a model for microbial phosphorus cycling in bioturbated marine sediments significance for phosphorus burial in the early paleozoic abstract a diagenetic model is used to simulate the diagenesis and burial of particulate organic carbon c org and phosphorus p in marine sediments underlying anoxic versus oxic bottom waters the latter are physically mixed by animals moving through the surface sediment bioturbation and ventilated by burrowing tube dwelling organisms bioirrigation the model is constrained using an empirical database including burial ratios of c org with respect to organic p c org p org and total reactive p c org p reac burial efficiencies of c org and p org and inorganic carbon to phosphorus regeneration ratios if p org is preferentially mineralized relative to c org during aerobic respiration as many previous studies suggest then the simulated p org pool is found to be completely depleted a modified model that incorporates the redox dependent microbial synthesis of polyphosphates and p org termed the microbial p pump allows preferential mineralization of the bulk p org pool relative to c org during both aerobic and anaerobic respiration and is consistent with the database results with this model show that p burial is strongly enhanced in sediments hosting fauna animals mix highly labile p org away from the aerobic sediment layers where mineralization rates are highest thereby mitigating diffusive po 4 3 fluxes to the bottom water they also expand the redox niche where microbial p uptake occurs the model was applied to a hypothetical shelf setting in the early paleozoic a time of the first radiation of benthic fauna results show that even shallow bioturbation at that time may have had a significant impact on p burial our model provides support for a recent study that proposed that faunal radiation in ocean sediments led to enhanced p burial and possibly a stabilization of atmospheric o 2 levels the results also help to explain c org p org ratios in the geological record and the persistence of p org in ancient marine sediments

distribution of organic and inorganic phosphorus compounds in mrine and lacustrine sediments a31nmr study abstract solution 31 p nmr spectroscopy has been used for the characterization of different classes of organic and inorganic phosphorus compounds in a number of different marine and lacustrine sediment environments all samples contain orthophosphate mono and di esters of which the former is always the major constituent of possible orthophosphate mono ester candidates inositol phosphates may be of importance the amount of orthophosphate di esters is much higher in the reduced sediments from the baltic sea than in those areas with anoxic suboxic conditions indicating a more efficient decomposition of di esters in oxic environments the same situation was also observed in the lake sediment profiles pyro and polyphosphate are found in the oxic sediments from the lakes whereas no sign of such compounds could be seen in the baltic sea sediment samples redox variations lake samples and cation strength variations between the sea water and the lacustrine water will most likely be the main explanation for the observed distribution patterns of pyro and polyphosphate small but sharp peaks indicate the occurrence of phosphoric acids in a sediment from the southern baltic sea several other unidentified peaks were also observed some of which could be assigned to aromatic di and mono esters

controls on phosphorus concentration and accumulation in oceanic sediments understanding phosphorus p sedimentation in the ocean is important both for quantifying outputs in the marine phosphorus cycle and for determining the controls on phosphogenesis the authigenic formation of carbonate fluorapatite and phosphorite deposition large accumulations of p rich sediments on continental margins in this study i have compiled literature data on sedimentary p concentrations and sedimentation rates from continental margins phosphogenic continental margins and open ocean environments i have also calculated p accumulation rates the product of p concentration sediment density and sedimentation rate in these settings sedimentary p concentrations exhibit a similar range in a wide variety of oceanic environments and sedimentation rate conditions for example p concentrations in continental margin sediments range from 8 to 108 mol p g 1 with sedimentation rates from 80 to 8 000 m my 1 in open ocean sediments the p concentration range is similar 7 307 mol p g 1 even though sedimentation rates are generally about 100 times lower 2 50 m my 1 the exception to this are phosphogenic environments where p concentrations are exceptionally high 580 3 700 mol p g 1 while sedimentation rates are relatively low 20 310 m my 1 phosphorus accumulation rates appear to be controlled by sedimentation rate in ocean sediments although p concentrations generally exhibit similar ranges the large difference in sedimentation rates between various environments results in p accumulation rates that are several orders of magnitude higher in continental margins 90 8 000 mol p cm 2 kyr 1 compared to open ocean sediments 2 75 mol p cm 2 kyr 1 in the case of phosphogenic environments low sedimentation rates result in p accumulation rates 80 6 300 mol p cm 2 kyr 1 that are surprisingly similar to those of non phosphogenic continental margin sediments

intact phospholipids microbial life markers in marine deep subsurface sediments abstract deep subsurface sediments from the nankai trough japan sea odp leg 190 sites 1173 1174 1177 and near surface sediments from hydrate ridge ne pacific have been analysed by high performance liquid chromatography hplc electrospray ionisation esi mass spectrometry ms the main objective was to utilize the presence of intact phospholipids as a direct indicator of viable microorganisms the extracts of nankai trough sediments were found to contain a variety of phospholipid pl structures well known to stem from microorganisms to depths as great as 745 mbsf and in situ temperatures as high as 85 c in addition high relative amounts of lysophospholipids e g lysophosphatidylcholines exceeding those of the regular phospholipids were detected diglyceride mass fragments of various pls have been assigned to fatty acyl side chains of typical chain length c14 c16 c18 c20 and degree of unsaturation zero one or two double bonds similar results were obtained for the phospholipid distribution in extracts of organic matter rich hydrate ridge sediments to date the enhanced occurrence of lysophospholipids cannot be explained completely but a response to increasing thermal and ecological stress seems probable

orographic influences on the distribution and generation of atmospheric variability in a gcm abstract the effect of large scale mountains on atmospheric variability is studied in a series of gcm experiments in which a single mountain is varied in height from 0 to 4 km high frequency 30 days variability are largest in the jet exit region while the intermediate frequency 7 30 days variability has its maximum upstream of the mountain where it exhibits enhanced equatorward propagation high and intermediate frequencies change from zonal wave trains to localized wave packets as orographic forcing is increased but they retain their characteristic scale and frequency the dominant pattern of low frequency is variability changes from a zonally symmetric oscillation for which transient eddy zonal flow interaction is the dominant mechanism to a more localized oscillation of the jet downstream of the mountain the transient eddy forcing still plays a significant role in maintaining the variations of this more localized jet however the total amount of wave

the nature of organic phosphorus in marine sediments new insights from 31p nmr abstract different classes of organic phosphorus compounds have been identified in marine sediment samples taken at depth in cores from pelagic lower slope and continental shelf depositional environments using solution and solid state magic angle spinning mas 31 p nuclear magnetic resonance nmr techniques phosphate esters have been identified as the major form of organic phosphorus in all sediment extracts and in separated bulk organic matter phosphonates a form of organic p previously unreported in marine sediments were identified in all but one of the samples the persistence of both phosphate esters and phosphonates at depth in sediment cores suggests that these compound classes include undegradable forms of organic phosphorus that represent an important sink for phosphorus in the ocean

