an example of health hazard people killed by gas during a phreatic eruption dieng plateau java indonesia february 20th 1979 on february 20th 1979 142 inhabitants of dieng plateau indonesia were asphyxiated by poisonous gases during a mild phreatic eruption from later fields gas collection and analysis the casualties are considered to be due to co2 rich volcanic gases

hydrologic processes in the different landscape zones of mafengou river basin in the alpine cold region during the melting period summary hydrologic processes of glacier snow frozen soil groundwater surface water and precipitation have always been the common concern of hydrologists the purpose of this study is to identify the hydrologic processes in different landscape zones based on the isotopic and hydrochemical analysis of glacier snow frozen soil and groundwater the chemical compositions were characterized by ca hco 3 in the glacier snow zone mg ca so 4 hco 3 in the alpine cold desert zone ca mg hco 3 in the marsh meadow zone ca mg hco 3 in the alpine shrub zone and na ca so 4 in the mountain grassland zone the end member mixing model was employed for hydrograph separation the results showed that during the melting period mafengou river water was recharged by glacier snow melt water about 34 thawed frozen soil water in each of the landscape zones about 12 and groundwater about 54 this study suggested that mafengou river water during the melting period was mainly recharged by glacier snow melt water groundwater and thawed frozen soil water

origin of the lethal gas burst from lake monoun cameroun abstract on 15 august 1984 a lethal gas burst issued from a submerged 96 m deep crater in lake monoun in cameroun western africa killing 37 people the event was associated with a landslide from the eastern crater rim which slumped into deep water waters below 50 m are anoxic dominated by high fe 2 600 mg l and hco 3 1900 mg l anoxic and supersaturated with siderite which is a major component of the crater floor sediments the unusually high fe 2 levels are attributed to reduction of laterite derived ferric iron gradually brought into the lake as loess and in river input sulfur compounds are below detection limits in both water and gas gases effervescing from depressurized deep waters are dominantly co 2 with minor ch 4 having 13 c of 7 18 and 54 8 per mil respectively bacterial decomposition of organic matter may account for the methane but 14 c of lake water indicates that only 10 of the carbon is modern giving an apparent age of 18 000 years the dominant source of carbon is therefore attributed to long term emission of co 2 as volcanic exhalation from vents within the crater which led to gradual build up of hco 3 in the lake the density stratification of the lake may have been upset by an earthquake and underwater landslide on 15 august which triggered overturn of the lake and caused nucleation of co 2 in the deep water the resultant ebullition of co 2 from deep lake waters led to a gas burst at the surface and locally generated a water wave up to 5 m high people travelling through the gas cloud were asphyxiated presumably from co 2 and suffered skin discoloration from unidentified components

origin of carbon dioxide emanation from the 1979 dieng eruption indonesia implications for the origin of the 1986 nyos catastrophe abstract in february 1979 co2 emanations accompanying a phreatic eruption killed 142 people at dieng volcano central java the gas emitted was nearly pure carbon dioxide with subordinate amounts of methane and sulfur compounds the 3c of the carbon dioxide was 4 0 identical to that of magmatic co2 from the nearby merapi volcano and close to that of mantle derived carbon this and data on helium supports the hypothesis that magmatic carbon dioxide was involved lower 13c ranging from 4 6 in 8 4 were measured in the fumarole gases from the area the lightest co2 occurs in samples in which methane is more abundant and which are poorer in 13c and thus may partly derive from biogenic carbon the su34 s 32 s ratio of sulfur in all samples suggests a volcanic origin it is proposed that magmatic carbon dioxide accumulated beneath the dieng volcanic complex was the source of the lethal gas the effusion of which was triggered by the pressure release generated by the phreatic eruption the total co2 discharge of the 1979 dieng event might have approached 0 1 km3 i e close to the lower output estimated for the 1986 nyos catastrophe the dieng example demonstrates that expansion and then effusion of pure magmatic carbon dioxide accumulated at shallow levels beneath volcanoes may account for a major hazard from phreatic eruptions be it a trigger or only a consequence of the eruptions

