coherence maps for wind forced quasigeostrophic flows abstract coherence maps are a useful tool to study the oceanic response to atmospheric forcing for a specific frequency band these maps display the coherence between the oceanic current or pressure at a single mooring location and the atmospheric forcing field at other locations as a function of separation this paper calculates such coherence maps from a simple linear quasigeostrophic model forced by a statistically stationary and homogeneous wind field the calculated coherence maps show values less than one such values are not due to the presence of noise but are a consequence of the ocean being forced at many locations the maps also show characteristic patterns with maxima either at the mooring location or away from it the locations of the maxima do not indicate the locations of the forcing but instead reflect the scales of the atmospheric forcing spectrum and of the green s function of the potential vorticity equation coherence maps can be used to estimate the green s function in a multiple re

13c and 15n nmr spectroscopic investigation on the formation of fossil algal residues 13c and 15n nmr spectroscopy was applied to modern a mixed algal culture its algaenan and its compost ancient algal derived sediments from mangrove lake bermuda and fossilized algal residues torbanite green river shale for the purpose of establishing the forms of nitrogen algal remains and evaluating their long term stabilities the results indicate that proteinaceous material can resist microbial degradation in sediments as old as 4000 yr possibly in refractory biopolymers by encapsulation into their macromolecular network the 15n nmr spectra of the torbanite and the green river shale show a relative enrichment of heterocyclic n which may derive from selective preservation of biogenic heterocyclic compounds or by rearrangement of peptide chains during diagenesis

subtidal bottom pressure observed at axial seamount in the northeastern continental margin of the pacific ocean since september 1987 bottom pressure bp has been observed at axial seamount 45 57 5 n 130 00 3 w 1540 m depth located 450 km off the oregon coast on the juan de fuca ridge observations from 1987 to 1992 show that subtidal axial bp is dominated by barotropic 2 to 5 mbar fluctuations with frequencies 1 9 cycles per day cpd they are slightly smaller than subtidal bp observed 720 km to the west during the ocean storms experiment and a factor of 2 4 smaller than the subtidal fluctuations of adjusted sea level asl at the coast for the period september 1987 to july 1988 axial bp and ocean storms bp are significantly coherent coh2 0 5 except at intraseasonal frequencies 1 100 1 20 cpd and in a band 1 8 1 6 cpd of low axial bp variance in the coherent frequency bands the phase relationships between the two bp series suggest independent atmospheric forcing on the other hand axial bp and coastal asl are not coherent except at the fortnightly tidal frequency looking for possible forcing of axial bp by the curl of the wind stress curl over the ne pacific data analyses show that axial bp and curl derived from european centre for medium range weather forecasts winds are significantly coherent in only two frequency bands one band narrowly peaked near 1 9 1 cpd for curl in regions south of axial seamount and a 1 5 1 3 5 cpd band for curl in a large region nw of the seamount in the 1 5 1 3 5 band axial bp also has a small amplitude spectral peak associated with bottom trapped baroclinic currents near axial seamount remote axial bp curl coherence at some frequencies is qualitatively consistent with the local forcing theory of lippert and muller 1995 that attributes the coherence to stable phase relationships and the spatial characteristics of the bp curl transfer function however the axial bp curl comparison is inhibited by the lack of accurate estimates of curl within 400 km of the coast fully understanding the origins and dynamics of subtidal bp at axial seamount will require a knowledge of how the complex topography in the region affects the barotropic and baroclinic responses to atmospheric forcing as well as the propagation of rossby and other waves

barotropic rossby waves radiating from tropical instability waves in the pacific ocean abstracttropical instability waves are triggered by instabilities of the equatorial current systems and their sea level signal with peak amplitude near 5 n is one of the most prominent features of the dynamic topography of the tropics cross spectral analysis of satellite altimetry observations shows that there is sea level variability in the pacific ocean as far north as hawaii i e 20 n that is coherent with the sea level variability near 5 n associated with tropical instability waves within the uncertainty of the analysis this off equatorial variability obeys the dispersion relation for nondivergent barotropic rossby waves over a fairly broad range of periods 26 38 days and zonal wavelengths 9 23 of longitude that are associated with tropical instability waves the dispersion relation and observed wave properties further suggest that the waves are carrying energy away from the instabilities toward the north pacific subtropical gyre which together with the observed coherence of the sea

geoelectric field measurements on a planetary scale oceanographic and geophysical applications the characteristics of an initial year of electric field measurements obtained from a long 3900 krn unpowered submarine cable extending from point arena california to hanauma bay hawaii are reported the power spectrum estimated from the cable time series is similar to that from seafloor point electric field sensors at frequencies above 1 cpd but differs at lower frequencies by decreasing monotonically down to at least 0 02 cpd the multiple squared coherence between the cable data and three component geomagnetic fluctuations measured at fresno ca is high t2 0 9 from 1 0 0 09 cpd then declines slowly with decreasing frequency maps of the squared coherence between the cable voltage and the sur face air pressure wind stress and wind stress curl derived from the fleet numerical oceanography center product over the entire eastern north pacific show no significant relationships at frequencies above 0 05 cpd but strong nonlocal coherence with the wind stress curl forcing obtains at lower frequencies taken together these observations support a transition from high frequency dominance by external sources to low frequency dominance by oceanic motional sources at 0 05 0 1 cpd a considerably smaller value than has previously been observed with point electric field sensors on the ocean bottom the difference is caused by horizontal averaging of the short spatial scale motional component over the long submarine cable

efficient sequestration of terrigenous organic carbon in the new britain trench abstract the fate of terrigenous organic carbon octerr in the ocean remains an enigma for four decades hadal trenches the deepest ocean realm 6 11 km deep were recently proposed to be oc depocenters but whether and how much octerr was sequestrated there remain elusive here we conducted comprehensive analyses for four sediment cores from the new britain trench nbt close to papua new guinea to assess source translocation and burial of oc the bulk and molecular radiocarbon data suggest that the nbt landward slope and axis sediments mainly receive young and biogenic rather than petrogenic oc the three endmember mixing model based on 14c 13c and oc contents reveals that sediments of the nbt axis 8225 m comprise relatively high oc contents 0 66 0 08 of which biogenic octerr accounts for 62 10 the high proportion of biogenic octerr was attributed to the selective translocation of octerr enriched coarse particles and rapid delivery of sediments supported by unique v shape feature of the trench in contrast the sediment oc at the oceanward slope is primarily of a marine origin suggesting that octerr was efficiently trapped in the trench bottom it is estimated that the burial rate is 2 75 0 32 g c m 2 yr 1 for oc and 1 69 0 41 g c m 2 yr 1 for octerr in the nbt given a fact that many trenches are close to the landmasses we propose that the hadal trenches may contribute significantly to the burial of octerr in the ocean