vivianite is a key sink for phosphorus in sediments of the landsort deep an intermittently anoxic deep basin in the baltic sea phosphorus p is an essential nutrient for marine organisms its burial in hypoxic and anoxic marine basins is still incompletely understood recent studies suggest that p can be sequestered in sediments of such basins as reduced iron fe p but the exact phase and the underlying mechanisms that lead to its formation are unknown in this study we investigated sediments from the deepest basin in the baltic sea the landsort deep site m0063 that were retrieved during the integrated ocean drilling project iodp baltic sea paleoenvironment expedition 347 the record comprises the whole brackish marine littorina sea stage including past intervals of extensive hypoxia in the baltic sea that occurred during the holocene thermal maximum htmhi and the medieval climate anomaly mca1hi and mca2hi various redox proxies e g the presence of laminations and high mo contents suggest almost permanent bottom water hypoxia during the littorina sea stage in the landsort deep the bottom waters were likely even seasonally anoxic or sulfidic during the mca1hi and mca2hi and permanently sulfidic during the htmhi with the use of micro analysis of sieved minerals sem eds xrd and synchrotron based xas we show that mn and mg rich vivianite crystals are present at various depths in the littorina sea sediments we also have indications for vivianite in the mca1hi mca2hi and htmhi deposits the formation of vivianite thus likely explains the high fe bound p fraction throughout the whole littorina sea stage shuttling of fe and mn from the shelves into the basin and high inputs of p in settling organic matter are likely key drivers for vivianite formation our study shows that vivianite can likely form in near surface sediments under a broad range of bottom water redox conditions varying from hypoxic and anoxic to sulfidic

carbon and phosphorus burial associated with modern phosphorite formation phosphorite formation plays a significant but poorly constrained role in the marine c and p cycles this report concerns a site of modern phosphorite formation on the upper continental slope off southern baja california mexico sta 6 380 m water depth 23 41 n 111 05 w at this site a series of six narrow 1 3 cm partially indurated phosphorite layers have formed authigenically during the last 15 000 years within a surficial section of slowly but steadily accumulating 3 8 10 3 cm year 1 organic rich mud a poorly oxygenated benthic environment has prevailed at the study site since approximately 8100 year b p probably helping to produce and preserve the pristine phosphorite layers the mean p burial flux 1 1 mol cm 2 year 1 recorded by these deposits agrees closely with the downward diffusive p flux 1 3 mol cm 2 year 1 attributed to active francolite growth such a coincidence implies that the phosphorite layers could have formed entirely under present conditions however a much larger upward diffusive p flux 4 2 mol cm 2 year 1 directed out of the sediment limits the efficiency of ongoing phosphorite formation and the most recently deposited sediment does not contain enough labile p to maintain the overall p regeneration rate indefinitely attendant burial fluxes of inorganic and especially organic c 7 7 and 6 6 mol cm 2 year 1 respectively do not accord with a depositional model of coastal upwelling suggesting that an alternative mechanism possibly fe redox cycling controls porewater p concentrations and hence phosphorite formation a comparison with previously published p burial fluxes for a wide variety of other modern marine settings reveals that phosphorite formation in general does not disproportionately affect the global p burial flux from these data we tentatively estimate a minimum global p burial flux of approximately 70 109 mol year 1 with almost 80 occurring on continental margins

sedimentary phosphorus dynamics and the evolution of bottom water hypoxia a coupled benthic pelagic model of a coastal system the present study examines oxygen and phosphorus dynamics at a seasonally hypoxic site in the arkona basin of the baltic sea a coupled benthic pelagic reactive transport model is used to describe the evolution of bottomwater solute concentrations as well as pore water and sediment profiles aerobic respiration dominates remineralization with iron reduction denitrification and sulphate reduction playing secondary roles while other pathways are negligible sediments represent a significant oxygen sink chiefly due to the aerobic degradation of organic matter as well as nitrification and iron oxyhydroxide precipitation most phosphorus deposited in sediments is in organic matter yet cycling is dominated by iron bound phosphorus due to rapid dissimilatory iron reduction coupled with aerobic iron oxyhydroxide formation sustained hypoxia results in an initial decrease in sediment phosphorus content due to dissolution of phosphorus bearing iron oxyhydroxides resulting in a pulse of phosphate to overlying waters although an organic rich layer is formed under low oxygen conditions enhanced remineralization of organic phosphorus relative to organic carbon tempers sedimentary phosphorus accumulation upon reoxygenation of bottom waters after a decade of sustained hypoxia oxygen concentrations do not immediately achieve values observed prior to hypoxia because the organic rich layer creates a higher benthic oxygen demand artificial reoxygenation of bottom waters leads to a substantial increase in the ironbound phosphorus pool the total phosphorus content of the sediment however is unaffected a relapse into hypoxia would consequently produce a large pulse of phosphate to the overlying waters potentially exacerbating the situation

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

microbial sequestration of phosphorus in anoxic upwelling sediments organic phosphorus is removed from the ocean by its conversion to phosphorite laboratory incubations suggest that bacteria catalyse phosphorite formation and that the rate of conversion is greatest under anoxic conditions phosphorus is an essential nutrient for life in the ocean phosphorus burial regulates marine primary production1 2 phosphorus is removed from the ocean by sedimentation of organic matter and the subsequent conversion of organic phosphorus to phosphate minerals such as apatite and ultimately phosphorite deposits3 4 bacteria are thought to mediate these processes5 but the mechanism of sequestration has remained unclear here we present results from laboratory incubations in which we labelled organic rich sediments from the benguela upwelling system namibia with a 33p radiotracer and tracked the fate of the phosphorus we show that under both anoxic and oxic conditions large sulphide oxidizing bacteria accumulate 33p in their cells and catalyse the nearly instantaneous conversion of phosphate to apatite apatite formation was greatest under anoxic conditions nutrient analyses of namibian upwelling waters and sediments suggest that the rate of phosphate to apatite conversion beneath anoxic bottom waters exceeds the rate of phosphorus release during organic matter mineralization in the upper sediment layers we suggest that bacterial apatite formation is a significant phosphorus sink under anoxic bottom water conditions expanding oxygen minimum zones are projected in simulations of future climate change6 potentially increasing sequestration of marine phosphate and restricting marine productivity

tracing sources and cycling of phosphorus in peru margin sediments using oxygen isotopes in authigenic and detrital phosphates abstract many bio geochemical processes that bring about changes in sediment chemistry normally begin at the sediment water interface continue at depth within the sediment column and may persist throughout the lifetime of sediments because of the differential reactivity of sedimentary phosphate phases in response to diagenesis dissolution precipitation and biological cycling the oxygen isotope ratios of phosphate 18op can carry a distinct signature of these processes as well as inform on the origin of specific p phases here we present results of sequential sediment extraction sedex analyses combined with 18op measurements aimed at characterizing authigenic and detrital phosphate phases in continental margin sediments from three sites sites 1227 1228 and 1229 along the peru margin collected during odp leg 201 our results show that the amount of p in different reservoirs varies significantly in the upper 50 m of the sediment column but with a consistent pattern for example detrital p is highest in siliciclastic rich layers the 18op values of authigenic phosphate vary between 20 2 and 24 8 and can be classified into at least two major groups authigenic phosphate precipitated at near the sediment water interface in equilibrium with paleo water oxygen isotope ratios 18ow and temperature and phosphate derived from hydrolysis of organic matter porg with subsequent incomplete to complete re equlibration and precipitated deeper in the sediments column the 18op values of detrital phosphate which vary from 7 7 15 4 suggest two possible terrigenous sources and their mixtures in different proportions phosphate from igneous metamorphic rocks and phosphate precipitated in source regions in equilibrium with 18ow of meteoric water more importantly original isotopic compositions of at least one phase of authigenic phosphates and all detrital phosphates are not altered by diagenesis and other biogeochemical changes within the sediment column these findings help to understand the origin and provenance of p phases and paleoenvironmental conditions at near the sediment water interface and to infer post depositional activities within the sediment column

