the application of geochemical methods in earthquake prediction in china several geochemical anomalies were observed before the haichen longling tangshan and songpan earthquakes and their strong aftershocks they included changes in groundwater radon levels chemical composition of the groundwater concentration of ca mg cl so4 and hco3 ions conductivity and dissolved gases such as h2 co2 etc in addition anomalous changes in water color and quality were observed before these large earthquakes before some events gases escaped from the surface and there were reports of ground odors being smelled by local residents the large amount of radon data can be grouped into long term and short term anomalies the long term anomalies have a radon emission build up time of from a few months to more than a year the short term anomalies have durations from a few hours or less to a few months

invasion of anthropogenic co2 recorded in planktonic foraminifera from the northern gulf of aqaba the stable carbon isotopic composition of the planktonic foraminifera globigerinoides sacculifer and g ruber white and sedimentary organic matter from the northern gulf of aqaba have been investigated to estimate changes in 13cdic in surface waters during the last 1 000 years the high sedimentation rates at the core sites about 54 cm kyear provide high temporal resolution 10 years recent sediments at the top of the cores reflect conditions younger than 1950 the 13c records of the planktonic foraminifera from three multicores display similar trends showing a uniform and consistent pattern before the 1750s and a gradual decrease of approximately 0 63 over the last two centuries this decrease seems to track the decrease of 13cdic in surface waters which is mainly caused by the increase of anthropogenic input of 13c depleted co2 into the atmosphere similarly a trend towards lighter values of the carbon isotopic composition of sedimentary organic matter 13corg during the last 200 years supports the interpretation obtained from the planktonic foraminiferal 13c furthermore direct measurements of seawater show that 13c of the dissolved inorganic carbon dic in the northern gulf of aqaba has decreased by about 0 44 during the period 1979 2000 the average annual decrease is 0 021 which is similar to that observed globally the 13c values of planktonic foraminifera combined with organic matter 13c from marine sediments are good indicators for reconstructing past changes in atmospheric co2 concentrations from the northern gulf of aqaba

field examination of the oceanic carbonate ion effect on stable isotopes in planktonic foraminifera we determined the 18o and 13c of individual globigerinoides ruber and pulleniatina obliquiloculata from sediment traps located from 5 n to 12 s along 140 w in the pacific ocean to evaluate the effects of varying co3 on shell 18o and 13c variations in the offset between shell 13c and 13cdic 13cs dic are attributed to differences in co3 temperature and shell size between sample sites when 13cs dic of g ruber was corrected for variations in co3 using the experimental slope of bijma et al 1998 the residual 13cs dic was correlated with mixed layer temperature 0 10 0 04 c 1 the slope of this temperature effect is consistent with experimental results in p obliquiloculata 13cs dic and temperature were strongly anticorrelated 0 14 0 03 c 1 we are unable to separate the influences of co3 and temperature in this species without independent experimental data correcting for co3 variability on 18os of g ruber improves the accuracy of estimated sea surface temperatures

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

impulsive radon emanation on a creeping segment of the san andreas fault california radon emanation was continuously monitored for several months at two locations along a creeping segment of the san andreas fault in central california the recorded emanations showed several impulsive increases that lasted as much as five hours with amplitudes considerably larger than meteorologically induced diurnal variations some of the radon increases were accompanied or followed by earthquakes or fault creep events they were possibly the result of some sudden outbursts of relatively radon rich ground gas sometimes triggered by crustal deformation or vibration

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

monitoring of hydrogen along the san andreas and calaveras faults in central california in 1980 1984 hydrogen h2 has been monitored continuously at 1 5 m depth at nine sites along the san andreas and calaveras faults in central california since december 1980 site characteristic small noninstrumental diurnal variations were recorded during quiescent periods at most sites abrupt h2 changes were observed concurrently at two sites on the calaveras fault some of these were correlated with oscillatory fault slips large 1000 4000 ppm h2 increases were recorded at some sites on the san andreas fault between july 1982 and november 1983 which may be correlated with eleven m 5 earthquakes that occurred near coalinga during this period we attribute both the h2 increases and the triggering of the earthquakes to a large scale compressive stress field within the ductile mafic crust near the plate boundary the stress perhaps caused bulging of the base of the brittle upper crust and thus caused dilation of the san andreas fault zone allowing the escape of pent up h2 generated by hydration reaction of the mafic crust at the same time mobile serpentinites may have squeezed into the seismogenic fault beneath the coalinga area triggering the earthquakes

