an effect of dissolved nutrient concentrations on alkenone based temperature estimates the ratio of 37 carbon diunsaturated to diunsaturated and triunsaturated alkenones uk 37 produced by some haptophytes is widely used as a proxy for past sea surface temperatures however our isothermal culturing experiments with emiliania huxleyi clone ccmp372 show uk 37 values to also vary with nutrient availability and cell division rate these results provide a reasonable explanation for large isothermal variation in uk 37 values of single coccolithophorid strains grown in culture they also suggest that alkenone based estimates of past sea surface temperatures may have been influenced by dissolved nutrient concentrations as well as by temperature

seasonal variability of the long chain alkenone flux and the effect on the u37k index in the norwegian sea a seasonally varying sedimentation pattern was observed for the alkenone flux measured with sediment traps in the northern north atlantic in the norwegian sea traps were set at 500 1000 and 3000 m the alkenone flux varied between 0 1 and 7 1 g m 2 d 1 and followed the seasonal pattern of the bulk parameters maximum fluxes occurred from mid october until mid november and were also high in may a surprising result was that considerably higher particle fluxes were observed at 3000 m for the alkenone flux the highest additional input of 250 was observed during the period when sediment resuspension was greatest in summer at the barents sea continental margin traps at 1840 and 1950 m the alkenone fluxes follow the sedimentation pattern of the bulk parameters with a less visible signal of distinct seasonality observed in the 1950 m trap the sedimentation of total alkenones varied between 0 8 and 144 g m 2 d 1 at 1840 m and between 0 5 and 31 0 g m 2 d 1 at 1950 m resuspension and lateral advection contributed significantly to measured fluxes in the two near bottom traps alkenone concentrations were determined in faecal pellets of appendicularia ostracods and euphausids from selected samples at the barents sea site the alkenone flux in pellets 4 to 24 of total was 5 to 6 times higher at 1950 m depth than at 1840 m and the major part 77 78 of the total flux of c37 3 reaching the near bottom trap at 1950 m was associated with faecal pellets of the meso zooplankton spatial and temporal variations of the u37k signals were observed indicating that the imprint in the alkenone signal depends on the origin and transport pathway of the organic material strong deviations occur in areas where nepheloid layers contribute particles of long residence times to the primary flux

depth ranges of alkenone production in the central pacific ocean we report analytical results of long chain c 37 c 39 alkenones in the surface sediments taken along a latitudinal transect at 175 e from 48 n to 15 s unsaturation degree of c 37 alkenones u k 37 indicated that alkenone temperature is the highest about 28 3 c in the tropical pacific and decreases toward 48 n about 10 1 c although the latitudinal trend of the alkenone temperature is generally similar to that of the observed sea surface temperature of the surface mixed layer the former exhibits markedly lower values than the latter does in the midlatitude 35 19 n on the basis of the comparisons between water column temperatures and alkenone temperatures in the surface sediments we estimated that in the midlatitudes alkenones are produced in the thermocline waters whereas in the high 48 40 n and low 10 n 2 s latitudes they are produced in the surface mixed layer this result is supported by the depth distribution of emiliania huxleyi and gephyrocapsa oceanica along a 155 w transect in the central pacific the latitudinal distribution of the alkenone production layers estimated from u k 37 is found to be consistent with that of the nitrate suggesting that the depth of alkenone production is mainly controlled by the nutrient supply from deeper waters alkenones in the sediments exhibited relatively large abundances in 43 27 n with a maximum at 30 n which may be explained by high productivity of haptophyte algae in kuroshio extension

oceanographic aspects of the emperor seamounts region effects of the emperor seamount chain on the thermohaline structure and baroclinic flow are investigated on the basis of historical hydrographi data the amplitudes of dynamic height perturbations are 3 to 5 times larger west than east of the chain the intensity of the thermal fronts is stronger west than east of the seamounts near the crest of the southern seamounts strong east west thermohaline fronts and a strong northward baroclinic flow are observed the kuroshio extension west of the seamount chain is a well defined meandering current the axis of which generally lies between 33 and 36 n the available data indicate that the kuroshio extension turns northward and then flows eastward through the gaps of the seamount chain east of the seamounts the kuroshio extension widens threefold and appears to be poorly defined

volcanic structures and oral traditions of volcanism of western samoa sw pacific and their implications for hazard education abstract the samoan islands have experienced 2 million years of volcanism culminating in historic eruptions at both the east and western ends of the chain including a major lava producing episode on the island of savai i from ad 1905 1911 upolu in western samoa has several areas mapped as early holocene in age 5 ka but here we present new evidence for fresh volcanic landforms and deposits supported by a radiocarbon date of 1915 65 yrs b p giving a maximum age to a phreatomagmatic tuff cone offshore of cape tapaga east upolu in addition we report on a parallel investigation of the oral traditions of communities surrounding fresh volcanic landforms that may reflect distant volcanic memories passed down over generations to accommodate samoan cultural structures oral traditional knowledge was sought through semi structured interviews with small groups 3 4 or individuals samoan facilitators focused on high ranking and traditionally respected particularly elderly individuals for explanations of the origins of local features including their genesis use and any related geo hazards areas targeted were those where young eruptions

correlation of nitrate profiles with groundwater and sediment characteristics in a shallow sandy aquifer abstract sediment profiles of a shallow sandy aquifer in an agricultural area of denmark can be characterized by a new term called total reduction capacity trc quantifying the total amount of reduced compounds in the aquifer material ferrous iron reduced sulfur compounds solid organic carbon a distinct increase of trc was observed at and below the oxidation reduction front in this study the front was a zone 30 cm wide oxygen nitrate and sulfate were present above the oxidation reduction front but disappeared at the front detailed porewater profiles indicate that denitrification also takes place above the front supposedly in anaerobic microenvironments not evident in the water samples from the small wells the trc profiles showed that some reduction capacity is still present above the oxidation reduction front and is apparently able to support denitrification

