h2 generation in wet grinding of granite and single crystal powders and implications for h2 concentration on active faults 1 granite and single crystals of quartz alkali feldspar biotite and muscovite are ground in ph controlled and pure water solutions using a ball mill at ambient condition to examine the production of h2 the amount of h2 generated by grinding is linearly related with the surface area of ground samples the slope of the straight line indicates h2 productivity of each mineral 3 9 10 3 mol m2 quartz 1 0 10 3 mol m2 alkali feldspar 3 6 10 2 mol m2 biotite 2 2 10 2 mol m2 muscovite 4 5 10 3 mol m2 granite high productivity of biotite and muscovite is probably related to the existence of hydroxyls in their crystal structures interestingly h2 production did not depend on the ph of the solution in the case of biotite and granite while comparisons between fluid acidity and h2 concentration on several active faults suggest that anomalously high h2 is commonly observed at relatively acidic water springs this correlation may be explained by locally high abundance of phyllosilicates

application of an inverse method to interpret 231pa 230th observations from marine sediments constraints then sediment 231 pa 230 th data for each time interval are combined with an advection scavenging model in order to determine their in consistency with the modern circulation estimate we find that the majority of sediment 231 pa 230 th data for the holocene lgm or h1 can be brought into consistency with the modern circulation if plausible assumptions are made about the large scale distribution of 231 pa and about model uncertainties moreover the adjustments in the data needed to reach compatibility with a hypothetical state of no flow no advection are positively biased for each time interval suggesting that the 231 pa 230 th data including that for h1 are more consistent with a persistence of some circulation than with no circulation our study does not imply that earlier claims of a circulation change during the lgm or h1 are inaccurate but that these claims cannot be given a rigorous basis given the current uncertainties involved in the analysis of the 231 pa 230 th data

preseismic hydrogen gas anomalies caused by stress corrosion process preceding earthquakes simultaneous monitoring of he h2 ar n2 ch4 and rn in gas bubbles of groundwater from the 1 500 m deep nagashima well in the active yoro fault zone central japan reveals that three microearthquakes with m 1 6 2 6 in the fault zone are accompanied and preceded by increases of h2 as is a moderately large event with m 5 4 in the same fault zone all the focal distances of the earthquakes are within 25 km no comparable anomalies were seen in the gas species other than h2 we suggest that the selective and preseimic increases of h2 in groundwater gas bubbles are geochemical signals of the earthquake nucleation process of stress corrosion mechanism aseismic slips preceding earthquakes in the active fault zone are likely to have enhanced h2 production by mechanochemical reaction of fractured rock surface with water in pre existing fault planes as groundwater conduits

thorium 230 profiling in deep sea sediments high resolution records of flux and dissolution of carbonate in the equatorial atlantic during the last 24 000 years variations in carbonate flux and dissolution which occurred in the equatorial atlantic during the last 24 000 years have been estimated by a new approach that allows the point by point determination of paleofluxes to the seafloor an unprecedented time resolution can thus be obtained which allows sequencing of the relatively rapid events occurring during deglaciation the method is based on observations that the flux of unsupported 230th into deep sea sediments is nearly independent of the total mass flux and is close to the production rate thus excess 230th activity in sediments can be used as a reference against which fluxes of other sedimentary components can be estimated the study was conducted at two sites ceara rise western equatorial atlantic and sierra leone rise eastern equatorial atlantic in cores raised from three different depths at each site from measurements of 230th and caco3 changes in carbonate flux with time and depth were obtained a rapid increase in carbonate production starting at the onset of deglaciation was found in both areas this event may have important implications for the postglacial increase in atmospheric co2 by increasing the global carbonate carbon to organic carbon rain ratio and decreasing the alkalinity of surface waters and possibly the north atlantic deep water increased carbonate dissolution occurred in the two regions during deglaciation followed by a minimum during mid holocene and renewed intensification of dissolution in late holocene during the last 16 000 years carbonate dissolution was consistently more pronounced in the western than in the eastern basin reflecting the influence of antarctic bottom water in the west this trend was reversed during stage 2 possibly due to the accumulation of metabolic co2 below the level of the romanche fracture zone in the eastern basin

boundary scavenging at the east atlantic margin does not negate use of 231pa 230th to trace atlantic overturning abstract the 231 pa 230 th method is a promising tool to reconstruct ocean circulation over the past glacial interglacial cycle however marine particle flux may constrain the applicability of this ratio as a direct quantitative proxy for the strength of atlantic meridional overturning circulation amoc by influencing the fractionation between the in situ produced 231 pa and 230 th in ocean water here we present 231 pa 230 th down core profiles from high particle flux areas off namibia and senegal covering the past 35 ka the 231 pa 230 th profiles at these sites show very different responses to temporal variations of particle fluxes and to changes in water masses our results show that sedimentary 231 pa 230 th in the eastern atlantic margin is linked to particle flux but controlled primarily by the mode of the amoc our data suggest that during the past 30 ka the high productivity eastern margin was not capable of importing and storing significant amounts of 231 pa from the open ocean consequently the applicability of the 231 pa 230 th proxy to reconstruct past ocean circulation is not hampered by this potentially additional 231 pa sink

anomalous changes of ch4 ar ratio in subsurface gas bubbles as seismogeochemical precursors at matsuyama japan the results of seismogeochemical monitoring of subsurface gases associated with ground waters from deep artesian wells in matsuyama japan are presented the weekly collections of bubble gas samples from the two borehole wells and gas chromatographic determinations of their he ar h2 ar n2 ar and ch4 ar ratios for the recent nineteen months have revealed that the bubble gas ch4 ar ratios at the two stations are correlated with the seismic activity in this area positive anomalies of the ch4 ar ratio were accompanied by five earthquakes with relatively large magnitudes and or relatively small epicentral distances among thirty earthquakes that occurred during the monitoring period the anomalous increases in the ch4 ar ratio had evidently begun prior to the respective earthquakes

particulate removal of230th and231pa in the biologically productive northern north pacific settling particles were collected by sediment traps at four stations in the high latitudes of the north pacific and analyzed for234th 232th 230th 228th and231pa in the northern north pacific including the bering sea the average activity ratio of unsupported230th to231pa in settling particles was 5 5 whereas that in the gulf of alaska in the eastern north pacific was about 14 the northern north pacific may be an efficient sink for231pa relative to230th because the average ratio in the world ocean is equal to the production ratio of 10 8 in seawater the activity ratios of230th 231pa of the settling particles agree well with those of the surface sediments at the respective stations this indicates that both nuclides in the surface sediments originated from settling particles and their dissolution or uptake during early diagenesis are not effective the ratio of the particulate nuclide flux f to the overlying water column production rate p did not correlate well with the total mass flux for230th however that for231pa increased almost linearly with increase in total mass flux and reached unity when the total mass flux was about 110 mg m2 d this suggests that231pa transported from oligotrophic regions is being actively removed in the biologically productive northern north pacific

seismically induced changes of the fluid signature detected by a multi isotope approach he co2 ch4 n2 at the wettinquelle bad brambach central europe 1 we present a study considering the systematics of gas and isotope compositions 3 he 4 he 13 c co2 13 c ch4 15 n of a permanent magmatic co 2 flux in the hydrothermal system of the spring wettinquelle in bad brambach and their relation to the seismic activity beneath the western eger rift the gas and isotope compositions were monitored for more than 3 years the time series includes periods before during and after a 4 month long seismically active period from the end of august to the end of december 2000 shifts due to admixture of crustal components were found for all monitored isotope ratios during and after the seismically active period in case of helium and nitrogen isotopic anomalies occurred already about 6 weeks before the beginning of the seismically active period contemporaneous with a water level anomaly of the well vl4 near the wettinquelle on the one hand preseismic deformations may be responsible for the observed isotope anomalies on the other hand coseismic fracturing processes in the surroundings of the hypocenters may play a role both effects produce greater permeability and result in the release of crustal fluids the migration and admixture of these crustal components to the permanent upper mantle derived fluid flux result in geochemical anomalies that persist for more than 2 years the results of the detailed isotope monitoring have proven to be an important contribution to understand the geodynamic processes that may presently be going on in the region vogtland nw bohemia

origin and coseismic behavior of mineral spring gas at byakko japan studied by automated gas chromatographic analyses abstract the origin and coseismic behavior of mineral spring gas were examined on the basis of continual monitoring data for several gas species the automatic monitoring system used in this study consists of two gas chromatographs and a personal computer several gas species can simultaneously be analyzed with these analyzers the system was so stable and sensitive that minute coseismic anomalies in these species could be detected a positive correlation between n 2 ar and ch 4 ar implies that the mineral spring gas is a mixture of atmospheric air and lithospheric gas the lithospheric gas is mainly composed of n 2 and ch 4 and also contains trace amounts of he it is inferred from isotopic data that lithospheric n 2 and ch 4 are thermogenic and he is mostly radiogenic in contrast o 2 and h 2 in trace amounts show large diurnal fluctuations suggesting that these species should be mostly biogenic ten earthquakes felt around the station occurred during the monitoring period and four of them coincided with coseismic anomalies in the he ar ratio the anomalies may be interpreted as follows by the ground motion at these felt quakes he accumulated in the ground was additionally released into the spring water the continual monitoring of these gas species enables us to discuss in detail the origin and behavior of the spring gas and to evaluate background noise of the data

fluxes of 230th and 231pa to the deep sea implications for the interpretation of excess 230th and 231pa 230th profiles in sediments abstract analysis of samples obtained with deep sea moored sediment traps deployed at 15 sites representing a wide range of oceanic conditions confirms that the flux of 230 th scavenged to the seafloor remains close to its production rate from the decay of 234 u in the overlying water column and generally validates the use of 230 th as a normalizing tool for paleoflux reconstruction after correction for trapping efficiency the flux of 230 th measured in the low flux regions amounts to 90 6 of the production rate with the notable exceptions of one site near the arabian sea upwelling and one site in the weddell sea a 230 th flux equivalent to 120 of the production rate was found in panama basin similar or more extensive scavenging of 230 th may be occurring at a pacific margin site off california and south of the polar front but these estimates are obscured by large errors on our trapping efficiency estimates in contrast the flux of 231 pa and the 231 pa 230 th ratio can vary strongly with particle flux following distinct trends in different oceanic basins in the atlantic ocean 231 pa fluxes and 231 pa 230 th are low and not sensitive to particle flux this is because of the short residence time of deep water in this basin resulting from thermohaline circulation which prevents the full development of lateral concentration gradients and full expression of boundary scavenging in the pacific ocean the sensitivity of 231 pa 230 th to particle flux is highest reflecting the longer residence time of deep water in the southern ocean 231 pa 230 th ratios are invariably high even when particle fluxes are low reflecting the predominance of opal which fractionates minimally between the two radionuclides interpretation of 231 pa 230 th recorded in sediments is thus complex in the atlantic this ratio is better suited for recording past changes in the strength of thermohaline circulation in the pacific it has the best potential for providing synoptic maps of past changes in particle flux in the southern ocean retrieval of information from 231 pa 230 th is more difficult and requires a more quantitative understanding of the influence of particle composition