temporal isotopic variations of dissolved silicon in a pristine boreal river abstract it has previously been concluded that the stable si isotopes are fractionated during geochemical and biogeochemical elemental transfers such as weathering and precipitation of clays and biogenic si which has opened up the possibility of using si as a tracer in natural terrestrial ecosystems furthermore quantification of the biogenic impact on the biogeochemical si cycle has attracted significant scientific interest since biological control has been suggested previous observations of seasonal variations in the dissolved si isotopic pattern further imply that high frequency riverine sampling during main hydrological events might provide important information about natural processes governing the fluvial biogeochemical si cycle therefore temporal variations in the isotopic composition of riverine dissolved si were investigated for the kalix river northern sweden the largest pristine river system in europe based on high frequency sampling during a period of 25 weeks from early april to early october 2006 temporal variations spanning 0 4 for 29si and 0 8 for 30si of dissolved si in the kalix river were observed during the period suggesting that the riverine dissolved si input to the oceans cannot be considered to have a constant si isotopic composition on a short time scale the results implicate biogeochemical si cycling via formation and dissolution of biogenic silica as processes significantly affecting the dissolved si transport in boreal systems during april to early october the si budget in the river system appeared to be controlled by relative si enrichment during high discharge events and relative si depletions in the subarctic mountainous and lake dominated areas the si enrichments and depletions were accompanied by decreasing and increasing riverine 29si and 30si respectively these isotope variations can be explained by release of plant derived silica depleted in heavier si isotopes during the spring snowmelt further increased volumetric contribution from the headwater and losses of dissolved si due to biogenic silica formation by diatoms in the subarctic lakes at a later period are expected to be responsible for the preferential losses of lighter isotopes as further verified by land cover analysis

a stable isotope study of the garda lake northern italy its hydrological balance summary discontinuous measurements of the isotopic composition of surface water samples of the garda lake carried out between 1998 and 2006 showed almost constant 18 o d and d excess values through time during 2006 and 2007 monthly vertical profiles of water samples were collected in the northernmost section of the lake not far from the main inflow sarca river to check whether there was any detectable influence from this inflowing river and whether there was a vertical isotopic stratification of the lake water the isotopic measurement of water samples from the vertical profiles yielded isotopic values which were almost equal to those obtained from surface waters showing no detectable effect of the inflowing river water and no isotopic vertical stratification the attempt to evaluate the evaporation rate of lake water by means of current models was totally unsuccessful despite the marked summer warming of the surface layer no isotopic fractionation related to evaporation processes could be detected this anomalous behaviour may be related to the large amount of spring and summer precipitation characteristic of this area the water balance of the lake calculated according to the amount of the inflowing water sarca river water plus rain water on the lake plus 20 of the precipitations on the whole catchment basin and to the amount of outflowing water mincio river showed a large imbalance the river outflow alone resulting on average during the last decade at least double the inflow to explain this imbalance of the lake a large recharge by concealed groundwater is suggested its isotopic composition should be quite close to the mean isotopic composition of precipitations over that area this would be in agreement with the almost constant isotopic composition of both surface and deep waters and with the lack of vertical isotopic stratification a few measurements of the tritium concentration carried out on lake water show values that are considerably higher than modern tritium values either in precipitation or in the sarca river water these results are in good agreement with the hypothesis of a recharge of the lake by deep aquifers

carbon dioxide emissions from soils at hakkoda north japan 1 a soil gas and co2 efflux survey was carried out at hakkoda north japan to investigate the spatial distribution and origin of the gas which caused the accidental death of three japanese soldiers on 12 july 1997 in the study area no fumarolic and or thermal activity is observed chemical composition of the gas from areas with high co2 effluxes 5 000 g m 2 d 1 and high co2 contents 15 vol indicate a strong deep sourced contribution for co2 whereas air and or air saturated water is suggested for the rest of the discharged gases which are mainly released from a shallow aquifer isotopic analysis of soil gas and hot spring discharges suggests a combination of magmatic degassing and thermal decarbonation with magmatic degassing being the main contributior to the high co2 emission approximately 74 t d 1 of deep seated magmatic plus thermal decarbonation origin co2 were estimated to contribute to the total output of co2 from this area