the global distribution of f h and the barotropic response of the ocean the barotropic response of the ocean over smoothly varying topography is directly related to the potential vorticity gradient f h a global estimate of f h and f h have been constructed from a high resolution digital topographic data base four different regimes of the barotropic response of the ocean are suggested by these maps 1 in the tropical latitudes from 20 s to 20 n f h h the response will be similar to a flat bottom sverdrup regime 2 in mid latitudes 20 to 70 north of 30 s f h h the response will be quasi stationary weak and dominated by nonlocal forcing flow along isolines of f h 3 in a number of small regions throughout the mid latitudes in both hemispheres f h h in these regions the local response flow across isolines of f h should be amplified and wavelike motions may occur over a broader bandwidth of frequencies 4 south of 30 s the mid ocean ridge system becomes zonal and isolates several large regions within closed lines of f h in these regions principally the abyssal plains of the southern ocean the low frequency barotropic response of the ocean may be wavelike in character and much stronger than the sverdrup response consequently this analysis suggests that the southern ocean may have a stronger barotropic response to wind forcing than the other five major ocean basins

using motionally induced electric signals to indirectly measure ocean velocity instrumental and theoretical developments abstract the motion of conductive sea water through the earth s magnetic field generates electromagnetic em fields through a process called motional induction direct measurements of oceanic electric fields can be easily converted to water velocities by application of a first order theory this technique has been shown to obtain high quality velocities through instrumental advances and an accumulation of experience during the past decades em instruments have unique operational considerations and observe for instance vertically averaged horizontal velocity from stationary sensors or vertical profiles of horizontal velocity from expendable probes or autonomous profiling floats the first order theory describes the dominant electromagnetic response in which vertically averaged and vertically varying horizontal velocities are proportional to electric fields and electric currents respectively after discussions of the first order theory and deployment practices operational capabilities are shown through recently published projects that describe stream coordinate velocity structure of the antarctic circumpolar current quickly evolving overflow events in the denmark strait and time development of momentum input into the ocean from a hurricane a detailed analysis of the gulf stream at its separation point from the continental slope serves as a case study for interpreting em measurements including the incorporation of geophysical knowledge of the sediment in addition the first order approximation is tested by the many features at this location that contradict the approximation s underlying assumptions sharp horizontal velocity gradients steep topography and thick and inhomogeneous sediments numerical modeling of this location shows that the first order assumption is accurate to a few percent a few cm s 1 in almost all cases the errors in depth varying velocity are 1 are substantiated by the direct observations and can be corrected by iterative methods though errors in the depth uniform velocity are 1 1 or less in almost all regions of the ocean an error similar to the instrumental accuracy of em instruments

barotropic rossby wave radiation from a model gulf stream 1 the barotropic rossby wave field in the north atlantic ocean is studied in an eddy resolving ocean model simulation the meandering model gulf stream radiates barotropic rossby waves southward through preferred corridors defined by topographic features the smoother region between the bermuda rise and the mid atlantic ridge is a particularly striking corridor of barotropic wave radiation in the 20 50 day period band barotropic rossby waves are also preferentially excited at higher frequencies over the bermuda rise suggesting resonant excitation of topographic rossby normal modes the prevalence of these radiated waves suggests that they may be an important energy sink for the equilibrium state of the gulf stream

specific surface areas in coastal sediments relationships with other textural factors abstract sediment specific surface area can be a controlling variable in sediment biogeochemistry therefore a variety of granulometric techniques have been employed to infer relative and absolute surface areas in sediments this study compares specific surface areas with other textural parameters for a suite of aluminosilicate sediments from the gulf of maine and contiguous estuaries the intragranular porosity of sediment grains increases with grain size and is probably due to varying relative contributions of nanometer and micrometer sized pores poor sorting of sediments causes underestimation of absolute surface areas by geometrical calculation using measures of central tendency underestimation is worse in coarser estuarine sediments owing to a combination of increased roughness factors of coarser grains and poorer sorting relative surface areas among sediments may be accurately assessed by measuring the proportion clay or fine silt means and medians do not provide accurate estimation of relative surface areas unless the samples share similar sorting characteristics an algorithm to predict absolute surface areas from grain size distributions of gulf of maine sediments is presented

surface area control of organic carbon accumulation in continental shelf sediments the relationship between organic carbon oc and grain size found in most continental shelf sediments is here reinterpreted in terms of the surface area of the sediments cores from many north american shelf environments show downcore decreases in oc to similar refractory background concentrations if expressed relative to the surface area of the sediments this consistent concentration is 0 86 mg oc m 2 which is equivalent in concentration to a monolayer of organic matter coating all mineral surfaces a more global collection of sediment water interface samples show that this relationship is even more extensive with exceptions occurring in areas of very high riverine sediment input organic pollution or low oxygen water columns density separations indicate that organic matter is largely adsorbed to mineral grains the microtopography of surfaces was examined with n2 sorption and most surface area was found to be inside pores of 10 nm width these data lead to a hypothesis that organic matter is protected by its location inside pores too small to allow functioning of the hydrolytic enzymes necessary for organic matter decay such protection would likely work in concert with other protection mechanisms such as humification this consistent surface area correlation with oc concentration may explain control of spatial and temporal variations in oc burial rates by sedimentation rates the pore protection hypothesis provides a causal mechanism for this observed control

the effects of surface area grain size and mineralogy on organic matter sedimentation and preservation across the modern squamish delta british columbia the potential role of sediment surface area in the formation of petroleum source rocks abstract surface sediment samples were collected from the squamish river delta british columbia in order to determine the role of sediment surface area in the preservation of organic matter om in a paralic sedimentary environment the squamish delta is an actively prograding delta located at the head of howe sound bulk total organic carbon toc values across the squamish delta are low ranging from 0 1 to 1 0 wt the carbon total nitrogen ratio c org n ranges from 6 to 17 which is attributed to changes in om type and facies variations the org n ratio that ranges from 14 to 16 the 53 106 m fraction has higher toc concentrations and c org n ratios relative to the 25 53 m fraction the c org n ratio ranges from 9 to 18 in the 53 106 m fraction and 5 5 10 5 in the 25 53 m fraction surface area values for bulk sediments are low 0 5 3 0 m 2 g due to the large proportion of silt size material good correlation between surface area and toc in bulk samples suggests that om is adsorbed to mineral surfaces similar relationships between surface area and toc were observed in size fractionated samples mineralogy and elemental composition did not correlate with toc concentration the relationships between surface area toc and total nitrogen tn can be linked to the hydrodynamic and sedimentological conditions of the squamish delta as a result the squamish delta is a useful modern analogue for the formation of petroleum source rocks in ancient deltaic environments where toc concentrations are often significantly lower than those in source rocks formed in other geological settings

near 13 day barotropic ocean response to the atmospheric forcing in the north pacific 1 in the kuroshio extension system study kess east of japan bottom pressure observations over the 2 year study period exhibit strong high frequency variability near 13 days the first cyclostationary empirical orthogonal function mode for the band pass filtered kess bottom pressure explains about 57 of the near 13 day variance and exhibits almost in phase variability in space with a hint of westward propagation the 13 day variability is strong during the winter and is driven by the large scale wind stress curl over a broad region of the north pacific modeling results over the north pacific closely follow the observations and indicate that topography confines the barotropic response to the west of emperor seamount chain and slows the westward propagation of the near 13 day bottom pressure variability