seismo geochemical variations in sw taiwan multi parameter automatic gas monitoring results gas variations of many mud volcanoes and hot springs distributed along the tectonic sutures in southwestern taiwan are considered to be sensitive to the earthquake activity therefore a multi parameter automatic gas station was built on the bank of one of the largest mud pools at an active fault zone of southwestern taiwan for continuous monitoring of co2 ch4 n2 and h2o the major constituents of its bubbling gases during the year round monitoring from october 2001 to october 2002 the gas composition especially ch4 and co2 of the mud pool showed significant variations taking the co2 ch4 ratio as the main indicator anomalous variations can be recognized from a few days to a few weeks before earthquakes and correlated well with those with a local magnitude 4 0 and local intensities 2 it is concluded that the gas composition in the area is sensitive to the local crustal stress strain and is worthy to conduct real time monitoring for the seismo geochemical precursors

boundary scavenging in the pacific ocean a comparison of 10be and 231pa concentrations of u th 231pa and 10be were measured in holocene sediments from two cores collected off the west coast of south america two cores from the east pacific rise two from the equatorial pacific and one from the south pacific central gyre our results together with data from 5 cores reported in the literature show that boundary scavenging plays a major role in the removal of 10be from the pacific ocean deposition rates of 10be at three margin sites are more than an order of magnitude greater than at sites of red clay accumulation in the deep central pacific deposition of 231pa is 4 to 5 fold greater at the margin sites the residence time of 10be with respect to chemical scavenging defined as its inventory in the water column divided by its rate of removal to the sediments varies regionally from 1000 years at the red clay sites in the deep central pacific to 100 years at the margin sites different factors control boundary scavenging of pa and be for example scavenging of 231pa is enhanced by metal oxide coatings of particles whereas this seems to have little influence on the scavenging of 10be 1990

on the importance of opal carbonate and lithogenic clays in scavenging and fractionating 230th 231pa and 10be in the ocean abstract the influence of particle composition on the scavenging of 230 th 231 pa and 10 be in the ocean is critically re examined based on the particle solution distribution coefficient k d data reported by chase et al earth planet sci lett 204 2002 215 229 our re examination shows that the k d s for these radionuclides are strongly influenced by the amount of lithogenic material lithogenics in particulates as reported previously by us and that a strong correlation between the lithogenic and carbonate contents in open ocean particulates results in an apparent non linear correlation between caco 3 and k d for each of the three radionuclides using a three end member model we estimate that the respective k d s g g of 230 th 231 pa and 10 be in the open ocean are 2 3 10 8 1 2 10 7 and 3 8 10 6 for lithogenics 1 0 10 6 1 0 10 5 and 3 0 10 4 for carbonate and 2 5 10 5 1 2 10 6 and 7 5 10 5 for opal suggesting that lithogenics have a much stronger affinity for any of the three nuclides than does carbonate or opal lithogenics and carbonate preferentially scavenge 230 th over 231 pa and 10 be whereas opal slightly favors 231 pa and 10 be over 230 th relative to lithogenics carbonate plays a very limited role in fractionating 230 th 231 pa and 10 be due to its orders of magnitude smaller k d values for the three nuclides our results indicate that fractionations between pa and th and between be and th through particle scavenging are mainly determined by the opal to lithogenic ratio in particulates rather than the opal to carbonate ratio suggested by chase et al

the african humid period and the record of marine upwelling from excess 230th in ocean drilling program hole 658c using a high resolution 230 th normalized record of sediment flux we document the deglacial and holocene history of north african aridity and coastal upwelling at ocean drilling program hole 658c at both the end of the younger dryas and after the 8 2 ka event there are significant drops in terrigenous accumulation at our site indicating an increase in the monsoon moisture flux over africa at this time at 5 5 ka there is an abrupt end to the african humid period and a return to stronger upwelling conditions for carbonate and opal fluxes the 230 th normalization completely changes the shape of each record based on percentage variations alone this site is a clear example of how variations in one sediment component can obscure changes in the others and it demonstrates the need for radionuclide measurements more generally in paleoceanography by taking our new records and a large amount of previous data from this site we conclude that increases in african moisture are tightly coupled to decreases in coastal upwelling intensity

radon variations at arrowhead and murrieta springs continuous and discrete measurements two continuous radon monitors crms have been deployed at arrowhead hot springs along the san andreas fault near san bernardino and at murrieta hot springs along the elsinore fault the recorded hourly and daily radon variations during 1983 are within 5 of the mean values the radon levels increased however by about 10 20 above their normal baseline levels in midyear several small magnitude earthquakes m 3 0 3 5 occurred within 20 km of the arrowhead site near the end of the period of the radon increase

radon signals related to seismic activity in ecuador march 1987 a radon concentration measurement survey was carried out in ecuador using the ssntd technique the data analysis shows a definite radon anomaly prior to march 6 1987 m 6 9 earthquake anomalies found before october 18 and october 28th mild earthquakes in 1986 could be correlated with these events other anomalies that we cannot correlate with any geophysical event were also found

the influence of particle composition and particle flux on scavenging of th pa and be in the ocean we have examined the relative affinity of th pa and be for sorption from seawater onto particles of variable composition opal carbonate lithogenic particles and organic carbon nuclide concentrations in particles collected from time series sediment traps were normalized by the dissolved nuclide concentration in the overlying water column in order to compute partition coefficients under conditions spanning a wide range of particle flux and particle composition our results suggest that the affinity of particles for pa and be increases with their increasing opal content and decreasing carbonate content while the affinity of particles for th increases with increasing carbonate content and decreases with increasing opal content we find no correlation between the aluminosilicate content of particles and their affinity for scavenging of any of these elements extrapolating to a pure caco3 end member the partition coefficient for th 9 0 106 g g 1 is 40 times greater than for pa and roughly 100 times greater than for be whereas for a pure opal end member the partition coefficient for th 3 9 105 g g 1 is slightly less than that for pa and be partition coefficients decrease with increasing particle flux in open ocean settings but not in an ocean margin region this kinetic effect reflects the increasing contribution of unaltered surface material reaching the sediment traps as particle flux increases the degree of fractionation between pa and th and between be and th depends on the opal carbonate rain ratio these results challenge the use of sedimentary 231pa 230th and 10be 230th ratios as simple proxies of particle flux however the strong dependence of nuclide scavenging on the opal carbonate rain ratio may provide a needed tool for reconstructing past changes in planktonic community composition

continuous monitoring of distal gas emanations at vulcano southern italy the increasing activity of vulcano island italy since 1985 led to the initiation of continuous geochemical monitoring of the lateral soil gas emissions on the basis both of their relative geochemical characteristics and of local considerations three gaseous components were selected for monitoring namely co2 he and 222rn monitoring has been performed by means of specific analysers gases extracted from a water well located at the foot of the active cone were selected for monitoring on the basis of their geochemical and isotopic characters that indicate their genetic link with central high temperature fumarolic gases emitted at the crater very strong variations of gas composition can be observed within one day from 1 to about 94 for co2 some variations display a daily character and can be correlated with that of atmospheric pressure the three monitored gases are highly correlated suggesting very high kinetics of gas transfer in the system because of these considerable variations of chemical composition bulk concentrations obviously are not suitable for monitoring at vulcano however the evolution with time of ratios such as 222rn co2 and he co2 the latter being corrected for atmospheric contamination supplies numerical parameters that the expected to characterize the intensity of the degassing process a new input of magmatic gases that would lead to an increase in the 222rn co2 and he co2 ratios should therefore be detected by such a monitoring station

trapping efficiencies of sediment traps from the deep eastern north atlantic the 230th calibration bottom tethered sediment traps deployed in the deep eastern north atlantic between 54 n 20 w and 33 n 20 w l1 l2 l3 at the european continental margin at 49 n omex and off the canary islands estoc were investigated for the determination of 230th trapping efficiencies the ratios of 230th flux measured in the traps fa to the expected 230th flux from the production rate of 230th in the overlying water column fp ranged between 0 09 and 1 26 for the traps with deployment periods 300 days the interannual variation of fa fp ratios different years but same location and water depth were up to 10 suggesting that the average 230th flux to the sediment traps did not vary significantly the influence of lateral advection on the 230th flux was taken into account either by applying a mass balance of 230th and 231pa or by assuming a constant removal rate of 230th from the water column an assumption based on similar 230th concentration depth profiles observed at most locations investigated 230th trapping efficiencies were between 9 and 143 showing a trend of increasing efficiencies with increasing water depth no relation was found between current velocities and 230th trapping efficiencies our investigations suggest that the observation of constant or even increasing particle flux rates with increasing water depths in several sediment trap arrays investigated may be a result of sediment trap biases the correction for the trapping biases is important for the understanding of the regional differences in the particle flux in the eastern north atlantic