northward and southward migrations of frontal zones during the past 40 kyr in the kuroshio oyashio transition area 1 the variation of sea surface temperature sst in the kuroshio oyashio transition area and the okhotsk sea during the last 40 kyr was estimated using long chain unsaturated alkyl ketones alkenones the temperature difference between the present and the last glacial period was about 5 6 c in the kuroshio oyashio transition area slightly larger than the 4 c previously reported moreover alkenones were not detected before 18 kyr b p in or near the okhotsk sea perhaps because of nearly year round sea ice expansion which would have prevented the growth of alkenone producers or because alkenones were less well preserved in surface sediments during the glacial period the northward and southward migrations of frontal zones were evaluated using differences in alkenone temperatures between stations located in the vicinity of the subarctic front saf subarctic boundary sab and kuroshio bifurcation front kbf all three frontal zones migrated southward during the glacial period compared with their present positions and their relative positions were different between the holocene and glacial periods in particular the distance between the saf and the sab was reduced during the glacial period compared with at present the northward and southward migration of the frontal zones may relate to both mid to low atmospheric circulation and polar atmospheric circulation

hydrogeochemistry and strontium isotopes in the arno river basin tuscany italy constraints on natural controls by statistical modeling summary in this paper the chemistry of major and trace elements and for the first time strontium isotopic ratios measured in running waters from the arno river basin tuscany central northern italy and thermal springs discharging in the same hydrographic system are presented and discussed classical graphical methods e g mixing diagrams have here been improved to identify in a correct statistical sample space extreme chemical compositions attributable to the action of geochemical processes and or inherited from specific lithologies namely contributions or components 1 2 and 3 to be used in inverse modeling procedures due to the absence of clear end members a linear least squares problem with non negativity constraints and distances as required for compositional data convex linear mixing was solved by considering the contribution of the most discriminant variables given by the 87 sr 86 sr isotopic ratios and the concentration of ca 2 mg 2 sr and rb following such approach it can be assumed p 2 mg 2 hco 3 radiogenic rich 87 sr 86 sr 0 71274 rb sr 0 039 represents a dominant feature at basin scale with a weight ranging from 69 to 100 much lower percentages are related to component 2 represented by a ca 2 mg 2 so 4 2 facies with intermediate 87 sr 86 sr 0 70874 and low rb sr 2 8 10 4 ratios and component 3 identified by ca 2 hco 3 facies with less radiogenic 87 sr 86 sr 0 70827 and low mg 2 ca 2 0 011 ratios these components are mainly dominated by the dissolution of evaporitic rocks and or mixing with thermal waters in the southern part of the arno river basin and by dissolution of the carbonatic fraction kinetically favored with respect to that of the silicatic minerals in the upper reaches of the main course and its tributaries respectively

an integrated approach to hydrogeologic investigations a case history this paper presents a case history in which several investigative techniques were applied to a particular hydrogeologic problem the study addressed the occurrence and migration of nitrate in a thin 3 7 m phreatic sand aquifer beneath agricultural land at an early stage in the investigation high nitrate concentrations were found at shallow depths in the aquifer while at greater depth in the aquifer the nitrate concentration was close to zero the interface between the shallow groundwater containing nitrate and the deeper nitratefree water was sharp throughout the study area two explanations for the nitrate distribution were considered 1 the shallow high nitrate water originated as infiltration through the soil of the study area and the deeper nitrate free water entered the study area from upgradient of the study area and 2 the vertical nitrate distribution was the result of denitrification in the aquifer through the application of physical hydrogeologic methods of investigation test drilling groundwater instrumentation hydraulic head monitoring and hydraulic conductivity measurements geochemical studies major ion analyses ph eh dissolved oxygen methane and alkalinity environmental isotope studies 18o deuterium and tritium numerical simulations of groundwater flow and solute transport and an analytical solution of solute transport it was shown that denitrification is the principal cause of the nitrate distribution and the first hypothesis was invalid the study showed that denitrification can be an important process in groundwaters on a regional scale without the application of an integrated investigative approach the importance of the denitrification process would probably not have been recognized and confirmed although not easily anticipated it is possible that over interpretation of results from any one of the study methods could have produced erroneous conclusions this paper demonstrates some of the limitations and advantages of the various methods used in the investigation

anisotropy repeating earthquakes and seismicity associated with the 2008 eruption of okmok volcano alaska 1 we use shear wave splitting sws analysis and double difference relocation to examine temporal variations in seismic properties prior to and accompanying magmatic activity associated with the 2008 eruption of okmok volcano alaska using bispectrum cross correlation a multiplet of 25 earthquakes is identified spanning five years leading up to the eruption each event having first motions compatible with a normal fault striking ne sw cross correlation differential times are used to relocate earthquakes occurring between january 2003 and february 2009 the bulk of the seismicity prior to the onset of the eruption on 12 july 2008 occurred southwest of the caldera beneath a geothermal field earthquakes associated with the onset of the eruption occurred beneath the northern portion of the caldera and started as deep as 13 km subsequent earthquakes occurred predominantly at 3 km depth coinciding with the depth at which the magma body has been modeled using geodetic data automated sws analysis of the okmok catalog reveals radial polarization outside the caldera and a northwest southeast polarization within we interpret these polarizations in terms of a magma reservoir near the center of the caldera which we model with a mogi point source sws analysis using the same input processing parameters for each event in the multiplet reveals no temporal changes in anisotropy over the duration of the multiplet suggesting either a short term or small increase in stress just before the eruption that was not detected by gps or eruption triggering by a mechanism other than a change of stress in the system

long chain alkenones and alkyl alkenoates in the coastal and pelagic sediments of the northwest north pacific with special reference to the reconstruction of emiliania huxleyi and gephyrocapsa oceanica ratios abstract long chain n c37 c39 alkenones and n c37 c38 alkyl alkenoates in marine sediments are derived mainly from two marine coccolithophorids emiliania huxleyi and gephyrocapsa oceanica laboratory cultured strains of e huxleyi strain eh2 and g oceanica strain go1 isolated from the great barrier reef and mutsu bay in northern japan 41 n 141 e respectively were cultured at 10 c 15 c 20 c 22 c 25 c 28 c and analyzed for c37 to c39 alkenones c36 methyl alkenoate fame and c36 ethyl alkenoate faee results obtained indicated significant differences in the alkenone and alkyl alkenoate profiles between these two algal species the ratios of faee to c37 alkenones ee k37 and c38 alkenones ee k38 in g oceanica were higher than those in e huxleyi and for both algal species these ratios showed strong negative nonlinear exponential correlations when plotted against the unsaturation index of c37 alkenones uk 37 using fitted equations for these relationships the relative abundance of e huxleyi and g oceanica in the sediment samples from the northwest north pacific and the coastal and inland waters of japan were estimated and compared with direct microscopic determinations e huxleyi comprised more than 80 of the sedimentary coccolith assemblage in the open ocean whereas g oceanica was exclusively dominant in the inland waters these results almost agreed with microscopic counts of these coccoliths occurring in the sediment samples in the light of these findings we suggest that there is a possibility that the relative abundance of e huxleyi and g oceanica in sediments may be estimated using nonlinear exponential calibrations based on ee k37 to uk 37 and ee k38 to uk 37 regressions