shrimp u pb zircon dating of the wulian complex defining the boundary between the north and south china cratons in the sulu orogenic belt china abstract neoproterozoic metasedimentary and metavolcanic rocks of the wulian group are associated with gneissic granitoids at the northern margin of the sulu uhp belt adjacent to the wulian yantai fault and are collectively referred to as the wulian complex shrimp u pb dating of detrital zircon from the metasedimentary rocks of the wulian group indicates a range in age from 3478 to 625 ma based on zircons 3000 ma with the oldest age being 3339 ma 2700 2400 ma with a peak at 2436 ma 2200 1800 ma with a peak at 2156 ma and at 770 ma these results indicate that deposition of the wulian group was after 770 ma and that some detrital material most likely came from neoproterozoic sources in the south china craton scc shrimp u pb zircon dating of a metavolcanic rock defines a weighted mean 206 pb 238 u age of 761 8 ma which is consistent with other rocks of south china affinity and can be correlated with syn rift magmatism during the breakup of the supercontinent rodinia the wulian group together with neoproterozoic granites of the wulian complex constrains the location of the triassic suture zone between the north china and south china cratons based on our new data the suture must lie north of the wulian complex and is marked by the baichihe yantai fault

natural and industrial analogues for leakage of co2 from storage reservoirs identification of features events and processes and lessons learned instances of gas leakage from naturally occurring co2 reservoirs and natural gas storage sites serve as analogues for the potential release of co2 from geologic storage sites this paper summarizes and compares the features events and processes that can be identified from these analogues which include both naturally occurring releases and those associated with industrial processes the following conclusions are drawn 1 carbon dioxide can accumulate beneath and be released from primary and secondary shallower reservoirs with capping units located at a wide range of depths 2 many natural releases of co2 are correlated with a specific event that triggered the release 3 unsealed fault and fracture zones may act as conduits for co2 flow from depth to the surface 4 improperly constructed or abandoned wells can rapidly release large quantities of co2 5 the types of co2 release at the surface vary widely between and within different leakage sites 6 the hazard to human health was small in most cases possibly because of implementation of post leakage public education and monitoring programs 7 while changes in groundwater chemistry were related to co2 leakage waters often remained potable lessons learned for risk assessment associated with geologic carbon sequestration are discussed

liquid carbon dioxide of magmatic origin and its role in volcanic eruptions natural liquid carbon dioxide is produced commercially from a 2 5 km deep well near the 4 500 yr old maar volcano mount gambier south australia the carbon dioxide has accumulated in a dome that is located on the extension of a linear chain of volcanic activity a magmatic origin for the fluid is suggested by the geological setting 13cpdb of 4 0 for the co2 where pdb represents the carbon isotope standard and a relatively high 3he component of the contained helium and high 3he c ratio 6 4 x 10 10 the 3he 4he and he ne ratios are 3 0 and 1 370 times those of air respectively the co2 as collected at the earth s surface at 29 5 c and 75 bar expands more than 300 fold to form a gas at 1 atm and 22 c we suggest that liquid co2 or high density co2 fluid the critical point is 31 1 c 73 9 bar of volcanic origin that expands explosively from shallow levels in the earth s crust may be a major contributor to phreatic volcanic eruptions and maar formation less violent release of magmatic co2 into crater lakes may cause gas bursts with equally disastrous consequences such as occurred at lake nyos cameroon in august 1986

isotopic composition of precipitation in central iowa abstract the isotopes of hydrogen and oxygen have been used extensively as indicators of groundwater age 3h and paleotemperature of groundwater recharge 18o 16o 2h 1h however comparisons of values in groundwater with those in recent precipitation are few this study describes and interprets the isotopic composition of precipitation in central iowa for the year 1992 an unusually mild winter driven by south westerly flow of the jet stream was followed by an unusually cool and predominantly dry summer that was caused by a persistent northwesterly flow in the upper atmosphere temperature was below normal 9 0 c precipitation was above normal 868 4 mm and was mostly derived from a gulf of mexico moisture source fifty one precipitation samples were collected from 37 events and analyzed for hydrogen and oxygen isotopes tritium activities ranged from 0 to 44 tritium units tu and the weighted mean 3h activity was 11 02 tu a value consistent with international atomic energy agency iaea data anomalously high 3h activities suggested input of technogenic 3h weighted mean values of 18o and 2h were 8 02 and 53 62 respectively and the equation of the local meteoric water line was 2h 9 26 18o 4 65 weighted mean 18o and 2h values from the gulf pacific moisture source 10 80 74 82 were more depleted than those ascribed solely to a gulf of mexico moisture source 7 24 47 39 seasonal differences in temperature primarily controlled these differences in isotopic composition