size fractionated major particle composition and concentrations from the us geotraces north atlantic zonal transect the concentration and the major phase composition particulate organic matter caco3 opal lithogenic matter and iron and manganese oxyhydroxides of marine particles is thought to determine the scavenging removal of particle reactive teis particles are also the vector for transferring carbon from the atmosphere to the deep ocean via the biological carbon pump and their composition may determine the efficiency and strength of this transfer here we present the first full ocean depth section of size fractionated 1 51 m 51 m suspended particulate matter spm concentration and major phase composition from the us geotraces north atlantic zonal transect between woods hole ma and lisbon portugal conducted in 2010 and 2011 several major particle features are notable in the section intense benthic nepheloid layers were observed in the western north american margin with concentrations of spm of up to 1648 g l two to three orders of magnitude higher than surrounding waters that were dominated by lithogenic material a more moderate benthic nepheloid layer was also observed in the eastern mauritanian margin 44 g l that had a lower lithogenic content and notably significant concentrations of iron and manganese oxyhydroxides 2 5 each an intermediate nepheloid layer reaching 102 g l an order of magnitude above surrounding waters was observed associated with the mediterranean outflow finally there was a factor of two enhancement in spm at the tag hydrothermal plume due almost entirely to the addition of iron oxyhydroxides from the hydrothermal vent we observe correlations between poc and caco3 in large 51 m particles in the upper 2000 m but not deeper than 2000 m and no correlations between poc and caco3 at any depth in small 51 m particles there were also no correlations between poc and lithogenic material in large particles overall there were very large uncertainties associated with all regression coefficients for mineral ballast carrying coefficients suggesting that mineral ballast was not a strong predictor for poc in this section

the use of atmospheric relative angular momentum to diagnose the arctic oscillation abstract recent studies suggest that the north atlantic oscillation is a regional expression of the northern hemisphere annular mode however the lack of an apparent link between atlantic and pacific sectors questions the annular paradigm in any case the phenomenon is the largest and most fundamental mode of variability in the northern hemisphere troposphere being responsible for much of the warming in the northern hemisphere surface temperature the main aim of this study is to diagnose the northern hemisphere annular mode using an annular magnitude such as the relative angular momentum ram ram from 500 hpa to 200 hpa is computed for the polar cap using 60 longitude sectors as well as the whole cap from 55 to 90 n and for the period 1958 1998 using ncep ncar reanalysis data annual values of ram are then correlated to temperature and geopotential height at 200 500 and 850 hpa the artic region is dominated by very negative correlations for the northern hemisphere ram and for the six different ram sectors midlatitudes are dominated by positive correlation with intermittent or alternating significant regions not showing a regular annular pattern the pacific ocean area is only significantly correlated with the pacific ram sector since an annular pattern is characterized by its hemispheric symmetry two symmetric latitude rings are expected but only the polar one is detected the rest being incomplete due to the proximity of the grid points near the pole which can lead to artificial zonal symmetry all the calculations are repeated for ram from 45 to 65 n finding a similar pattern with lower correlations and less symmetry so the results do not support the annular paradigm understood as organized along latitude sectors but a hemispheric dimension cannot be excluded

propagation of the arctic oscillation from the stratosphere to the troposphere geopotential anomalies ranging from the earth s surface to the middle stratosphere in the northern hemisphere are dominated by a mode of variability known as the arctic oscillation ao the ao is represented herein by the leading mode the first empirical orthogonal function of low frequency variability of wintertime geopotential between 1000 and 10 hpa in the middle stratosphere the signature of the ao is a nearly zonally symmetric pattern representing a strong or weak polar vortex at 1000 hpa the ao is similar to the north atlantic oscillation but with more zonal symmetry especially at high latitudes in zonal mean zonal wind the ao is seen as a north south dipole centered on 40 45 n in zonal mean temperature it is seen as a deep warm or cold polar anomaly from the upper troposphere to 10 hpa the association of the ao pattern in the troposphere with modulation of the strength of the stratospheric polar vortex provides perhaps the best measure of coupling between the stratosphere and the troposphere by examining separately time series of ao signatures at tropospheric and stratospheric levels it is shown that ao anomalies typically appear first in the stratosphere and propagate downward the midwinter correlation between the 90 day low pass filtered 10 hpa anomaly and the 1000 hpa anomaly exceeds 0 65 when the surface anomaly time series is lagged by about three weeks the tropospheric signature of the ao anomaly is characterized by substantial changes to the storm tracks and strength of the midtropospheric flow especially over the north atlantic and europe the implications of large stratospheric anomalies as precursors to changes in tropospheric weather patterns are discussed

oxygen isotope variations in phosphate of biogenic apatites i fish bone apatite rechecking the rules of the game abstract the major advantage of the oxygen in phosphate isotope paleothermometry is that it is a system which records temperatures with great sensitivity while bone and teeth building organisms are alive and the record is nearly perfectly preserved after death fish from seven water bodies of different temperatures 3 23 c and different 18 o values 16 to 3 of the water were analysed the 18 o values of the analysed po 4 vary from 6 to 25 the system passed the following tests a the temperatures deduced from isotopic analyses of the sequence of fish from lake baikal are in good agreement with the temperatures measured in the thermally stratified lake b the isotopic composition of fish bone phosphate is not influenced by the isotopic composition of the phosphate which is fed to the fish but only by temperature and water composition isotopic analysis of fossil fish in combination with analysis of mammal bones should be a useful tool in deciphering continental paleoclimates

relation between sedimentation rate and burial of organic phosphorus and organic carbon in marine sediments organic carbon and organic phosphorus concentrations in marine sediment cores with known sedimentation rates were determined and collected from the literature with the exception of organic rich sediments from upwelling areas organic phosphorus concentrations in marine sediments do not correlate linearly with organic carbon concentrations the c p ratios of organic matter buried in marine sediments vary systematically with sedimentation rate over the range studied 0 0001 to 2 5 cm y low c p ratios 200 atomic occur in sediments with sedimentation rates both less than 0 002 cm y and greater than 1 cm y higher c p ratios up to 600 are found at intermediate sedimentation rates a simple steady state model is developed for the early diagenesis of organic carbon and organic phosphorus in marine sediments the processes included are sediment burial pore water diffusion and bacterial decomposition of organic matter by oxic respiration and sulfate reduction preferential regeneration of phosphorus relative to carbon is assumed to take place during oxic respiration the modeling shows that both organic matter preservation and the degree of elemental fractionation between phosphorus and carbon depend strongly on the overall sedimentation rate very high sedimentation rates coastal deltaic environment result in a good preservation of deposited organic matter with an initial c p ratio close to the redfield value at very slow sedimentation rates pelagic environment the oxidation of the sedimentary organic matter is nearly complete and produces a low c p residual organic material this residual organic matter may represent either refractory detrital organic compounds enriched in phosphorus or in situ synthesized low c p bacterial remains the high c p ratios at intermediate sedimentation rates slope and shelf environment reflect the preferential regeneration of phosphorus during the incomplete decomposition of the metabolizable organic matter