recent volcanism in the puyehue cordon caulle region southern andes chile 40 5 s petrogenesis of evolved lavas

the link between volcanism and tectonics in the southern volcanic zone of the chilean andes a review abstract the nature of the interplay between tectonics and volcanism is a major question in continental margin tectonics the southern andes volcanic zone svz located at the obliquely convergent nazca south america plate margin between 33 s and 46 s offers a unique opportunity to address this question because of along strike changes in crustal thickness tectonic style and well constrained long term and short term kinematic history the complex interaction between tectonic and magmatic processes is evidenced by both the architecture and geochemical signature of volcanic systems main first order factors accounting for the along strike variations in the nature and composition of volcanism are crustal thickness and the existence of a major intra arc fault system the liquine ofqui fault zone lofz second order factors include the local nature of the volcanic arc basement two main categories of volcano tectonic associations have been identified according to the spatial distribution and internal organization of individual volcanoes and clusters of volcanoes with respect to both the overall strike of the volcanic arc and the first and second order active inactive basement faults kinematically coupled associations those that are directly related to the current dextral transpressional tectonic regime include ne trending volcanic alignments of stratovolcanoes and or monogenetic cones kinematically uncoupled associations in which coupling with the current regime is not required include stratovolcanoes built on top of ancient reverse and strike slip faults of the volcanic arc basement and monogenetic cones lying along master faults of the lofz whereas mostly primitive magmas are found in the first category more evolved terms can occur genetically associated with the second category we propose a simplified three dimensional model for the magma plumbing system along and across the svz that integrates kinematically coupled and kinematically uncoupled volcano tectonic associations within the framework of first and second order geological and structural constraints

volcanic hazard communication using maps an evaluation of their effectiveness hazard maps are considered essential tools in the communication of volcanic risk between scientists the local authorities and the public this study investigates the efficacy of such maps for the volcanic island of montserrat in the west indies using both quantitative and qualitative research techniques normal plan view maps which have been used on the island over the last 10 years of the crisis are evaluated against specially produced three dimensional 3d maps and perspective photographs thirty two demographically representative respondents of mixed backgrounds sex education and location were interviewed and asked to complete a range of tasks and identification on the maps and photographs the overall results show that ordinary people have problems interpreting their environment as a mapped representation we found respondents ability to locate and orientate themselves as well as convey information relating to volcanic hazards was improved when using aerial photographs rather than traditional plan view contour maps there was a slight improvement in the use of the 3d maps especially in terms of topographic recognition however the most striking increase in effectiveness was found with the perspective photographs which enabled people to identify features and their orientation much more readily for montserrat it appears that well labelled aerial and perspective photographs are the most effective geo spatial method of communicating volcanic risks

characteristics of alkenones synthesized by a bloom of emiliania huxleyi in the bering sea abstract we investigated the characteristics of the alkenones produced by a bloom of emiliania huxleyi in the eastern bering sea in 2000 alkenones were detected in surface waters between 57 n and 63 n where phosphate concentrations were low and the ammonium nitrate ratio was high the total alkenone content c37 2 c37 3 and c37 4 ranged from 22 0 to 349 g g 1 in suspended particles and from 0 109 to 1 42 g g 1 in surface sediments this suggests that a large proportion of the particulate alkenones synthesized in the surface water rapidly degraded within the water column and or at the water sediment interface of the bering shelf the change in the stable carbon isotopic composition 13c of c37 3 alkenone could not be explained only by variation in co2 aq in the surface water but also depended on the growth rate of e huxleyi the alkenone unsaturation index uk 37 was converted into an alkenone temperature with three equations prahl et al 1988 sikes et al 1997 muller et al 1998 sikes et al s 1997 equation gave the best correlation with the observed sea surface temperature sst in the eastern bering sea however some temperatures estimated by sikes et al s 1997 equation from the uk 37 varied from the observed sst possibly because of the rapidly changing rate of alkenone synthesis in the logarithmic growth stage or the low rate of alkenone synthesis when nutrients were limiting temperatures estimated from uk 37 in the surface sediments 6 8 8 2 c matched the observed sst in september 7 8 c but differed from the annual average sst of 4 to 5 c suggesting that most of the alkenone in the eastern bering sea was synthesized during limited periods for instance in september the relative amounts of c37 4 alkenone as proportions of the total alkenones referred to as c37 4 were high ranging from 18 3 to 41 4 low salinity water

the liquine ofqui fault zone a long lived intra arc fault system in southern chile abstract plate reconstructions for the cenozoic document relatively steady right oblique subduction of the farallon nazca plate beneath the chilean continental margin the kinematic signature recorded along the intra arc liquine ofqui fault zone lofz a major feature of the southern andes may help to understand the way in which the nazca south america slip vector has been partitioned into strain and displacement along and across the continental margin the lofz consists of two nne trending right stepping straight lineaments a strike slip duplex at the right step and curved features which splay off the straight lineaments toward the northwest the lofz runs mostly through heterogeneously deformed cenozoic plutonic rock of the north patagonian batholith and patchy metamorphic wall rock early cenozoic volcano sedimentary rocks and dyke swarms found in close spatial association with the strike slip duplex are believed to have developed in strike slip related basins quaternary volcanoes are aligned parallel to the lofz both ductile and brittle kinematic indicators within centimeter to meter wide high strain zones document late cenozoic dextral shear deformation contrasting left lateral deformation recorded on older and wider mylonitic zones suggests that the lofz may be a long lived shear zone that accommodated continental scale deformation arising from the farallon nazca south america plate convergence a block rotation pattern as indicated by paleomagnetic data is consistent with the geometry and cenozoic kinematics of the lofz

