently extracted from surrounding rocks into the brine end member 228 ra 226 ra ratios are exceptionally low 0 07 to 0 9 mostly less than 0 2 this apparently reflects the u over th enrichment in the source rocks that contribute the ra ra enrichment both 228 ra and 226 ra is locally correlated throughout the rift valley with water salinity this correlation can be used to constrain the age of the brine freshwater mixing process in one of the hydrologic subsystems studied the fuliya block the mixing of the shallow ground water must have occurred in less than 200 to 300 yr ago probably before no more than some 30 yr high radon activities in surface waters along the dead sea rift valley result from the formation of radium enriched linings on the aquifer rock surface the mixing of the radium extracting brines with fresh water leads to continual adsorption of radium as water salinity decreases the unique combination of fast upward flow and continual mixing in the dead sea rift valley accounts for a constant replenishment of radium in the waters this causes a gradual buildup of a radium lining on the aquifer walls until eventually a steady state surface activity is established

structural pattern and co2 ch4 degassing of ustica island southern tyrrhenian basin brittle tectonics and ground degassing including fracture field soil gas and exhalation flux analyses of co2 and ch4 were studied at ustica island a pleistocene volcanic complex in the southern tyrrhenian sea the mesoscopic fracture pattern perfectly fits an e w trending left lateral strike slip master fault in agreement with the main morpho structural submarine alignment including ustica island and anchise seamount along the sw ne high angle normal arso fault geological evidence of reactivation with different kinematics left to right lateral displacements was recognised major co2 and ch4 degassing with fluxes up to 93 750 and 20 t km 2 a 1 respectively and soil gas concentrations of 11 3 and 5 7 ppm occur over the arso fault although this fault is mapped just in the sw sector of the island soil gas co2 anomalies point out its clear continuation up to the ne margin of the island these data together with those of previous geophysical and geochemical results from off shore ustica suggest that the arso fault is the local evidence of a more important active gas bearing structure this tectonic feature is interpreted as a reactivation of a preexistent sw ne trend inherited as a second order structure of the e w deep shear zone the reactivation is related to the interplay among different structures of the southern tyrrhenian basin

local and deep ocean forcing contributions to anomalous water properties on the west florida shelf 1 material property distributions on continental shelves result from the mixing and modifications of estuarine and deep ocean source waters how this occurs depends on the momentum and buoyancy that are input either locally on the shelf or from the deep ocean at the shelf break we address this question of local versus deep ocean forcing for the west florida shelf wfs using in situ data and a numerical circulation model the spring and summer seasons of 1998 and 1999 show distinctively different water properties on the shelf and at the shelf break we account for these differences by a combination of local forcing independent of the adjacent gulf of mexico loop current and interactions of the loop current with the shelf the primary role of the deep ocean is to set the height of material isopleths along the shelf slope whether or not these material isopleths broach the shelf break is then a consequence of local shelf wide wind and buoyancy forcing the subsequent along and across shelf distributions are accomplished through a combination of local and deep ocean effects with the bottom ekman layer being the major conduit for the across shelf transport of ecologically important materials

geochemical behaviour of radium isotopes and radon in a coastal thermal system balaruc les bains south of france abstract the behaviour of the four ra isotopes measured by gamma spectrometry and 222 rn measured with an alphaguard ionisation chamber has been investigated in nacl rich thermal waters of balaruc les bains on the mediterranean coast south of france this study allows identification of the deep thermal water signature and reveals the influence of seawater or karst water inflows on ra isotopes and 222 rn the deep thermal water has 226 ra and 222 rn activities of 840 and 1900 mbq l respectively a 228 ra 226 ra activity ratio of 0 59 and low 224 ra 228 ra and 223 ra 226 ra ratios of 0 67 and 0 025 respectively several arguments suggest a dominant role of radioactive decay for short lived ra isotopes and rn during the relatively rapid ascent of thermal water through wide open fractures and drains the low 223 ra 226 ra ratio constrains the maximum ascent velocity of thermal water to 8 10 m h seawater inflow into the hydrothermal system results in an enrichment in short lived ra isotopes and 222 rn the high 223 ra 226 ra ratio 0 23 suggests that 223 ra 224 ra and 222 rn produced by alpha recoil in the upper jurassic limestone are entrained by seawater percolation through the coastal basement due to active pumping in one of the near shore production well this process would be enhanced by a low water rock ratio i e in a low porosity micro fractured limestone mixing of this enriched seawater with thermal water induces barite precipitation with co precipitation of a large fraction of ra short lived ra isotopes may thus be useful tracers of seawater flux towards the continent conversely the inflow and mixing of karst groundwater result in a general dilution of all dissolved elements only a small enrichment in 224 ra and 223 ra but a large enrichment in 222 rn up to 26 bq l the combination of ra isotopes and 222 rn data provides a good way to trace the dynamics of different water masses along coastal areas