a method of inferring changes in deep ocean currents from satellite measurements of time variable gravity 1 the nasa deutsches zentrum fur luft und raumfahrt dlr satellite gravity mission gravity recovery and climate experiment grace launched in march 2002 will map the earth s gravity field at scales of a few hundred kilometers and greater every 30 days we describe a method of using those gravity measurements to estimate temporal variations in deep ocean currents we examine the probable accuracy of the current estimates by constructing synthetic grace data based in part on output from an ocean general circulation model we ignore the possible contamination caused by short period gravity signals aliasing into the 30 day solutions we conclude that in the absence of aliasing grace should be able to recover the 30 day variability of midlatitude currents at a depth of 2 km with an error of about 6 15 in variance when smoothed with 500 700 km averaging radii

observations and modeling of wind driven currents in the northeast pacific abstract velocity measurements from the interior of the alaskan gyre are presented from a current meter mooring deployed in 4000 m of water at 49 33 n 138 38 w in the vicinity of ocean weather station p the mooring held five current meters which spanned the depth of the water column the data reveal surface intensified motions with flow fluctuations in the upper layers of the water column characterized by long period o 100 d time scales of variability at abyssal depths the flow displays shorter o 20 d time scales of variability the data are compared with observations from one of the nepac moorings in the northeast pacific 42 n 152 w similar characteristics in kinetic energy levels in the vertical structure of the flow and in the vertical variation of eddy time scales are found at this location the current measurements are considered in terms of the linear theory of directly wind driven variability of muller and frankignoul a comparison with simulated currents from a quasigeostrophic num

efficient preservation of young terrestrial organic carbon in sandy turbidity current deposits burial of terrestrial biospheric particulate organic carbon in marine sediments removes co2 from the atmosphere regulating climate over geologic time scales rivers deliver terrestrial organic carbon to the sea while turbidity currents transport river sediment further offshore previous studies have suggested that most organic carbon resides in muddy marine sediment however turbidity currents can carry a significant component of coarser sediment which is commonly assumed to be organic carbon poor here using data from a canadian fjord we show that young woody debris can be rapidly buried in sandy layers of turbidity current deposits turbidites these layers have organic carbon contents 10 higher than the overlying mud layer and overall woody debris makes up 70 of the organic carbon preserved in the deposits burial of woody debris in sands overlain by mud caps reduces their exposure to oxygen increasing organic carbon burial efficiency sandy turbidity current channels are common in fjords and the deep sea hence we suggest that previous global organic carbon burial budgets may have been underestimated

the relationship between deep ocean currents and winds east of barbados abstract observations of currents collected at the polymode array iii cluster c 16 n 54 w are compared with radiosonde winds measured at barbados 13 n 62 w using a linear response analysis the winds and the currents are coherent throughout the water column 5400 m over the subinertial frequency range of 0 025 to 0 25 cpd the coherence is highest between the east west wind stress and north south currents over smooth topography the wind related ocean currents have a rms of 2 5 cm s 1 at 500 m and 1 1 cm s 1 at 4000 m and account for approximately one third of the total eddy kinetic energy the wind current phase is depth independent and does not vary significantly over the 200 km horizontal scale of the array the response amplitude is surface intensified and increases with decreasing frequency which is consistent with a deterministic theoretical model the coherence values and response estimates suggest an off resonant barotropic response to large scale wind forcing

δ14c of the organic matter in sediments from the antarctic polar front origin and dynamics of sedimentary organic carbon abstract 14 c of sedimentary organic matter was measured on one sediment core from the deep sea below the subantarctic front of the indian ocean using acceleration mass spectrometry in the mixed layer values decrease from the sediment water interface 263 to 10 cm depth 446 with a sharp gradient in the first 2 cm this indicates the loss of organic younger fractions due to mineralization of labile organic matter during bioturbation and burial in the upper sediment layer a previously published model limnol oceanogr 43 1998 420 combined with suppositions concerning the 14 c content of each organic carbon fraction produces a good agreement with the radiocarbon data our data set supports a strong biogeochemical coupling between the pelagic zone and the sediment in this region the low 14 c values found at depth in the sediment point to a particular source of the refractory organic matter it could originate from adsorption of old deep sea dissolved organic carbon on falling particles nature 347 1990 172 and contribute largely to the burial of organic carbon in this type of sediment

a 3 800 million year isotopic record of life from carbon in sedimentary rocks an increased ratio of 12c to 13c an indicator of the principal carbon fixing reaction of photosynthesis is found in sedimentary organic matter dating back to almost four thousand million years ago a sign of prolific microbial life not long after the earth s formation partial biological control of the terrestrial carbon cycle must have been established very early and was in full operation when the oldest sediments were formed

sedimentary organic matter geochemistry of clayoquot sound vancouver island british columbia surface sediment samples from three interconnected fjords of clayoquot sound british columbia were density fractionated 1 6 g cm 3 to isolate discrete organic debris od from mineral associated organic matter mom total organic carbon oc values varied greatly ranging from 0 1 to 8 8 by weight with a general decreasing trend from fjord head to the continental shelf within the sediment terrestrial om was present either as vascular plant debris or soil mom down fjord the woody vascular plant material in the od fraction acquires nitrogen which is hypothesized to be due to the bacterial incorporation of nitrogen from the water terrestrial oc in the mom is incompletely replaced by marine oc within the fjords resulting in a 65 net loss of mom sediments deposited under oxic and intermittently anoxic water column conditions have organic carbon to surface area ratios oc sa ranging from 0 4 to 1 2 mg c m 2 similar to that of typical continental margin sediments given that temperate fjords contain an estimated 12 of the continental margin sediment deposited during the last 100 000 yr and that they bury at least a margin equivalent amount of oc either weight or surface area normalized we hypothesize that temperate fjords may contain 12 or more of the sedimentary oc buried during this time