migration of contaminants in groundwater at a landfill a case study 6 hydrogeochemistry multilevel point samplers located on a longitudinal cross section through the plume of contaminated groundwater in the sand aquifer at the abandoned borden landfill were used to obtain a suite of small volume samples for analysis of major ions and of minor and trace level inorganic constituents calcium is the dominant cation and sulphate and bicarbonate are the dominant anions in the contaminant plume with maximum concentrations of 400 2000 and 1200 mg l 1 respectively beneath the landfill the most highly contaminated water in the aquifer has total dissolved solids of 4000 mg l 1 sulphate and iron are the only inorganic constituents that exceed the recommended limits for drinking water the plume contains above background concentrations of dissolved zinc and manganese no heavy metals or other hazardous inorganic trace elements occur at levels above the maximum limits for drinking water the plume contains levels of total dissolved organic carbon that are above background levels ranging from 30 mg l 1 beneath the landfill to 5 mg l 1 near the front of the plume the landfill which is almost entirely above the water table contains high partial pressures of carbon dioxide and methane the high carbon dioxide levels induce substantial dissolution of calcite which occurs in sand layers in the landfill and in the aquifer immediately below the landfill calcite dissolution is the origin of much of the dissolved inorganic carbon and some of the calcium in the plume most of the sulphate and much of the calcium in the plume appears to be derived from gypsum in construction debris in the landfill groundwater beneath the landfill is saturated with respect to gypsum and slightly supersaturated with respect to calcite some of the dissolved iron in the plume results from the release under reducing conditions of iron from ferric iron coatings on sand grains located in the aquifer beneath the landfill and in the layers in the refuse dissolved iron concentrations appear to be limited by the solubility of siderite dissolved sulphide is present at only very low concentrations and is probably controlled by ferrous sulphide solubility exchange of cations between the aquifer material and the leachate contaminated groundwater is an apparent cause of calcium release and subsequent precipitation of calcite in the plume as much of 80 of the k 20 of the mg2 and 15 of the na in the plume exists on the exchange sites the effects of dispersive and geochemical attenuation were evaluated from the ratios of chloride to other species along a central flow path from the landfill to the front of the plume platinum electrode measurements and electrochemical potentials calculated from equilibrium speciation of analysed constituents varied over a wide range of values and provided poor agreement among methods for the same sample only potentials derived from the iron redox couples and pt electrode measurements exhibited fair agreement for any one sample the rather narrow range of pt electrode potential values along the central flow line through the plume suggest that the electrochemical potentials are buffered apparently as a result of fe oh 3 s ag feco3 s equilibria

migration of contaminants in groundwater at a landfill a case study 4 a natural gradient dispersion test abstract a natural gradient tracer test using a chloride solution with an initial injection volume of 0 7 m 3 was performed in the sandy aquifer at the borden site the solution was injected into five well points set 1 m below the water table in an uncontaminated zone situated above the contaminant plume at a location 450 m downflow from the landfill under conditions of natural groundwater flow the tracer slug was monitored for a period of 4 months by withdrawing small volume samples from points in a three dimensional array of bundle type multilevel samplers measurements of hydraulic head were obtained from a network of miniature piezometers soon after injection the tracer slug gradually split into two halves one half moving horizontally at an average velocity of 2 9 10 6 ms 1 and the other horizontally at 8 2 10 7 ms 1 although the split has been attributed to local lateral heterogeneity the nature of the heterogeneity and its influence on the hydraulic head distribution were not clearly distinguishable in the field data obtained before during or after the test the chloride patterns for each of the two halves of the tracer slug evolved into gaussian forms although the patterns demonstrated some irregularity at early time the relatively smooth gaussian forms were unexpected because the aquifer has numerous small scale heterogeneities observed in vertical cores obtained from the tracer zone and because the glaciofluvial origin of the aquifer suggests that heterogeneities are not laterally continuous simulated chloride distributions from a three dimensional analytical solution to the advection dispersion equation were fitted to the field data to obtain best fit estimates of the values of longitudinal transverse horizontal and transverse vertical dispersivity at various travel distances for each of the two halves of the tracer zone this is the first known field test that has permitted the estimation of three principal dispersion coefficients in layered media the longitudinal dispersivity was found to increase from 0 01 m at a distance of 0 75 m from the source to 0 08 m at 11 0 m the transverse horizontal dispersivity increased also to a value of 0 03 m at 11 0 m transverse vertical dispersion was very weak and was accounted for by molecular diffusion the relative lack of vertical dispersion is consistent with the shape of the plume of leachate contamination from the landfill it was concluded that the observed increase in dispersivity along the path of migration is likely caused by heterogeneities information on the dispersion controlling heterogeneities is not yet available as practical field methodologies for their identification and description have not yet been developed until such information is incorporated into mass transport models a realistic solution of the dispersion problem in heterogeneous media will remain elusive

oceanographic considerations for the application of the alkenone based paleotemperature u37k index in the gulf of california abstract alkenone concentrations were determined in sediment trap samples and surficial sediments collected from guaymas basin gulf of california to investigate the factors that control the relationship between the u37k index and sst the results from the sediment trap study reveal a positive correlation r2 0 5 between alkenone fluxes and satellite avhrr sea surface temperature sst and a strong correlation r2 0 9 between u37k and sst over an annual temperature range of 20 c although sst and u37k are tightly coupled throughout two upwelling seasons the relationship deviates from the expression developed by prahl et al 1988 at temperatures higher than 26 c the possible reasons for this deviation are varied but include the observed changes in the coccolithophore species assemblage and the evolution of the thermocline during periods of high sst the seasonal pattern of alkenone fluxes higher fluxes during warm periods observed throughout the 1996 to 1997 study period causes a bias in the annually averaged u37k record resulting in temperature estimates that are 1 c higher than the annual avhrr sst average furthermore the u37k ratios obtained from core top sediments indicate an additional 2 c warm bias in the sedimentary record that may be related to the lateral inputs of alkenones from other regions of the gulf these results highlight the importance of oceanographic processes in determining the alkenone temperature signal that is preserved in sediments after accounting for such effects u37k ratios from a box core were used to reconstruct a sst record extending back to the 18th century for the guaymas basin these results indicate a steady 2 c warming of the surface waters of the gulf from early 1700s to the 1950s followed by a rapid apparent 1 c cooling between the 1950s and the 1980s