combining radon short lived radium isotopes and hydrodynamic modeling to assess submarine groundwater discharge from an anthropized semiarid watershed to a mediterranean lagoon mar menor se spain summary in highly anthropized watersheds surface water tributaries may carry unexpected high quantities of radon and radium to coastal lagoons investigating submarine groundwater discharge sgd with radionuclide tracers is therefore a complex task in order to quantify sgd and decipher the influence of the different water sources we combined a radon 222 rn and short lived radium 223 ra 224 ra survey with the hydrodynamic modeling of a lagoon we applied it to the mar menor lagoon se spain where surface water tributaries and undocumented emissaries carry water from groundwater drainage and brines from groundwater desalinization we identified the areas of influence of the plume of radionuclides from the river located major areas of sgd and proposed a location for two submarine emissaries porewater i e interstitial water from underlying sediments was found to be the most representative sgd end member compared to continental groundwater collected from piezometers mass balances in winter and summer seasons provided yearly sgd fluxes of water of 0 4 2 2 10 8 m 3 y 222 rn 4 4 19 0 10 8 m 3 y 224 ra and 1 3 10 8 m 3 y 223 ra measured in winter only tidal pumping was identified as a main driver for recirculated saline groundwater while fresh submarine groundwater discharge from the aquifer ranged between 2 and 23 of total sgd

intercomparison of volcanic gas monitoring methodologies performed on vulcano island italy 1 volcanic gas emissions from fumaroles on the rim of la fossa crater vulcano island italy were measured simultaneously using direct sampling for h2o co2 total sulfur hcl and hf filter packs for so2 hcl hf and short path active mode ftir measurements for h2o co2 so2 hcl and hf in an intercomparison study in may 2002 the results show that cl f ratios were in good agreement between all three methods and that ftir and direct sampling determined comparable proportions of co2 and h2o amounts of total s observed in direct sampling data were approximately double the amounts of so2 measured with filter packs and ftir this difference could be attributed either to the fact ftir and filter packs do not measure reduced sulfur species e g h2s or to sublimation of elemental s upon exit from the fumarole after collection by direct sampling but before detection with ftir and filter packs

modelling the effect of salinity on radium desorption from sediments abstract the desorption of the four naturally occurring radium isotopes 223 ra 224 ra 226 ra and 228 ra from estuarine sediments is investigated these isotopes are created within sediments by the radioactive decay of insoluble thorium parents due to competition from other ions for the occupation of adsorption sites on the sediment grains radium desorption is a function of salinity a model is developed to describe radium desorption as it is affected by salinity grain size and sediment concentration it is shown that to model the desorption of radium for a particular sediment requires the estimation of two independent parameters one of these parameters is the concentration of radium available for exchange on the sediment the other depends on major ion and radium exchange coefficients desorption experiments performed on sediments from the bed of the bega river australia are used to validate the model and to evaluate the parameters needed for model application

using ra isotopes to examine transport processes controlling benthic fluxes into a shallow estuarine lagoon measurements of the benthic flux of four naturally occurring radium isotopes in a shallow lagoon in the bega river estuary has provided information on the types and rates of transport processes operating in the lagoon sediments the measurement techniques included ra mass budgets of the lagoon ra fluxes into benthic chambers and modelling of the pore water and solid phase ra profiles in a sediment core the sediment profile of 210pb and the solid phase and pore water profiles of the longer lived ra isotopes 228ra half life 5 7 years and 226ra half life 1600 years indicate bioturbation to a depth of 10 cm a diffusion bioturbation model has been used to assess the relative importance of molecular diffusion and bioturbation as transport processes controlling the benthic flux of ra the flux of the shortest lived isotope 224ra half life 3 7 days is not significantly enhanced by bioturbation and its flux is consistent with diffusion controlled release however bioturbation enhances the 228ra flux by a factor of more than two over the flux due to molecular diffusion alone modelled pore water profiles and flux calculations are consistent with a bioturbation time scale between 0 5 and 2 years the measured benthic flux of 226ra is much greater than can be accounted for by the modelled profile and may be due to slow 226ra desorption from the sediment variable sediment accumulation rates or groundwater flow based on 226ra pore water and flux measurements at the time of this study groundwater flow has an upper limit of 0 3 cm d 1

