salinity history of the earth s early ocean it is commonly thought that the oceans are becoming saltier with time as sodium and chlorine are weathered out of continental rocks and transported to the sea here we argue that the salinity of the early ocean was 1 5 to 2 times the modern value and that it did not decline significantly until surprisingly late in the earth s history if correct this theory could help explain why the evolution of higher life took so long

internal waves across the pacific 1 the long range propagation of the semidiurnal internal tide northward from the hawaiian ridge and its susceptibility to parametric subharmonic instability psi at the critical latitude c 28 8 n were examined in spring 2006 with intensive shipboard and moored observations spanning 25 37 n along a tidal beam velocity and shear at c were dominated by intense vertically standing inertially rotating bands of several hundred meters vertical wavelength these occurred in bursts following spring tide contrasting sharply with the downward propagating wind generated features seen at other latitudes these marginally stable layers which have inverse 16 meter richardson number ri16 1 0 7 are interpreted as the inertial waves resulting from psi of the internal tide elevated near inertial energy and parameterized diapycnal diffusivity and reduced asymmetry in upgoing downgoing energy were also observed at and equatorward of c yet simultaneous moored measurements of semidiurnal energy flux and 1 km deep velocity sections measured from the ship indicate that the internal tide propagates at least to 37 n with no detectable energy loss or phase discontinuity at c our observations indicate that psi occurs in the ocean with sufficient intensity to substantially alter the inertial shear field at and equatorward of c but that it does not appreciably disrupt the propagation of the tide at our location

climatic impacts of parameterized local and remote tidal mixing abstractturbulent mixing driven by breaking internal tides plays a primary role in the meridional overturning and oceanic heat budget most current climate models explicitly parameterize only the local dissipation of internal tides at the generation sites representing the remote dissipation of low mode internal tides that propagate away through a uniform background diffusivity in this study a simple energetically consistent parameterization of the low mode internal tide dissipation is derived and implemented in the geophysical fluid dynamics laboratory earth system model with gold component gfdl esm2g the impact of remote and local internal tide dissipation on the ocean state is examined using a series of simulations with the same total amount of energy input for mixing but with different scalings of the vertical profile of dissipation with the stratification and with different idealized scenarios for the distribution of the low mode internal tide energy dissipation uniformly over ocean basins co

overturning circulation driven by breaking internal waves in the deep ocean a global estimate of the water mass transformation by internal wave driven mixing in the deep ocean is presented the estimate is based on the energy conversion from tidal and geostrophic motions into internal waves combined with a turbulent mixing parameterization we show that internal wave driven mixing in the deep ocean can sustain 20 30 sv of water mass transformation one third or more of this transformation is attributed to lee waves generated by geostrophic motions flowing over rough topography primarily in the southern ocean while these results are uncertain due to many assumptions poorly constrained parameters and data noise that enter in the calculation the result that lee wave driven mixing plays an important role in the abyssal ocean circulation is likely robust the implication is that lee wave driven mixing should be represented in ocean and climate models but currently it is not citation nikurashin m and r ferrari 2013 overturning circulation driven by breaking internal waves in the deep ocean geophys res lett 40 doi 10 1002 grl 50542

bed sediment associated trace metals in an urban stream oahu hawaii of the 117 stream and lake systems sampled nationwide fish from manoa stream on oahu hawaii have consistently shown the highest pb concentrations therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5 8 km stretch of manoa stream a total of 123 samples 63 m were examined for 18 elements and 14 samples for 21 elements selected samples were also examined using different leach solutions to examine metal phase associations all trace metal data computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for cr and ni minor anthropogenic contamination for ba cd cu hg and zn and a very strong contamination signal for pb maximum pb contents up to 1080 mg kg 1 were associated with anthropogenic material dumping in minor tributaries storm sewer sediments and sediments in the lower section of the basin proportionally pb had the highest non residual component of elements examined dominantly in the reducible phase associated with mn and amorphous fe oxyhydroxides the contamination signal was typically lowest in the undisturbed headwater reach of the basin above 5 1 km with significant increases throughout the residential and commercial institutional zones of the mid basin the spatial pattern of bed sediment contamination and evidence from storm sewer outlet sediments strongly indicates that pb and to a lesser degree some other metals is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments the primary source of sediment associated metals is considered to be the automobile though other minor sources can not be ruled out

saturation of the internal tides and induced mixing in the abyssal ocean as part of an ongoing effort to develop a parameterization of wave induced abyssal mixing the authors derive an heuristic model for nonlinear wave breaking and energy dissipation associated with internal tides then the saturation and dissipation of internal tides for idealized and observed topography samples are investigated one of the main results is that the wave induced mixing could be more intense and more confined to the bottom than previously assumed in numerical models furthermore in this model wave breaking and mixing clearly depend on the small scales of the topography below 10 km or so which is below the current resolution of global bathymetry this motivates the use of a statistical approach to represent the unresolved topography when addressing the role of internal tides in mixing the deep ocean