monitoring of helium and carbon isotopes in the western eger rift area czech republic relationships with the 2014 seismic activity and indications for recent 2000 2016 magmatic unrest abstract we report new data of the regional distribution pattern of total gas compositions as well as he and co2 isotopic compositions from 25 gas exhalations in the western eger rift and its surroundings additionally the first time series data from gas exhalations in a clay pit within the cheb basin cb are given at 21 degassing locations the first data were obtained 20 years ago from 7 locations within the degassing center cb and from 3 degassing sites belonging to the marianske lazn ml degassing center neon and argon isotope compositions were determined also co2 is the major component at all degassing sites the 13c values display a small range 1 7 to 5 1 and the 3he 4he ratios vary from 1 9 to 5 9 ra the highest 3he 4he ratios are found at locations along the pocatky plesna fault zone followed by the degassing site in the clay pit on the nova ves fault and the locations on the ml fault at the edge of the cb although gas flow and co2 concentrations in all degassing centers are very high the fractions of mantle derived helium are different with presently up to 94 in relation to the sclm 3he 4he of 6 32 ra in the cb up to 73 in the ml and up to 35 in the karlovy vary degassing center at the locations in the eastern part of the cb a clear progressive increase of the 3he 4he ratio has been observed since the first sampling campaigns there in 1993 and 1994 whereas at the other degassing sites the helium isotope ratio remained essentially the same the progressive increase of the 3he 4he ratio in the eastern part of the cb together with further short time increases up to 6 3 ra at one location bublak before both the 2000 and 2008 earthquake swarms indicate an ongoing magmatic process beneath this area which seems to be associated with the occurrence of seismicity the cb is located close to the nov kostel focal zone where since the beginning of our investigations four strong periods of seismicity with magnitudes 3 occurred the latest gas data confirm our earlier findings time series studies showed that in relation with seismic events decreased 3he 4he ratios were repeatedly observed due to admixed seismically released crustal helium presently the eastern part of the cb is the most active non volcanic region in the european cenozoic rift system with gas signatures similar to those found in free mantle derived gases from the east african rift system

scavenging of 231pa and thorium isotopes based on dissolved and size fractionated particulate distributions at drake passage antxxiv 3 abstract drake passage is a major route for many water masses in the strong antarctic circumpolar current during the antxxiv 3 expedition in 2008 the vertical distributions of dissolved and size fractionated particulate 231pa and thorium isotopes 230th 232th and 234th were investigated in order to better define the scavenging regimes and the effects of the oceanic circulation on the fate of particulate material and on the pa th distributions in the water column the reversible scavenging model applied to both 230th and 234th in the upper 1500 m depth gives estimates of the particle dynamics settling velocities s 500 1300 m year 1 adsorption and desorption rate constants of 0 1 0 4 and 1 6 year 1 respectively the particulate 234th 230th activity ratio decreases with increase in depth which is in agreement with previous studies but no relationship with particle size is found 231pa and thorium isotope fractionation and particle water partition coefficients were investigated as a function of particle size vs depth and latitude and appeared to vary horizontally following a north south gradient both the radionuclides are mostly bound to the fine suspended particles at drake passage the 230thxs distribution is controlled by the southward upwelling of deep water clearly visible on the vertical section of total 230thxs defined as dissolved particulate concentrations and reversible scavenging processes linear increase of 230thxs with increasing depth with north of the southern acc front higher settling velocities and less adsorption desorption cycles than south of it distributions of dissolved and total 231paxs also reflect the influence of the north south upwelling but this effect is limited to the upper depth 1500 m of the water column below this depth 231paxs vertical profiles exhibit contrasting concentrations with some highly dissolved activities in the deep water of the stations in the northern part of acc and not to the south of acc these n s differences in dissolved 231paxs are attributed to different origins and the scavenging history of the deep pacific waters flow across drake passage in the north radionuclides rich deep water originates from the central pacific while the deep water in the south is thought to be derived from the southern pacific and the observed low radionuclides concentrations are attributed to high opal abundance in that region in the southern part of the drake passage highly dissolved and particulate activities of 230th and 232th confirmed the westward intrusion of 230th rich weddell sea deep water wsdw close to the antarctic peninsula

biogeography in 231pa 230th ratios and a balanced 231pa budget for the pacific ocean the ratio of unsupported protactinium 231 to thorium 230 in marine sediments pa th xs is potentially sensitive to several processes of oceanographic and climatological interest deep ocean circulation marine biological productivity as it relates to total particle flux and particle composition specifically biogenic opal and authigenic mn in order to attribute variations in pa th xs observed in sediment records to changes in specific processes through time a better understanding of the chemical cycling of these elements in the modern ocean is necessary to this end a survey was undertaken of pa th xs in surface sediments from the subarctic pacific so202 inopex expedition in combination with a pacific wide compilation of published data throughout the pacific pa th xs is robustly correlated with the opal content of sediments in the north and equatorial pacific simultaneous positive correlations with productivity indicators suggest that boundary scavenging and opal scavenging combine to enhance the removal of pa in the eastern equatorial pacific and subarctic pacific deep ocean water mass ageing 3 5 km 3 5 km associated with the pacific overturning appears to play a secondary role in determining the basin scale distribution of pa th xs a basin wide extrapolation of pa removal is performed which suggests that the pacific pa budget is nearly in balance we hypothesize that through time pa th xs distributions in the pacific could define the evolving boundaries of contrasting biogeographic provinces in the north pacific while the influence of hydrothermal scavenging of pa potentially confounds this approach in the south pacific

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

removal of230th and231pa from the open ocean concentrations of230th and231pa were measured in particulate matter collected by sediment traps deployed in the sargasso sea site s2 the north equatorial atlantic site e and the north equatorial pacific site p as well as in particles collected by in situ filtration at site e concentrations of dissolved th and pa were determined by extraction onto manganese dioxide adsorbers at site p and at a second site in the sargasso sea site d dissolved230th 231pa activity ratios were 3 6 at sites p and d in contrast for all sediment trap samples from greater than 2000 m unsupported230th 231pa ratios were 22 35 average 29 7 ratios were lower in particulate matter sampled at shallower depths particles filtered at 3600 m and 5000 m at site e had ratios of 50 and 40 results show that suspended particulate matter in the open ocean preferentially scavenges th relative to pa most of the230th produced by decay of234u in the open ocean is removed by adsorption to settling particulate matter in contrast less than 50 of the231pa produced by decay of235u is removed from the water column by this mechanism mixing processes transport the remainder to other sinks

seismically triggered anomalies in the isotope signatures of mantle derived gases detected at degassing sites along two neighboring faults in nw bohemia central europe the vogtland and nw bohemia region is known for its earthquake swarms the most intensive swarm since 1985 86 occurred in october 2008 to find further indications for the interaction of ascending mantle derived fluids and the occurrence of earthquake swarms detailed fortnightly studies of gas compositions co2 n2 ar he h2 and ch4 and isotope ratios 13c 15n and 3he 4he were carried out between october 2008 and april 2011 at four locations close to the nov kostel focal zone and at the wettinquelle spring bad brambach from the start of the 2008 earthquake swarm seismically induced isotope geochemical anomalies were recorded at locations along the pocatky plesna fault zone ppz and were for the first time also found at degassing locations on the marianske lazn fault zone mlf variations were observed in both the temporal and spatial distributions of the anomalies as well in anomaly strengths probably due to the positions of these fault zones relative to the focal zone and to differences in fluid migration pathways prior to both the 2000 and 2008 swarms 3he 4he ratios 6 ra were recorded at the bublak mofette these anomalous pre seismic 3he 4he ratios suggest that both the 2000 and 2008 swarms may have been associated with the supply of fresh magma from a less degassed reservoir in the lithospheric mantle the temporal 13cco2 pattern from detailed studies at bublak between 2005 and 2011 indicates progressive magma degassing as well as seismically induced variations in the 13c providing additional support to the interpretation derived from the 3he 4he ratios

oceanic 231pa 230th ratio influenced by particle composition and remineralization abstract we have investigated the role of particle compositions in affecting the distribution of 231pa and 230th in the ocean by separating sediments collected by sediment traps and cores into three size fractions and analyzed for their excess 231pa 231paex excess 230th 230thex and major chemical components the samples came from stations along 140 w in the equatorial pacific and from the blake outer ridge in the north atlantic results indicate that aluminosilicates clays are the major carrier of 231pa and 230th and the ratio 231paex 230thex in marine particulates decreases with increasing 232th concentration model simulation shows that sea floor sediments and trap collected particles have similar 231paex 230thex ratios in their biogenic components which are very close to the seawater ratio but are about one order higher than the ratios in coexisting clays preferential scavenging of 230th over 231pa by clays is primarily responsible for the 231pa 230th fractionation in the ocean the fractionation factor between 230th and 231pa fth pa varies from 10 for aluminosilicates to 1 for biogenic 232th free particles changes in fth pa as a function of particle composition exert primary controls on 231paex 230thex in marine particulates and bottom sediments and on the boundary scavenging of pa remineralization of biogenic particles in the water column may result in a decrease of 231paex 230thex our observations place an important constraint on the use of sediment 231paex 230thex as a paleoproductivity proxy namely in order to use down core variations of 231paex 230thex to assess past changes in surface productivity one must either verify or assume that the lithogenic particle flux and water column particle remineralization have remained essentially constant at the core site

anomalously high radon discharge from the atotsugawa fault prior to the western nagano prefecture earthquake m 6 8 of september 14 1984 abstract radon alpha tracks monitored at six sites increased gradually three months before detected by microscopic counting and increased remarkably 2 weeks before detected by both mechanical and microscopic counting the western nagano prefecture earthquake m 6 8 which occurred on september 14 1984 the monitoring sites were located about 65 km northwest of the epicenter on the shear zone of the atotsugawa fault the changes in radon emanation are considered to be related to the earthquake rather than to changes in meteorological conditions

what do benthic δ13c and δ18o data tell us about atlantic circulation during heinrich stadial 1 approximately synchronous with the onset of heinrich stadial 1 hs1 13c decreased throughout most of the upper 1000 2500 m atlantic and at some deeper north atlantic sites this early deglacial 13c decrease has been alternatively attributed to a reduced fraction of high 13c north atlantic deep water nadw or to a decrease in the nadw 13c source value here we present new benthic 18o and 13c records from three relatively shallow 1450 1650 m subpolar northeast atlantic cores with published data from other cores these data form a depth transect 1200 3900 m in the subpolar northeast atlantic we compare last glacial maximum lgm and hs1 data from this transect with data from a depth transect of cores from the brazil margin the largest lgm to hs1 decreases in both benthic 13c and 18o occurred in upper waters containing the highest nadw fraction during the lgm we show that the 13c decrease can be explained entirely by a lower nadw 13c source value entirely by a decrease in the proportion of nadw relative to southern ocean water or by a combination of these mechanisms however building on insights from model simulations we hypothesize that reduced ventilation due to a weakened but still active atlantic meridional overturning circulation also contributed to the low 13c values in the upper north atlantic we suggest that the benthic 18o gradients above 2300 m at both core transects indicate the depth to which heat and north atlantic deglacial freshwater had mixed into the subsurface ocean by early hs1