characteristics of isotope in precipitation river water and lake water in the manasarovar basin of qinghai tibet plateau the stable hydrogen and oxygen of lake river rain and snow waters were investigated to understand the water cycle characteristics of the drainage basin of manasarovar lake in tibet both d and 18o of river water are larger than those of lake water and the effect of altitude on both d and 18o is not very significant this phenomenon was suggested to occur because manasarovar basin is located in qinghai tibet plateau which has low latitude high altitude abundant glaciers thin air and intensive solar radiation resulting in higher evaporation in lake water

use of chloride mass balance and environmental isotopes for evaluation of groundwater recharge in the alluvial aquifer wadi tharad western saudi arabia groundwater recharge estimation has become a priority issue for humid and arid regions especially in regions like saudi arabia where the precipitation varies over space and time as a result of topography and seasonality wadi tharad is a typical arid area in western saudi arabia within its drainage area of 400 km 2 the groundwater system shows a graded hydrochemical zonation from the hydrocarbonate in the upper reach to the chloride zone in the lower reach the saturation index si varies depending on the concentrations of carbonate minerals the mean for calcite and dolomite is about in equilibrium e g zero value as halite and gypsum indices are negative it is undersaturated isotopic compositions of h and o in the groundwater show that the groundwater recharge resources are mainly from meteoric water the chloride mass balance method was refined to estimate the amount of recharge which is probably 11 of the effective annual rainfall these results can be used to improve the accuracy of future groundwater management and development schemes

hydrochemical and hydrological processes in the different landscape zones of alpine cold region in china investigation of water sources and flow pathways is crucial to understand and evaluate the characteristics of surface water and groundwater systems this article aims to identify the hydrochemical and hydrological processes in different landscape zones based on hydrochemical analyses of various samples including samples from glacier snow frozen soil meltwater surface water groundwater and precipitation in the alpine cold region of china hydrochemical tracers indicated that chemical compositions are characterized by the ca hco3 type in the glacier snow zone the mg ca so4 type in the alpine cold desert zone the ca hco3 so4 type in the marsh meadow zone the ca mg hco3 type in the alpine shrub zone and the ca na so4 type in the mountain grassland zone an end member mixing model was used for hydrograph separation the results showed that the mafengou river in the wet season was recharged by groundwater in the alpine cold desert and alpine shrub zones 67 surface runoff in the glacier snow zone 11 surface runoff in the alpine cold desert zone 8 thawed water from frozen soil in the marsh meadow and mountain grassland zones 9 and direct precipitation on the river channel 5 this study suggests that precipitation from the whole catchment yielded little direct surface runoff precipitation was mostly transformed into groundwater or interflow and was then concentrated into the river channel this study provides a scientific basis for evaluation and management of water resources in the basin

spatial domain analysis of carbon dioxide from soils on vulcano island implications for co2 output evaluation abstract the carbon dioxide emissions of volcanoes have been targeted as effective contributors of co 2 to the atmosphere however different sources can be effective and active at the same time in the generation and release of co 2 in volcanic zones since isotopic fingerprinting of co 2 allows the precise identification of different sources coupling carbon isotope and co 2 flux measurements enables the evaluation of the mass contribution of each source to the carbon dioxide emissions this paper accounts for the first extensive spatial analysis of coupled measurements of carbon isotopologues of co 2 in the soil gases and co 2 fluxes discharged by soils on vulcano island an innovative method has been designed tested and fine tuned in the laboratory to measure 13 c co 2 values directly in field using a new type of laser based isotopologues analyzer namely a deltaray thermo fisher scientific the method can be used to determine the carbon isotope composition across the full range of co 2 concentrations in the soil gases 0 100 vol these data have been combined with measurements of the co 2 contents in the soil gases to distinguish co 2 from deep origins from co 2 of biogenic origin in the inhabited area of vulcano porto the method of evaluating the amount of deep origin co 2 in the soil gases is widely applicable in volcanic and geothermal zones for evaluation and monitoring purposes for both gas and volcanic hazards