textural and geochemical constraints on andesitic plug emplacement prior to the 2004 2010 vulcanian explosions at galeras volcano colombia hazardous sequences of vulcanian explosions are thought to result from the repeated emplacement and destruction of degassed highly crystalline magma plugs in the shallow conduit of arc volcanoes the processes governing the timing and magnitude of these explosions are thought to be related to magma ascent rate and efficiency of degassing and crystallisation we study a rare suite of time constrained ballistic bombs from the 2004 2010 period of activity of galeras volcano to reconstruct magma plug architecture prior to six individual vulcanian explosions we find that each plug was vertically stratified with respect to crystallinity vesicularity and melt volatile content melt composition and viscosity we interpret this structure as resulting from multiple bubble nucleation events and degassing driven crystallisation during multi step ascent of the magma forming the plug followed by spatially variable crystallisation within the plug under contrasting conditions of effective undercooling created by degassing we propose that the shallow conduit evolved from more open degassing conditions during 2004 2008 to more closed conditions during 2009 2010 this resulted in explosions becoming smaller and less frequent over time during 2004 2008 then larger and more frequent over time during 2009 2010 this evolution was controlled by changing average ascent rates and is recorded by systematic changes in plagioclase microlite textures our results suggest that small volume vulcanian explosions 105 m3 should generally be associated with longer repose times hundreds of days and produce ballistics characterised by small numbers of large prismatic plagioclase microlites larger volume vulcanian explosions 106 m3 should be associated with shorter repose times tens of days and produce ballistics characterised by high numbers of small more tabular plagioclase microlites

submarine groundwater discharge into typical tropical lagoons a case study in eastern hainan island china assessing submarine groundwater discharge sgd into lagoons and bays can be helpful to understand biogeochemical processes especially nutrient dynamics in the present paper radium ra isotopes were used to quantify sgd in two typical tropical lagoons laoye lagoon ly lagoon and xiaohai lagoon xh lagoon of eastern hainan island china the ra mass balance model provided evidence that sgd plays an important role in the hydrology of the ly lagoon and the xh lagoon delivering average sgd fluxes of 1 7 106 94 l m 2 d 1 and 1 8 106 41 l m 2 d 1 m3 d 1 respectively tidal pumping was one of the important driving forces for sgd fluxes in the ly and the xh lagoons tidal driven sgd into the tidal channels of both lagoons can account for approximately 10 of the total sgd flux into the lagoons in addition the dissolved inorganic nutrient budgets were reassessed in the ly lagoon and the xh lagoon which showed that sgd was the major source of nutrients entering the ly lagoon and that the ly lagoon behaved as a source for dissolved inorganic nitrogen din and dissolved inorganic phosphorus dip and as a sink for dissolved silicate dsi nutrient loads in the xh lagoon were mainly derived from riverine inputs and sgd and the xh lagoon behaved as a source for dip but a sink for din and dsi this article is protected by copyright all rights reserved

radium as internal tracer of mediterranean outflow water radium 226 and 228ra data are presented for the western mediterranean sea and the ne atlantic in the nw mediterranean sea the near shore surface waters of the ligurian current contain much higher 228ra concentrations than surface waters collected in the open ligurian seawater the gradient of 228ra along a villefranche calvi transect has been used to calculate values of the horizontal eddy diffusion coefficient perpendicular to the flow direction of the ligurian current of about 106 cm2 s 1 the observed decay of 228ra as the mediterranean deep water flows toward the gibraltar straits is in good agreement with the assumption of a rapid turnover of the mediterranean basin concentration profiles of 226ra and 228ra were measured in the mediterranean outflow water mow off the gibraltar straits in the ne atlantic basin at two stations 36 30 n 15 35 w and 36 27 n 10 35 w these sites showed the hydrographic characteristics of meddies mow which propagates as eddies in the ne atlantic at intermediate depth at the center of the meddies around 1000 m depth the activity of the short half life 228ra increases up to 0 9 10 2 disintegrations per minute per liter higher than usually found in north atlantic deep water this young 228ra results from the contact a few months earlier of the mow with the spanish continental shelf in the vicinity of the gibraltar straits the decay of 228ra used as an internal tracer of water mass motion leads to a transit time of the meddy yseult of less than 1 year since its formation

hydrothermal buffering of the so2 h2s ratio in volcanic gases evidence from la fossa crater fumarolic field vulcano island 1 sulfur speciation in volcanic gases is a potentially valuable tracer of degassing processes at volcanoes hitherto observations of sulfur speciation in volcanic gas plumes have however been limited both in number and quality here we report on periodic measurements of so2 to h2s proportions in the volcanic gases from la fossa volcano vulcano island performed during 2004 2006 a period which encompasses two heating events of the fumarolic field in january april 2005 and december 2005 results indicate a systematic relative increase by a factor of 2 6 of so2 to h2s proportions in the fumaroles during the heating events which we ascribe to a temperature increase in the mixing zone between magmatic and hydrothermal fluids we also demonstrate that sulphur speciation in la fossa fumaroles reflects re equilibration within a poly baric hydrothermal system and that this hydrothermal re equilibration erases the pristine so2 h2s ratios of any magma derived sulphur present