dynamic intermediate ocean circulation in the north atlantic during heinrich stadial 1 a radiocarbon and neodymium isotope perspective the last deglaciation was characterised by a series of millennial scale climate events that have been linked to deep ocean variability while often implied in interpretations few direct constraints exist on circulation changes at mid depths here we provide new constraints on the variability of deglacial mid depth circulation using combined radiocarbon and neodymium isotopes in 24 north atlantic deep sea corals their aragonite skeletons have been dated by uranium series providing absolute ages and the resolution to record centennial scale changes while transects spanning the lifetime of a single coral allow sub centennial tracer reconstruction our results reveal that rapid fluctuations of water mass sourcing and radiocarbon affected the mid depth water column 1 7 2 5 km on timescales of less than 100 years during the latter half of heinrich stadial 1 the neodymium isotopic variability 14 5 to 11 0 ranges from the composition of the modern northern sourced waters towards more radiogenic compositions that suggest the presence of a greater southern sourced component at some times however in detail simple two component mixing between well ventilated northern sourced and radiocarbon depleted southern sourced water masses cannot explain all our data instead corals from 15 0 ka and 15 8 ka may record variability between southern sourced intermediate waters and radiocarbon depleted northern sourced waters unless there was a major shift in the neodymium isotopic composition of the northern endmember in order to explain the rapid shift towards the most depleted radiocarbon values at 15 4 ka we suggest a different mixing scenario involving either radiocarbon depleted deep water from the greenland iceland norwegian seas or a southern sourced deep water mass since these mid depth changes preceded the bolling allerod warming and were apparently unaccompanied by changes in the deep atlantic they may indicate an important role for the intermediate ocean in the early deglacial climate evolution

origin of hydrogen and carbon dioxide in fault gases and its relation to fault activity gases occluded in fracture zones of active faults are characterized by a high concentration of h 2 and or co 2 a predominant gas species h 2 or co 2 is related to the lithofacies which the fault cuts carbon dioxide concentration in sediments fluctuates with temperature this evidence and sigma 13 c of co 2 about 20 suggests that co 2 originates from organic materials carbon dioxide with sigma 13 c of 5 to 17 in brecciated gneiss containing marble may have been produced by interaction between organically derived co 2 and the marble or alternatively may have been magmatically derived hydrogen usually occurs in sheared silicate rocks and its concentration fluctuates a great deal the concentration of h 2 from active faults associated with historical earthquakes usually amounts to as high as several percent in maximum whereas the concentration of h 2 from quaternary faults not associated with historical earthquakes is at most 1

u and th series isotopes in deep baffin bay sediments tracers of detrital sources and of contrasted glacial interglacial sedimentary processes abstract uranium u and thorium th series have been used to document the sedimentary sources processes and fluxes of the last 115 ka in central baffin bay a major gateway between the arctic ocean and the north atlantic ocean which has been fed throughout the last ice age by sediments and meltwaters from the northeastern laurentide ice sheet the innuitian ice sheet and the western greenland ice sheet measurements have been made with a 1 6 ka time resolution in sedimentary core hu2008 029 016pc 70 27 n 64 39 w 2063 m water depth the lack of correlation between u concentration 234 u 238 u activity ratio 234 u 238 u ar organic carbon and redox sensitive elements suggests minimum early diagenetic u uptake if any likely due to very low organic matter sedimentary fluxes in such a subarctic environment throughout the last glaciation u and th concentrations and their mass ratio as well as 234 u 238 u ar do not show either any unequivocal linkage with detrital dolomitic carbonate and or detrital silicate fluxes data rather suggest sedimentary supplies with singular u and th series signatures linked to specific glacial margin ice streaming events and highlighting the diversity of sedimentary sources surrounding this small oceanic basin large surplus of 230 th 230 th xs 0 well above the production from dissolved u decay in the overlying water column are observed throughout the last glacial interval in response to sediment focusing and high sedimentation rates in the deepest part of the bay during this interval high frequency fluctuations in 230 th xs 0 indicate either a similar variability in sedimentation rates not captured by the age model used and or grain size or mineralogical dependent 230 th xs scavenging rates in the much lower sedimentation rate holocene core top section the 230 th xs 0 inventory falls below production in the overlying water column despite evidence for some primary productivity revival as suggested by the higher organic carbon content 230 th xs losses through lateral advection via baffin bay water masses overflowing through davis strait might account for this pattern pointing to ocean circulation drastically differing from that of the glacial interval

gas geochemistry and seismotectonics a review abstract publications on soil and spring gases have been examined regarding their relationships with both tectonic and seismic activities the main sources behaviours and uses of species detected in soils and springs are displayed and their mode of sampling and analysing briefly described the main patterns of degassing in soils are described and we outline the wide range of geochemical signatures as the result of both permeability and mineralogical contrasts because thermomineral waters have been in contact with great volumes of crustal rocks at various depths spring gases might be more representative of the local environment than soil gases moreover gas signature comparisons show that spring gases are much more enriched with deep gases and slightly contaminated by atmospheric gases therefore they can be considered as better samples for identifying precursors of earthquakes environmental perturbations are examined and it is shown from divergent cases that pressure temperature soil moisture or earth tides may generate very high perturbations of the degassing process such effects demonstrate that no systematic correction law can be proposed and that removing external contributions from gas concentrations must be performed case by case this demonstrates therefore the need for the simultaneous measurement of external parameters during gas monitoring a qualitative examination of about 150 claimed precursors proposed in the literature has been reviewed as noted by previous authors anomalies appear at distances sometimes much greater than typical source dimensions and occur in the field of strain higher than 10 9 most of them being in the field of strain higher than 10 8 taking into account the very high heterogeneity of such a set of data we can suggest that amplitudes of gas anomalies are independent of both magnitudes and epicentral distances of related earthquakes suggesting local conditions to control amplitudes on the contrary precursory time and duration of anomalies seem to increase both with magnitudes and epicentral distances abundant evidence demonstrates the major role of crustal fluids in the earthquake cycle many works have outlined the fact that crustal instabilities can appear as the result of low stress strain perturbations during loading it has been suggested that motion of fluids may occur at various scales from microcrack fluid transfer up to changes of hydraulic levels of water tables the study of subsequent anomalies is expected to supply a tool for earthquake prediction following previous authors we outline the need for further methodological improvements including the setting up of multiparameter station networks and the simultaneous recording of the main external parameters atmospheric pressure water and air temperature soil moisture for signal processing

glacial interglacial circulation changes inferred from 231pa 230th sedimentary record in the north atlantic region 1 studies from the subtropical western and eastern atlantic ocean using the 231pa 230th ratio as a kinematic proxy for deep water circulation provided compelling evidence for a strong link between climate and the rate of meridional overturning circulation moc over the last deglaciation in this study we present a compilation of existing and new sedimentary 231pa 230th records from north atlantic cores between 1710 and 4550 m water depth comparing sedimentary 231pa 230th from different depths provides new insights into the evolution of the geometry and rate of deep water formation in the north atlantic during the last 20 000 years the 231pa 230th ratio measured in upper holocene sediments indicates slow water renewal above 2500 m and rapid flushing below consistent with our understanding of modern circulation in contrast during the last glacial maximum lgm glacial north atlantic intermediate water gnaiw drove a rapid overturning circulation to a depth of at least 3000 m depth below 4000 m water renewal was much slower than today at the onset of heinrich event 1 transport by the overturning circulation declined at all depths gnaiw shoaled above 3000 m and significantly weakened but did not totally shut down during the bolling allerod ba that followed water renewal rates further decreased above 2000 m but increased below our results suggest for the first time that ocean circulation during that period was quite distinct from the modern circulation mode with a comparatively higher renewal rate above 3000 m and a lower renewal rate below in a pattern similar to the lgm but less accentuated moc during the younger dryas appears very similar to ba down to 2000 m and slightly slower below

assessing the collection efficiency of ross sea sediment traps using 230th and 231pa abstract annual fluxes of particulate 230th and 231pa collected by sediment traps deployed at two locations in the ross sea are compared to expected fluxes derived by combining the seasonal depletion of 230th and 231pa in surface waters with the steady state production of each nuclide by radioactive decay of its respective dissolved uranium parent conservative minimum estimates of the expected 230th flux are greater than the flux collected by sediment traps deployed at 200 m by factors of 3 and 6 at the two sites the actual discrepancy may be much larger the discrepancies between expected and measured fluxes of 231pa are slightly smaller but comparable in magnitude to those for 230th the discrepancies between expected and measured fluxes for these natural radionuclides are similar in magnitude to those determined previously using the same sediment traps for particulate organic carbon which suggests that the sediment traps undercollected the actual flux of sinking particles

scavenging of thorium in the ocean the distributions of th isotopes in both suspended participate matter and sea water were measured in the western north pacific and japan sea suspended particulate matter was collected simultaneously on four 142 mm diameter nuclepore filters 1 0 m in pore size by using an in situ deep sea pumping system particle associations were found to be 6 40 for 228th 9 52 for 230th and 9 72 for 232th with mean values of 26 32 for all three isotopes in order to explain the observed th isotope distributions in the pacific a reversible exchange model was developed that includes two classes fine and large of particle population in the ocean the fine particles are defined as those collected by filtration and comprising most of the standing crop of particles in seawater with no significant settling flux the large particles on the other hand are defined as those collected via sediment traps and represent a negligible standing stock in the water but play a predominant role in the vertical flux the model calculation suggests that the transfer of th from solution to fine particles is controlled by an adsorption desorption process which depends upon the chemical reactivity of elements aggregation of fine particles to fast sinking large particles was estimated to occur throughout the water column on a time scale of one to five months the large aggregates seem to disintegrate on a time scale of less than a few days suggesting their extremely fragile nature

reply to the comment by j f kenney on mantle hydrocarbons abiotic or biotic this article discusses the comments of j f kenney regarding the paper presented by sugisaki and mimura on the possible abiogenic origin of hydrocarbons in mantle rocks they discuss the problems pointed out by kenney and emphasize the consistency between their results and the studies of several russian scientists