zigzag microstructure in rugose corals a possible indicator of relative seawater mg ca ratios low mg calcite lmc and high mg calcite hmc have been identified confidently as original biominerals in different rugose corals devonian tabulophyllum had a lmc skeleton whereas pennsylvanian lophophyllidium had a hmc skeleton zigzag microstructure a diagenetic microstructure in rugose corals may be related to early migration of mg2 ions during transformation of hmc into lmc therefore zigzag microstructure may indicate that the original mineral was hmc even in specimens that subsequently converted to lmc stratigraphically corals with zigzag microstructure are confined to the late paleozoic which is coincident with the aragonite sea of p a sandberg hence fluctuating mg ca ratios may have directly controlled oscillations in marine carbonate chemistry and the mineral composition of rugose corals so that hmc skeletons as indicated by zigzag microstructure formed during intervals with aragonite seas and lmc skeletons e g tabulophyllum formed during intervals with calcite seas

chemical diagenesis of a multicomponent carbonate system 2 stable isotopes abstract this study examines the oxygen and carbon isotopic distribution in the brachiopods crinoids rugose corals and matrix cement from the mississippian burlington limestone iowa and missouri and the silurian read bay formation arctic canada the isotopic data can be reconciled with textural and trace element observations only if the 18o content of ancient oceans differed from that of the present oceans this postulated secular variation in the 18o content of seawater requires a separate evaluation of the mississippian and silurian carbonate components examination of the 18o content of the least altered low mg calcite fossil components of the two formations suggests that the 18o of mississippian seawater was on average about 1 5 lighter and that of silurian seawater was about 5 5 lighter than the 18o of present day ocean water the average diagenetic shift in 18o for the read bay formation which stabilized in a partly closed diagenetic phreatic meteoric system is about 1 for the original low mg calcite and about 2 for the original high mg calcite and aragonite components conversely for the burlington limestone which stabilized in an open diagenetic phreatic meteoric system the average diagenetic shift in 18o is about 3 for the original low mg calcite and about 4 f r the original high mg calcite components the 13c values of the originally low mg calcite or high mg calcite with less than 7 mole mgco3 brachiopods and rugose corals the originally high mg calcite crinoids and the originally aragonite lime mud of the burlington limestone and read bay formation are bimodally distributed this bimodal 13c distribution is independent of geologic age inferred original mineralogy of the component degree of diagenetic alteration and the type of diagenetic meteoric system with components from both the read bay formation and burlington limestone contributing to both 13c groups the mode of the light 13c group is 0 25 and for the heavy 13c group it is 3 25 pdb both 13c groups also show a decrease in 13c of about 1 with increasing diagenetic alteration stabilization

forcing of oceanic mean flows by dissipating internal tides we present a theoretical and numerical study of the effective mean force exerted on an oceanic mean flow due to the presence of small amplitude internal waves that are forced by the oscillatory flow of a barotropic tide over undulating topography and are also subject to dissipation this extends the classic lee wave drag problem of atmospheric wave mean interaction theory to a more complicated oceanographic setting because now the steady lee waves are replaced by oscillatory internal tides and most importantly because now the three dimensional oceanic mean flow is defined by time averaging over the fast tidal cycles rather than by the zonal averaging familiar from atmospheric theory although the details of our computation are quite different we recover the main action at a distance result from the atmospheric setting namely that the effective mean force that is felt by the mean flow is located in regions of wave dissipation and not necessarily near the topographic wave source specifically we derive an explicit expression for the effective mean force at leading order using a perturbation series in small wave amplitude within the framework of generalized lagrangian mean theory discuss in detail the range of situations in which a strong secularly growing mean flow response can be expected and then compute the effective mean force numerically in a number of idealized examples with simple topographies