southern ocean contributions to glacial interglacial changes of atmospheric pco2 an assessment of carbon isotope records in diatoms eleven new antarctic records of diatom bound 13corg show significantly lighter values during the last glacial maximum than during the holocene with a general trend of increasing depletions southward of the modern antarctic polar front mapf in contrast glacial diatoms from cores farther north of the mapf show 13corg values which are 1 heavier than during the holocene likely causes for the low glacial 13corg in antarctic diatoms are higher co2 aq lower growth rates and changes in diatom abundance or size taken at face value the glacial depletions of 13corg suggest that antarctic surface waters south of the mapf might have been a source of atmospheric pco2 during the glacial period alternatively the glacial depletions might have been caused by either a relatively small decrease in growth rates or changes in the abundance of the two dominant diatom species or their average cell size interpretations of the subantarctic records are complicated by similar uncertainties

on the sources formation and circulation of red sea deep water red sea deep water is renewed from sources in the far north of the red sea upwelling of deep water throughout the basin maintains the sharp pycnocline with its base near the depth of the sill at bab el mandeb before now deep water renewal was thought to occur mainly by means of convective deep water formation in the north which renews the bottom water and gives rise to a southward flowing bottom current carbon 14 and 3he data from the geosecs indian ocean expedition lead to the identification of an additional volumetrically larger mode of northern deep water formation in which new deep water is injected immediately beneath the pycnocline this mode of deep water formation to be called the isopycnal mode also gives rise to a southward flowing current in this case at the top of the deep water mass geosecs data also demonstrate the existence at intermediate depths in the deep water of a return flow to the north the surface history in the nuclear era of the 14c in the deep water source region was reconstructed by direct radiocarbon measurements on annual growth bands of corals calculation then shows that new deep water forms in the convective mode at a rate of 0 05 0 01 sverdrup sv expressed as if the flow were continuous and is due principally to processes occurring in the mouth of the gulf of suez the injection beneath the pycnocline of new deep water formed in the isopycnal mode is 0 11 0 02 sv this new deep water appears to originate mainly in the extreme open northern red sea the gulf of aqaba makes a modest but significant contribution to both modes the total deep water renewal rate is about 0 16 sv yielding a bulk deep water residence time of about 36 years oxygen consumption in the deep water shows approximately exponential decrease of consumption rate with depth as expected on geological and geophysical grounds hydrographically significant fluxes of heat and salt from the sea floor into the red sea deep water are discernible in the hydrography helium 3 flux from the sea floor into the deep water is about 69 1 stp year

anomalous hydrogen emissions from the san andreas fault observed at the cienega winery central california we began continuous monitoring of h2 concentration in soil along the san andreas and calaveras faults in central california in december 1980 using small h2 o2 fuel cell sensors ten monitoring stations deployed to date have shown that anomalous h2 emissions take place occasionally in addition to diurnal changes among the ten sites the cienega winery site has produced data that are characterized by very small diurnal changes a stable baseline and remarkably distinct spike like h2 anomalies since its installation in july 1982 a major peak appeared on 1 10 november 1982 and another on 3 april 1983 and a medium peak on 1 november 1983 the occurrences of these peaks coincided with periods of very low seismicity within a radius of 50 km from the site in order to methodically assess how these peaks are related to earthquakes three h2 degassing models were examined a plausible correlational pattern was obtained by using a model that 1 adopts a hemicircular spreading pattern of h2 along an incipient fracture plane from the hypocenter of an earthquake 2 relies on the feo h2o reaction for h2 generation and 3 relates the accumulated amount of h2 to the mass of serpentinization of underlying ophiolitic rocks the mass was tentatively assumed to be proportional to the seismic energy of the earthquake

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

organic carbon isotopic composition of phytoplankton and sea surface pco2 reconstructions in the southern indian ocean during the last 50 000 yr simultaneous measurements of chlorophyll and carbon content carboxylase activities in phytoplankton isotopic composition of suspended particulate organic carbon poc and pco2 in surface sea water in the south indian ocean indicate that plankton populations have different carbon metabolisms on both sides of the subtropical convergence stc north of stc communities are dominated by mixo heterotrophic organisms while south of the stc physiological or biomass parameters are diagnostic of autotrophic phytoplankton only phytoplankton 13c values in the southern part showed a strong correlation with co2 aq in surface waters which permitted a relationship between these parameters using this empirical relationship we derive from sedimentary organic carbon soc 13c a reconstruction of the paleo pco2 in surface water of the southern indian ocean for the last 50 kyr during the glacial and deglacial periods the obtained paleo pco2 were higher than those recorded in the vostok ice core suggesting that the southern ocean was a potential source of co2 for the atmosphere these results are consistent with those of soc content and indicate that the biological pump was off during glacial times and unable to lower atmospheric co2 aq moreover these data confirm that stratification of the surface water in summer caused a reduction of gas exchange with the atmosphere during that period copyright