a nested model study of the loop current generated variability and its impact on the west florida shelf 1 a west florida shelf model based on the regional ocean modeling system roms is nested in the north atlantic hybrid coordinate ocean model nat hycom the focus of this work is the study of the impact of the loop current on the west florida shelf in order to assess the model s accuracy it is compared quantitatively to in situ temperature and velocity measurements on the shelf a series of sensitivity experiments are conducted to determine the appropriate wind forcing sea surface temperature relaxation and mixing scheme by the inclusion of the loop current we are able to study the propagation of an anticyclonic vortex detaching from the loop current we found that the ambient gradient of potential vorticity is able to explain the vortex path and speed the statistics of such loop current generated flow features were examined by including a tracer marking loop current water this allows to track the loop current water on the west florida shelf and to quantify the amount of loop current water reaching the shelf

large submarine groundwater discharge sgd from a volcanic island 1 we measured seepage rates of coastal groundwater from a volcanic island standing in the south sea of korea the seepage rates measured along the sandy coast were in the range 50 300 m yr which are much higher than those reported from typical continental coast the 18o tracer in potential seeping waters signifies that they are mixtures of basal groundwater and pristine seawaters on the eastern coast of jeju almost all groundwater discharge is attributed to recirculating seawater while fresh groundwater contributes about 20 of the total submarine groundwater discharge sgd on the western coast of jeju thus sgd appears to be important for the management of water resources in western jeju the measured radionuclides 228ra 226ra and 222rn and nutrients in the groundwater suggest that the discharge of both fresh and recirculated seawater will have a significant influence on the budget of coastal nutrients and other chemical constituents in this region

submarine groundwater discharge effects of hydrogeology and of near shore surface water bodies submarine groundwater discharge is investigated numerically for a confined aquifer considering three types of permeability distribution uniform anisotropic and heterogeneous lognormal as well as for an aquifer in which a surface water body is embedded the latter case corresponds to aquifers with lagoons flat lakes or wetlands near the coast the numerical simulations are performed using the code fast c 2d developed by holzbecher 1998 for the confined aquifer the portion of recirculated seawater in submarine groundwater discharge and the length of the recirculation zone are investigated the parameters influencing these variables in the case of homogeneous aquifer isotropic or anisotropic are discussed further the validity of a linear relationship between the submarine groundwater discharge and the flux of terrestrial groundwater toward the sea proposed by destouni and prieto 2003 is investigated as far as possible our results are compared with results presented by smith 2004 which were obtained using different codes the investigation of a heterogeneous model aquifer concerns the influence of the variability of the permeability distribution on the portion of recirculated seawater and is performed by means of monte carlo analyses finally for coastal aquifers in which surface water bodies are embedded the main flow features are investigated particularly the pathway of terrestrial groundwater to the sea the flux of groundwater of marine origin to the surface water body the recirculation of seawater and the flux from the surface water body to the sea have been considered the parameters influencing these fluxes which are important for the transfer of pollutants and tracers from the groundwater to the surface water and to the near shore seawater are discussed

nutrient biogeochemistry in a gulf of mexico subterranean estuary and groundwater derived fluxes to the coastal ocean we hypothesize that biogeochemical processes in a subterranean estuary in the northeastern gulf of mexico significantly alter nutrient concentrations that are discharged into the ocean via submarine groundwater discharge sgd this subterranean estuary is a site of steep gradients over small spatial scales so selecting the appropriate groundwater endmember for flux calculations is difficult two endmember mixing models typically applied to investigate biogeochemical processes in surface estuaries are not useful in this case because of aquifer heterogeneity and complex solid fluid interactions groundwater residence times redox potential source strength and aquifer matrix appear to be the most important drivers for dissolved organic carbon doc and nutrient concentrations in this pristine coastal plain aquifer the distribution of dissolved species was consistent with a sequence of reactions in a narrow 2 m surface layer in which nitrate is initially exhausted likely because of denitrification organic nitrogen is remineralized releasing ammonium and some doc remains on the basis of a 222rn derived non steady state box model total terrestrial marine sgd rates were estimated to oscillate around 11 cm d21 the sgd is composed almost entirely of recirculated seawater accounting for 95 of total sgd fluxes conservative estimates of groundwater derived nitrogen inputs into the coastal ocean were 8 2 6 1 2 mmol m22 d21 consisting of ammonium 58 organic nitrogen 28 and nitrate 14 we suggest that these mainly represent recycled rather than new nutrient additions when extrapolated to the florida gulf coast the nitrogen and doc fluxes were comparable to the main regional rivers supporting the proposition that sgd plays a major role in coastal biogeochemistry the biogeochemical implications of submarine groundwater discharge sgd into coastal environments are becoming increasingly recognized globally groundwater discharge has been estimated to be only a few percent of the total freshwater flux to the oceans burnett et al 2006 in spite of that small fraction the input of nutrients to coastal environments via groundwater pathways could be globally more important because nutrient concentrations in groundwater are often much higher than those in river water in addition high dissolved n p ratios in groundwater relative to surface waters might drive the coastal ocean toward p limitation within the coming decades perhaps changing the present n limited coastal primary production slomp and van cappellen 2004