stable isotopic composition of precipitation in the semi arid north central portion of the us great plains abstract where data are available hydrologic studies may use stable oxygen and hydrogen isotopes to investigate groundwater surface water interaction groundwater recharge and advective diffusive transport to estimate groundwater ages or to unravel paleohydrology such studies require that the isotopic composition of precipitation be known as precipitation is a major input to groundwater and surface water systems oxygen 18 18 o and deuterium 2 h data for precipitation are lacking for the semi arid portion of the north central great plains of the us and thus there is need to establish additional meteoric water lines as isotope input functions across the region as well as to develop better understanding of the isotopic climate linkages that control oxygen and hydrogen isotope ratios in precipitation this study examines the 18 o and 2 h composition of precipitation for a representative site near north platte nebraska in the semi arid north central great plains during the years 1989 through 1994 oxygen 18 values range from 30 5 to 1 7 deuterium values range from 228 to 11 yearly arithmetic mean values for the north platte station are 9 8 and 71 respectively weighted yearly means for 18 o and 2 h over the 6 year period were 9 6 and 69 respectively north platte values show a strong isotopic enrichment between winter and summer precipitation and a strong 18 o t correlation r 2 0 845 for mean monthly values of 0 54 per degree celsius the local meteoric water line for the site is 2 h 7 66 18 o 4 96

hydrogen and oxygen isotopic records in monthly scales variations of hydrological characteristics in the different landscape zones of alpine cold regions monthly scale variations in stable isotopic composition in precipitation and various water bodies were analyzed in this study using data collected from a field station experimental observation was performed to analyze processes in the glacier snow zone alpine cold desert zone marsh meadow zone alpine shrub zone and mountain grassland zone based on the isotopic and hydrochemical analyses of glacier snow frozen soil groundwater and other water sources in the headwater catchment of the alpine cold region delta o 18 and delta d values of precipitation and various water bodies in mafengou river basin exhibited strong seasonal variations precipitation and various water bodies were rich in delta o 18 and delta d during the wet season and relatively negative in delta o 18 and delta d during the dry season the isotopic content of various water bodies in mafengou river basin was dependent on temperature elevation of the recharge area and amount of precipitation lower temperatures were typically associated with lower delta o 18 and delta d values and are believed to be mainly responsible for the seasonal patterns observed in the isotopic values of various water bodies in mafengou river basin in the alpine cold region seasonal variations were larger in streams where recent precipitation is the main source of the flow and smaller in streams where groundwater is the dominant source of water c 2013 published by elsevier b v

variations in the isotopic composition of molybdenum in freshwater lake systems variations in molybdenum isotopic composition spanning the range of similar to 2 3 parts per thousand in the terms of mo 97 mo 95 ratio have been measured in sediment cores from three lakes in northern sweden and north western russia these variations have been produced by both isotopically variable input of mo into the lakes due to mo isotopic heterogeneity of bedrock in the drainage basins and fractionation in the lake systems due to temporal variations in limnological conditions mo isotope abundances of bedrock in the lake drainage basins have been documented by analysis of mo isotope ratios of a suite of molybdenite occurrences collected in the studied area and of detrital fractions of the lake sediment cores the median delta mo 97 value of the investigated molybdenites is 0 26 parts per thousand with standard deviation of 0 43 parts per thousand n 19 whereas the median delta mo 97 value of detrital sediment fractions from two lakes is 0 40 parts per thousand with standard deviation of 0 36 parts per thousand n 15 the isotopic compositiori of mo in the sediment cores has been found to be dependent on redox conditions of the water columns and the dominant type of scavenging phases hydrous fe oxides have been shown to be an efficient scavenger of mo from porewater under oxic conditions oxidative precipitation of fe ii in the sediments resulted in co precipitation of mo and significant authigenic enrichment at the redox boundary in spite of a pronounced increase in mo concentration associated with fe oxides at the redox boundary the isotopic composition of mo in this zone varies insignificantly suggesting little or no isotope fractionation during scavenging of mo by hydrous fe oxides in a lake with anoxic bottom water a chironomid inferred reconstruction of o 2 conditions in the bottom water through the holocene indicates that increased o 2 concentrations are generally associated with low delta mo 97 mo 95 values of the sediments whereas lowered o 2 contents of the bottom water are accompanied by relatively high delta mo 97 mo 95 values thus confirming the potential of mo isotope data to be a proxy for redox conditions of overlying waters however it is pointed out that other processes including input of isotopically heterogeneous mo and mn cycling in the redox stratified water column can be a primary cause of variations in mo isotopic compositions of lake sediments less