speciation and burial flux of phosphorus in the surface sediments of the eastern mediterranean the distribution of various forms of p in surface sediments across the eastern mediterranean and in saharan dust and nile particulates as a potentially important source of sediment to the basin has been determined using the sedex procedure ruttenberg 1992 the distribution of most phases could be described by a rather simple mixing between adriatic sediment and saharan dust across the ionian sea and between saharan dust and nile particulates across the levantine basin the relative proportions of p between the various phases were similar to that found previously in other marine systems with p aut p fe p det p ex however p org in the eastern mediterranean was approximately 15 to 20 percent which was lower than that found in many other marine sediments p fe was higher approximately 36 percent in the areas adjacent to the nile delta than elsewhere across the basin saharan dust was a source of p to surface waters there was however no evidence of uptake of phosphate by saharan dust in levantine deep water ldw by contrast nile particulates adsorb phosphate from ldw probably into an fe bound phase the organic c p ratio in the deep part of the basin was 136 which is typical of low sedimentation rate ocean sediments and indicates that the organic p being buried is likely to be refractory however on the israeli shelf where nile particulates predominate the organic c p was also low approximately 164 which is unusual for a sediment with a relatively high sedimentation rate 0 005 0 3 cm yr it was suggested that this was due to the unusual nature of the nile system in which inorganic particulates were jetted out into the basin beyond the plume of increased primary productivity the burial flux of total p in the eastern mediterranean was calculated as 5 5 10 12 mmole p yr previous estimates of the p budget of the eastern basin have used the net flux of p through the straits of sicily to calculate the terrestrial and atmospheric input to the basin these estimates which ignored sediment burial of p need to be increased by a factor of approximately 2 however 3 0 10 12 mmole p yr of this input was from the river nile which as a result of the completion of the aswan dam in 1965 no longer supplies sediment to the basin

the preferred structure of variability of the northern hemisphere atmospheric circulation a nonlinear generalisation of principal component analysis pca is applied to the 500mb geopotential height field of the northern hemisphere extratropical atmosphere it is found that the low frequency variability of the mid troposphere is characterised by three distinct quasi stationary states the states are described and compared to those obtained from applications of cluster analyses and linear pca to the height field evidence is provided that modes obtained through pca notably the arctic oscillation ao are not independent dynamical modes of variability of the northern hemisphere extratropics rather they arise as the optimal linear compromise between the preferred quasi stationary states of the circulation

a new particulate mn fe p shuttle at the redoxcline of anoxic basins abstract pelagic redoxclines of anoxic basins and deeps form the suboxic transition between oxygenated surface and anoxic or even sulfidic bottom waters intense element cycling favoured by elevated microbial activity causes steep gradients of physico chemical parameters nutrients and redox sensitive trace metals this study presents a conceptual model for authigenic particle formation at pelagic redoxclines which is based on the tight coupling of mn fe and p cycles besides the well known occurrence of mn oxides textural sem edx and geochemical icp oes icp ms analyses of particles from the redoxclines of the black sea and the baltic sea gotland basin landsort deep evidence the existence of earlier postulated fe oxyhydroxo phosphates and emphasize mixed phases consisting of mn oxides and fe oxyhydroxo phosphates as a new solid species most of the analyzed particles are star shaped of about 5 m in size and occur as single particles or aggregates without any morphological differences between mn oxides fe oxyhydroxo phosphates and mixed phases throughout the redoxcline these minerals show a general succession with maximum abundance of mn oxides above the redoxcline followed by mixed phases and almost pure fe phosphates within and below the redoxcline respectively molar fe p ratios of single particles argue against the formation of known pure fe phosphates like vivianite or strengite at the lower end of the redox transition zone but are consistent with recent experimental findings for colloidal p bearing hydrous ferric oxides moreover morphological similarities suggest the formation of irregular fe oxyhydroxo coatings due to oxidation of upward diffusing fe 2 by oxygen and stepwise replacement of mn iv by fe iii on sinking mno x particles followed by immediate adsorption or even co precipitation of phosphate batch type experiments using biogenic mno x particles demonstrate the efficient potential of fe 2 oxidation by sinking mno x particles when entering sulfidic waters mno x particles are progressively reduced leading to an increasing relative abundance of fe and p rich particles in deeper parts of the water column these particles are also reductively dissolved thereby releasing fe 2 and phosphate to the water column this mn fe p shuttle likely affects phosphate transport throughout the water column and thus impacts primary production at least over longer time scales furthermore the particulate mn fe p shuttle must have played an important role for the cycling of p and certain trace metals in ancient ocean basins e g during certain periods of cretaceous black shale formation and should be considered in future mass balances and modeling approaches dealing with oxic anoxic interfaces of aquatic ecosystems

evaluation of paired carbon isotopic signals from the ediacaran doushantuo phosphorites diagenetic or primary abstract this study reports high resolution c isotopic data of carbonate carbon 13ccarb and organic carbon 13corg from the ediacaran doushantuo carbonate and phosphorite as well as from the underlying tillite of the nantuo formation from the datang mine and chuanyuandong sections for the nantuo tillite in the datang section the striking negative 13ccarb values ranging mostly from 10 to 16 with negative 18o values down to 27 2 and clear covariance between 13ccarb and 18o suggest that nearly all of the primary c and o isotopic compositions have been reset by meteoric diagenesis the near complete modification of the primary isotopic signals may be due to frequent exposure to fresh water conditions during diagenesis and the lithification of porous tillite sediment the extremely negative 13ccarb values down to 16 8 suggest the contribution of 12c enriched dissolved inorganic carbonate which originated from the remineralization of organic carbon during burial diagenesis these observations suggest that caution is needed when using tillite samples for paleoenvironmental reconstruction the correlative lower phosphorite deposits from the datang and chuanyuandong sections show clear covariance between 13ccarb and 18o although the chuanyuandong phosphorites have more negative values of 13ccarb and 18o than the datang section although most of the 18o values of the lower phosphorites may have been altered by secondary diagenetic processes the 13ccarb values of 3 5 and the 13corg values of

on the teleconnectivity of the arctic oscillation the term arctic oscillation ao has recently been introduced to describe the leading structure of slp variability over the northern hemisphere a key feature of the ao is its zonally symmetric appearance with a primary center of action over the arctic and opposing anomalies in midlatitudes does the ao s annular appearance result from significant temporal correlations between slp anomalies at distant longitudes the results presented indicate that the temporal coherence between the arctic and midlatitudes is strongest over the atlantic sector with weak correlations between the atlantic and pacific midlatitudes both on intraseasonal and interannual time scales during the past 50 yrs hence the annular character of the ao is more a reflection of the dominance of its arctic center of action than any coordinated behavior of the atlantic and pacific centers of action in the slp field the ao is nearly indistinguishable from the leading structure of variability in the atlantic sector e g the north atlantic oscillation their temporal correlation is 0 95 for monthly data

authigenic apatite formation and burial in sediments from non upwelling continental margin environments abstract evidence for precipitation of authigenic carbonate fluorapatite cfa in long island sound and mississippi delta sediments suggests that formation of cfa is not restricted to environments of active coastal upwelling we present porewater data suggestive of cfa formation in both these areas application of a sequential leaching procedure designed specifically to separate authigenic carbonate fluorapatite from other phosphorus containing phases including detrital apatite of igneous or metamorphic origin provides strong supporting evidence for authigenic apatite formation in these sediments the size of the authigenic apatite reservoir increases with depth indicating continued formation of cfa during early diagenesis this depth increase is mirrored by a decrease in solid phase organic p at both sites suggesting that cfa is forming at the expense of organic p mass balance considerations application of diagenetic models to interstitial water nutrient data and the saturation state of the interstitial water are consistent with this interpretation diagenetic redistribution of phosphorus among the different solid phase reservoirs is observed at both sites and results in near perfect retention of p by these sediments over the depth intervals sampled formation of cfa in continental margins which do not conform to the classically defined regions of phosphorite formation renders cfa a quantitatively more important sink than has previously been recognized including this reservoir as a newly identified sink for reactive p in the ocean the residence time of p in the modern ocean must be revised downward the implication for ancient oceans of cfa formation in continental margin sediments other than phosphorites is that phosphorite formation may be less a representation of episodicity in removal of reactive p from the oceans than of localized concentration of cfa in phosphatic sediments by secondary physical processes