living near volcanoes scoping the gaps between the local community and volcanic experts in southern chile abstract human societies have always inhabited volcanic zones but only recently scientists and decision makers have turned the attention to volcanic risk prevention and reduction despite a growing consensus about the importance of engaging with nearby populations in practice there is little dialogue with them regarding volcanic threats and opportunities we study the experiences impacts and concerns of an indigenous community inhabiting in between two major volcanic systems carran los venados and puyehue cordon caulle regarding past and recent eruptions results show a longstanding cultural and economic interrelationship between people and volcanoes representing both benefits and barriers to development existing local traditional knowledge is necessary but not sufficient to meet people s needs for adequate understanding and forecasting despite community interest on volcanic science and risk reduction important communication and trust gaps with experts persist our findings suggest the importance for scientists to establish collaborative and participatory relationships with local communities and decision makers with the goal of not only reducing negative volcanic impacts and uncertainty but also taking advantage of the potential of volcanic environments to boost local sustainable livelihoods

apparent long term cooling of the sea surface in the northeast atlantic and mediterranean during the holocene reconstructions of upper ocean temperature t during the holocene 10 0 ka b p were established using the alkenone method from seven high accumulation sediment cores raised from the northeast atlantic and the mediterranean sea 361n 751n all these paleo t records document an apparent long term cooling during the last 10 kyr in records with indication of a constant trend the apparent cooling ranges from 0 27 to 0 151c kyr 1 records with indication of time variable trend show peak to peak amplitudes in apparent temperatures of 1 2 2 91c a principal component analysis shows that there is one factor which accounts for a very large fraction 67 of the total variance in the biomarker paleo t records and which dominates these records over other potential secondary influences two possible contributions are 1 a widespread surface cooling which may be associated with the transition fromthe hypsithermal interval b9 5 7 ka b p to the neoglaciation b5 7 0 ka b p and 2 a change in the seasonal timing and or duration of the growth period of alkenone producers prymnesiophyte algae the first contribution is consistent with many climate proxy records from the northeast atlantic area and with climate model simulations including milankovitch forcing the second contribution is consistent with the divergence between biomarker and summer faunal paleo t fromearly to late holocene observed in two cores further work is necessary and in particular the apparent discordance between biomarker and faunal t records for the relative stable holocene period must be understood to better constrain the climatic and ecological contributions to the apparent cooling observed in the former records r 2002 elsevier science ltd all rights reserved

eruptive history geochronology and magmatic evolution of the puyehue cordon caulle volcanic complex chile forty three 40 ar 39 ar age determinations of lava flows domes ignimbrites and dikes plus 14 c dates from seven distal tephra layers combined with stratigraphy geochemistry and sr and th isotope data establish an eruptive chronology for the puyehue cordon caulle volcanic complex at 40 5 s in the andean southern volcanic zone svz the complex preserves 131 km 3 of lava and tephra that erupted from numerous vents widely separated in time and space approximately 80 of the total volume consists of basaltic to andesitic lava that formed two broad shield volcanoes between 314 and 70 ka the modern puyehue stratovolcano was built on the southerly shield during the past 69 k y following a hiatus of 25 k y puyehue has erupted 15 km 3 of basaltic to rhyolitic magma that spans the entire compositional range found in the southern svz and evolved via at least six phases including 1 basaltic andesitic to dacitic lavas between 69 and 32 ka 2 a shift to bimodal magma compositions that is first expressed by a rhyodacite mingled with inclusions of mgo rich basaltic andesite at 34 ka 3 dacitic to rhyolitic flows and domes from 19 to 12 ka 4 basaltic to basaltic andesitic flows between 15 and 12 ka 5 subsequent rhyolitic dome growth in several effusive and explosive stages between 7 and 5 ka followed by 6 a powerful series of phreatomagmatic and sub plinian eruptions at ca 1 1 ka that obliterated the preceding rhyolite domes and formed the present 2 5 km diameter 280 m deep summit crater along the cordon caulle fissure zone 5 km 3 of rhyodacitic to rhyolitic lavas domes and cones have formed during the past 16 5 k y including explosive and effusive eruptions in 1921 1922 and 1960 eruptive rates were nonuniform over time with background growth at 0 04 km 3 k y or less punctuated by spurts at up to 0 90 km 3 k y the time averaged rate 0 42 km 3 k y is nearly double that at the tatara san pedro complex 500 km to the north during the past 300 k y these findings indicate that within a single arc the magmatic and eruptive fluxes at individual frontal volcanoes can be highly variable the last three stratocone building events on puyehue began during periods of deglaciation suggesting a relationship between unloading of ice and ease of magma ascent puyehue basalt exhibits subtle changes in 238 u 230 th 87 sr 86 sr and trace element composition over time that signal shifts in the composition and degree of melting of the mantle wedge or the extent to which basalt was modified by assimilation of heterogeneous crustal melts the complex has become exceptionally bimodal and more explosive over time with recent rhyolites evolving by extreme crystal fractionation of mafic magma and lesser volumes of andesite and dacite created via mixing of rhyolite and basalt despite the high flux of basalt during the past 300 k y no large silicic magma reservoir formed in the upper crust instead 238 u 230 th data favor rapid ascent of several small bodies of basaltic and silicic magma from the lower crust promoted perhaps by conduits that reflect strike slip faulting beneath the complex

physiological impacts on alkenone paleothermometry we conducted isothermal 15 c batch culture experiments with the coccolithophorid emiliania huxleyi strain nepcc 55a to evaluate the extent to which nutrient and light stress contribute to variability in the alkenone unsaturation index u37k alkenone content and composition were constant throughout exponential growth in both experiments when nutrients nitrate and orthophosphate were replete stationary phase nutrient starved cells continued to produce alkenones amassing concentrations alk 3 times higher than those dividing exponentially 1 5 2 pg cell 1 and the u37k of excess alkenone dropped by 0 11 units in contrast 5 days of continuous darkness resulted in a 75 decrease in cellular alk and a significant u37k increase 0 11 units given an established 0 034 unit c response for exponentially growing cells of this strain the observed range of u37k variability at 15 c corresponds to an uncertainty of 3 2 c in predicted growth temperature this level of variability matches that of the global u37k annual mean sea surface temperature calibration for surface marine sediments begging the question what is the physiological condition of alkenone producing cells exported to marine sediments comparison of our laboratory results for a strain of e huxleyi isolated from the subarctic pacific ocean with depth profiles for alkenones in surface waters from two contrasting sites in the northeast pacific ocean suggests that the answer to this question depends on the ocean regime considered a possibility with significant bearing on how stratigraphic u37k records in marine sediments are to be interpreted paleoceanographically