the influence of air sea exchange on the isotopic composition of oceanic carbon observations and modeling although the carbon isotropic composition of ocean waters after they leave the surface ocean is determined by biological cycling air sea exchange affects the carbon isotopic composition of surface waters in two ways the equilibrium fractionation between oceanic and atmospheric carbon increases with decreasing temperature in southern ocean surface waters this isotopic equilibrium enriches delta sup 13 c relative to the delta sup 13 c expected from uptake and release of carbon by biological processes alone similarly surface waters in the subtropical gyres are depleted in delta sup 13 c due to extensive air sea exchange at warm temperatures countering the tendency toward isotopic equilibration with the atmosphere a relatively slow process are the effects of the equilibration of co sub 2 itself a much faster process in regions where there is a net transfer of isotopically light co sub 2 from the ocean to the atmosphere e g the equator surface waters become enriched in sup 13 c whereas in regions where isotopically light co sub 2 is entering the ocean e g the north atlantic surface waters become depleted in sup 13 c a compilation of high quality oceanic delta sup 13 c measurements along with experiments performed using a zonally averaged three basin dynamic ocean model are used to explore these processes 40 refs 14more figs 1 tab less

the imprint of anthropogenic co2 in the arctic ocean evidence from planktic δ13c data from watercolumn and sediment surfaces 13c values of n pachyderma sin from the water column and from core top sediments are compared in order to determine the 13c decrease caused by the addition of anthropogenic co2 to the atmosphere this effect which is referred to as the surface ocean suess effect is estimated to be about 0 9 0 2 within the arctic ocean halocline waters and to about 0 6 0 1 in the atlantic derived waters of the southern nansen basin this means that the area where the arctic ocean halocline waters are formed the arctic shelf regions are relatively well ventilated with respect to co2 nevertheless 13c of dissolved inorganic carbon 13cdic in the arctic ocean halocline waters is far from isotopic equilibrium absolute values of 13c of n pachyderma sin covary with the surface ocean suess effect and we interprete changes in both parameters as a reflection of the degree of ventilation of the waters on the shelf sea measurements of 13c of n pachyderma sin in the arctic ocean from plankton tows reveal a vital effect of about 2 significantly different from other published values a first order estimate of the total anthropogenic carbon inventory shows that despite of its permanent sea ice cover the arctic ocean with 2 of the global ocean area is responsible for about 4 6 of the global ocean s co2 uptake

experimental studies of the mechanisms of seismo geochemical precursors the following aspects of modeling experiments on seismo geochemical precursors are described 1 gas emission during laboratory stress loading and rupture of rocks 2 field measurements with explosion sources 3 aquifer mixing tests in the field 4 experimental studies of physico chemical processes caused by stress events from these studies three conclusions have been drawn 1 long term seismo geochemical anomalies appear to be related to the stage of elastic deformation of rocks under stress loading prior to a seismic event short term anomalies appear to be related to the plastic deformation of rock and spike like anomalies appear to be related to shear displacement before an earthquake 2 anomalous changes in chemical composition of groundwater and the escape of gases from the ground appear to result from rock fracturing which opens up pathways for the upward migration of water from deep confined aquifers and for the upward migration of gases from the deeper crust 3 chemical reactions induced by increasing stress in the epicentral region may result in the anomalous changes in chemical composition of groundwater observed before some large earthquakes

preliminary results of seismogeochemical research in china several kinds of geochemical anomaly before strong earthquakes have been observed in china since 1966 they include changes in groundwater radon levels ion content of water ca 2 mg 2 cl so4 2 f dissolved gases h2 co2 and gases escaping from the aeration zone through abandoned dry wells ar n2 co2 the radon anomalies may be grouped as long term and short term anomalies most of the geochemical anomalies observed are characterized by a pattern of increase the largest amplitude recorded was 37 times the base level preliminary study indicates that the types of seismogeochemical anomaly observed prior to strong earthquakes depend on tectonic geologic lithologic and hydrogeological conditions at the monitoring station results obtained from modelling experiments on the mechanisms of some anomalies are given

anthropogenic co2 in southern ocean surface waters evidence from stable organic carbon isotopes we present an approach for tracing the fate of anthropogenic co2 compiling a large data set of stable organic carbon isotope ratios from surface sediments plankton and sinking matter in the atlantic ocean the 13c values of sinking matter are generally lower by 0 5 4 6 compared to the surface sediments this difference increases with increasing latitude which is explained by a stronger modern increase in surface water co2 aq in the southern ocean relative to the tropical subtropical ocean preindustrial dissolved co2 concentrations in atlantic surface waters estimated from the 13corg of surface sediments are compared to recently measured surface water co2 aq values taken from literature we obtain only a slight increase in co2 aq at lower latitudes but a significant change of about 7 2 m in high latitudinal surface waters which we attribute to anthropogenic perturbation our results suggest that co2 released by human activities has been stored in southern ocean surface waters