patterns of ocean current variability on the west florida shelf using the self organizing map 1 patterns of ocean current variability are examined on the west florida shelf by a neural network analysis based on the self organizing map som using time series of moored velocity data that span the interval october 1998 september 2001 three characteristic spatial patterns are extracted in a 3 4 som array spatially coherent southeastward and northwestward flow patterns with strong currents and a transition pattern of weak currents on the synoptic weather timescale the variations of these patterns are coherent with the local winds on the seasonal timescale the variations of the patterns are coherent with both the local winds and complementary sea surface temperature patterns the currents are predominantly southeastward during fall winter months from october to march and northwestward during summer months from june to september the spatial patterns extracted by the nonlinear som method are asymmetric a feature that is not captured by the linear empirical orthogonal function method thus we find for the synoptic weather and longer timescales that 1 southeastward currents are generally stronger than northwestward currents 2 the coastal jet axis is located further offshore for southeastward currents than for northwestward currents and 3 the velocity vector rotations with depth are larger in shallower water when the currents are southeastward relative to when the currents are northwestward

geochemical precursors of the activity of an open conduit volcano the stromboli 2002 2003 eruptive events 1 marked increases of co2 h2 and he dissolved in thermal waters and changes in the dissolved carbon isotopic composition were observed at stromboli before the 28 december 2002 eruption and before a violent explosive paroxysm occurred on 5 april 2003 high anomalous co2 flux values were recorded at the crater rim since a week before the eruption onset the first anomalies in the thermal waters dissolved co2 amount appeared some months before the eruption when magma column rose at a very high level in the conduit high peaks of dissolved h2 and he were recorded a few days before the paroxysm carbon isotopic composition indicates a magmatic origin of the dissolved co2 whose increase together with those of h2 and he is attributed to an increasing output of deep gases likely produced by depressurization of a rising batch of a deep gas rich magma whose fragments have been emitted during the explosion

nutrient inputs through submarine groundwater discharge in an embayment a radon investigation in daya bay china abstract daya bay a semi closed bay of the south china sea is famous for its aquaculture agriculture and tourism although routine environmental investigations in the bay have been conducted since the early 1980s evaluations of submarine groundwater discharge sgd an important process in exchange between groundwater and coastal seawater and its environmental impacts have never been reported in this study naturally occurring radon isotope 222 rn was measured continuously at two sites north west and middle east sites and used as a tracer to estimate sgd and associated nutrient inputs into the bay the sgd rates estimated based on the 222 rn mass balance model were on average 28 2 cm d at north west site and 30 9 cm d at middle east site the large sgd rate at middle east site may be due to the large tidal amplitude and the sandy component with high permeability in sediments the sgd driven nutrient fluxes which were calculated as the product of sgd flux and the difference of nutrient concentrations between coastal groundwater and seawater were 3 28 10 5 mol d for dissolved nitrates no 3 n 5 84 10 3 mol d for dissolved inorganic phosphorous dip and 8 97 10 5 mol d for reactive silicate si these nutrient inputs are comparable to or even higher than those supplied by local rivers in addition these sgd driven nutrients have a nitrogen phosphorous ratio as high as 43 which may significantly affect the ecology of coastal waters and lead to frequent occurrence of harmful algal blooms

wind induced sea surface slopes on the west florida shelf abstract tidal and meteorological records at stations in the eastern gulf of mexico have been studied the sea level response is a maximum for winds along the coast and varies symmetrically with angle the coherence is maximum at periods of 4 10 days the horizontal coherence of sea level is high out to 500 km for 4 10 day periods the horizontal coherence for wind measured at coastal stations is high out to at least 500 km the amplitude of the response of sea level to winds is larger by a factor of 4 here on a broad shelf than on the oregon coast which is more narrow by about the same ratio a response of 16 cm is induced by 4 m s 1 wind this response or transfer function is uniform over the spectral range 4 100 days the sea level response to the longshore wind stress is not linear but to the power 0 8 0 1 and is attributed to the relatively low tidal currents in this region the large horizontal coherences of wind and sea level imply broad longshore flows extending 500 km or more along