phosphorus burial in sediments of the sulfidic deep black sea key roles for adsorption by calcium carbonate and apatite authigenesis abstract sedimentary burial of the essential nutrient phosphorus p under anoxic and sulfidic conditions is incompletely understood here we use chemical and micro scale spectroscopic methods to characterize sedimentary p burial along a water column redox transect six stations 78 2107 m water depth in the black sea from the shelf with its oxygenated waters to the anoxic and sulfidic deep basin organic p is an important p pool under all redox regimes accounting for up to 60 of p burial we find a general down core increase in the relative importance of organic p especially on the shelf where p bound to iron fe and manganese mn oxyhydr oxides is abundant in the uppermost sediment but rapidly declines in concentration with sediment depth our chemical and spectroscopic data indicate that the carbonate rich sediments unit i 3000 years 0 30 cm depth of the sulfidic deep black sea contain three major p pools calcium phosphate apatite organic p and p that is strongly associated with caco3 and possibly clay surfaces apatite concentrations increase from 5 to 25 of total p in the uppermost centimeters of the deep basin sediments highlighting the importance of apatite formation for long term p burial iron ii associated p ludlamite was detected with x ray absorption spectroscopy but was shown to be a minor p pool 5 indicating that lateral fe p transport from the shelf shuttling likely occurs but does not impact the p burial budget of the deep black sea the caco3 p pool was relatively constant throughout the unit i sediment interval and accounted for up to 55 of total p our results highlight that carbonate bound p can be an important sink for p in caco3 rich sediments of anoxic sulfidic basins and should also be considered as a potential p sink and p source in case of caco3 dissolution when reconstructing past ocean p dynamics from geological records

phosphogenesis and active phosphorite formation in sediments from the arabian sea oxygen minimum zone in this study porewater chemistry solid phase analysis and microscopic observations were combined to evaluate phosphogenesis in three boxcores located within the intensive oxygen minimum zone of the arabian sea three parameters namely a decrease of the dissolved phosphate and fluoride concentrations with depth saturation with respect to carbonate fluorapatite and the presence of a solid phase ca phosphate mineral all indicate that phosphogenesis is currently taking place at all three sites authigenic apatite precipitation rates vary between 0 076 and 1 04 molp cm 2 yr 1 and are of the same order of magnitude as reported for other high productivity areas precipitation of an intermediate precursor precedes francolite formation in the continental slope sediments on the karachi margin results of a diagenetic p model indicate that phosphogenesis is induced by high rates of organic matter degradation dissolution of fish debris is likely to provide a substantial additional source of phosphate redox iron cycling does not influence phosphogenesis in these environments model results suggest that sediment mixing is essential in promoting early diagenetic phosphogenesis the highest rate of francolite formation was observed in a boxcore taken on the oman margin where it contributes to the formation of a holocene phosphorite deposit this observation contrasts with previous reports of only old phosphorites in this area phosphorites are presently forming on the oman margin as a result of a deposition of older reworked material from the continental shelf which has undergone an earlier phase of phosphogenesis b a high input of reactive p fish debris and degradable organic matter c a relatively low sediment accumulation rate and d the absence of winnowing on this location holocene phosphorite deposits may be less common on the oman margin than in other coastal upwelling areas because of the narrowness of the shelf and the steepness of the slope which limit the area where phosphorite formation may occur

magnitude and composition of sinking particulate phosphorus fluxes in santa barbara basin california examined particulate p cycling in the santa barbara basin sbb off the coast of southern california using a 520 m deep moored sediment trap deployed from 1993 2006 and a sediment core collected in 2005 directly beneath the sediment trap at 590 m total particulate p tpp particulate inorganic p pip and particulate organic p pop were quantified using a 5 step sequential extraction method sedex that chemically separates pip into loosely bound oxide bound authigenic and detrital p phases pop fluxes while similar in magnitude to other coastal regions 22 10 mmol m 2 d 1 were a small component of the tpp pool 15 seasonal trends revealed significant increases in pop fluxes during upwelling due to increased biological production in surface waters by organisms that increased mineral ballast high particulate organic carbon poc to pop ratios 337 18 further indicated rapid and efficient remineralization of pop relative to poc as particles sank through the oxic water column however further reduction of pop ceased in the deeper anoxic waters loosely bound oxide bound and authigenic p dominated the tpp pool with pip fluxes substantially higher than those measured in other coastal settings strong correlations between oxide associated authigenic and detrital p fluxes with lithogenic material indicated a terrestrial source associated with riverine discharge furthermore more than 30 of the loosely bound and oxide bound p was remineralized prior to burial with the magnitude of dissolution far exceeding that of pop these results highlight the dynamic nature of the particulate p pool in coastal ecosystems and how changes in p source can alter the composition and lability of p that enters coastal waters

sequential extraction and analysis of phosphorus in marine sediments streamlining of the sedex procedure we streamlined the five step sedex sedimentary extraction procedure for characterizing sedimentary phosphorus to a four step procedure we combined extraction of adsorbed and oxide associated pools into a single step retaining steps for authigenic detrital and organic p in addition we used automated spectrophotometric flow injection analysis fia to determine p concentrations rather than traditional spectrophotometric techniques we decreased our total extraction and analytical time from 12 d for 24 replicate samples to 5 d without sacrificing our geo chemical objectives detection limits or analytical reproducibility

phosphorus cycling in marine sediments advances and challenges abstract phosphorus p is a critical macronutrient for all living cells as it provides the phosphate ester backbone of nucleic acids plays a crucial role in the transmission of chemical energy by the atp molecule and is also a structural constituent in many cell components while p cycling in the marine water column has been the subject of many studies and reviews many aspects of the sedimentary p cycling remain poorly understood this is mainly due to low p concentrations in sediments and analytical difficulties associated with isolating distinct p forms from sediment samples the aim of this review is to highlight the advances made in our understanding of p cycling in marine sediments as a result of improved instrumentation and novel approaches some of these techniques range from sediment sequential extractions sedex to spectroscopic techniques 31p nmr and innovative isotope tracer experiments stable oxygen ratios in phosphate radioactive p isotopes while our understanding of p cycling has considerably improved numerous aspects of sedimentary p cycling including the fate of organic p in sediments as a function of redox conditions organic matter content and burial depth as well as turnover rates of different sedimentary p compounds remain poorly constrained the techniques presented in this review along with yet to be utilized innovative approaches used in soil and lacustrine sediment p research will play an important role in addressing these important questions and in furthering our understanding of this critical component of the p global biogeochemical cycle