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

a note on the barotropic response of sea level to time dependent wind forcing this study examines the extent to which sea level variations at periods between 30 days and 1 year and spatial scales greater than 1000 km can be described by the wind driven linear barotropic vorticity dynamics the topex poseidon altimetric observations of sea level and the wind products of the national meteorological center are used as the database for the study each term of the linear barotropic vorticity equation was evaluated by averaging over regions of 10 10 in most of the open ocean the result of the analysis suggests that the sea level variabilities at the scales considered cannot be fully described by the equation the apparent net vorticity change is more than what can be explained by the local wind stress curl in the few regions where the wind stress curl is strong enough to balance the vorticity budget predominantly in the northeast pacific and the southeast pacific the balance is basically achieved in terms of the time dependent topographic sverdrup relation namely the balance between the advection of the planetary vorticity plus the topography induced vorticity and the forcing by the wind stress curl

the barotropic electromagnetic and pressure experiment 1 barotropic current response to atmospheric forcing during 1986 1987 an array of horizontal electrometers which measure the subinertial barotropic velocity was deployed for 11 months in the central north pacific to study atmospherically forced motions in a low eddy kinetic energy region significant coherence is found to be ubiquitous between the barotropic velocity and one or more surface atmospheric variables over the north pacific the maximum squared coherence between currents and wind stress curl at all periods greater than 3 days is typically 0 6 rarely below 0 4 and occasionally above 0 8 and is dominantly nonlocal although local coherence is seen at some sites especially at the shorter periods both the coherence and the intersite pattern similarity are strongest at the periods of relative maxima in the barotropic current autospectra e g at 6 8 10 14 and 20 50 days the locations at which the wind stress curl forces the motions at each site and for each period have been determined while there is substantial intersite variability some of the observed patterns of squared coherence over the north pacific are very similar to those predicted by simple linear smooth bottomed quasi geostrophic models of atmospherically forced barotropic currents the forcing location is occasionally found to be the same spot for all oceanic instruments especially at the autospectral maxima in barotropic current more commonly distinct forcing locations are found for each instrument even when closely spaced suggesting topographic influence in other cases multiple forcing locations are implicated for the motions at a single station all of this site and period dependent variability of the forcing location is incompatible with the simple models and is due either to the known spatial inhomogeneity of the curl forcing field or to topographic effects the importance of the former is emphasized using simple arguments based on analytic transfer functions between the atmospheric and oceanic variables and on observed wavenumber spectra for wind stress curl quantitative assessment of topographic effects must await suitable numerical models in addition maximum likelihood wavenumber spectra of the barotropic currents have been estimated in those bands with an adequate number of coherent sensors the wavenumbers at the spectral peaks are compatible with the dispersion relation for rossby waves modified by the observed large scale linearly sloping topography which shoals to the northeast the observed group velocities are in general quite consistent with the inferred forcing locations based on the ocean atmosphere coherences

variability of the wind stress curl over the north pacific implications for the oceanic response the subinertial frequency wavenumber structure and spatial coherence of wind stress curl and their spatial and temporal variability are described with the emphasis on characteristics which affect the ocean s response to the wind stress curl forcing function wind stress curl over the north pacific between 25 o and 60on was computed for 3 years 1985 1988 from the fleet numerical oceanography center wind product the range from winter peak to summer trough for the mean and variance are typically a factor of 3 4 and 10 respectively with superimposed interannual changes of up to a factor of 2 power spectra vary seasonally and interannually in an essentially frequency independent manner that is consistent with the curl variance however the spectrum over the period band 5 100 days often fails a statistical test for whiteness at the 95 level zonal and meridional wavenumber spectra were estimated for 13 sites distributed around the central eastern north pacific using the maximum likelihood method directional trends with frequency are comparable to those from earlier studies if 3 year long data segments are analyzed with approximate wavenumber symmetry except for the zonal term at mid latitudes for periods shorter than 10 days where eastward propagation is dominant however spectra for shorter data sections sometimes display eastward and westward excursions which are only weakly similar over distances of 1000 km and essentially dissimilar over longer separations the spatial correlation structure of wind stress curl is shown typically to have a main lobe of 1000 km and multiple intercorrelation lobes separated by 2000 km the strength and location of the intercorrelation peaks vary slowly with time these results suggest that curl behavior is more complex than was previously believed that the use of long term averages of or simple parameterizations for the frequency wavenumber spectrum of wind stress curl in model studies may be unrealistic and that more attention to actual curl characteristics at the time oceanic measurements are collected will be required to reconcile models with observations

observations of vortex rossby waves associated with a mesoscale cyclone abstract short wavelength l 100 km rossby waves with an eastward zonal phase velocity were observed by high frequency radio doppler current meters and moored adcps west of oahu hawaii during spring 2003 they had rossby numbers ro f o 1 periods of 12 15 days and phase speeds of 8 9 cm s 1 and they were surface trapped with vertical e folding scales of 30 170 m they transferred horizontal kinetic energy to the background flow of a mesoscale cyclone lying 160 190 km west of oahu revealed by altimetry the waves approximately satisfied the dispersion relation of vortex rossby waves propagating through the radial gradient of potential vorticity associated with the cyclone vertical shear of the background currents may also affect wave propagation theoretical studies have shown that vortex rossby waves provide a mechanism by which perturbed vortices axisymmetrize and strengthen and may be important to the dynamics of oceanic vortices

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

on subinertial oscillations trapped by the juan de fuca ridge northeast pacific spectra of currents measured along the 2100 m deep juan de fuca ridge in the northeast pacific have prominent tidal inertial and weather band 3 7 day period spectral peaks the weather band peak in particular has a number of interesting features it is strongest in close lateral proximity to the ridge and strongest near ridge depth intensification near the ridge is characteristic of trapped motion spectral peak intensities vary seasonally with largest amplitudes occurring in autumn and winter seasonal variation suggests that surface weather is forcing flow at depth together trapping and seasonality indicate opportunistic amplification of oscillatory motion at the ridge at all frequencies forcing topography and stratification together shape current and hydrographic distributions near the ridge effects of those interactions for subinertial motion are quantified here using a primitive equation numerical model forcing period 1 10 days and friction are the principal dependencies examined results show that flow over the juan de fuca ridge can be amplified by factors of 3 4 for diurnal and up to a factor of 7 for weather band frequencies amplification is ridge trapped with effects extending many hundreds of meters upward and extending 5 10 km laterally for 5 day period flow the strength and area of amplification increase with increasing period over the 1 to 10 day period band oscillatory weather band flow leads to vertical velocities on the order of 0 3 cm s 1 on ridge flanks which in turn cause periodic temperature t and salinity s variations with amplitudes of as much as 0 05 c and 0 01 practical salinity units respectively the vertical motion and consequent vertical displacement 100 m lead to isotherms that plunge below the crest alternately each side of the ridge a distribution observed in conductivity temperature depth transect data near the ridge crest cross ridge baroclinic pressure gradients caused by cyclically plunging isopycnals are in near geostrophic balance with the coriolis force associated with along ridge flow along ridge current amplification is therefore closely tied to isopycnal movement up and down ridge flanks since weather band oscillations lead to much larger cross ridge baroclinic pressure gradients than do diurnal motions of the same amplitude weather band forcing causes greater along ridge current amplification results vary strongly with forcing period and direction of forcing with respect to the ridge but depend only moderately on friction and turbulent mixing coefficients

surface area measurements of marine basalts implications for the subseafloor microbial biomass colonization ssa ranged from 0 3 to 52 m 2 g of basalt with the lowest value coming from pillow basalt and the highest value from breccia the average for massive and pillow basalts combined was 2 3 m 2 g the total specific surface area of the extrusive volcanic rocks of the ocean crust is estimated to be 10 24 m 2 this surface area could provide attachment for up to 10 34 cells if cell density is the same as that of experimentally colonized basalt surfaces independent measures and calculations of biomass in basalts suggest that cell densities on surfaces are only 10 4 times those in laboratory experiments and therefore the surface area of basalt does not limit microbial biomass in the igneous ocean crust citation nielsen m e and m r fisk 2010 surface area measurements of marine basalts implications for the subseafloor microbial biomass geophys res lett 37 l15604 doi 10 1029 2010gl044074