relationships between diffuse co2 emissions and volcanic activity on the island of vulcano aeolian islands italy during the period 1984 1994 measurements of co2 flux from the ground were periodically carried out on the island of vulcano aeolian islands italy between 1984 and 1994 three high flux areas were identified at the foot of the volcanic cone la fossa either inside or very close to the main village effect of the choice of the sampling grid was evaluated a different sampling grid resulted in similar distribution patterns but with different co2 fluxes therefore the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty but repeated measurements with permanent sampling sites are accurate and can detect small changes no correlation of the flux with atmospheric parameters was found at sites with high fluxes some periods characterized by high co2 fluxes were observed and a close correlation was found between the gas emissions from the ground and other geochemical and geophysical parameters such as temperature chemical composition steam and so2 flux from fumaroles seismic energy release and ground deformations the results show that major temporal variations of diffuse co2 flux are related to variations in volcanic activity

patterns in the recent 2007 2008 activity of mount etna volcano investigated by integrated geophysical and geochemical observations 1 seismic deformation and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment in spite of their wide use there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques here we combine seismic volcanic tremor and long period seismicity deformation gps and geochemical volcanic gas plume co2 so2 ratios measurements in an attempt to interpret trends in the recent 2007 2008 activity of etna volcano we show that each eruptive episode occurring at the southeast crater sec was preceded by a cyclic phase of increase decrease of plume co2 so2 ratios and by inflation of the volcano s summit captured by the gps network these observations are interpreted as reflecting the persistent supply of co2 rich gas bubbles and eventually more primitive magmas to a shallow depth of 1 2 8 km asl magma storage zone below the volcano s central craters ccs overpressuring of the resident magma stored in the upper ccs conduit triggers further magma ascent and finally eruption at sec a process which we capture as an abrupt increase in tremor amplitude an upward 2800 m asl and eastward migration of the source location of seismic tremor and a rapid contraction of the volcano s summit resumption of volcanic activity at sec was also systematically anticipated by declining plume co2 so2 ratios consistent with magma degassing being diverted from the central conduit area toward sec

coastal ocean wind fields gauged against the performance of an ocean circulation model 1 atmosphere model derived flux fields are used to force coastal ocean models coarse resolution and incomplete boundary layer dynamics limit the accuracy of these forcing fields and hence the performance of the ocean models we address this limitation for the west florida shelf using optimal interpolation to blend winds measured in situ with winds produced by model analyses by improving the coastal wind field we improve the fidelity between currents modeled and currents observed comparisons between momentum analyses performed independently from the model and the data demonstrate the fidelity to be of a correct dynamical basis we conclude that the primary limitation to coastal ocean model performance lies with the boundary conditions

soil efflux and total emission rates of magmatic co2 at the horseshoe lake tree kill mammoth mountain california 1995 1999 abstract we report the results of eight soil co 2 efflux surveys by the closed circulation chamber method at the horseshoe lake tree kill hltk the largest tree kill on mammoth mountain the surveys were undertaken from 1995 to 1999 to constrain total hltk co 2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills hltk effluxes range from 1 to 10 000 g m 2 day 1 grams co 2 per square meter per day they are not normally distributed station efflux rates can vary by 7 35 during the course of the 8 to 16 h surveys disturbance of the upper 2 cm of ground surface causes effluxes to almost double semivariograms of efflux spatial covariance fit exponential or spherical models they lack nugget effects efflux contour maps and total co 2 emission rates based on exponential spherical and linear kriging models of survey data are nearly identical similar results are also obtained with triangulation models suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions in addition model estimates of total co 2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of co 2 surveys since 1997 indicate that contrary to earlier speculations a termination of elevated co 2 emissions at the hltk is unlikely anytime soon the hltk co 2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995 1999 surveys but maintained a n s elongation presumably reflecting fault control of co 2 transport from depth total co 2 emission rates also fluctuated greatly ranging from 46 to 136 t day 1 metric tons co 2 per day and averaging 93 t day 1 the large inter survey variations are caused primarily by external meteorological processes operating on time scales of hours to days the externally caused variations can mask significant changes occurring at depth a striking example is the masking of a degassing event generated at depth and detected by a soil gas sensor network in september 1997 while an efflux survey was in progress thus occasional efflux surveys are not an altogether effective surveillance tool for the hltk and making them effective by greatly increasing their frequency may not be practical