non explosive constructional evolution of the ice filled caldera at volcan sollipulli chile a radar and gravity survey of the ice filled caldera at volcan sollipulli chile indicates that the intra caldera ice has a thickness of up to 650 m in its central part and that the caldera harbours a minimum of 6 km3 of ice reconnaissance geological observations show that the volcano has erupted compositions ranging from olivine basalt to dacite and have identified five distinct volcanic units in the caldera walls pre or syn caldera collapse deposits the sharkfin pyroclastic unit comprise a sequence which evolved from subglacial to subaerial facies post caldera collapse products which crop out along 17 of the 20 km length of the caldera wall were erupted almost exclusively along the caldera margins in the presence of a large body of intra caldera ice the alpehue crater formed by an explosive eruption between 2960 and 2780 a bp in the southwest part of the caldera is shown to post date formation of the caldera sollipulli lacks voluminous silicic pyroclastic rocks associated with caldera formation and the collapse structure does not appear to be a consequence of a large magnitude explosive eruption instead lateral magma movement at depth resulting in emptying of the magma chamber may have generated the caldera the radar and gravity data show that the central part of the caldera floor is flat but within a few hundred metres of the caldera walls the floor has a stepped topography with relatively low density rock bodies beneath the ice in this region this coupled with the fact that most of the post caldera eruptions have taken place along the caldera walls implies that the caldera has been substantially modified by subglacial marginal eruptions sollipulli caldera has evolved from a collapse to a constructional feature with intra caldera ice playing a major role the post caldera eruptions have resulted in an increase in height of the walls and concomitant deepening of the caldera with time

hawaiian oral tradition describes 400 years of volcanic activity at kīlauea article i nfo culturally significant oral tradition involving pele the hawaiian volcano deity and her youngest sister hi iaka may involve the two largest volcanic events to have taken place in hawai i since human settlement the roughly 60 year long ail au eruption during the 15th century and the following development of k lauea s caldera in 1823 rev william ellis and three others became the first europeans to visit k lauea s summit and were told stories about k lauea s activity that are consistent with the pele hi iaka account and extend the oral tradition through the 18th century recent geologic studies confirm the essence of the oral traditions and illustrate the potential value of examining other hawaiian chants and stories for more information about past volcanic activity in hawai i published by elsevier b v

metal and nutrient behavior in the raritan estuary new jersey u s a the effect of multiple freshwater and industrial waste inputs abstract a geochemical analysis of the raritan estuary during high and low river flow is presented several statistical and graphical approaches in addition to a hydrodynamic model of the raritan estuary are used to demonstrate the effects of lateral inputs on trace element distribution in a complicated fluvial marine system results from factor and cluster analysis show that nutrient salinity distributions on both sampling dates are controlled primarily by freshwater saltwater mixing industrial and municipal waste sources within the estuary are important in controlling dissolved organic carbon at low flow and dissolved and bottom sediment trace metals biological and physico chemical reactions have a significant but secondary effect on nutrient and trace metal distributions with salinity apparent flux calculations and property property plots show that for dissolved phosphate nitrate and inorganic carbon the raritan estuary can be divided into two mixing zones with the raritan river controlling nutrient concentrations in the lower salinity stretches and the south river controlling their distributions at intermediate and higher salinities high enrichment factors of most metals in estuary bottom sediment reveal that this is an important and semi permanent sink for trace metals in the raritan system previous work on suspended sediment in the estuary and river substantiates that this load is also an important sink for trace metals however many of these metals are in leachable modes which are more susceptible to release and incorporation into the food chain

volcanoes on borders a scientific and geo political challenge while the scientific community readily collaborates across international borders the boundaries of administrative units particularly the nation state can be critical in defining the availability of scientific resources the management of crises and the use of land managing border eruptions can be particularly challenging when international relations between the relevant nation states are strained or complex or when political agendas become involved given that over 700 volcanoes lie within 100 km of an international border and over 1300 are within 250 km the potential for cross border eruption impacts is significant this paper aims to provide an overview of the topic it presents results from a global study of volcanoes on or near borders and uses five case studies to highlight key issues that arise in the management of risk at such volcanoes while volcano monitoring provides critical support for hazard assessment and decision making its availability depends on the policies of particular governments and institutions furthermore the complexity and diversity of volcanic hazards activity and impacts can exacerbate existing cross border inequalities in vulnerabilities in scientific resources in disaster management and mitigation capacity and indeed public awareness we suggest that pre crisis planning and communication resource sharing and international agreements can help to mitigate the challenges of cross border eruptions

glacial interglacial deep water changes in the nw pacific inferred from single foraminiferal δ18o and δ13c abstract oxygen and carbon isotope values of single benthic foraminiferal tests in a core from the shatsky rise nw pacific ocean show greater intra horizon variance during the holocene than during the last glacial maximum lgm this greater variance is caused by the introduction of glacial specimens some 20 cm upward from their original deposition layer due to bioturbation in contrast foraminiferal populations belonging to glacial layers do not include holocene specimens the difference in direction of bioturbation greatly modifies climate information in horizons formed during and after deglacial events after omitting glacial specimens from holocene sediments the glacial interglacial difference in 18o suggests that pacific deep water temperature changed by 2 4 3 8 c at the most the 13c values suggest that nutrient concentration was higher during the lgm than the holocene the glacial deep north pacific ocean apparently was influenced by cold deep waters of southern origin

people s behaviour in the face of volcanic hazards perspectives from javanese communities indonesia abstract this paper is concerned with the way in which the indonesian people living on the slopes or near active volcanoes behave in the face of volcanic threats it explores the role of three factors in the shaping of this behaviour e g risk perception cultural beliefs and socio economic constraints the paper is mainly based on field data collected during the last 5 years on four volcanoes in central java namely sumbing sindoro dieng and merapi the common assumption that hazard knowledge risk perception and people s behaviour are closely related and conditional on volcanic activity is debatable in the indonesian context factors that play a role in hazard knowledge e g basic knowledge of volcanic processes personal experience of volcanic crisis time lapsed since the last volcanic eruption etc differ from those that influence risk perception indeed local people often underestimate the scientifically or statistically estimated risk this poor risk perception is characterized by an approximate personal representation of the volcanic processes an excess of trust in concrete countermeasures the presence of a physical visual obstructions or cultural beliefs related to former eruptions in addition the commonly acknowledged factors that influence hazard knowledge and or risk perception may be at odds with the non hazard related factors that prompt or force people to live in or to exploit areas at risk these factors may be either socio cultural e g attachment to place cultural beliefs etc or social and socio economical e g standard of living strength of people s livelihoods well being these factors are fundamental in explaining the short term behaviour in the face of a developing threat during a volcanic crisis