radon and hydrologic anomalies on the rough creek fault possible precursors to the m5 1 eastern kentucky earthquake 1980 soil radon emanation increased sharply on the rough creek fault near the illinois kentucky border in april 1980 3 1 2 months before a m5 1 earthquake in eastern kentucky july 27 1980 the spikelike anomaly was similar to a radon anomaly in the new madrid seismic zone in 1979 that preceded by 2 months a m3 9 tremor at the site of that anomaly weekly radon monitoring was initiated on the rough creek fault after abrupt cessation of spring flow on the fault occurred at a site that had experienced similar flow cessation 1 month prior to a m5 3 earthquake in southeastern illinois in 1968 although the recent kentucky epicenter was 380 km east of the site of the detected radon anomaly factors relating to regional structures recent seismicity additional radon data and the stress regime suggest that the hydrologic and radon anomalies may have been precursors to an eastward progression of strain that culminated in the eastern kentucky tremor

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

prediction of central california earthquakes from soil gas helium fluctuations the observations of short term decreases in helium soil gas concentrations along the san andreas fault in central california have been correlated with subsequent earthquake activity the area of study is elliptical in shape with radii approximately 160 80 km centered near san benito and with the major axis parallel to the fault for 83 percent of them 4 earthquakes in this area a helium decrease preceded seismic activity by 1 5 to 6 5 weeks there were several earthquakes without a decrease and several decreases without a corresponding earthquake owing to complex and unresolved interaction of many geophysical and geochemical parameters no suitable model is yet developed to explain the observations

when did the anthropocene begin a mid twentieth century boundary level is stratigraphically optimal abstract we evaluate the boundary of the anthropocene geological time interval as an epoch since it is useful to have a consistent temporal definition for this increasingly used unit whether the presently informal term is eventually formalized or not of the three main levels suggested an early anthropocene level some thousands of years ago the beginning of the industrial revolution at 1800 ce common era and the great acceleration of the mid twentieth century current evidence suggests that the last of these has the most pronounced and globally synchronous signal a boundary at this time need not have a global boundary stratotype section and point gssp or golden spike but can be defined by a global standard stratigraphic age gssa i e a point in time of the human calendar we propose an appropriate boundary level here to be the time of the world s first nuclear bomb explosion on july 16th 1945 at alamogordo new mexico additional bombs were detonated at the average rate of one every 9 6 days until 1988 with attendant worldwide fallout easily identifiable in the chemostratigraphic record hence anthropocene deposits would be those that may include the globally distributed primary artificial radionuclide signal while also being recognized using a wide range of other stratigraphic criteria this suggestion for the holocene anthropocene boundary may ultimately be superseded as the anthropocene is only in its early phases but it should remain practical and effective for use by at least the current generation of scientists

vertical water mass mixing and plankton blooms recorded in skeletal stable carbon isotopes of a red sea coral the environmental interpretation of the 13c 12c variations in the skeletons of massive corals is still a matter of debate a 19 year seasonal skeletal 13c 12c record of a shallow water porites coral from the northern red sea gulf of aqaba documents interannual events of extraordinarily large plankton blooms indicated by anomalous 3c depletions in the coral skeleton these blooms are caused by deep vertical water mass mixing convectively driven in colder winters which results in increased supplies of nutrients to the surface waters the deep vertical mixings can sometimes be driven by the cooling occurring throughout the middle east after large tropical volcanic eruptions we therefore have evidence in our coral skeletal 13c 12c record for an indirect volcanic signal of the eruptions of e1 chich6n 1982 and mount pinatubo 1991 deep mixing induced 13c 12c variations of the dissolved inorganic carbon in the surface waters can be neglected at this location we therefore suggest that the 3c skeletal depletions can be best explained by changes in the coral s autotrophy heterotrophy diet through increased heterotrophic feeding on zooplankton during the blooms increased feeding on 3c depleted zooplankton or increased heterotrophy at the expense of autotrophy can both 3 result in a c depleted coral skeleton however this suggestion requires more testing if our conclusions are substantiated seasonal skeletal 3c r2c records of corals which change from autotrophy under normal conditions to increased heterotrophy during bloom events may be used as indicators of ocean paleoproductivity at interannual resolution available from no other source

natural and anthropogenic changes in atmospheric co2 over the last 1000 years from air in antarctic ice and firn a record of atmospheric co2 mixing ratios from 1006 a d to 1978 a d has been produced by analysing the air enclosed in three ice cores from law dome antarctica the enclosed air has unparalleled age resolution and extends into recent decades because of the high rate of snow accumulation at the ice core sites the co2 data overlap with the record from direct atmospheric measurements for up to 20 years the effects of diffusion in the firn on the co2 mixing ratio and age of the ice core air were determined by analyzing air sampled from the surface down to the bubble close off depth the uncertainty of the ice core co2 mixing ratios is 1 2 ppm 1 preindustrial co2 mixing ratios were in the range 275 284 ppm with the lower levels during 1550 1800 a d probably as a result of colder global climate natural co2 variations of this magnitude make it inappropriate to refer to a single preindustrial co2 level major co2 growth occurred over the industrial period except during 1935 1945 a d when co2 mixing ratios stabilized or decreased slightly probably as a result of natural variations of the carbon cycle on a decadal timescale