oxygen isotope fractionation between apatite and aqueous phase phosphate 20 45 c abstract replacement of biogenic caco3 by apatite is an important mode of authigenic apatite formation in marine sediments active along the peru margin today synthesis experiments mimicking this process were undertaken in abiotic inorganic systems in order to determine the oxygen o isotope fractionation between apatite and aqueous phase inorganic phosphate po4 aq caco3 solids were added to po43 solutions made with 18o labeled waters and o isotope fractionations between solid and aqueous phase po43 were determined in a series of experiments at 20 45 c results of 18o analyses of apatite synthesis systems indicate that o isotope fractionation between solid and aqueous phase po43 is 1 not affected by variations in water 18o values 2 initially non equilibrium and 3 relatively small 1 fractionations determined from long term up to 6 years room temperature experiments were 1 due to initial rapid precipitation short experimental run periods 1 week to 4 months resulted in fractionations between apatite and po4 aq that were initially reversed from those of long term experiments over time and with progressive recrystallization these fractionations evolved to reach values consistent with long term experiments

revised phosphate water fractionation equation reassessing paleotemperatures derived from biogenic apatite oxygen isotopes of biogenic apatite have been widely used to reassess anomalous temperatures inferred from oxygen isotope ratios of ancient biogenic calcite more prone to diagenetic alteration however recent studies have highlighted that oxygen isotope ratios of biogenic apatite differ dependent on used analytical techniques this questions the applicability of the phosphate water fractionation equations established over 25 years ago using earlier analytical techniques to more recently acquired data in this work we present a new phosphate water oxygen isotope fractionation equation based on oxygen isotopes determined on fish raised in aquariums at controlled temperature and with monitored water oxygen isotope composition the new equation reveals a similar slope but an offset of about 2 to the earlier published equations this work has major implications for paleoclimatic reconstructions using oxygen isotopes of biogenic apatite since calculated temperatures have been underestimated by about 4 to 8 c depending on applied techniques and standardization of the analyses

phosphorus accumulation in marine sediments and the oceanic phosphorus cycle ideas about key factors in the oceanic mass balance of dissolved reactive phosphate have changed substantially i present an integrated overview of these here with an emphasis on evaluating the burial sinks for p and defining areas needing further research the major source of reactive p to the ocean is river input reactive p is delivered to the oceanic sediment water interface primarily in particulate organic matter p scavenged by hydrothermal iron rich oxyhydroxide particles with uptake in proportion to deep water phosphate concentrations represents a substantially smaller flux to the sediment water interface diagenetic transformations are important influences on the form of reactive p burial in marine sediments p burial occurs with organic carbon burial and as p associated with iron rich oxyhydroxide particles and coatings formation of authigenic p rich phases presumably apatite at the expense of organic p and oxide associated p is significant in open ocean marine sediments the authigenic p sink may represent a substantially larger portion of the sedimentary burial than indicated by previous estimates focused on p burial in organic rich continental margin sediments

phosphorus cycling in the north and south atlantic ocean subtropical gyres despite similar physical properties the northern and southern atlantic subtropical gyres have different biogeochemical regimes the northern subtropical gyre which is subject to iron deposition from saharan dust1 is depleted in the nutrient phosphate possibly as a result of iron enhanced nitrogen fixation2 although phosphate depleted rates of carbon fixation in the euphotic zone of the north atlantic subtropical gyre are comparable to those of the south atlantic subtropical gyre3 which is not phosphate limited here we use the activity of the phosphorus specific enzyme alkaline phosphatase to show potentially enhanced utilization of dissolved organic phosphorus occurring over much of the north atlantic subtropical gyre we find that during the boreal spring up to 30 of primary production in the north atlantic gyre is supported by dissolved organic phosphorus our diagnostics and composite map of the surface distribution of dissolved organic phosphorus in the subtropical atlantic ocean reveal shorter residence times in the north atlantic gyre than the south atlantic gyre we interpret the asymmetry of dissolved organic phosphorus cycling in the two gyres as a consequence of enhanced nitrogen fixation in the north atlantic ocean4 which forces the system towards phosphorus limitation we suggest that dissolved organic phosphorus utilization may contribute to primary production in other phosphorus limited ocean settings as well

kinetics of selenium release in mine waste from the meade peak phosphatic shale phosphoria formation wooley valley idaho usa abstract phosphorite from the meade peak phosphatic shale member of the permian phosphoria formation has been mined in southeastern idaho since 1906 dumps of waste rock from mining operations contain high concentrations of se which readily leach into nearby streams and wetlands while the most common mineralogical residence of se in the phosphatic shale is elemental se se 0 se is also an integral component of sulfide phases pyrite sphalerite and vaesite pyrite ss in the waste rock it may also be present as adsorbed selenate and or selenite and fese 2 and organo selenides se release from the waste rock has been observed in field and laboratory experiments release rates calculated from waste rock dump and column leachate solutions describe the net overall se release from all of the possible sources of se listed above in field studies se concentration in seepage water ph 7 4 7 8 from the wooley valley unit 4 dump ranges from 3600 g l in may to 10 g l by sept surface water flow q from the seep also declines over the summer from 2 l s in may to 0 03 l s in sept se flux se q reaches a steady state of q se release mg l follows a first order reaction with a rate constant k 1 35 6 35e 3 h 1 11 8 55 6 yr 1 laboratory experiments were performed with the waste shale in packed bed reactors residence time varied from 0 09 to 400 h and outlet ph 7 5 here se concentration increased with increasing residence time and release was modeled with a first order reaction with k 2 19e 3 h 1 19 2 yr 1 rate constants reported here fall within an order of magnitude of reported rate constants for oxidation of se 0 formed by bacterial precipitation this similarity among rate constants from both field and laboratory studies combined with the direct observation of se 0 in waste shales of the phosphoria formation suggests that oxidation of se 0 may control steady state se concentration in water draining the wooley valley waste dump

determination of oxygen isotope fractionation between water and phosphate from living lingulids potential application to palaeoenvironmental studies abstract lingulids are inarticulate brachiopods with phosphatic shells which live exclusively in marine waters their distribution is generally restricted to the continental shelf within the 40 belt from temperate to equatorial areas they show a range of morphological physiological and behavioral features that have remained remarkably constant since the cambrian the oxygen isotope fractionation between water and phosphate from living lingulids was determined as a tool to investigate the temperature and or salinity of past coastal seawater oxygen isotope measurements were performed according to the silver phosphate method on a collection of lingulids coming from well known and varied marine environments a global 18o variation of 3 5 was found for these lingulids which proves their good sensitivity to environmental factors namely the oxygen isotope composition and the temperature of seawater oceanographic data provided average temperature and salinity values in the living sites of the studied specimens least squares treatment of the data gave the following fractionation equation t c 112 2 15 3 4 20 0 71 18o po4 18o h2o which is similar to the equations determined by longinelli and nuti 1973a and kolodny et al 1983 for other phosphate bearing invertebrates and fishes all these results suggest that a unique equation describes the phosphate water fractionation of many marine organisms except for mammals

phosphorus diagenesis in deep sea sediments sensitivity to water column conditions and global scale implications abstract the geological record bears evidence of various periods of wide scale oceanic anoxia that are associated with perturbations of the marine carbon and phosphorus p cycles in this study we examine the impact of changes in bottom water oxygen and organic matter om input on burial of p in deep sea sediments using a reactive transport model results show that the burial of key reactive p phases namely authigenic calcium associated p minerals ca p organic p org p and iron bound p fe p responds non linearly to both water column forcings namely water column oxygenation and om loading high organic matter om flux with either very low or high oxygen 180 m favor the formation of authigenic ca p while low oxygen and intermediate to high om fluxes promote org p burial iron bound p is only preserved in the sediment when oxygen levels are high and om fluxes low the conditions for maximum p recycling or minimum p burial are low bottom water oxygen concentrations and low om fluxes to the sediment water interface hypoxic oligotrophic deep sea settings the bivariate dependence of p burial on oxygen and om flux was implemented in an existing box model of the global marine p oxygen and organic carbon cycles replacing simple empirical redox functions for p burial the response of the original and new box model to decreased ocean mixing was then assessed in the context of a long term response in the new model org p instead of authigenic ca p is the dominant burial phase of p in deep sea environments during periods of oceanic anoxia nevertheless reduced ocean mixing leads to a similar response in total p burial and as a consequence to a similar increase in deep water anoxia and decrease in open ocean productivity whether an empirical or mechanistic description of phosphorus diagenesis is considered