towards explaining the nd paradox using reversible scavenging in an ocean general circulation model abstract the isotopic composition of the rare earth element neodymium nd has the potential to serve as water mass tracer because it is naturally tagged by continental sources with distinct ages and lithologies however in order to understand the limitations of this approach we need to know more about the physical and biogeochemical processes controlling the distribution of nd in the modern ocean for example nd isotope ratios behave quasi conservatively while concentrations in the water column generally increase with depth showing a broadly nutrient like behaviour we define this decoupling of nd concentrations and isotopic compositions as the nd paradox for the first time we model nd concentrations and isotopic compositions simultaneously and address the hypothesis that the nd paradox can be explained by a combination of lateral advection and reversible scavenging we impose a reversible scavenging model of nd removal from the ocean on the ocean circulation fields from the mit general circulation model using the transport matrix method we conclude that reversible scavenging is an active and important component in the cycling of nd in the ocean in the absence of an adequate alternative explanation reversible scavenging should be considered a necessary component in explaining the nd paradox

behavior and origin of helium neon argon and nitrogen from active faults compositional variations of gas species occluded in fracture zones type i within active faults are essentially the same as those in bubble gases type ii separating from mineral springs along faults the variation in type ii is hydrogeochemically interpreted as a result of dissolving and degassing of atmospheric air in groundwater at various temperatures the comparison of these variations in both types of gases suggests that ne ar and n2 in the type i gases are of atmospheric origin and their fluctuation is strongly controlled by the circulation of groundwater which recharges and discharges atmospheric air at various temperatures further hydrogeochemical evaluation shows that a part of he observed in fault zones is of radiogenic origin but its proportion is very small in active faults in these zones juvenile he emission related to the tectonic stresses causing earthquake may be substantially modified by the compositional fluctuation of gases controlled by the water circulation within the fault system accordingly monitoring of rare gases except for h2 from historically active faults may be less effective for earthquake prediction in contrast gas bubbles of high he content issuing from mineral springs which usually occur along prehistorically active faults are less contaminated by air and may provide some general precursory information concerning regional stresses at depth prior to an earthquake

10be in a deep sea core implications regarding10be production changes over the past 420 ka abstract the influx of 10 be into a globigerinid ooze core ch72 02 from the eastern north atlantic has been studied this core contains a depositional record of the first 11 18 o stages covering the last 423 ka it is shown that the marine deposition of 10 be is strongly influenced by the sedimentation of clays clay particles appear 10 times more efficient than the carbonate component as a carrier in bringing 10 be to the bottom sediments in core ch72 02 the deposition rates of 10 be averaged over each oxygen isotope stage for the past 11 stages show a scatter of 40 about the mean value of 6 6 10 8 atoms cm 2 ka 1 however after correction for changes in lithology the data show that the production rate of 10 be over the same period has varied no more than 25 and the variations are not systematic in that high or low 10 be production appear to be associated with either cold or warm climates on the time scale of this investigation intervals of ca 50 ka over the last 420 ka with resolutions as fine as 10 ka for portions of the record it is unlikely that the shielding effect of the solar wind has deviated by more than 25 or the geomagnetic field intensity has deviated by more than a factor of 1 6 from their long term averages

distribution of dissolved and particulate230th and232th in seawater from the gulf of mexico and off cape hatteras as measured by sims we present vertical and horizontal profiles of dissolved and particulate230th and232th concentrations in seawater from shelf and slope areas of the gulf of mexico and off cape hatteras in the middle atlantic bight as measured by secondary ion mass spectrometry sims and compare the partitioning of long lived230th between particles and seawater with that of short lived234th concentrations of dissolved and particulate230th and232th in surface seawater decreased from near shore to off shore in the gulf of mexico demonstrating terrestrial input to the surface waters vertical profiles indicate that lateral transport as well as surface inputs e g fluvial and aeolian and bottom sediment resuspension could be an important source of230th and232th in ocean margin regions sea water samples collected off cape hatteras contained significantly higher dissolved and particulate230th and232th concentrations than those found in the open gulf of mexico likely the distributions of230th and232th in seawater off cape hatteras are to a large extent controlled by terrestrial particles in contrast in situ production for230th and scavenging are the major processes regulating the concentrations of dissolved230th and232th in the open gulf of mexico the observed negative correlation between log kd particle solution distribution coefficient and log cp concentration of suspended particulate matter for234th and230thxs in both study areas demonstrated a particle concentration effect down to very low cp concentrations 20 g l based on the230th inventory in situ production and the small estimated surface input the overall residence time of230th in the water column at a slope station in the gulf of mexico is calculated to be about 5 yr

a high resolution authigenic 10be 9be record of geomagnetic moment variations over the last 300 ka from sedimentary cores of the portuguese margin a high resolution study of authigenic be isotopes 10be and 9be combined with continuous relative paleointensity records has been performed along the same marine sedimentary sequences from the portuguese margin n e atlantic covering the past 300 ka in order to assess relationships between geomagnetic moment variations and 10be production rate variations a carefull examination of the various ways of taking into account environmental disturbing effects on the authigenic 10be concentration leads to the conclusion that the most reliable proxy of cosmonuclide production rates is presently the authigenic 10be 9be ratio eight intervals of significant authigenic 10be 9be enhancement evidence geomagnetic moment drops related to global paleomagnetic excursions some being already admitted others being proposed as new geomagnetic features since contrarily to sedimentary magnetic remanence the authigenic 10be 9be records dipole moment variations without significant acquisition delay it provides better constraints on their timing comparison of 10be 9be and benthic 18o records from the same cores suggests that dipole moment lows preferentially occured during or at the end of interglacial episodes with a quasi period of 100 ka

anomalous diffuse co2 emissions at the masaya volcano nicaragua related to seismic volcanic unrest anomalous changes in the diffuse emission of carbon dioxide within the masaya caldera have been observed before two seismic events that occurred at 10 and 30 km from the observation site their epicenters are located respectively south of managua in las colinas 4 3 magnitude and the xiloa caldera 3 6 magnitude in 2002 and 2003 recorded by the geochemical station located at el comalito masaya volcano nicaragua anomalous increases were observed which occurred around 50 and 8 days before the main seismic event that took place in las colinas and 4 days before the seismic swarm at the xiloa caldera with a maximum co2 efflux of 9 3 and 10 7 kg m 2 day 1 respectively the anomalous co2 efflux increases remained after filtering with multiple regression analysis was applied to the co2 efflux time series which indicated that atmospheric variables during the first 4 months explained 23 co2 variability whereas during the rest of the time series co2 efflux values are poorly controlled with only 6 the observed anomalies of the diffuse co2 emission rate might be related to pressure changes within the volcanic hydrothermal system and or to geostructural changes in the crust due to stress strain changes caused before and during the earthquakes formation and seem not to be related to the activity of the main crater of masaya volcano

transport of10be and9be in the ocean beryllium isotopes 10be and9be have been measured in suspended particles of 1 mm size collected by mid water sediment traps deployed in the eastern pacific at manop sites h 6 32 n 92 50 w water depth 3600 m and m 8 50 n 104 00 w 3100 m for comparison surface sediments from box cores taken from the two sites were also studied the concentrations of10be and9be in sediment trap particles are about an order of magnitude smaller than those in the bottom sediments which contain about 8 109 and 6 1016 atoms g 1 of10be and9be respectively the sediment trap samples collected from 50 m off the bottom showed significant 26 63 contributions from resuspended bottom sediments the10be 9be ratio in trap samples varies from 3 to 20 10 8 the variation may partly result from varied proportion of authigenic detrital material the fluxes of both isotopes exhibit a very strong seasonality the fluxes of10be into the traps at about 1500 m are estimated as 9 105 and 4 105 atoms cm 2 a 1 at sites h and m respectively these values are to be compared with the fluxes into the sediments of 4 5 105 atoms cm 2 a 1 at both locations good correlations exist between10be 9be and27al indicating that the primary carrier phase s for the beryllium isotopes in the water column may be aluminosilicates

transport of mantle volatiles through the crust traced by seismically released fluids a natural experiment in the earthquake swarm area vogtland nw bohemia central europe abstract vogtland which is located on the czech german border near the crossing of the eger rift and the marianske lazn fault zone is characterised by co 2 rich mineral springs fed by a magmatic source and swarm earthquake activity the free gas of the eisenquelle mineral spring was studied weekly from april 1994 to june 1996 a period which included a quake swarm on december 4 and 5 1994 comprising approximately 500 individual events m local 2 2 co seismic shifts in he content after about a month as well as in the 13 c of co 2 and 3 he 4 he after about 220 days were resolved from seasonal background variations the he concentration shift is assumed to originate near the discharge whereas the isotopic shifts are probably caused by the addition of crustal fluids released by crushing rocks within the hypocentre from the distance of 14 km between the hypocentre to the mineral spring the transport velocity of the released crustal fluids was determined to be at least 50 m day such a high speed indicates gaseous fluid transport along channel like conduits rather than being predominantly controlled by dissolution in water using a simple mass balance it is shown that the amount of crustal fluids potentially released by seismic activity strongly exceeds that required for the observed shifts in 3 he 4 he and 13 c this fact along with the coincidence of both shifts supports the hypothesis that magmatic fluids occurring in mineral waters of the eisenquelle environs flush the hypocentral crustal block by means of advectional transport

scavenging of 230th 231pa and 10be in the southern ocean sw pacific sector the importance of particle flux particle composition and advection abstract the scavenging of 230 th 231 pa and 10 be was studied in the pacific sector of the southern ocean along 170 w using measurements from surface sediments time series sediment traps and the water column all sediment traps collected an annual flux of 231 pa greater than the integrated rate of production by 235 u decay up to 5 5 times greater and a flux of 10 be greater than the global average deposition rate of 10 be up to 3 4 times greater fluxes of 230 th were on average close to the production rate in the overlying water column these large fluxes of 231 pa and 10 be and high unsupported 231 pa 231 th and 10 be 230 th ratios in the sediments are not associated with depletion of nuclides in the water column and therefore are not the result of the classical boundary scavenging mechanism we estimate that of the 231 pa and 230 th advected into the southern ocean as part of the large scale overturning circulation only those nuclides associated with the upper limb of this circulation i e those that pass through the surface as part of the wind driven ekman flow are scavenged efficiently the majority of the nuclides advected into the southern ocean and associated with the bottom water limb are not scavenged to the sediments of the southern ocean but are returned northward throughout the year the unsupported 231 pa 230 th and 10 be 230 th ratios of material reaching sediment traps at 1000 m at a given site increase with increasing particle flux this behavior is explained by a conceptual model in which th pa and be are scavenged reversibly by fine grained suspended particles at all depths while pa and be are in addition scavenged strongly by diatom rich aggregates in surface waters spatial variability in the annually averaged unsupported 231 pa 230 th and 10 be 230 th ratios of sinking particulate matter reflects primarily the variability in particle composition and in the ratio and quantity of nuclides upwelled to the mixed layer rather than variability in particle flux