ambiguities in direct dating of rock surfaces using radiocarbon measurements an attempt was made to date rock surfaces with accelerator mass spectrometry ams radiocarbon measurements of rock varnishes or rock weathering rinds in two case studies samples pretreated in the laboratory of dr ronald dorn prior to ams analysis have been found to contain significant quantities of carbon rich materials of two distinct classes type i material resembles bituminous coal whereas type ii material resembles pyrolized wood charcoal fragments in samples where these type i and type ii materials were separated and ams radiocarbon dated they were found to have widely differing radiocarbon ages in these cases the measurement of the radiocarbon age of the entire sample would yield results that are at best ambiguous neither type i nor type ii materials were found in comparable samples that were independently prepared

a local time dependent sverdrup balance in the eastern north pacific ocean direct observations of the dynamic balance between time dependent winds and deep ocean currents are described for the eastern north pacific ocean at 42 n 152 w currents from 150 to 4000 meters below the surface at frequencies from 0 01 to 0 1 cycle per day are significantly correlated with the wind stress curl derived from u s navy operational wind fields the horizontal currents are depth independent below 300 meters and they flow parallel to the potential vorticity gradient derived from the earth9s rotation and the large scale bottom topography these characteristics are expected for such periodic motions with horizontal scales larger than 500 kilometers and represent a generalized sverdrup balance between the atmospheric forcing and the oceanic response

bioturbation and holocene sediment accumulation fluxes in the north east atlantic ocean benthic boundary layer experiment sites bioturbation and holocene sediment accumulation are quantified in the three experimental areas of the benthic boundary layer benbo programme by means of the natural radionuclides 14c and 210pb and the artificial radionuclides 137cs and 241am the holocene accumulation rates determined by the radiocarbon method are 4 4 and 6 5 cm kyr 1 at sites b rockall plateau 1100 m water depth and c feni drift 1925 m water depth respectively accumulation at site a situated between feni drift and porcupine bank at 3570 m water depth was interrupted by an erosional event in the mid holocene which removed 0 25 m or more of the uppermost sediment present at that time the estimated accumulation rate since that event is 2 1 cm kyr 1 different estimates of surficial bioturbation mixing depths at site b are returned by the 210pbexcess and 14c methods with the former indicating 10 cm and the latter unusually deep at 17 cm at site c 210pbexcess and the fallout radionuclides 137cs and 241am are present in two distinctly separated depth zones with the deepest mixing down to 15 cm similar to the 14c mixed layer depth this is ascribed to deep burrowing by sipunculid or echiuran worms at site c and similar deep mixing is inferred to be necessary at site b to produce the differences in mixed layer depths derived from the longer and shorter lived radionuclide profiles although the deep burrowing episodes must be rare 1 event per 102 yr the greater accumulation rate at site c compared with site b is produced by an enhanced flux of current driven clay and silt sized material this fine material both dilutes the caco3 content of the site c sediment and is responsible for the higher corg content observed at site c compared with site b unlike the site b and c sediments which are fine grained the coarse 63 125 m size fraction is the most abundant size class in the late holocene sediments at site a suggesting that the sediments at this location are winnowed

observations of motional electromagnetic fields during emslab the long period 1 day behavior of the seafloor electromagnetic fields during emslab is considered in detail with an emphasis on interpretation in terms of oceanic motions the study begins with a summary of the physics of motional electromagnetic induction in which the seawater conductivity weighted vertically integrated velocity measured by the horizontal electric field is emphasized using frequency domain methods it is shown that seafloor and terrestrial magnetic variations have similar spectral shapes indicating a common origin but the seafloor electric field is not consistent with either at periods longer than 4 days suggesting an oceanic source the magnetic field variations are highly coherent across the emslab array at periods shorter than 9 days but the similarity decreases at longer periods probably due to long term instrumental drift the seafloor horizontal electric field data exhibit the broadband coherence characteristic of ionospheric sources only at periods shorter than 1 2 days and are essentially incoherent between 4 days and a week except in association with certain propagating wave phenomena the distinction between the depth averaged velocity inferred from the horizontal electric field and its point measurement by the vertical electric field is demonstrated with data some specific properties of the seafloor electric fields are then considered in detail the first of these is a 4 day wave observed to propagate from north to south along the east flank of the juan de fuca ridge the wavelength propagation sense and association with the ridge are all consistent with topographically trapped rossby wave behavior at a zero in the group velocity a second north to south propagating wave is seen at periods of 8 12 days in the middle of the emslab area with a probable wavelength of order 1000 km unresolved low frequency structures in the electric field are also mentioned these observations clearly demonstrate the power of electromagnetic array methods for the study of long period oceanic behavior

stochastically forced current fluctuations in vertical shear and over topography the effects of constant vertical shear of zonal velocity uniform meridional bottom slope and a deep meridional wall representing the mid atlantic ridge on the response of a linear two layer quasi geostrophic ocean to stochastic wind stress curl forcing are investigated the model is motivated by discrepancies in energy levels and distributions between recent observations and a similar model without shear or topography that predicted remote coherences relatively well the results indicate that the presence of mean shear can significantly enhance the wind generation of surface intensified oceanic kinetic energy at frequencies above the zero shear cutoff for free baroclinic waves the primary effect of the sloping topography is enhanced barotropic response near the barotropic topographic sverdrup resonance where topographic and planetary potential vorticity gradients cancel the wall inhibits the barotropic response and increases coherences on the mooring side of the wall remote coherences for 49 day period fluctuations are due to long barotropic waves as in the previous model so the present model only partially reconciles the previous discrepancies

motional induction effect on the planetary scale geoelectric potential in the eastern north pacific geoelectric potentials induced by seawater motion on a planetary scale were studied using voltage differences measured on the hawaii 1 haw 1 submarine cable between hanauma bay oahu hawaii and point arena california the motionally induced field was extracted from a 3 6 year segment of the haw 1 voltage by cancelling the component that is coherent with the externally produced geomagnetic field at honolulu the corrected voltage shows significant coherence with atmospheric variables wind stress curl wind stress and surface pressure estimated from the european centre for medium range weather forecasts product at points throughout the pacific basin at periods from 5 to 133 days this suggests that the voltage reflects regional to basin wide depth averaged barotropic water currents that are directly wind driven contour maps of the squared coherence reveal that 1 peak coherence as large as 0 6 0 8 is seen at points both near the cable and nonlocally 2 higher coherence is seen at periods where the cable voltage power spectrum peaks and 3 spatial patterns of the coherence vary with period comparison of power spectra or coherence maps for individual years shows that the wind driven flow fluctuates temporally owing to long term variations of the wind field the main features of these observations are consistent with those from point electric field measurements suggesting that planetary scale voltages measured with cables can serve as a useful tool to monitor large scale water currents at long periods