phosphorus sequestration in fe rich sediments from two brazilian tropical reservoirs abstract this study investigates the important role of fe oxide hydroxide rich bottom sediments from two brazilian tropical reservoirs on p sequestration from the overlying waters which decreases the risk of eutrophication data on p fractionation indicates that p adsorption capacity of sediments is predominantly associated with fe followed by orthosphosphate adsorbed onto al hydr oxides and onto different forms of apatite ca p the soluble and loosely bound p forms are low to have a better understanding of the role of fe oxides on the adsorption and sequestration of p in the reservoirs data obtained by sequential extraction of p have been related to concentrations of total fe and of various fe fractions extracted through an optimized fractionation scheme these analyses indicated high levels of fe bound to oxides hydroxides these mineral oxides and the preponderance of ph dependent charged clay minerals kaolinite in the clay fraction induce the sequestration of the p entering the lakes mainly in particulate form by strong retention of po 4 3 through surface adsorption and precipitation phenomena phosphorus retention provided by the replacement of oh groups on the basal plane of the minerals for p anions decreases the negative impact of p inputs in these water systems there is significant correlation between the concentrations of soluble reactive p in the water srp and major chemical components of sediments sio2 fe2o3 al2o3 k2o p2o5 which are related to the dominant bedrock geology the interaction of srp with bed sediments and the chemical conditions of the environment decrease of redox potential with depth and in the dry period a low o2 abundance can explain fluctuations of srp and tp total p in the water column due to the dynamic equilibrium in the sediment water interface in the dry season reducing conditions in hypoliminia enhance the reduction of fe iii to the more soluble fe ii with subsequent release of the strongly retained p this mechanism increases the soluble p fraction in sediments and the soluble reactive p in the water column in this period the straight linkage between geochemical properties of sediments and p concentration in the water column reported in this article suggests that study of the mineralogical and geochemical composition of bottom sediments could help to improve model predictions of p concentrations in surface waters

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

status of sedimentation in king talal dam case study from jordan this paper focuses on characterizing the current status of physical and chemical characteristics of king talal dam ktd sediments the quality of sediments was investigated based on several international sediment quality guidelines the volume of sediment and sedimentation rate in ktd was also estimated five types of granulometric textural facies were observed for the sediments of ktd reservoir bed with an average grain size distribution of gravel 1 38 sand 32 38 silt 32 35 and clay 32 38 the fraction of pb zn co cr ni fe cu sr mn and cd zn pb co cr ni cu sr mn respectively based on the sonic survey of ktd reservoir the annual sedimentation rate was about 0 4061 mcm year in which about 18 66 of the reservoir initial storage capacity was lost to sediments and a projected lifespan of about 198 years

parametric subharmonic instability of the internal tide at 29 n observational evidence is presented for transfer of energy from the internal tide to near inertial motions near 298n in the pacific ocean the transfer is accomplished via parametric subharmonic instability psi which involvesinteractionbetweena primarywave the internaltide in this case andtwo smaller scale waves of nearly half the frequency the internal tide at this location is a complex superposition of a low mode waves propagating north from hawaii and higher mode waves generated at local seamounts making application of psi theory challenging nevertheless a statistically significant phase locking is documented between the internal tide and upward and downward propagating near inertial waves the phase between those three waves is consistent with that expected from psi theory calculated energy transfer rates from the tide to nearinertial motions are modest consistent with local dissipation rate estimates the conclusion is that while psi does befall the tide near a critical latitude of 298n it does not do so catastrophically

heavy metal concentrations in surface sediments from the two coastal inlets golden horn estuary and izmit bay of the northeastern sea of marmara a total of 57 surficial sediment samples collected in the golden horn estuary and izmit bay northeastern marmara sea was analyzed for the heavy metals fe mn cr ni co zn pb and cu and the results were compared with various natural and anthropogenic sources it was observed that the concentrations of zn cu pb and to some extent cr in the golden horn sediments are comparable with those in most other seas in the vicinity of highly industrialized and densely populated regions based on calculations from the metal al and metal fe ratios the bottom sediments of golden horn were found to be enriched in zn cu pb and to a lesser extent cr by factors of up to 192 compared with the regional background levels of these metals fe mn co and to some extent ni are mostly at natural levels in contrast the metal levels of the bottom sediments in izmit bay are significantly lower and they appear to be controlled by lithogenic rather than the anthropogenic influences highly significant correlation coefficients between the metals zn cu and pb are widely attributed to the common sources of these metals the metal smelters and shipyards in the vicinity of the areas studied based on the numerical value of the geoaccumulation index of heavy metals it was found that the bottom sediments of izmit bay can be regarded as basically uncontaminated exceptionally high igeo values are found for the bottom sediments of the golden horn indicating moderate to extreme contamination in this region by the metals pb zn cu and cr the presence of a large number of anthropogenic metal point sources higher river run off via the two major creeks particularly coastal topography and hydrodynamic conditions associated with the very high sedimentation rates all strongly favour the accumulation of anomalously high metal concentrations in the golden horn estuary while the opposite is true for izmit bay