a systematic compilation of earthquake precursors article a survey of published scientific literature was undertaken to identify and catalog observed earthquake pre cursors the earthquake precursors selected for analysis included electric and magnetic fields gas emissions groundwater level changes temperature changes surface deformations and seismicity for each of these precursors the published scientific literature was searched to document the statistics of each reported earth quake precursor spatial extent time duration amplitude signal noise ratio to analyze dependence of the observable for each precursor on earthquake magnitude and to explore proposed physical models to explain eachearthquakeprecursor somegeneralcharacteristics wereobservedfortheseprecursoryphenomena first the largest amplitude precursory anomalies tend to occur before the largest magnitude earthquakes also the number of precursory anomalies tends to increase the closer in time to the occurrence of the earthquake finally theprecursoryanomaliestendtooccurclosetotheeventualepicenterof theearthquake ingeneral the physical models indicate that all of the precursory phenomena are related to deformation that occurs near the fault prior to the main earthquake while the models provide plausible physical explanations for the pre cursors there are many free parameters in the models that are poorly resolved

removal of 230th and 231pa at ocean margins abstract uranium thorium and protactinium isotopes were measured in particulate matter collected by sediment traps deployed in the panama basin and by in situ filtration of large volumes of seawater in the panama and guatemala basins concentrations of dissolved th and pa isotopes were determined by extraction onto mno 2 adsorbers placed in line behind the filters in the in situ pumping systems concentrations of dissolved 230 th and 231 pa in the panama and guatemala basins are lower than in the open ocean whereas dissolved 230 th 231 pa ratios are equal to or slightly greater than ratios in the open ocean particulate 230 th 231 pa ratios in the sediment trap samples ranged from 4 to 8 in contrast to ratios of 30 or more at the open ocean sites previously studied particles collected by filtration in the panama basin and nearest to the continental margin in the guatemala basin contained 230 th 231 pa ratios similar to the ratios in the sediment trap samples the ratios increased with distance away from the continent suspended particles near the margin show no preference for adsorption of th or pa and therefore must be chemically different from particles in the open ocean which show a strong preference for adsorption of th ocean margins as typified by the panama and guatemala basins are preferential sinks for 231 pa relative to 230 th furthermore the margins are sinks for 230 th and to a greater extent 231 pa transported by horizontal mixing from the open ocean

new insights into cycling of 231pa and 230th in the atlantic ocean abstract we use the bern3d model of intermediate complexity to examine the marine cycle of isotopes 231pa and 230th and the relationship between the particle bound ratio pa p th p and changes in the formation of the north atlantic deep water nadw model parameters describing reversible scavenging of isotopes by organic particles opal calcite and resuspended sediments were systematically varied and alternative sink parametrisations explored it proves difficult to simultaneously achieve a good agreement with observations of dissolved and particle associated concentrations of 231pa and 230th pa d th d pa p th p as well as the particle bound ratio pa p th p within the classical concept of reversible scavenging alone agreement between simulated and observed pa d th d and estimates of mean ocean residence times is improved by taking into account simplified representations of additional sinks at the sea floor bottom scavenging and at continental boundaries boundary scavenging we also find improved agreement between model and data by increasing lateral advection in particular for pa d these results point to the importance of sink processes that act in addition to reversible scavenging to shape the steady state distribution of 231pa and to a lesser degree of 230th in transient experiments in which the strength of the atlantic meridional overturning circulation amoc is periodically turned on and off we find a strong statistical relationship between variations in amoc strength and pa p th p at great depths in the northwest atlantic region these conclusions are robust across the range of sink parametrisations that are consistent with estimates in the mean ocean residence time of 231pa and 230th our results indicate that the relationship between pa p th p and amoc strength may not be fundamentally affected by uncertainties in sink processes at least on the large spatial and temporal scale considered here and support the idea that changes in pa p th p in sediments of the northwest atlantic are indicative of changes in amoc strength taking into account our simplified approach our results indicate that the relationship between pa p th p and amoc strength in the deep northwest atlantic is not affected by boundary scavenging or bottom scavenging our results thus support the idea that changes in pa p th p in sediments of the northwest atlantic are indicative of changes in amoc strength

did north atlantic overturning halt 17 000 years ago models indicate that a complete shutdown of deep and intermediate water production is a possible consequence of extreme climate conditions in the northern north atlantic and the high ratio of 231pa to 230th on bermuda rise is evidence that this might have happened 17 ka during heinrich event 1 h1 however new radiocarbon data from bivalves that lived at 4 6 km on the bermuda rise during h1 lead to a different conclusion the bivalve data do indeed indicate ventilation of the deep western north atlantic was suppressed during h1 but not as much as it was during the last glacial maximum we propose that high diatom flux to the bermuda rise during h1 is at least in part responsible for increased 231pa 230th at that time although we cannot say for sure why opal production was so high in a gyre center location at that time increased leakage of silica rich waters from the southern ocean to the north atlantic is one possibility

radiocarbon dating and stable isotopes analyses of caiman latirostris daudin 1801 crocodylia alligatoridae from the late pleistocene of northeastern brazil with comments on spatial distribution of the species abstract caiman latirostris is a crocodilian reptile widely distributed in south america the fossil records for this species are limited in the continent and radiocarbon dating plus isotope analysis has not been performed to the existing records which prevent accurate paleoecological reconstructions thus the present study aimed to record the occurrence of a fossil of c latirostris in sergipe state northeastern brazil providing the first data of radiocarbon dating and stable isotopes 13 c and 18 o for this species as well as maps of the potential distribution for the present time and for the last glacial maximum 21 ka our results indicate that the analyzed specimen occurred in sergipe brazil between 11 068 11 211 cal bp 9680 30 bp and fed on mixed feeder animals 13 c 3 00 possibly insects shrimp snail fish and birds it appears that its body temperature was 26 c similar to the extant crocodilian species crocodylus niloticus indicating that the species lived in the nearby rivers or in tanks ancient lagoons a map displays the current distribution while the map for 21 ka indicates a restricted distribution for this species in south america perhaps caused by the dry and cold climate in the last glacial maximum which affected the distribution of water sources for this organism

the laschamp geomagnetic dipole low expressed as a cosmogenic 10 be atmospheric overproduction at 41 ka authigenic 10be 9be ratiomeasurementswere performed at high resolution along a portuguese margin deep sea core 37 48 n 10 09w spanning the 20 50 ka time interval in order to reconstruct variations in atmospheric cosmogenic 10be production rates and derive the related geomagnetic dipole moment modulation a complementary approach consisting in 230thxs normalized 10be deposition rate determination on selected samples confirmed the reliability of the authigenic 10be 9be record this study constitutes the first successful comparison of the two widely used normalization techniques of 10be concentrations for both methods the presented results herein evidence a factor of 2 cosmogenic nuclide overproduction linked to a minimum dipole moment associated with the laschamp excursion the latter is stratigraphically constrained beneath heinrich event 4 its age is estimated at 41 ka on the basis of direct correlation between the series of rapid paleoclimatic events recorded in the portuguese margin sediments and in the greenland ice sheet and is confirmed by calibrated radiocarbon dating carried out on the same sediments the remarkable agreement between the authigenic 10be 9be and the greenland ice cores 10be deposition rate records attests to their global significance this new authigenic 10be 9be record has been combined with that previously obtained at the same site to produce a stacked record that is calibrated using absolute values of virtual dipole moment determined on lava flows this provides a reconstruction of dipole geomagnetic moment variations over the 20 50 ka interval independent frompaleomagnetically constrainedmethods that documents the laschamp dipole low but fails to express any dipole low related to t e mono lake excursion this high resolution record responds to the necessity of supplementing the knowledge of the atmospheric 14c variations in the 30 45 ka interval during which the 14c calibration curve suffers from a lack of accurate data and during which a discrepancy of about 5500 yr between the 14c and u th ages is due to the laschamp geomagnetic dipole low such new high resolution datasets from records obtained from different latitudes will be required to make significant advances in understanding the causes of atmospheric 14c variations

glacial interglacial changes in sediment rain rate in the sw indian sector of subantarctic waters as recorded by 230th 231pa u and δ15n high resolution records of opal carbonate and terrigenous fluxes have been obtained from a high sedimentation rate core md84 527 43 50 s 51 19 e 3269 m by normalization to 230th this method estimates paleofluxes to the seafloor on a point by point basis and distinguishes changes in sediment accumulation due to variations in vertical rain rates from those due to changes in syndepositional sediment redistribution by bottom currents we also measured sediment 15n to evaluate the changes in nitrate utilization in the overlying surface waters associated with paleoflux variations our results show that opal accumulation rates on the seafloor during the holocene and stage 3 based on 14c dating were respectively tenfold and fivefold higher than the vertical rain rates at this particular location changes in opal accumulation on the seafloor appear to be mainly controlled by sediment redistribution by bottom currents rather than variations in opal fluxes from the overlying water column correction for syndepositional sediment redistribution and the improved time resolution that can be achieved by normalization to 230th disclose important variations in opal rain rates we found relatively high but variable opal paleoflux during stage 3 with two maxima centered at 36 and 30 kyr b p low opal paleoflux during stage 2 and deglaciation and a pronounced maximum during the early holocene we interpret this record as reflecting variations in opal production rates associated with climate induced latitudinal migration of the southern ocean frontal system sediments deposited during periods of high opal paleoflux also have high authigenic u concentrations suggesting more reducing conditions in the sediment and high pa 231 th 230 ratios suggesting increased scavenging from the water column sediment 15n is circa 1 5 per mil higher during isotopic stage 2 and deglaciation the low opal rain rates recorded during that period appear to have been associated with increased nitrate depletion this suggests that opal paleofluxes do not simply reflect latitudinal migration of the frontal system but also changes in the structure of the upper water column increased stratification during isotopic stage 2 and deglaciation could have been produced by a meltwater lid leading to lower nitrate supply rates to surface waters