kerogen origin evolution and structure kerogen commonly defined as the insoluble macromolecular organic matter om dispersed in sedimentary rocks is by far the most abundant form of om on earth this fossil material is of prime importance as the source of oil and natural gas moreover kerogen can provide essential information on major topics such as past environments climates and biota this review reports the main advances in kerogen studies since the comprehensive synthesis edited by durand durand b ed kerogen insoluble organic matter from sedimentary rocks editions technip paris 1980 it is organized into eight sections the first two are concerned with the successive definitions of kerogen and the definition used here the different techniques used for kerogen isolation without loss or degradation and basic kerogen analysis the third and fourth focus on sedimentary om sources and preservation processes in relation to depositional environment including sedimentation conditions favourable for kerogen accumulation and extrapolation to past geological time great strides have been made in the latter topics over the last 25 years owing to a combination of classical studies in organic geochemistry and studies in other domains such as biogeochemistry oceanography hydrology and soil science along with the development of powerful analytical tools the next two sections deal with the different kerogen classifications by type and kerogen evolution and maturation upon burial in sediments structural modelling of coal and kerogen based on physical and or chemical structural analysis is described in the following section although only statistical the models thus derived provide a synthetic view of the main structural resemblances and differences among various samples in relation to source maturity or physicochemical properties finally the last section explores some of the advances in kerogen understanding expected for the near future the review includes a list containing about 500 references

observations of wind forced deep ocean currents in the north pacific this study examines the atmospheric response of the deep ocean using 200 instrument years of moored current measurements from across the breadth of the mid latitude north pacific we have found evidence of a seasonal modulation in the ocean eddy kinetic energy beneath the thermocline at several locations north of 35 n this modulation is often in phase with the local atmospheric forcing function at frequencies between 0 1 and 0 01 cpd correlations between the local wind stress curl and the deep currents have been found for a few locations the local forced response is parallel to the potential vorticity gradient f h and consistent in amplitude with a local topographic sverdrup balance nonlocal forcing in the form of flow along isolines of potential vorticity has been estimated and it is comparable to the observed flow at some locations but the modeled flow is not correlated with the observations throughout the mid latitude north pacific the bottom slope tends to enhance the effect this suggests that topography narrows the available bandwidth for forced barotropic rossby waves facilitating a quasi steady topographic sverdrup response over most of the basin however the enhanced effect reduces the magnitude of the ocean s response to wind forcing nonlocally forced sverdrup currents flow along isolines of f h are the dominant component but are only of the order of 1 cm s 1 locally forced sverdrup currents flow across isolines of f h are typically of the order of 0 1 cm s 1 rms and are not commonly measured hence these wind forced variations are a background level signal in the mid latitude eddy kinetic energy in a few isolated areas the bottom slope reduces the effect in these regions the local sverdrup response is amplified and has been observed

biomarkers and geochemical indicators of holocene environmental changes in coastal lake sarbsko poland organic rich samples from the holocene sedimentary sequence of lake sarbsko were investigated to reconstruct variations in the aquatic system in response to environmental change the aims were to i identify organic matter om sources ii examine changes in soluble om composition in relation to fluctuations in limnological conditions and iii validate the sensitivity of organic geochemical indicators in tracing environmental changes diatom frustules are abundant in all samples alginite macerals and terrigenous organic matter further contribute to the sedimentary om organic petrography total organic carbon toc n ratio values and high content of biogenic silica sio2 biogenic argue for a predominant algal source of om in contrast the n alkane distributions high relative abundance of c29 steroid hydrocarbons and high content of detrital quartz in the sediments provide evidence for the input of terrigenous material as a major om source within the basin the terpenoid biomarker composition indicates a contribution from conifers and angiosperms from the diterpenoids in the samples a contribution from species of the coniferales family pinaceae is concluded toc s and mg ca values as well as steroid hopanoid concentration ratios reflect enhanced water salinity in this coastal lake due to ingression of brackish water from the baltic sea during the atlantic and sub atlantic periods as indicated by the positive relationship between d 13 c of toc and mg ca d 13 c values are influenced by changing contribution of marine vs freshwater phytoplankton additional isotopic heterogeneity in d 13 c may result from differences in terrigenous om supply vs autochthonous om production in the lake the isotopic composition of calcites supports the establishment of freshwater conditions in the lake during the sub boreal period pristane phytane and fe mn ratios are interpreted to reflect differences in the redox conditions oxygenation of bottom waters was temporarily variable with highest levels of oxygen availability during the sub boreal freshwater lake high contents of hopanoid hydrocarbons argue for enhanced microbial activity in the water column and sediment the occurrence of 2b methyl hopanes is related to the presence of cyanobacteria or methylotrophic bacteria

disentangling marine soil and plant organic carbon contributions to continental margin sediments a multi proxy approach in a 20 000 year sediment record from the congo deep sea fan abstract a 20 kyr long sediment sequence from the congo deep sea fan core geob 6518 1 one of the world s largest deep sea river fans has been analysed for bulk and molecular proxies in order to reconstruct the marine soil and plant organic carbon oc contributions to these sediments since the last glacial maximum the bulk proxies applied c n ratio and 13 c org ranged from 10 to 12 5 and from 24 5 to 21 vpdb respectively as molecular proxies concentrations of marine derived alkenones and terrestrial derived odd numbered n alkanes were used which varied between 0 2 and 4 g g dry weight sediment in addition the branched vs isoprenoid tetraether bit index a proxy for soil organic matter input was used which varied from 0 3 to 0 5 in this core application of binary mixing models based on the different individual proxies showed estimates for terrestrial oc input varying by up to 50 due to the heterogeneous nature of the oc application of a three end member mixing model using the 13 c org content the c n ratio and the bit index enabled the distinction of soil and plant organic matter as separate contributors to the sedimentary oc pool the results show that marine oc accounts for 20 to 40 of the total oc present in the deep sea fan sediments over the last 20 kyr and that soil oc accounts for about half 45 on average of the oc present this suggests that soil oc represents the majority of the terrestrial oc delivered to the fan sediments accumulation rates of the plant and soil oc fractions over the last 20 kyr varied by a factor of up to 5 and are strongly related to sediment accumulation rates they showed an increase starting at ca 17 kyr bp a decline during the younger dryas peak values during the early holocene and lower values in the late holocene this pattern matches with reconstructions of past central african humidity and congo river discharge from the same core and revealed that central african precipitation patterns exert a dominant control on terrestrial oc deposition in the congo deep sea fan marine oc accumulation rates are only weakly related to sediment accumulation rates and vary only little over time compared to the terrigenous fractions these variations are likely a result of enhanced preservation during times of higher sedimentation rates and of relative small fluctuations in primary production due to wind driven upwelling