isotope study of moisture sources recharge areas and groundwater flow paths within the eastern batinah coastal plain sultanate of oman oxygen and hydrogen isotope analyses of rainfall samples collected on the eastern batinah coastal plain of northern oman between 1995 and 1998 indicate two different principal water vapor sources for precipitation in the area a northern mediterranean source and a southern indian ocean source as a result two new local meteoric water lines were defined for the study area isotopic analyses of groundwater samples from over 200 springs and wells indicate that the main source of water to the batinah coastal alluvial aquifer is high altitude rainfall from the adjacent jabal akhdar mountains originating from a combination of northern and southern moisture sources the groundwater recharged at high altitude forms two plumes of water which is depleted in the heavy isotopes 18o and 2h and stretches from the mountains across the coastal plain to the sea thereby retaining a chemical homogeneity horizontally and vertically down to a depth exceeding 300 m in contrast in areas adjacent to these two plumes the alluvial aquifer is geochemically stratified near the coast saline intrusion results in abrupt changes in chloride concentrations and isotope values

hydrological processes and chemical characteristics of low alpine patterned wetlands south central new zealand summary patterned wetlands in new zealand are not only rare but they are distinguished from their northern hemisphere counterparts by their vegetation and the supply of rainfall which is relatively free of pollution hydrological processes in two low alpine patterned wetlands 5 and 220 ha on block faulted uplands in south central south island new zealand were investigated using hydraulic head gradients and chemical and isotope data there was no significant spatial variability in chemical parameters within either wetland although the larger wetland is characterised by a lower trophic status than the smaller one ca2 concentrations and ph of surface water of both wetlands are within the range of that of northern hemisphere ombrotrophic mesotrophic bogs and poor fens pool water chemistry only partially overlaps with the lower end of the ca2 distribution for the northern hemisphere wetlands likely to be caused by the low level of ca2 in aeolian dust the ph in the pools of the small wetland was generally higher probably as a result of differing organic acid production by the sphagnum and sedge species both of which were common and dominant or sub dominant in the wetlands some temporal variability was observed possibly due to seasonal variations in plant uptake and or rainfall a steady increase in na concentrations in the pools over 4 years was tentatively attributed to an excess of supply from rainfall and or groundwater cation and stable isotope data indicate strong evaporation in pools and surface water despite the high ambient relative humidity and mixing within the top of the wetland sequence stratigraphy indicates that peat formation has been interrupted by flooding or runoff bringing mineral matter into the wetlands particularly in the earlier development stages of the larger wetland the peat sequence is thicker in the smaller wetland reaching up to 2 8 m with limited mineral input during wetland development the relatively low ph and ionic concentrations in the contemporary water and peat sequence of the larger wetland indicate that it has become isolated from runoff and mineral input

hydrograph separation for karst watersheds using a two domain rainfall discharge model highly parameterized physically based models may be no more effective at simulating the relations between rainfall and outflow from karst watersheds than are simpler models here an antecedent rainfall and convolution model was used to separate a karst watershed hydrograph into two outflow components one originating from focused recharge in conduits and one originating from slow flow in a porous annex system in convolution parameters of a complex system are lumped together in the impulse response function irf which describes the response of the system to an impulse of effective precipitation two parametric functions in superposition approximate the two domain irf the outflow hydrograph can be separated into flow components by forward modeling with isolated irf components which provides an objective criterion for separation as an example the model was applied to a karst watershed in the madison aquifer south dakota usa simulation results indicate that this watershed is characterized by a flashy response to storms with a peak response time of 1 day but that 89 of the flow results from the slow flow domain with a peak response time of more than 1 year this long response time may be the result of perched areas that store water above the main water table simulation results indicated that some aspects of the system are stationary but that nonlinearities also exist