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

gas anomalies at three mineral springs and a fumarole before an inland earthquake central japan conspicuous anomalies in gas compositions were observed at a fumarole and three mineral springs about 1 3 months prior to an inland earthquake of 6 8 magnitude in central japan on september 14 1984 the epicentral distances are 9 km for the fumarole and 50 71 and 95 km for the springs the anomalies in he ar n2 ar and ch4 ar ratios of bubble gases from the springs can be attributed to fluctuations in the emission rate of some deep seated gas due to change in pore pressure which is subjected to crustal stress resulting in the earthquake the anomaly at the fumarole showed an increase in discharge rate of deep volcanic gas under a compressional stress near the focal region since the behavior of subsurface fluids represented by he ar and other ratios is presumably controlled by the change of pore pressure temporal variations in the fluids can be used as a strain gauge for the crust on the other hand the precursory emissions of h2 which were observed after changes in he ar and other ratios had occurred may have resulted from a reaction between groundwater and the surface of newly formed cracks the timing and amplitude of the geochemical anomalies are compatible with the result predicted by a dilatancy model without fluid diffusion although h2 emission may be related to groundwater permeation into newly formed cracks monitoring of several gases with automatic gas chromatographs at several stations may be useful for unraveling earthquake mechanisms and for predicting earthquakes

relation between hydrogen emission and seismic activities measurements of chemical composition of bubbles from a mineral spring at yuya spa situated close to the median tectonic line the longest active fault in japan showed that the periods of increased h2 emission coincided with occurrences of the ohno earthquake swarm nearby four cases of the coincidence without exception were observed in the last three years the fluctuation of h2 concentration ranges between 0 5 and 200 ppm whereas other gases such as he ar n2 and ch4 do not fluctuate much the h2 concentration is correlated with the energy released by the seismic activity this field evidence together with the results of laboratory experiments conducted bysugisakiet al 1983 leads to the conclusion that h2 observed at the mineral spring was produced by the reaction between groundwater and rock fractured in the seismic activities the observation that h2 in the mineral spring tends to appear prior to an earthquake suggests that microcracks may occur in rocks prior to earthquakes the precursory emission of h2 may be useful for earthquake prediction

enhanced scavenging of 231pa relative to 230th in the south atlantic south of the polar front implications for the use of the 231pa 230th ratio as a paleoproductivity proxy abstract the fractionation of 230th and 231pa was investigated throughout the atlantic sector of the southern ocean published scavenging models generally assume that the 231pa 230t ratio of surface sediments is primarily determined by the mass flux of particles this relationship holds north of the polar front where low primary productivity coincides with ratios of unsupported 231pa 230th xs 231pa 230th in surface sediments below the production ratio of both radionuclides in the water column however we observed high xs231pa 230th ratios conventionally interpreted as a high productivity signal in surface sediments south of the polar front especially throughout the weddell sea in contradiction with the low particle flux of this region measurements of both dissolved and particulate fractions of 231pa and 230th in the water column revealed a strong n s decrease in the th pa fractionation factor from typical open ocean values around 10 north of the polar front to values between 1 and 2 south of 60 s this observation clearly indicates that the high xs231pa 230th ratios in surface sediments south of the antarctic circumpolar current are produced by a n s increase in the relative scavenging efficiency of 231pa relative to 230th most probably due to a change in the chemical composition of particulate matter and not by a high mass flux it is speculated that biogenic opal suggested not to significantly fractionate231pa and 230th may explain the enhanced scavenging of 231pa to the south this assumption is further supported by extremely high 231pa 230th ratios up to 0 34 in material collected with sediment traps south of the polar front where fluxes are primarily determined by biogenic opal based on these results we conclude that in regions where the sedimenting flux is dominated by biogenic opal the 231pa 230th ratio is not a reliable indicator for the mass flux of particles thus limiting its use as a paleoproductivity proxy in the southern ocean

the competition between coastal trace metal fluxes and oceanic mixing from the 10be 9be ratio implications for sedimentary records at an ocean margin site 37 s offshore chile we use the meteoric cosmogenic 10be 9be ratio to trace changes in terrestrial particulate composition due to exchange with seawater we analyzed the marine authigenic phase in surface sediments along a coast perpendicular transect and compared to samples from their riverine source we find evidence for growth of authigenic rims through coprecipitation not via reversible adsorption that incorporate an open ocean 10be 9be signature from a deep water source only 30 km from the coast overprinting terrestrial 10be 9be signatures together with increasing 10be 9be ratios particulate bound fe concentrations increase which we attribute to release of fe rich pore waters during boundary exchange in the sediment the implications for the use of 10be 9be in sedimentary records for paleodenudation flux reconstructions are the following in coast proximal sites the authigenic record will likely preserve local riverine ratios unaffected by exchange with seawater whereas sites beneath well mixed seawater will preserve global flux signatures

natural laboratory nw bohemia comprehensive fluid studies between 1992 and 2005 used to trace geodynamic processes comprehensive studies of co2 rich fluids close to the swarm earthquake region nov kostel at the czech german border have been started 15 years ago and have in particular included two extended chemical and isotope monitoring studies lasting for several years each the regional surface distribution patterns of the fluid signatures including the identification of the origin of fluid components are the focus of the detailed studies three degassing centers cheb basin marianske lazn and karlovy vary with high co2 flux and the same level of 13c values but different levels of 3he 4he ratios have been identified the studies have located the co2 source and have investigated seismically induced changes in fluid characteristics on the basis of unique weekly sampling campaigns at selected locations a seismically triggered release of crustal helium was confirmed by both monitoring campaigns finally indications for a presently active magmatic process beneath the cheb basin have been found in contrast to volcanically active regions magma accumulation in the study area takes place at the crust mantle boundary and is not yet accompanied by heat transfer to the surface likewise reactive magma derived components are absent in the degassing fluids the area of investigation has the potential to be a natural laboratory for fundamental studies of active geodynamic processes the results of our fluid monitoring including the stunning observation of mantle derived free fluids marked by 3he 4he ratios within the subcontinental mantle range are supported by geophysical findings from seismic studies and geologic indications

particle fluxes to the interior of the southern ocean in the western pacific sector along 170 w abstract an array of five bottom tethered moorings with 19 parflux time series sediment trap at three depths 1 and 2 km below the surface and 0 7 km above the sea floor was deployed in the western pacific sector of the southern ocean along 170 w the five stations were selected to sample settling particles in the main hydrological zones of the southern ocean the sampling period spanned 425 days november 28 1996 january 23 1998 and was divided into 13 or 21 synchronized time intervals a total of 174 sequential samples were recovered and analyzed to estimate fluxes of total mass tmf organic carbon carbonate biogenic silica and lithogenic particles the fluxes of biogenic material were higher than anticipated challenging the notion that the southern ocean is a low productivity region organic carbon fluxes at 1 km depth within the polar frontal zone and the antarctic zone were relatively uniform 1 7 2 3 g m 2 yr 1 and about twice the estimated ocean wide average ca 1 g m 2 yr 1 carbonate fluxes were also high and uniform between the subantarctic front and ca 64 s 11 13 g m 2 yr 1 a large fraction of the carbonate flux in the antarctic zone was due to the presence of pteropod shells coccoliths were found only to the north of the polar front and calcium carbonate became the dominant phase in the subantarctic zone in contrast carbonate particles were nearly absent near 64 s latitudinal variations in biogenic silica fluxes were substantial the large opal flux 57 g m 2 yr 1 measured in the antarctic zone suggests that opal productivity in this region has been previously underestimated and helps to explain the high sedimentary opal accumulation often found south of the polar front unlike biogenic material fluxes of lithogenic particles were among the lowest measured in the open ocean 0 12 0 05 g m 2 yr 1 reflecting a very low dust input

particulate fluxes of 230th 231pa and 10be in the northeastern pacific ocean abstract measurements of 230th 231pa and 10be in sediment trap samples and holocene sediments collected along a transect in the northeastern pacific indicate that the removal of these nuclides from the ocean is greatly influenced by boundary scavenging more than 35 of the 230th at least 70 of the 231pa and as much as 85 of the 10be fluxes collected by sediment traps at a nearshore site located 120 km off shore are supplied by lateral transport of the dissolved nuclides from the open ocean these findings are consistent with the hypothesis that boundary scavenging is proportional to the oceanic residence times of the nuclides 10 40 y for 230th 100 y for 231 pa and 1000 y for 10be results of this study indicate that particle flux is a principal factor influencing scavenging of 230th 231pa and 10be from the water column the marine geochemistry of 10be in ocean margins is fundamentally different from that in the open ocean scavenging of 10be occurs throughout the water column at the margin area in this study in contrast to the pattern of 10be being removed only in the surface waters and then remineralized at depth in the open ocean aluminosilicate may be a major phase removing 10be from the water column in the open ocean but not at ocean margins nuclide accumulation rates in the underlying holocene sediments are all higher than the corresponding fluxes collected by sediment traps several possibilities that could account for this observation include downslope sediment transport deployment of the traps during a period when the particle flux was not representative of long term average conditions and scavenging of the nuclides from near bottom waters the high accumulation rate of authigenic mn in some holocene sediments which can be attributed to redox cycling of mn may have caused near bottom scavenging of 230th and 231pa as well as certain other trace elements such as ba cu and zn