a seasonal signal in ocean currents to abyssal depths long term 9 32 month current meter records from the eastern north atlantic 41 n 59 n suggest that remote from the influence of the western boundary current eddy kinetic energy ke at all depths is principally a function of wind stress and stratification generated during the winter and early spring propagating to abyssal depths and decaying to a minimum in late summer although this seasonal variation in ke has not previously been described from the midlatitude ocean some theoretical basis for it is presented

the barotropic response of the subpolar north pacific to stochastic wind forcing in a recent observational study koblinsky et al 1989 attempted to demonstrate that the topographic sverdrup balance can account for mesoscale current fluctuations with periods between 10 and 100 days in the abyssal north pacific however the topographic sverdrup balance proved difficult to verify systematically over the north pacific in this paper the conditions required to obtain the topographic sverdrup balance are investigated through numerical experiments with a stochastically forced barotropic quasi geostrophic numerical model of the subpolar north pacific in the numerical experiments the topographic sverdrup balance emerges from area averages of the terms in the vorticity equation but only for periods longer than about 40 days when the averages are taken over 4 4 region this period increases when averages are taken over progressively smaller regions an examination of vorticity balances at individual points along sections through the model domain indicates that the topographic sverdrup balance is not obtained at individual points even for very long period motions the possibility of verifying topographic sverdrup dynamics with oceanic data is considered it is argued that topographically generated small scales in the velocity field reduce the likelihood that the topographic sverdrup balance can be systematically observed in velocity measurements from individual current meter moorings the results suggest that the vorticity balance is complex and that topographic sverdrup dynamics cannot be expected to provide an adequate explanation for the seasonal modulation of the abyssal eddy kinetic energy that is observed with moored instrumentation in the north pacific

alpine debris flows triggered by a 28 july 1999 thunderstorm in the central front range colorado on 28 july 1999 about 480 alpine debris flows were triggered by an afternoon thunderstorm along the continental divide in clear creek and summit counties in the central front range of colorado the thunderstorm produced about 43 mm of rain in 4 h 35 mm of which fell in the first 2 h several debris flows triggered by the storm impacted interstate highway 70 u s highway 6 and the arapahoe basin ski area we mapped the debris flows from color aerial photography and inspected many of them in the field three processes initiated debris flows the first process initiated 11 of the debris flows and involved the mobilization of shallow landslides in thick often well vegetated colluvium the second process which was responsible for 79 of the flows was the transport of material eroded from steep unvegetated hillslopes via a system of coalescing rills the third which has been termed the firehose effect initiated 10 of the debris flows and occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans these three processes initiated high on steep hillsides 30 in catchments with small contributing areas 8000 m2 however shallow landslides occurred on slopes that were significantly less steep than either overland flow process based on field observations and examination of soils mapping of the northern part of the study area we identified a relation between the degree of soil development and the process type that generated debris flows in general areas with greater soil development were less likely to generate runoff and therefore less likely to generate debris flows by the firehose effect or by rilling the character of the surficial cover and the spatially variable hydrologic response to intense rainfall rather than a threshold of contributing area and topographic slope appears to control the initiation process in the high alpine of the front range because debris flows initiated by rilling and the firehose effect tend to increase in volume as they travel downslope these debris flows are potentially more hazardous than those initiated by shallow landslides which tend to deposit material along their paths

speciation and spatial distribution of solid phase iron in surface sediments of the east china sea continental shelf abstract speciation and reactivity characterization of solid phase fe in marine sediments are of significance to understanding its heterogeneous mineralogy and crystallinity the diagenetic cycling of fe and its regulating roles on many other elements in sediments in this study a combination of sequential and single step extractions was used for the determination of seven fe pools in surface sediments of the east china sea ecs continental shelf 1 carbonate associated fe fe ii carb plus acid volatile sulfide fe fe ii avs 2 easily reducible amorphous poorly crystalline fe oxides fe ox1 3 reducible crystalline fe oxides fe ox2 4 magnetite fe mag 5 poorly reactive sheet silicate fe fe prs 6 pyrite fe fe py and 7 unreactive silicate fe fe u total fe fe t in the sediments is largely determined by terrestrial aluminosilicate particles as indicated by a great similarity of the fe t with that of the yangtze river and global riverine particulates the size of fe prs is found to be the largest pool followed by fe u fe ox2 fe mag fe ii avs carb fe ox1 and fe py the large fe prs may result from neoformation of fe rich clay minerals via reverse weathering and subsequent ageing the small sizes of fe ii avs carb and fe py pools is believed to be the result of low so 4 reduction due to generally low labile organic matter together with the oxic suboxic dynamic environments of the surface sediments the occurrence of fe ox1 fe ox2 and fe prs in the sediments is closely associated with the clay fraction as indicated by a high spatial correlation between the former and the latter highly reactive fe fe hr in the sediments is comparable to that in global marine sediments but apparently lower than in the yangtze river and global riverine particulates due probably to sequestration in the yangtze estuary the ratios of fe hr fe t fe pr fe t and fe u fe t in the ecs surface sediments consistently show more similarity to those in the yangtze river particulates than in the global continental margin or deep sea sediments the surface sediments maintain a high level of buffering capacity toward sulfidation suggested by a large fraction of highly reactive fe iii oxides fe iii hr in fe hr

exceptional preservation of expandable clay minerals in the ca 2 1 ga black shales of the francevillian basin gabon and its implication for atmospheric oxygen accumulation abstract clay minerals are exceptionally well preserved in marine black shale of the ca 2 1 ga francevillian group in southeastern gabon the fb formation of the francevillian group is characterized by smectite rich clay minerals including randomly ordered r0 type and ordered r1 type mixed layer illite smectite i s the preservation of r0 type clay minerals suggests unexpectedly slow mineral transformation and a moderate degree of diagenesis which is unique considering the paleoproterozoic age of the sedimentary rocks r0 and r1 type smectite rich particles occur in stratigraphic intervals with high organic carbon content and are associated with carbonaceous filamentous structures suggesting formation of clay organic matter complexes our data suggests that clay minerals may have enhanced organic matter preservation providing the oldest example where a link between clay minerals and organic matter sequestration can be established our findings are consistent with the hypothesis that clay minerals enhanced organic carbon burial and aided in atmospheric oxygen accumulation through time

evidence for wind driven current fluctuations in the western north atlantic two subsurface current meter moorings were deployed for 20 months along 70 w in a low energy portion of the western north atlantic the resulting data were compared with estimates of the wind stress curl in an attempt to seek a relationship between currents below the mixed layer and meteorological forcing at subinertial frequencies currents and temperature tend to be significantly coherent with the curl and are most coherent with the curl at remote locations usually more than 500 km away from the mooring and generally to the east coherences generally decrease with increasing frequency the current response is surface intensified a linear stratified model for stochastically wind forced rossby waves in a flat bottomed ocean is presented as an attempt to rationalize the results the effort was not entirely successful so that it appears that a more realistic model perhaps including bottom topography and mean currents will be needed to rationalize these observations fully