phosphorus composition of sinking particles in the guaymas basin gulf of california phosphorus p composition and fluxes were measured in samples collected using a moored sediment trap located at 500 m in depth in the center of guaymas basin gulf of california from february 1991 through september 1997 p composition was measured using a sequential extraction technique that chemically separates the particulate inorganic p pip pool into exchangeable oxide bound authigenic and detrital phases pip comprised 69 6 15 of the total particulate p pool with significantly higher concentrations during the rainy summer strong relationships between authigenic and detrital p fluxes with lithogenic material r2 0 85 indicate that a significant component of pip is terrestrially derived and varies with large scale changes in regional climate particulate organic p pop fluxes were significantly higher during the winter as a result of stimulation of biological production during upwelling average particulate organic carbon poc pop ratios also varied seasonally with higher ratios in the summer 221 vs the winter 158 the fact that poc fluxes remained relatively constant throughout the year indicates that in winter fresher less degraded organic material was more effectively transported to depth strong correlations between pop and opal fluxes r2 5 0 63 further support a ballast mechanism whereby enhanced sinking rates reduce the time during which organic matter is subjected to water column degradation compared to trap concentrations pop is preferentially remineralized over pip in concert with an increase in the authigenic p pool this signifies rapid diagenetic transformations of sedimentary p between the sediment trap and underlying sediments

experimental study of igneous and sedimentary apatite dissolution control of ph distance from equilibrium and temperature on dissolution rates apatite dissolution experiments were conducted using both a fluidized bed and stirred tank reactor over a range of ph temperature solution saturation state and on non carbonated and carbonated apatite compositions igneous fluorapatite fap and sedimentary carbonate fluorapatite cfa respectively from 2 8 5 were not possible due to detection limits of the analytical techniques used in this study and the high insolubility of fap for the cfa compositions studied the dissolution rate decreased with increasing ph from 4 ph 7 during early stages of the dissolution reaction for both fap and cfa mineral components were released in non stoichiometric ratios with reacted solution ratios of dissolved ca p and ca f being greater than mineral stoichiometric ratios suggesting that ca was preferentially released compared to p and f from the mineral structure during the early stages of dissolution an increase in reacted solution ph accompanies this early elevated release of ca as the dissolution reaction proceeded to steady state dissolution became congruent when normalized to bet measured surface area fap dissolved faster from 4 ph 7 compared to cfa the apparent arrhenius activation energy ea of fap dissolution over the temperature range of 25 55 c at ph 3 0 i 0 1 and pco2 0 is 8 3 0 2 kcal mol 1 both the apparent exchange of solution h for solid bound ca at low ph in the early stage of dissolution and the ea of dissolution suggest a surface and not a diffusion controlled dissolution reaction for fap and cfa the degree of undersaturation of the solution gr with respect to fap was important in determining the dissolution rate at ph 3 0 i 0 1 and pco2 0 the dissolution rate of fap was 5 greater in the far from equilibrium region compared to the near equilibrium slope region a simple apatite weathering model incorporating the experimental results from this study was constructed and numerical calculations suggest that during the phanerozoic both the surface area of igneous rock available for weathering and the average global temperature were important factors in determining the p weathering flux from apatite dissolution it is possible that elevated global temperatures coupled with relatively high surface area of igneous rock during the early to mid paleozoic resulted in elevated p weathering fluxes which along with climatic evolutionary pressures of the neoproterozoic facilitated the radiation of multicellular organisms large scale phosphorite deposition and abundance of calcium phosphate shelled organisms during the early cambrian

the arctic oscillation signature in the wintertime geopotential height and temperature fields the leading empirical orthogonal function of the wintertime sea level pressure field is more strongly coupled to surface air temperature fluctuations over the eurasian continent than the north atlantic oscillation nao it resembles the nao in many respects but its primary center of action covers more of the arctic giving it a more zonally symmetric appearance coupled to strong fluctuations at the 50 hpa level on the intraseasonal interannual and interdecadal time scales this arctic oscillation ao can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft it is proposed that the zonally asymmetric surface air temperature and mid tropospheric circulation anomalies observed in association with the ao may be secondary baroclinic features induced by the land sea contrasts the same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature sea level pressure and 50 hpa height over the past 30 years parts of eurasia have warmed by as much as several k sea level pressure over parts of the arctic has fallen by 4 hpa and the core of the lower stratospheric polar vortex has cooled by several k these trends can be interpreted as the development of a systematic bias in one of the atmosphere s dominant naturally occurring modes of variability

intense biological phosphate uptake onto particles in subeuphotic continental margin waters elucidating the processes that affect particulate phosphorus p export from the euphotic zone and burial in sediments is important for models of global phosphorus nitrogen and carbon cycling we investigated dissolved inorganic pi incorporation into particles 0 2 m in the sub euphotic zone and benthic boundary layer bbl of high productivity mauritanian and namibian shelf waters using 33po43 tracer experiments combined with a sequential chemical extraction analysis pi uptake 5 4 to19 9 nmol p l 1d 1 by particulate matter was biologically mediated 50 into the organic fraction and similar to estimated rates of heterotrophic growth thus a substantial fraction of pi must be recycled through a particle associated microbial pool rapid adsorption of 33p in the anoxic waters of namibia indicated the additional existence of a large pool of surface exchangeable p particle associated pi recycling and adsorption may influence the export flux and ultimate fate of particle bound p in continental shelf waters

vivianite is a major sink for phosphorus in methanogenic coastal surface sediments abstract studies of authigenic phosphorus p minerals in marine sediments typically focus on authigenic carbonate fluorapatite which is considered to be the major sink for p in marine sediments and can easily be semi quantitatively extracted with the sedex sequential extraction method the role of other potentially important authigenic p phases such as the reduced iron fe phosphate mineral vivianite fe ii 3 po4 8h2o has so far largely been ignored in marine systems this is in part likely due to the fact that the sedex method does not distinguish between vivianite and p associated with fe oxides here we show that vivianite can be quantified in marine sediments by combining the sedex method with microscopic and spectroscopic techniques such as micro x ray fluorescence xrf elemental mapping of resin embedded sediments as well as scanning electron microscope energy dispersive spectroscopy sem eds and powder x ray diffraction xrd we further demonstrate that resin embedding of vertically intact sediment sub cores enables the use of synchrotron based microanalysis x ray absorption near edge structure xanes spectroscopy to differentiate between different p burial phases in aquatic sediments our results reveal that vivianite represents a major burial sink for p below a shallow sulfate methane transition zone in bothnian sea sediments accounting for 40 50 of total p burial we further show that anaerobic oxidation of methane aom drives a sink switching from fe oxide bound p to vivianite by driving the release of both phosphate aom with sulfate and fe oxides and ferrous fe aom with fe oxides to the pore water allowing supersaturation with respect to vivianite to be reached the vivianite in the sediment contains significant amounts of manganese 4 8 wt similar to vivianite obtained from freshwater sediments our results indicate that methane dynamics play a key role in providing conditions that allow for vivianite authigenesis in coastal surface sediments we suggest that vivianite may act as an important burial sink for p in brackish coastal environments worldwide