rapid reinflation following the 2011 2012 rhyodacite eruption at cordon caulle volcano southern andes imaged by insar evidence for magma reservoir refill cordon caulle is a large fissural volcano that has erupted rhyodacitic magma of the same composition in its past three historical eruptions in 1921 1960 and 2011 2012 there was significant ground deformation observed before and during the 2011 2012 eruption here we use c and x band insar time series results to document post eruptive uplift up to 0 8 m between march 2012 and may 2015 with los rates up to 45 cm yr that have been largely aseismic along with subsidence in the 2011 2012 lava flow the 2012 uplift rate is one of the largest for silicic systems and was likely produced by the intrusion of 0 125 km3 of magma in the same tectonically controlled plumbing system that has been active during the historical eruptions nevertheless the uplift ended before the reservoir refilled with the erupted volume maybe due to a change in the pressure gradient produced by the 2011 2012 eruption

2010 maule earthquake slip correlates with pre seismic locking of andean subduction zone analysis of seismic data and global positioning system gps observations from the region around the site of the recent magnitude 8 8 maule earthquake in chile have been combined with modelling of the andean subduction zone to build up a detailed image of the event the earthquake occurred at a seismic gap part of the fault that has not experienced a major earthquake since 1835 and it seems to have released most of the stress accumulated since that time the observations suggest that coseismic slip heterogeneity at the scale of single asperities and therefore the seismic potential of future great earthquakes might be anticipated by geodetic observations these authors show evidence for a high coherence between the slip distribution inferred from the 2010 maule earthquake chile and the patchwork of interseismic locking distribution derived from global positioning system observations during the previous decade their work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future earthquakes which thus might be anticipated by geodetic observations the magnitude 8 8 maule chile earthquake of 27 february 2010 ruptured a segment of the andean subduction zone megathrust that has been suspected to be of high seismic potential1 2 3 4 5 6 it is the largest earthquake to rupture a mature seismic gap in a subduction zone that has been monitored with a dense space geodetic network before the event this provides an image of the pre seismically locked state of the plate interface of unprecedentedly high resolution allowing for an assessment of the spatial correlation of interseismic locking with coseismic slip pre seismic locking might be used to anticipate future ruptures in many seismic gaps6 7 8 9 10 11 12 given the fundamental assumption that locking and slip are similar this hypothesis however could not be tested without the occurrence of the first gap filling earthquake here we show evidence that the 2010 maule earthquake slip distribution correlates closely with the patchwork of interseismic locking distribution as derived by inversion of global positioning system gps observations during the previous decade the earthquake nucleated in a region of high locking gradient and released most of the stresses accumulated in the area since the last major event in 1835 two regions of high seismic slip asperities appeared to be nearly fully locked before the earthquake between these asperities the rupture bridged a zone that was creeping interseismically with consistently low coseismic slip the rupture stopped in areas that were highly locked before the earthquake but where pre stress had been significantly reduced by overlapping twentieth century earthquakes our work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future great earthquakes which thus might be anticipated by geodetic observations

characteristics of alkenone distributions in suspended and sinking particles in the northwestern north pacific abstract we investigated alkenones recorded in suspended particles and a settling particle time series collected at three stations 40n 40 n 165 e knot 44 n 155 e and 50n 50 n 165 e in the northwestern north pacific from december 1997 to may 1999 emiliania huxleyi the most abundant alkenone producer in this area is present in surface to subsurface to 50 m depth waters the alkenone concentrations recorded in the suspended particles indicated that the seasonal alkenone particle distribution differed significantly interannually alkenone export fluxes at the three sediment trap stations ranged from 0 16 to 49 3 g m 2 day 1 and the maximum export flux which occurred in summer to fall july november was associated with a high organic carbon export flux the amount of alkenone produced during the maximum export season accounted for 60 80 of the total annual amount of alkenone and the alkenones accumulated in the sediment below the traps had characteristics corresponding to subsurface waters during the summer autumn season alkenone derived temperatures recorded in suspended particles corresponded to the in situ temperature within 2 c although alkenone derived temperatures corresponded approximately to the temperatures observed in the stratified subsurface waters at the three trap stations during the high export season large differences were observed during the low export winter spring period for example the alkenone derived temperatures observed at stations knot and 50n were much higher than the in situ subsurface temperatures reported in the world ocean atlas 2001 relatively large differences between alkenone derived temperatures and in situ temperatures in the subarctic might be due to 1 a low light limitation or 2 contributions of allochthonous alkenones in particulate material transported from subtropical areas within a warm core ring

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

volcanoes and human history abstract the study of volcanic hazards leads inevitably to questions of how past cultures have lived in volcanically active regions of the world here we summarize linkages between volcanological archaeological and anthropological studies of historic and prehistoric volcanic eruptions with the goal of evaluating the impact of past eruptions on human populations to better prepare for future events we use examples from papers collected in this volume to illustrate ways in which volcanological studies aid archaeological investigations by providing basic stratigraphic markers and information about the nature and timing of specific volcanic events we then turn to archaeological perspectives which provide physical evidence of the direct impacts of volcanic eruptions such as site abandonment and human migration as well as indirect impacts on local cultures as reflected in human artifacts finally we review anthropological studies of societal responses to past and recent volcanic eruptions we pay particular attention to both the psychological impact of catastrophic events and records of these impacts encoded within oral traditions taken together these studies record drastic short term eruption impacts but adaptation to volcanic activity over the longer term largely through strategies of adaptive land use