anomalous radon emanation at local and regional distances preceding earthquakes in the new madrid seismic zone and adjacent areas of the central mid continent of north america 1981 84 anomalous soil radon activity including several spike like surges over periods of 5 2 and 2 1 2 months and a year long declining trend preceded the most significant earthquakes of the central mid continental region of north america during 1981 and early 1984 the 5 month period of erratic weekly radon activity february june 1981 was followed by a tremor of magnitudem 4 0 40 km from the monitoring site in the new madrid seismic zone an unusual earthquake swarm in central arkansas 160 km from the new madrid seismic zone and 230 km from the monitoring site in the seismic zone began in january 1982 shortly after a year long declining trend in anomalous radon emanation earthquakes of magnitudes 4 5 4 1 and 4 0 occurred at the swarm s outset in early 1982 fitting a pattern anticipated for the new madrid seismic zone on the basis of the radon activity two periods of coincident peak radon emanation have since been observed in the arkansas and new madrid seismic regions as have synchronous seismic pulses for the two separate areas

opening the carbon isotope vital effect black box 2 quantitative model for interpreting foraminiferal carbon isotope data interpretation of carbon isotope records from late quaternary planktonic foraminifers are confounded due to the presence of a significant physiological component in the carbon isotopic signal a quantitative carbon isotope qc model is presented which relates the carbon isotopic composition of a foraminiferal shell to the physiological processes of respiration and symbiont photosynthesis and to the 13c value of seawater co2 the qc model is calibrated with physiological and stable isotopic data from laboratory experiments with living planktonic foraminifers model simulations of chamber and shell 13c values with the symbiont bearing foraminifers orbulina universa and globigerinoides sacculifer suggest 1 variations in symbiont density and photosynthetic rate light level or habitat depth are the primary physiological parameters controlling intraspecific carbon isotopic variability in these species 2 respiration has little effect on the 13c of o universa and 3 each chamber in a multichambered foraminiferal test will have a distinct 13c value depending on its position in the test whorl size 13c value relationships reported for g sacculifer from fossil assemblages can be explained as a function of increasing symbiont density during ontogenetic development

is there a component of pleistocene co2 change associated with carbonate dissolution cycles the only processes which could have decreased atmospheric co2 during glacial climates without appreciably changing the carbon isotope distribution in the sea appear to be 1 dissolved calcium carbonate input to the ocean e g coral reef buildup and erosion 2 the ocean solubility pump due to changes in surface temperature or air sea exchange or 3 decreased biological production of calcium carbonate it is assumed here that one of these mechanisms caused part of the atmospheric co2 changes recorded in the 200 kyr long vostok ice core two residual co2 records are generated by scaling the 13c difference between planktonic and benthic foraminifera in marine sediment cores to 82 ppm co2 per 1 increase in 13c and subtracting from this the measured co2 concentration in the ice core both residual co2 records exhibit two broad maximums between about 20 50 ka and 140 200 ka indicating that during these times about 40 ppm of the co2 decrease from interglacial levels cannot be explained by the interaction of the ocean s biological and vertical mixing cycles the shape of the residual co2 curve is similar qualitatively to the variation of calcium carbonate in central equatorial pacific sediments during this time period which would imply that changes in dissolved carbonate input to the ocean contributed the added component of co2 change however recent models of atmospheric co2 change in response to changing alkaline input to the ocean exhibit about a 25 to 35 ppm decrease per 1013 mol yr 1 increase in dissolved caco3 input if compensation for the changing input is occurring mostly within an area of about 40 106 km below the lysocline in the indo pacific the change in carbonate accumulation rate corresponding to a 40 ppm co2 change would be a minimum of 3 mg cm 2 yr 1 this can be compared to glacial increases of 0 5 to 1 0 mg cm 2 yr 1 during the last 200 kyr in central equatorial pacific sediments thus the added glacial accumulation of carbonate does not seem to match quantitatively with the 40 ppm amplitude of the residual co2 signal leading one to suspect that solubility plays a greater role than expected on the basis of a 2 c cooler surface ocean