tectonics and seismicity of the tindari fault system southern italy crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab 1 the tindari fault system southern tyrrhenian sea italy is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab onshore structural data an offshore seismic reflection profile and earthquake data are analyzed to constrain the present geometry of the tindari fault system and its tectonic evolution since neogene including the present seismicity results show that this zone of deformation consists of a broad nnw trending system of faults including sets of right lateral left lateral and extensional faults as well as early strike slip faults reworked under late extension earthquakes and other neotectonic data provide evidence that the tindari fault system is still active in the central and northern sectors and mostly accommodates extensional or right lateral transtensional displacements on a diffuse array of faults from these data a multiphase tectonic history is inferred including an early phase as a right lateral strike slip fault and a late extensional reworking under the influence of the subduction related processes which have led to the formation of the tyrrhenian back arc basin within the present regional geodynamic context the tindari fault system is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments these tectonic compartments relating to the complex processes of plate convergence occurring in the region the tindari fault system might also be included in an incipient oblique extensional transfer zone linking the ongoing contractional belts in the calabrian ionian and southern tyrrhenian compartments

submarine groundwater borne nutrients in a tropical bay maowei sea china and their impacts on the oyster aquaculture submarine groundwater discharge sgd has been recognized as an important pathway for nutrients into estuaries coasts and the adjacent seas in this study 222rn was used to estimate the sgd associated nutrient fluxes into an aquaculture area in a typical tropical bay maowei sea china the sgd into the maowei sea during june of 2016 was estimated to be 0 36 0 33 m d 1 and was associated with sgd derived dissolved inorganic nitrogen din dissolved inorganic phosphorus dip and dissolved silicon dsi fluxes mol d 1 of 4 5 5 5 106 5 3 9 1 104 and 9 4 9 3 106 respectively the sgd derived nutrients i e din dip and dsi were more than 1 9 0 9 and 3 6 times the amounts in the local river input and served as dominant sources in the nutrient budgets in the maowei sea moreover the n p ratios in the sgd around the maowei sea were high mean 64 and these ratios likely exceeded the environmental self purification capacity thereby enhancing the biomass and changing the phytoplankton community structure therefore sgd processes with derived nutrients may affect the biogeochemical cycles and marine ecological environment in the maowei sea furthermore the n p ratios 67 in oysters are very close to those in the sgd in the maowei sea this coincidence suggests that the high n p ratios in the sgd are likely to be one of the most important sources that support oyster aquaculture which might weaken the burden of water eutrophication in the maowei sea

geochemical monitoring system ii prototype gms ii installation at the acqua difesa well within the etna region first data during the 1999 volcanic crisis abstract the geochemical monitoring system ii gms ii prototype was designed assembled tested and installed at the acqua difesa test site near belpasso ct within the etna region in the frame of an ec funded program named automatic geochemical monitoring of volcanoes the easily changeable and versatile configuration of the remote station provides actual data every 10 min recording groundwater temperature electrical conductivity ph redox potential dissolved co 2 he atmospheric pressure and air temperature the radon sensor was assembled despite no jet added to the remote station an automatic sampler collects every 72 h 3 days two bottles of water acidified and not for further laboratory analyses the choice of the acqua difesa test site arises from preliminary volcanological studies deserving special interest i e for the high co 2 degassing for the high he isotopic values exhibiting a direct mantle signature of the volcanic gases and for the peculiar sensitivity to volcanic activity as tested by discrete monitoring in the past and confirmed by the present study during the discussed monitoring period october 1998 june 1999 an enhanced volcanic activity of etna was observed it started on july 1998 with enhanced plume degassing and since september 1998 with periodical lava fountains as well as with episodic low energy earthquakes and seismic swarms m max 3 1 till june 1999 the activity culminated with a summit crater fracture involving a sub terminal eruption on 04 02 1999 the summit crater fracture was not accompanied by enhanced seismicity despite moderate seismic energy release occurring in the succeeding months in that monitoring period the acqua difesa gms ii station recorded a few geochemical anomalies mostly in temperature ph co 2 electrical conductivity and eh as well as in the concentration of some major elements trend mostly in mg and hco 3 the geochemical continuous and discrete data set is discussed in comparison with the available information on the ongoing volcanic and seismic activity tentatively enhancing the comprehension of the aquifers mass heat transport properties of the volcano during crises the experimental observations may be defined at present the forerunners of the etna eruptions affecting the single out acqua difesa well it is nowadays a self consistent site with its own response to the pre eruptive processes defined sensitive to the etna aquifer modifications induced by the volcanic activity in a recurrent way thus we defined the typical answer of this specific test site to the pre eruptive processes and to the associated seismicity further data may modify this statement the station prototype configuration and the results may give hints for future volcanic eruption and seismic activity forecasting