controls on seawater 231pa 230th and 232th concentrations along the flow paths of deep waters in the southwest atlantic measurements of dissolved th 230 pa 231 and th 232 were made for twelve full depth profiles along a southwest atlantic section during geotraces cruise ga02s sampling captures all the main atlantic deep water masses along their meridional flow paths and allows insight into the control on th and pa in a setting where waters are flowing in opposing directions with direct relevance to understanding the use of pa 231 th 230 as an ocean circulation proxy water column th 230 increases linearly with depth in line with expected reversible scavenging models pa 231 increases from the surface to similar to 1200 1500 m but is invariant or decreases with greater depth deviating from the behavior expected for reversible scavenging dissolved pa 231 th 230 ratios display a mid water column maximum at similar to 1000 2000 m which is broadly coincident with upper circumpolar deep water below 2000 m nuclide distributions and ratios exhibit no dependence on water mass nor any indication of progressive change within a water mass challenging the use of pa 231 th 230 as a past circulation tracer in the south atlantic calculation of horizontal transport of th 230 and pa 231 by ocean circulation indicates a net southward export out of the atlantic of 19 of the pa 231 and 3 of the th 230 produced in that ocean this removal is all from the north atlantic while in the south atlantic removal to sediment equals production simple one dimensional modeling can simulate th 230 profiles but not the mid water column maximum observed in pa 231 profiles suggesting an additional source of pa 231 perhaps lateral transport from the margin or removal at depth due to bottom scavenging near seafloor minima in concentrations indicates bottom scavenging of th 230 and 231 pa which is enhanced in the presence of nepheloid layers particularly for 231pa this additional scavenging fractionates th 230 and pa 231 and in the presence of nepheloid layers may lead to an increase in sedimentary pa 231 th 230 ratios th 232 concentrations were paired with th 230 derived residence times in the upper 250 m of the water column to test the application of th as a tracer of dust deposition maxima in th 232 indicate high dust input from the african and possibly south american continents

constraints on deep water age and particle flux in the equatorial and south atlantic ocean based on seawater 231pa and 230th data high precision measurements of 231 pa and 230 th in filtered seawater and suspended particulate matter samples are reported for the equatorial and south atlantic distributions of 231 pa and 230 th clearly indicate the influence of advection as evidenced by departures from scavenging models that predict a linear increase with depth for these tracers application of a scavenging mixing model implies a deep water transit time of 60 100 years from the northern source water regions the average particulate 231 pa 230 th activity ratio is 0 0498 0 0160 a factor of 2 lower than the 231 pa 230 th production ratio of 0 093 and in agreement with reported excess 231 pa 230 th ratios of 0 06 0 004 in holocene sediments north of 50 s in the atlantic these water column data further suggest that lateral eddy diffusive transport combined with enhanced scavenging in high particle flux marginal regions boundary scavenging is weakly expressed in the atlantic particle fractionation of these tracers is also indicated by the elevated fractionation factors of f th pa 4 32 24 04 ave 9 97 4 98 compared to values of 1 4 in the southern ocean

geochemical monitoring of geothermal waters 2002 2004 along the north anatolian fault zone turkey spatial and temporal variations and relationship to seismic activity a total of nine geothermal fields located along an 800 km long e w transect of the north anatolian fault zone nafz turkey were monitored for three years 2002 2004 inclusive 3 sampling periods per year to investigate any possible relationship between seismic activity and temporal variations in the chemistry and isotope characteristics of waters in the fields the geothermal fields monitored in the study were from west to east yalova efteni bolu mudurnu seben kursunlu cankiri hamamozu gozlek and resadiye the chemical major anion cation contents and isotopic 18o 16o d h 3h compositions of hot and cold waters of the geothermal sites were determined in order to both characterize the chemical nature of the individual fields and identify possible temporal variations associated with localized seismic activity the geothermal waters associated with the nafz are dominantly na hco3 whereas the cold waters are of the ca hco3 type the oxygen and hydrogen isotope compositions reveal that the hot waters are meteoric in origin as are their cold water counterparts however the lower 18o d and 3h contents of the hot waters point to the fact that they are older than the cold waters and that their host aquifers are recharged from higher altitudes with virtually no input from recent post bomb precipitation although no major earthquakes e g with m 5 were recorded along the nafz during the course of the monitoring period variations in the chemical and isotopic compositions of some waters were observed indeed the timing of the chemical isotopic changes seems to correlate with the occurrence of seismic activity of moderate magnitude 3 m 5 close to the sampling sites in this respect cl 3h and ca seem to be the most sensitive tracers of seismically induced crustal perturbations and the yalova and efteni fields appear to be the key localities where the effects of seismic activity on the geothermal fluids are most pronounced over the monitoring period the present study has produced a baseline database for future studies directed at characterizing the effects of moderate major earthquakes on the composition of geothermal waters along the nafz future work involving longer monitoring periods with more frequent sampling intervals should lead to a better understanding of the underlying mechanism s producing the observed chemical and isotopic variations

sediment focusing in the panama basin eastern equatorial pacific ocean abstract age model derived sediment mass accumulation rates mars are consistently higher than 230th normalized mars in the equatorial pacific ocean during the past 25 ka the offset being highest in the panama basin suggests a significant role for deep sea sediment redistribution i e sediment focusing in this region here we test the hypothesis that downslope transport of sediments from topographically high regions that surround the panama basin is the cause of higher than expected xs230th inventories over the past 25 ka in the deeper parts of the basin we find little difference in xs230th inventories between the highest and lowest reaches of the basin furthermore there is no correlation between xs230th derived sediment focusing factors and water depth which suggests that the topographic highs do not serve as a source of xs230th a spatial analysis suggests that there may be an enhanced scavenging effect on xs230th concentrations in sediment closest to the equator where productivity is the highest although further data is necessary to corroborate this at the equator xs230th derived focusing factors are high and range from about 1 to 5 during the holocene and about 1 to 11 during the last glacial in contrast non equatorial cores show a smaller range in variability from about 0 7 to 2 8 during the holocene and from 0 7 to 3 6 during the last glacial based on 232th flux measurements we hypothesize that the location at which eolian detrital fluxes surpass the riverine detrital fluxes is approximately 300 km from the margin while riverine fluxes from coastal margins were higher during the holocene eolian fluxes were higher during the last glacial

variability in mid depth ventilation of the western atlantic ocean during the last deglaciation negative stable carbon isotopic excursions have been observed throughout most of the mid depth 1000 3000 m atlantic ocean during heinrich stadial 1 hs1 and the younger dryas yd although there is an agreement that these mid depth excursions were in some way associated with a slowdown of the atlantic meridional overturning circulation amoc there is still no consensus on the precise mechanism s here we present benthic stable carbon and oxygen isotopic 13c and 18o records from five cores from the western equatorial atlantic wea together with published benthic isotopic records from nearby cores we produced a wea depth transect 800 2500 m we compare hs1 and yd data from this transect with data from previously published north and south atlantic cores and demonstrate that the largest negative 13c excursions occurred in the wea during these times moreover our benthic 18o records require the presence of two water masses flowing from the southern ocean bisected by a northern component water ncw given that 18o is a conservative water mass tracer we suggest that 13c was decoupled from water mass composition and does not correspond to simple alternations between northern and southern sourced waters instead 13c behaved non conservatively during hs1 and the yd consistently with our new 231pa 230th record from the wea transect that allowed the reconstruction of amoc strength we hypothesize that the negative 13c excursions reflect an increase in the residence time of ncw in response to a weakened amoc allowing for a marked accumulation of 13c depleted respired carbon at the mid depth wea

soil gas emanations as precursory indicators of volcanic eruptions field measurements conducted on several active volcanoes in italy the lesser antilles and indonesia demonstrate the common occurrence of diffuse soil gas emanations from the volcanic piles at distances from active craters or fumarolic zones these emanations consist essentially of carbon dioxide and rare gases and their genetic link with crater fumaroles and or magma degassing at depth can be verified both chemically and isotopically we emphasize here the potential use of these fluids for continuous volcano monitoring and eruption forecasting

gas geochemical changes at mineral springs associated with the 1995 southern hyogo earthquake m 7 2 japan abstract gas concentrations monitored at a mineral spring in central japan over the past 15 years showed similar changes before and after two large earthquakes september 1984 m 6 9 50 km distant and january 1995 m 7 2 220 km distant namely a concurrent and abrupt drop in all three gas ratios he ar n 2 ar and ch 4 ar several months before the events improved measurements of gas compositions since 1991 and the addition of gas discharge rate monitoring since 1993 disclosed the following features for anomalies in response to small earthquakes as well as the large 1995 event 1 the gas ratios increased for both large and small earthquakes but they did not return to the preseismic values for the large event as they did within a few hours for the small events 2 at the 1995 event the gas discharge rate decreased remarkably 3 h before the event and then increased to higher than preseismic level for several months in contrast coseismic rates at small events generally increased for less than 15 min 3 during a seismically quiet period from january 1993 to december 1994 the variation in the he ar ratio was well correlated with that of gas discharge rate such correlation disappeared in august and september 1994 when the three gas ratios dropped before the large event 4 gas compositions at an auxiliary monitoring site revealed a coseismic change similar to that described above for the 1995 event these lines of evidence show that subsurface fluids may habitually respond to changes in physical conditions relating to earthquake occurrences and thus suggest the usefulness of monitoring subsurface fluids for earthquake prediction

meridional circulation across the antarctic circumpolar current serves as a double 231pa and 230th trap abstract upwelling of circumpolar deep water in the weddell gyre and low scavenging rates south of the antarctic circumpolar current acc cause an accumulation of particle reactive nuclides in the weddell gyre a ventilation reversible scavenging model that successfully described the accumulation of 230th in this area was tested with other particle reactive nuclides and failed to adequately describe the depth distributions of 231pa and 210pb we present here a modified model that includes a nutrient like accumulation south of the antarctic polar front in an upper meridional circulation cell as well as transport to a deep circulation cell in the weddell gyre by scavenging and subsequent release at depth the model also explains depletion of 231pa and 230th in weddell sea bottom water wsbw by ventilation of newly formed deep water on a timescale of 10 years but this water mass is too dense to leave the weddell gyre in order to quantify the processes responsible for the 231pa and 230th composition of newly formed antarctic bottom water aabw we present a mass balance of 231pa and 230th in the atlantic sector of the southern ocean based on new data from the geotraces program the acc receives 6 0 1 5 10 6 dpm s 1 of 230th from the weddell sea similar in magnitude to the net input of 4 2 3 0 10 6 dpm s 1 from the north for 231pa the relative contribution from the weddell sea is much smaller only 0 3 0 1 10 6 compared to 2 7 1 4 10 6 dpm s 1 from the north weddell sea deep water wsdw leaving the weddell gyre northward to form aabw is exposed in the acc to resuspended opal rich sediments that act as efficient scavengers with a th pa fractionation factor f 1 hydrothermal inputs may provide additional removal with low f scavenging in the full meridional circulation across the opal rich acc thus acts as a double 231pa and 230th trap that preconditions newly formed aabw