carbon isotopes in recent planktonic foraminifera a record of anthropogenic co2 invasion of the surface ocean abstract the release of isotopically light anthropogenic co 2 into the ocean atmosphere carbon reservoir has resulted in a decrease in the carbon isotopic composition of the surface ocean in this paper we examine differences between the carbon isotope composition of planktonic foraminifera from sediment traps with older late holocene material to estimate the change in 13 c 13 c in eastern atlantic surface waters as a result of the invasion of anthropogenic co 2 using stable oxygen isotopes we demonstrate that average trap values for a variety of species are more or less identical to core top values suggesting that foraminifera recovered in sediment traps are representitive of foraminifera deposited in the sediments however carbon isotopes recorded in planktonic foraminifera from recent trap material reveal a decrease in the 13 c composition of all species relative to the core top samples although the magnitude of the decrease varies significantly between species surface dwelling foraminifera g ruber g bulloides show 13 c values of 0 53 to 0 62 which is similar to other estimates from shallow water coral and sponge records for the decrease in the 13 c composition of dissolved organic carbon in surface waters which has taken place since the start of the anthropogenic emissions the magnitude of decrease in the 13 c of surface waters suggested by these records is also close to that predicted by global carbon cycle models deeper thermocline dwelling foraminifera such as g inflata however show 13 c values 0 2 which are substantially lower than their surface dwelling counterparts this reduction in 13 c with increasing depth habitat within the mixed layer may be related to limited vertical penetration of anthropogenic co 2 as a result of the strong upwelling which is observed in the eastern atlantic along the northwest african margin

late pleistocene variability of the carbon isotopic composition of organic matter in the eastern mediterranean monitor of changes in carbon sources and atmospheric co2 concentrations the organic carbon isotopic record of the sapropels s1 and s3 s10 and intercalated marl oozes has been determined in a 12 m piston core from the eastern mediterranean the 13corganic values are systematically lighter mean 21 0 0 82 in all sapropels and heavier mean 18 8 1 07 in the marl oozes these differences are not due to variable marine and terrestrial organic matter mixtures because all values are heavier than modern plankton in the mediterranean there is no relationship between the corganic n ratios and the isotopic values and published information on the abundance and distribution of organic biomarkers shows that terrestrial material constitutes a minor fraction of the total organic matter temperature effects on isotope fractionation are also discounted because the change in 13corganic values between glacial and interglacial horizons is in the opposite sense diagenesis which can produce relatively small changes in the carbon isotopic composition of sedimentary organic matter under certain circumstances is unlikely to have caused the observed differences because this mechanism would cause an enrichment in 12c implying that all values were even heavier originally and there is no secular trend in the 13corganic record the observed differences in 13corganic between the two lithologies are probably produced by changes in the isotopic composition and the concentration of dissolved co2 first freshwater flooding during the formation of the sapropels caused the isotopic composition of the dissolved inorganic carbon in the surface waters of the mediterranean to become lighter because of the 13c deficiency in fresh waters hence photosynthesis would have produced isotopically lighter organic material second changes in atmospheric pco2 between glacial and interglacial periods as shown by the vostok ice core caused marked changes in the concentration of free dissolved co2 in the mixed layer lower values during glacial maxima caused a smaller fractionation of the carbon isotopes by phytoplankton whereas levels were less limiting during the interglacials concentrations of dissolved co2 could also have been much higher during the deposition of the sapropels because of the supply of regenerated co2 to the mixed layer by upwelling and this could have further lightened the 13corganic values in the sapropels themselves carbon isotope records may provide an alternative method for estimating atmospheric pco2 levels over longer time periods than can be obtained from ice cores

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

declining trend in the 13c 12c ratio of atmospheric carbon dioxide from tree rings of south african widdringtonia cedarbergensis abstract stable carbon isotope chronologies using tree ring wood cellulose have proved useful for developing hypotheses on climate and environment change however within both the southern hemisphere and africa there has been very little tree ring based isotope research here we report the first high resolution annual 13 c 12 c chronology for both africa and the southern hemisphere the 77 yr stable carbon isotope chronology was developed from six widdringtonia cedarbergensis trees from a site in the cedarberg mountains western cape province south africa the results indicate that 13 c 12 c ratios are not different from 1900 to 1949 after 1949 however values become significantly more negative to 1977 the isotopic record from the pooled trees at the die bos site does not correlate with rainfall this correlation is not significant even when the widdringtonia stable carbon isotope record is de trended for the anthropogenic co 2 contribution the widdringtonia record does however correlate significantly with atmospheric 13 c 12 c co 2 values derived from ice core data tree ring 13 c 12 c chronologies from the northern hemisphere and recent southern hemisphere records

variations in mercury and radon emission at an aseismic site considerable variation occurs at one aseismic location in the emission rate of mercury and emanation rate of radon from the earth improvements are made in the use of seasonal parameters to explain variance in mercury emission the rate of emission of mercury and radon have contrasting seasonal fluctuations this may be the result of radon emanation being dominated by diffusion and possible convection processes whereas mercury emission is strongly influenced by sorption of mercury by soil particles an understanding of the non seismic induced variation in gas emission processes may allow reliable application of these techniques to earthquake prediction the data presented suggest radon offers more promise than mercury in this application