volatile fluxes integrated over four decades at grimsvotn volcano iceland samples of the subglacial lake in the crater of the tholeiitic basaltic caldera grimsvotn in iceland were obtained by using a hot water drill to sink two boreholes through the 250 m thick ice shelf covering the lake the lake generally shows an increase in solutes with increased depth as solutes are added from the lake s bottom and dilute glacial meltwater is added continuously from above the crater lake temperature ranges from 0 c in the upper part to temperatures of 1 c to 4 c near the bottom of the lake the lake water ph ranges between 7 0 and 5 7 the crater lake is assumed to be closed with respect to volatile components released from subsurface magma except for periodic draining by jokulhlaups from the periodicity and water chemistry of the jokulhlaups we have estimated the volcano s average release rates of carbon sulfur chlorine and fluorine between 1954 and 1991 and corrected these rates for dissolution of bedrock into the lake water and seepage of solutes to groundwater the corrected mean release rates are 5 3 107 kg c yr 1 5 3 106 kg s yr 1 6 6 105 kg cl yr 1 and 1 5 105 kg f yr 1 the emission rate estimates for grimsvotn one of the most active volcanoes in iceland are the longest integrated estimates obtained for an active volcano and are equal to or lower than those of other major active volcanoes worldwide this difference may imply that published release rates for other volcanoes are overestimated because they are usually not integrated over time the values of the s cl and f cl ratios for noneruptive periods are 0 53 0 20 and 0 013 0 003 and for the two eruptive events are 0 69 and 2 14 and 0 034 and 0 041 respectively the response of the elemental ratios to eruptive events followed by the return to lower ratios supports the assumption of steady state because no long term accumulation of volatiles occurs the energy output from the volcano estimated from the amount of ice melted by hydrothermal heat is 4250 mw over the last four decades using the energy output to calculate magma solidification rates and maximum possible volatile release rates we observe that emissions of f and s are strongly suppressed at grimsvotn while a significant portion of available cl and c are released these calculations also reveal that coverage of a volcano by a glacier and subsequent raising of the water table may cause significant scrubbing of magmatic gases so that these gases do not reach the atmosphere

a new raba chromatographic separation and its application to ra mass spectrometric measurement in volcanic rocks we have adapted the recent chromatographic method described by e p horwitz and coworkers for sr separation to perform an efficient ba ra separation for measuring ra isotopes in volcanic rocks by mass spectrometry extraction chromatography is used with a solution of a crown ether 4 4 5 bis tert butylcyclohexano 18 crown 6 in 1 octanol adsorbed on an inert substrate as an extractant the elchrom company markets this resin under the name sr spec we show that this technique gives a very efficient ba ra separation which compares favourably with previous chromatographic methods the chemical and mass spectrometric procedure is described in detail and is applied to ra measurements in volcanic rocks

submarine groundwater discharge in a subsiding coastal lowland a 226ra and 222rn investigation in the southern venice lagoon several recent studies have suggested that submarine groundwater discharge sgd occurs in the venice lagoon with discharge rates on the same order or larger than the surface runoff as demonstrated previously in several other coastal zones around the world here the first set of 222rn data along with new 226ra data are reported in order to investigate the occurrence and magnitude of sgd specifically in the southern basin of the lagoon the independent connection with the adriatic sea at the chioggia inlet in addition to the relative isolation of the water body from the main lagoon make this area an interesting case study there is probably only minimal fresh groundwater flux to the lagoon because the surrounding aquifer is subsiding and mainly has a lower hydraulic head than seawater the data show that the ra and rn activities are in slight excess in the lagoon compared to the open sea with values on the same order as those observed in the northern and central basins taking into account the water exchange rate between the lagoon and adjacent seawater provided by previous hydrodynamic numerical modelling it is shown that this excess cannot be supported at steady state by only riverine input and by diffusive release from the sediment interstitial water high activities observed in groundwater samples collected from 16 piezometers tapping into the shallow aquifer over the coastal lowland substantiate that the excess radioactivity in the lagoon may indeed be due to the advection of groundwater directly into the lagoon bottom water through the sediment interface however the data show that the groundwater composition is extremely heterogeneous with high ra activities concentrated within a narrow coastal strip where the contact between fresh and saline water takes place while rn strongly decreases when approaching the lagoon shore across the 20 km coastal plain assuming that the average groundwater activities measured in the coastal strip are representative of the sgd composition a sgd flux of 7 7 3 5 105 and 2 5 2 106 m3 d is calculated using a 226ra and 222rn budget respectively i e about 1 3 times the surface runoff substantially lower than in previous studies the influence of all assumptions on sgd estimates groundwater heterogeneity diffusive sediment flux one box versus multi boxes model calculations is discussed and a sensitivity analysis of the influence of imperfect exchange and mixing at the lagoon outlets that affects the lagoon composition is provided finally the results confirm that the sgd flux calculated with these assumptions is largely 80 composed of saline lagoon water circulating through the sediment under the lagoon margin and that the fresh water discharge associated with sgd is at most a minor term in the lagoon hydrologic balance