alkenones and alkenes in surface waters and sediments of the southern ocean implications for paleotemperature estimation in polar regions abstract the concentration of c37 c39 long chain alkenones and alkenes were determined in surface water and surface sediment samples from the subpolar waters of the southern ocean distributions of these compounds were similar in both sample sets indicating little differential degradation between or within compound classes the relative amounts of the tri to tetra unsaturated c37 alkenones increased with increasing temperature for temperatures below 6 c similar to the di and tri unsaturated c37 alkenones the c37 di tri and tetra unsaturated methyl alkenones are used in paleotemperature calculations via the u37k and the u37k ratios in these datasets the relative abundances of the c37 2 and the c37 3 alkenones as a proportion of the total c37 alkenones were opposite and strongly related to temperature the latter with more scatter but the abundance of the c37 4 alkenone showed no relationship with temperature the original definition of u37k includes the abundance of 37 4 in both the numerator and denominator and thus it is perhaps not surprising that there is considerable scatter in the values obtained for u37k at low temperatures of the two we suggest that u37k is the better parameter for use in paleotemperature estimations even in cold locations u37k values in the sediments fall on virtually the same regression line obtained for the water column samples of sikes and volkman 1993 indicating that their calibration is suitable for use in southern ocean sediments the comparison of water column data with sedimentary temperature estimates suggests that the alkenone distributions are dominated by contributions from the summer when the biomass of emiliania huxleyi and presumably flux to the sediment is expected to be high

groundwaters of florence italy trace element distribution and vulnerability of the aquifers geochemical and hydrogeological research has been carried out on 109 wells in the alluvial plain of florence in order to evaluate conductivity and main chemistry of ground waters the pattern of some possible pollutant chemical species fe mn cr cu pb zn no2 no3 and the vulnerability of the aquifers the plain is made up of plio quaternary alluvial and lacustrine sediments for a maximum thickness of 600 m silts and clays sometimes with lenses of sandy gravels are dominant while considerable deposits of sands pebbles and gravels occur along the course of the arno river and its tributary streams and represent the most important aquifer of the plain the groundwaters analyzed belong to this aquifer or to the smaller ones hosted in the gravel lenses most waters show conductivity values around 1000 1200 s and almost all of them have an alkaline earth bicarbonate chemical character these features are consistent with the mainly calcareous lithology of the aquifers in the western areas a higher salt content of the groundwaters is evident probably related to the presence of industrial activities which use water desalinators heavy metal and no2 no3 analyses point out that no important pollution phenomena affect the groundwaters all the mean values of the chemical considered species are below the maximum admissible concentration mac fixed by the european community for drinkable waters nevertheless some anomalies of no2 no3 fe mn and zn are present in the plain apart from mn which seems to be released by certain calcareous gravels the other anomalies have a local influence since they disappear even in the nearest wells the most plausible causes can be recognized in losses of the sewage system no2 3 4 mg t use of nitrate compounds in agriculture no3 60 70 mg l oxidation of well pipes fe 20 mg l zn 6 mg l as regards cr cu and pb all the observations are below the mac therefore the median values of 3 3 9 and 1 1 g l respectively could be considered reference concentrations for groundwaters circulating in calcareous lithotypes under undisturbed natural conditions finally a map of vulnerability related to the most superficial and important aquifer has been elaborated on the basis of thickness and permeability of the covers the map shows that the areas near the arno river are highly vulnerable for the minimum thickness or lacking of sediments covering the aquifer on the other hand in the case of pollution several factors not considered in the map could significantly increase the self purification capacity of the aquifer such as the dilution of groundwaters caused by the feeding of the rivers the bacteria oxidation of nitrogenous species and the sorption capacity of clay minerals and organic matter with respect to trace metals

alternative paradigms of volcanic risk perception the case of mt pinatubo in the philippines the literature on people s response to volcanic hazards tends to be split between two paradigms the first argues that the choice of adjustment depends on how people perceive rare and extreme volcanic phenomena and the associated risk the second considers that people s behavior in the face of natural hazards is constrained by social economic and political forces beyond their control the present paper addresses both paradigms and demonstrates that in order to understand people s behavior in the face of volcanic threats volcanic risk perception has to be balanced with non hazard related factors and structural constraints these conclusions are based on a case study of mt pinatubo and the lingering threat of lahars from the 1991 eruption drawing on the results of a questionnaire based survey and additional interviews with key informants it is shown that a high perception of risk does not stop people from choosing to forms of living that put them at high threat from lahars furthermore the paper argues that insufficient opportunity for making a livelihood in resettlement centers and strong attachment to native villages push people back to the banks of lahar channels everyday hazards of poverty and the threat to cultural heritage weighed heavier than this seasonal natural hazard in other words in a context of economic and social hardship risk perception of volcanic hazards is necessarily balanced with other risk perceptions this study does not argue that risk perception is unimportant for understanding people s adjustment to volcanic environments but rather stresses the need for placing it in its larger and daily contexts which are independent of volcanic hazards

review of alkenone calibrations culture water column and sediments 1 i review the status of alkenone unsaturation parameters as proxies for growth temperature and the potential for pco2 estimates using the carbon isotopic composition of alkenones culture studies allow investigators to manipulate parameters that could influence the relative proportions of c37 and c38 ketones in producing organisms and to assess the possible influence of genetic variability on the calibration of unsaturation to growth temperature culture studies suggest large variability in the relation of unsaturation indices to growth temperature and hint that growth rate may play a role along with temperature in controlling unsaturation water column studies match the unsaturation index measured in particulate matter to ambient temperature providing a snapshot of unsaturation temperature relationship in comparison to culture work assemblages of regional water column data sets give more consistent relations of the unsaturation index to temperature although the argument can be made for regional rather than basin wide or global calibrations a much simpler picture emerges from analyzing a global array of core top sediments regressions show that the sedimentary unsaturation indices follow a linear trend that is best correlated to mean annual temperature in the upper 10 m of the overlying water column the regression is indistinguishable from the original prahl et al 1988 culture calibration of the u37k index to growth temperature exceptions occur at high latitudes where the effects of highly seasonal production and the possible influence of salinity may affect the unsaturation index in sediments core top analyses also fail to reveal the variability of other alkenone parameters for example the ratio of c37 to c38 ketones which have been found in culture studies much of the variance that appears in culture and water column calibrations is thus apparently removed in sediments perhaps by temporal averaging the promising paleo pco2 approach based on the isotopic composition of alkenones awaits the arrival of a significant number of core top and stratigraphic studies that will determine the extent to which physiological factors compromise the alkenone paleobarometer