effect of microbial growth rate on temperature and metabolic water recorded in 18o 16o ratios of po4 in dna abstract it has been recently demonstrated that both temperature and intracellular metabolic water are recorded by the po4 moieties comprising the backbone of dna in microbial cells as well as in total microbial biomass po4 blake et al 2016 li et al 2016 temperature and intracellular water composition are reflected in the 18o 16o ratio of po4 18op in dna blake et al 2016 to determine whether the reported temperature recording by microbial dna po4 could be an artifact of variable microbial growth rate which may also vary as a function of temperature three strains of microorganisms having distinct and different growth rate patterns between 23 and 42 c pseudomonas fluorescens acinetobacter adp1 and marinobacter aquaeolei were cultured over a range of temperatures and growth rate patterns growth curve patterns for the different strains were distinct and growth rates increased with temperature however as we show here variations in 18op values of dna po4 did not correlate with changes in bacterial growth rates at a given temperature and o isotope fractionations i e partitioning of o isotopes between po4 in dna and o in water were not significantly different between strains

phosphate oxygen isotopes insights into sedimentary phosphorus cycling from the benguela upwelling system abstract marine sediments are the main sink in the oceanic phosphorus p cycle the activity of benthic microorganisms is decisive for regeneration reflux or burial of inorganic phosphate pi which has a strong impact on marine productivity recent formation of phosphorites on the continental shelf and a succession of different sedimentary environments make the benguela upwelling system a prime region for studying the role of microbes in p biogeochemistry the oxygen isotope signature of pore water phosphate 18op carries characteristic information of microbial p cycling intracellular turnover of phosphorylated biomolecules results in isotopic equilibrium with ambient water while enzymatic regeneration of pi from organic matter produces distinct offsets from equilibrium the balance of these two processes is the major control for 18op our study assesses the importance of microbial p cycling relative to regeneration of pi from organic matter from a transect across the namibian continental shelf and slope by combining pore water chemistry sulfate sulfide ferrous iron pi steady state turnover rate modeling and oxygen isotope geochemistry of pi we found 18op values in a range from 12 8 to 26 6 both in equilibrium as well as pronounced disequilibrium with water our data show a trend towards regeneration signatures disequilibrium under low mineralization activity and low pi concentrations and microbial turnover signatures equilibrium under high mineralization activity and high pi concentrations these findings are opposite to observations from water column studies where regeneration signatures were found to coincide with high mineralization activity and high pi concentrations it appears that preferential pi regeneration in marine sediments does not necessarily coincide with a disequilibrium 18op signature we propose that microbial pi uptake strategies which are controlled by pi availability are decisive for the alteration of the isotope signature this hypothesis is supported by the observation of efficient microbial pi turnover equilibrium signatures in the phosphogenic sediments of the benguela upwelling system

phosphorus burial and diagenesis in the central bering sea bowers ridge iodp site u1341 perspectives on the marine p cycle abstract to reconstruct the cycling of reactive phosphorus p in the bering sea a p speciation record covering the last 4 ma was generated from sediments recovered during integrated ocean drilling program iodp expedition 323 at site u1341 bowers ridge a chemical extraction procedure distinguishing between different operationally defined p fractions provides new insight into reactive p input burial and diagenetic transformations reactive p mass accumulation rates mars are 20 110 mol cm2 ka which is comparable to other open ocean locations but orders of magnitude lower than most upwelling settings we find that authigenic carbonate fluorapatite cfa and opal bound p are the dominant p fractions at site u1341 an overall increasing contribution of cfa to total p with sediment depth is consistent with a gradual sink switching from more labile p fractions fish remains fe oxides organic matter to stable authigenic cfa however the positive correlation of cfa with al content implies that a significant portion of the supposedly reactive cfa is non reactive detrital contamination by eolian and or riverine cfa in contrast to cfa opal bound p has rarely been studied in marine sediments we find for the first time that opal bound p directly correlates with excess silica contents this p fraction was apparently available to biosiliceous phytoplankton at the time of sediment deposition and is a long term sink for reactive p in the ocean despite the likelihood for diagenetic re mobilisation of this p at depth indicated by increasing ratios of excess silica to opal bound p average reactive p mars at site u1341 increase by 25 if opal bound p is accounted for but decrease by 25 if 50 of the extracted cfa fraction based on the lowest cfa value at site u1341 is assumed to be detrital combining our results with literature data we present a qualitative perspective of terrestrial cfa and opal bound p deposition in the modern ocean riverine cfa input has mostly been reported from continental shelves and margins draining p rich lithologies while eolian cfa input is found across wide ocean regions underlying the northern hemispheric dust belt opal bound p burial is important in the southern ocean north pacific and likely in upwelling areas shifts in detrital cfa and opal bound p deposition across ocean basins likely occurred over time responding to changing weathering patterns sea level and biogenic opal deposition

tracking selenium in the chalk aquifer of northern france sr isotope constraints groundwater at the southern and eastern edges of france s paris basin has a selenium content that at times exceeds the european framework directive s drinking water limit value of 10 g l to better understand the dynamics of the chalk groundwater being tapped to supply the city of lille and the se origins we used a combination of geochemical and isotopic tools strontium isotopes coupled with ca sr mg sr and se sr ratios were used to identify the main groundwater bodies and their mixings with the mg sr ratio constraining a ternary system groundwater in the agricultural aquifer recharge zone represents a first end member and displays the youngest water ages of the catchment along with the highest strontium isotopic signature 0 7084 and low se contents anaerobic groundwater constitutes a second major end member affected by water rock interactions over a long residence time with the lowest strontium isotopic signature 0 7079 and the lowest se content its low sf6 content confirming the contribution of old water se rich groundwater containing up to 30 g l of se represents a third major end member with an intermediate sr isotopic ratio and is mainly constrained by the clayey se rich formation overlying the chalk aquifer the spatial and temporal se variability in the groundwater is clearly linked to the presence of this formation identified as tertiary and also to the hydrological conditions saturation of the se rich clays by oxygenated groundwater enhances se mobility and also sr adsorption onto the clays this multi tool study including sr isotopes successfully identified the se origins in the aquifer and has led to a better understanding of the regional mixing and processes affecting the chalk groundwater

leaching behavior of selenium from the karst infillings of the hydrogeological experimental site of poitiers abstract the selenium enrichment in groundwater may be caused by the contact with sedimentary formations in many french regions geogenic sedimentary sources of se were identified as responsible of the se concentrations exceeding the european limit in many wells designated to produce drinking water this study focuses on the black argillaceous infillings of the hydrogeological experimental site of poitiers hesp and aims to better understand the se release mechanisms at the interface between these infillings and aqueous media using batch experiments with variable ph and contact time the se behavior as function of ph was similar in the ultrapure water and in the hesp water and can be discriminated in three main domains for very acidic domain the speciation of the released se that can be associated to the dissolution of some mineral phases was majorly unidentified for 2 in situ data confirm the diversity and the complexity of the release mechanisms of se that is not associated with a specific carrier phase but disseminated within the sedimentary matrix