increased seasonality in middle east temperatures during the last interglacial period the last interglacial period about 125 000 years ago is thought to have been at least as warm as the present climate owing to changes in the earth s orbit around the sun it is thought that insolation in the northern hemisphere varied more strongly than today on seasonal timescales which would have led to corresponding changes in the seasonal temperature cycle here we present seasonally resolved proxy records using corals from the northernmost red sea which record climate during the last interglacial period the late holocene epoch and the present we find an increased seasonality in the temperature recorded in the last interglacial coral today climate in the northern red sea is sensitive to the north atlantic oscillation a climate oscillation that strongly influences winter temperatures and precipitation in the north atlantic region from our coral records and simulations with a coupled atmosphere ocean circulation model we conclude that a tendency towards the high index state of the north atlantic oscillation during the last interglacial period which is consistent with european proxy records contributed to the larger amplitude of the seasonal cycle in the middle east

vostok ice core provides 160 000 year record of atmospheric co2 direct evidence of past atmospheric co2 changes has been extended to the past 160 000 years from the vostok ice core these changes are most notably an inherent phenomenon of change between glacial and interglacial periods besides this major 100 000 year cycle the co2 record seems to exhibit a cyclic change with a period of some 21 000 years

carbon isotope records from extant caribbean and south pacific sponges evolution of δ13c in surface water dic stable isotope records of demosponges from the caribbean and coral sea are described for the purpose of studying the influence of fossil fuel co2 on the carbon isotopic composition of dissolved inorganic carbon dic in surface water the slow growing sponges precipitate calcium carbonate in isotopic equilibrium with ambient sea water and are used to detect changes in 13cdic from pre industrial times early 19th century to the present we observed similar shapes and ranges in 13c curves measured on caribbean specimens collected from water depths of 25 84 and 91 m as well as a specimen collected in shallow waters off new caledonia the records reveal a highly significant correlation with atmospheric 13cco2 13cdic values for caribbean and coral sea surface waters were calculated using the 13c sponge records while 13c of atmospheric co2 decreased by about 1 4 from the early 19th century to 1990 13cdic of caribbean and coral sea surface waters decreased by 0 9 0 2 and 0 7 0 3 respectively no isotopic equilibrium between surface water dic and atmospheric co2 was observed either during the pre industrial steady state or during the last 100 years the lower amount of depletion in the surface water 13cdic with respect to the atmospheric anthropogenic signal is explained by the dilution of the surface waters by biologically altered subsurface water dic the lower 13c decrease in the coral sea points to a stronger influence of the subsurface water source compared to the caribbean

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

do planktic foraminifera accurately record shifts in the carbon isotopic composition of seawater σco2 abstract both the carbon isotopic composition of seawater and physiological vital effects such as respiration and symbiont photosynthesis influence the 13 c value of foraminiferal calcite the symbiont bearing planktic foraminifera orbulina universa was grown in a series of laboratory experiments to determine whether vital effects differentially obscure the 13 c signal such that changes in the 13 c of seawater co 2 cannot be quantitatively evaluated foraminifera were cultured under three different irradiance levels to elicit a full range of symbiont photosynthetic effects and in seawater with 13 c values ranging between 1 77 ambient and 5 76 power regression analysis of isotope data from individual shells plotted against culture irradiance yields three curves which are nearly parallel but are offset by the difference between the carbon isotopic composition of the culture waters when irradiance groups are combined and o universa 13 c values are plotted against seawater 13 c three parallel linear regressions are obtained with slopes ranging between 0 93 and 0 96 because the slopes are near unity it is concluded that the 13 c of o universa accurately tracks changes in the carbon isotopic composition of seawater regardless of the magnitude of its physiological vital effect o universa oxygen isotope data show that individuals maintained in the low and medium irradiance groups secrete their shells in isotopic equilibrium according to established paleotemperature equations in contrast individuals grown under high irradiance levels maximum symbiont photosynthetic rates are on average 0 35 depleted in 18 o relative to equilibrium symbiont enhanced calcification rates in the high light group may be responsible for the observed 18 o difference

relationship of the 1979 southern california radon anomaly to a possible regional strain event during the second half of 1979 anomalously high emanation of radon was recorded at two stations of the automated radon thoron monitoring network operated by the w k kellogg radiation laboratory of the california institute of technology the two stations exhibiting major anomalies kresge and dalton canyon are located approximately 30 km apart on the frontal fault system of the transverse ranges of southern california at kresge the anomaly began on june 21 1979 and continued through december 1979 at dalton canyon the anomaly started about 3 weeks later and also continued through december 1979 at both sites the anomalous levels of radon decreased but did not return entirely to normal values shortly before october 15 1979 during the week of october 15 1979 a 6 6 m earthquake occurred about 290 km to the southeast of the two stations and later in that week earthquakes of magnitude 4 2 and 4 1 occurred at malibu and lytle creek the latter two events were within 60 km of the monitors a radon thoron monitor at lytle creek recorded no long term anomaly but did record a sharp spikelike decrease in the radon level on october 13 1979 coincident with our observations of anomalous radon levels other investigators have reported anomalies or suspected anomalies in several other geodetic geophysical and geochemical signals from the same general region the rapid temporal development of several of the anomalies together with the large area over which they were observed suggests that a large scale strain event took place which may have been responsible both for the widespread anomalies and for the seismicity that occurred in the region subsequent to the onset of the anomalies