impact of storm induced remobilization on grain size distribution and organic carbon content in sediments from the blanes canyon area nw mediterranean sea abstract interactions between organic carbon and mineral particles are known to play a key role for the preservation of organic carbon in marine sediments in this study we combine meteorological hydrological and oceanographic information with grain size and geochemical analyses organic carbon oc its stable isotope 13 c and the nitrogen to oc ratio in different grain size fractions of surface sediments to determine the impact of a major storm on organic matter redistribution in a deep continental margin of the nw mediterranean sea sediment cores were obtained from the continental shelf along the axis of the blanes submarine canyon bc and in the adjacent southern open slope before november 2008 and after february and may 2009 the occurrence of one of the most severe coastal storms recorded in the last century in the study area the storm occurred the 26 of december 2008 and dramatically impacted the north catalan coast and its offshore area the high shear stress produced by this event on the shelf floor led to sediment erosion and subsequently to its transport and deposition into bc while sand and gravel sized particles up to 2500 m in diameter were deposited at 300 m of water depth in the canyon head the finer particles the results obtained show that the hydrodynamic processes that controlled the sorting and differential deposition of particles according to their grain size also controlled the redistribution of particles with different loads of oc thus whereas coarse particles transported to the canyon head were poorly loaded with oc fine particles reaching greater depths were relatively rich in oc a significant proportion of which was of marine origin i e derived from marine primary production this adds to evidence that the physical action of waves and currents during storms plays a key role in determining the amount of oc stored in surface sediments not only in the shelf but also in the deep margin and possibly deeper

loss of organic matter from riverine particles in deltas abstract in order to examine the transport and burial of terrigenous organic matter along the coastal zones of large river systems we assessed organic matter dynamics in coupled river delta systems using mineral surface area as a conservative tracer for discharged riverine particulate organic matter pom most pom in the rivers studied n 6 is tightly associated with suspended mineral material e g it is sorbed to mineral surfaces average organic loadings in the amazon river 0 67 0 14 mg c m 2 the river for which we have the largest dataset are approximately twice that of sedimentary minerals from the amazon delta 0 35 mg c m 2 stable carbon isotope analysis indicate that approximately two thirds of the total carbon on the deltaic particles is terrestrial the combined surface normalized isotope distinguished estimate is that 70 of the amazon fluvial pom is not buried in the delta consistent with other independent evidence aller et al 1996 losses of terrestrial pom have also been quantified for the river delta systems of columbia in the usa fly in new guinea and huange he in china if the losses of riverine pom observed in these river delta systems are representative of rivers worldwide then the surface constrained analyses point toward a global loss of fluvial pom in delta regions of 0 1 x 1015 g c y 1

stochastic forcing of the north atlantic wind driven ocean circulation part i a diagnostic analysis of the ocean response to stochastic forcing abstract at midlatitudes the magnitude of stochastic wind stress forcing due to atmospheric weather is comparable to that associated with the seasonal cycle stochastic forcing is therefore likely to have a significant influence on the ocean circulation in this work the influence of the stochastic component of the wind stress forcing on the large scale wind driven circulation of the north atlantic ocean is examined to this end a quasigeostrophic model of the north atlantic was forced with estimates of the stochastic component of wind stress curl obtained from the ncar community climate model analysis reveals that much of the stochastically induced variability in the ocean circulation occurs in the vicinity of the western boundary and some major bathymetric features thus the response is localized even though the stochastic forcing occurs over most of the ocean basin using the ideas of generalized stability theory the stochastically induced response in the ocean circulation can be interpreted as

relationships between mineral surfaces and organic carbon concentrations in soils and sediments abstract relationships between mineral specific surface area and organic carbon oc concentration are examined for sediments and soil a horizons from throughout the world i found published elsewhere that continental shelf sediments from many different regions exhibit downcore loss of oc to a refractory background level which shows a consistent relationship with mineral surface area slope 0 86 mg m 2 oc this trend is equivalent to a monolayer of organic matter over all surfaces and is termed the monolayer equivalent me level sediments and soils from other environments are compared to this empirically derived relationship several continental slope areas show extension of this relationship to considerable depth marked excesses of oc above this trend which persist downcore were found in sediments with high carbonate mineral content or slope sediments with low dissolved oxygen concentrations in the overlying water column about half of the soils examined also adhered to this relationship while soils with high carbonate content low ph or poor drainage showed oc concentrations higher than the me level oc concentrations below the me level are found in deltaic regions and areas with low organic matter delivery such as the deep sea or arid soils the nature of mineral surfaces was examined using n2 adsorption desorption isotherms and most surface area was found to be present as pores with

multiple plant wax compounds record differential sources and ecosystem structure in large river catchments abstract the concentrations distributions and stable carbon isotopes 13c of plant waxes carried by fluvial suspended sediments contain valuable information about terrestrial ecosystem characteristics to properly interpret past changes recorded in sedimentary archives it is crucial to understand the sources and variability of exported plant waxes in modern systems on seasonal to inter annual timescales to determine such variability we present concentrations and 13c compositions of three compound classes n alkanes n alcohols n alkanoic acids in a 34 month time series of suspended sediments from the outflow of the congo river we show that exported plant dominated n alkanes c25 c35 represent a mixture of c3 and c4 end members each with distinct molecular distributions as evidenced by an 8 1 0 7 1 standard deviation spread in 13c values across chain lengths and weak correlations between individual homologue concentrations r 0 52 0 94 in contrast plant dominated n alcohols c26 c36 and n alkanoic acids c26 c36 exhibit stronger positive correlations r 0 70 0 99 between homologue concentrations and depleted 13c values individual homologues average 31 3 and 30 8 respectively with lower 13c variability across chain lengths 2 6 0 6 and 2 0 1 1 respectively all individual plant wax lipids show little temporal 13c variability throughout the time series 1 0 9 indicating that their stable carbon isotopes are not a sensitive tracer for temporal changes in plant wax source in the congo basin on seasonal to inter annual timescales carbon normalized concentrations and relative abundances of n alcohols 19 58 of total plant wax lipids and n alkanoic acids 26 76 respond rapidly to seasonal changes in runoff indicating that they are mostly derived from a recently entrained local source in contrast a lack of correlation with discharge and low stable relative abundances 5 16 indicate that n alkanes better represent a catchment integrated signal with minimal response to discharge seasonality comparison to published data on other large watersheds indicates that this phenomenon is not limited to the congo river and that analysis of multiple plant wax lipid classes and chain lengths can be used to better resolve local vs distal ecosystem structure in river catchments

currents forced by stochastic winds with meridionally varying amplitude motivated by discrepancies between observations and previous theory we present a stochastically forced model of wind driven current fluctuations that includes the observed northward intensification of wind stress curl a feature absent from a previous model the model is linear barotropic and quasi geostrophic it is bounded by absorbing walls along lines of constant latitude in the north and south and is unbounded east and west the northward wind intensification causes a northward bias in the coherence of wind stress curl and currents that is similar to that observed art unanticipated secondary maximum occurs northeast of the mooring in the low frequency 37 day period meridional velocity coherence predictions