anomalous chemical changes in well waters and possible relation to earthquakes water level temperature salinity electric conductivity and ph have been measured periodically for several years at three water wells located along a 17 km segment of the san andreas fault between san jaun bautista and cienega winery in central california water samples were collected at the same time for subsequent chemical analyses in the laboratory some sudden large changes in salinity and conductivity were recorded in early march 1980 at the two wells near san juan bautista these changes coincided approximately with the beginning of an episode of increased local seismicity including a magnitude 4 8 earthquake on april 13 analyses of water samples revealed corresponding changes in ion concentrations especially of na sup ca sup mg sup so sup sub 4 sup hco sup sub 3 f sup and cl sup the observed changes may be the result of mixing of waters from different aquifers through cracks developed in the water barriers by a possible crustal strain episode that may have occurred in the study area

the indian ocean 13c suess effect the 13c of dissolved inorganic carbon dic decrease the 13c suess effect in the indian ocean was calculated using a multiparameter linear regression comparison of the 1978 geochemical ocean sections study and 1995 world ocean circulation experiment 13c of dic hydrographic and nutrient data the surface ocean 13c decrease rate along 80 and 115 e ranged from approximately 0 1 decade 1 at 55 s to a maximum of approximately 0 18 decade 1 at 35 s and decreased northward to around 0 13 decade 1 at the equator using a global extrapolation based on ocean model results bacastow et al 1996 and previous 13c changes calculated from 1970 to 1993 station reoccupations in the pacific ocean and based on preformed 13c versus chlorofluorocarbon age trends in the indian pacific and atlantic oceans sonnerup et al 1999 an ocean wide average surface ocean 13c rate of change of 0 15 to 0 17 decade 1 was estimated the average depth integrated 13c change rate between 1978 and 1995 along 80 and 115 e was 6 9 0 5 m yr 1 from 58 s to 5 n

radon anomalies in soil gas and groundwater as earthquake precursor phenomena abstract earthquake related changes in soil gas and groundwater radon have been detected at a sensitive observation site in the kangra valley himachal pradesh india using both instantaneous and time integrated techniques the recording station at palampur in the kangra valley is located near the main boundary fault of the himalayas eleven earthquake related anomalies have been recorded since august 1989 in both the soil gas and in the groundwater simultaneously in order to differentiate the real signal from noise the effect of meteorological variables soil and air temperature rainfall pressure humidity and wind velocity on radon emanation was also studied most of the radon anomalies are found to be correlated with earthquakes rather than to changes in meteorological conditions

short life span of the ore forming system at the porgera gold deposit papua new guinea laser 40 ar 39 ar dates for roscoelite biotite and hornblende the porgera gold deposit papua new guinea is associated with sodic alkalic hypabyssal intrusions of alkali basaltic to mugearitic composition the intrusions were emplaced into cretaceous mudstones and siltstones in the latest miocene and both igneous and sedimentary rocks are mineralized three types of veins occur 1 magnetite sulfide au carbonate veins 2 base metal sulfide au carbonate veins and economically most important 3 quartz roscoelite au veins and breccias magmatic hornblende and biotite hydrothermal biotite from alteration selvages associated with the magnetite sulfide au veins and roscoelite were dated using the laser 40ar 39ar step heating technique magmatic biotite yielded a date of 5 99 0 11 ma 2 error mswd 3 7 and two samples of magmatic hornblende provided dates of 6 35 0 23 ma mswd 1 0 and 6 3 0 7 ma mswd 2 6 hydrothermal biotite provided a date of 5 98 0 13 ma mswd 2 7 and analyses of two roscoelite samples yielded dates of 5 92 0 09 ma mswd 2 0 and 5 92 0 17 ma mswd 2 0 the date of the magmatic biotite is interpreted to represent the age of the intrusions more accurately than the hornblende dates because small amounts of excess 40ar were present in the hornblende samples the date for hydrothermal biotite is interpreted to be the age of the alteration associated with the magnetite sulfide au veins the paragenetically earliest veins and thus reflects the age of the onset of the mineralizing activity at porgera based on the two dates for roscoelite the age of the main ore deposition event is interpreted to be 5 92 0 08 ma the apparent ages for the intrusive and the mineralizing events are thus identical within error and suggest that the magmatic and ore forming system at porgera was short lived