oxygen and stable carbon isotopes from a nautiloid from the middle pennsylvanian late carboniferous impregnation lagerstatte buckhorn asphalt quarry primary paleo environmental signals versus diagenesis abstract two shell fragments one of an undetermined cephalopod and one of an orthoconic nautiloid pseudorthoceratidae gen et sp indet from the pennsylvanian buckhorn asphalt lagerstatte oklahoma were studied to reconstruct paleotemperatures and to explore possible diagenetic alterations for the first time not only parts of the shell of an orthoconic nautiloid but also its cameral deposits were sampled in high resolution the mineralogy geochemistry and microstructure of both shell remains the pseudorthoceratid and the undetermined cephalopod were investigated in detail before high resolution transects for oxygen and stable carbon isotopes were sampled the shell fragment of the undetermined cephalopod showed no or very little diagenetic alteration therefore the measured 18o variation 18o range of 0 68 and the inferred temperature range of 28 to 31 c are interpreted to represent an original signal the temperatures indicate that the specimen lived in shallow warm tropical waters the 13c signal with a 13c range of 3 43 is interpreted to be the consequence of a strong metabolic effect a septum of the phragmocone of the pseudorthoceratid nautiloid was only slightly altered by diagenesis and a largely original 18o signal could be obtained the 18o values exhibit an inferred temperature range of 14 to 15 c indicating that this species lived in deeper and cooler waters the cameral deposits were investigated in detail by energy dispersive x ray edx and by xrd gadds x ray diffraction general area detector diffraction system analyses part of the cameral deposits in the orthoconic nautiloid turned out to originally consist of high mg calcite hmc instead of the estimated aragonite anyhow the massive cameral deposits show signs of strong small scale alteration resulting in a distinct spreading of oxygen values the oxygen and carbon isotope plots show a linear trend for the oxygen carbon correlation this is interpreted as the mixing of two end members with the lightest end members suggesting a meteoric diagenesis with a diagenetic fractionation of the aragonite to low mg calcite lmc respectively the hmc to lmc and dolomite the calculated temperatures of the pseudorthoceratid specimen and the undetermined cephalopod indicate two different paleoenvironments additionally the pseudorthoceratid nautiloid displays the narrow range of temperatures in the deeper parts of the sea and the undetermined cephalopod the more fluctuating temperatures in the shallow areas it is also shown how important a detailed investigation of microstructures and mineralogy of samples with an according cautious interpretation of the achieved dataset is the importance of an intensive examination of samples is pointed out to avoid small scale alterations to be overlooked since this would lead to a misinterpretation of the results

a mechanism for local dissipation of internal tides generated at rough topography abstract fine and micro structure observations indicate that turbulent mixing is enhanced within o 1 km above rough topography enhanced mixing is associated with internal wave breaking and in many regions of the ocean has been linked to the breaking and dissipation of internal tides the generation and dissipation of internal tides are explored in this study using a high resolution two dimensional nonhydrostatic numerical model which explicitly resolves the instabilities leading to wave breaking configured in an idealized domain with a realistic multiscale topography and flow characteristics the control simulation chosen to represent the brazil basin region produces a vertical profile of energy dissipation and temporal characteristics of finescale motions that are consistent with observations results suggest that a significant fraction of mixing in the bottom o 1 km of the ocean is sustained by the transfer of energy from the large scale internal tides to smaller scale internal waves by nonlin

subtropical catastrophe significant loss of low mode tidal energy at 28 9 1 an idealized numerical study of a northward propagating internal tide reveals a dramatic loss of energy to small scale subharmonic instabilities near 28 9 n inspired by observations of the internal tide radiating northward from the hawaiian ridge a three dimensional numerical model is initialized with a northward baroclinic tidal flux of approximately 1 7 kw m after an initial spinup period energy is quickly transferred from the baroclinic tide to subharmonic motions with half the horizontal tidal wavenumber and small vertical scales through nonlinear advection of horizontal tidal velocity gradients potential oceanic implications are twofold first once a steady state has been reached the instability acts as a partial filter of northward tidal flux between 27 5 and 29 5 n in rough agreement with some altimetric tidal observations second elevated shear of the subharmonic motions suggests the potential for elevated near surface dissipation rates near the critical latitude that may be important for upper ocean mixing

turning ocean mixing upside down abstractit is generally understood that small scale mixing such as is caused by breaking internal waves drives upwelling of the densest ocean waters that sink to the ocean bottom at high latitudes however the observational evidence that the strong turbulent fluxes generated by small scale mixing in the stratified ocean interior are more vigorous close to the ocean bottom boundary than above implies that small scale mixing converts light waters into denser ones thus driving a net sinking of abyssal waters using a combination of theoretical ideas and numerical models it is argued that abyssal waters upwell along weakly stratified boundary layers where small scale mixing of density decreases to zero to satisfy the no density flux condition at the ocean bottom the abyssal ocean meridional overturning circulation is the small residual of a large net sinking of waters driven by small scale mixing in the stratified interior above the bottom boundary layers and a slightly larger net upwelling driven b

palaeoenvironmental reconstructions by stable isotopes of middle miocene gastropods of the central paratethys abstract the stable isotopes of carbon and oxygen were used to provide information of mixing of marine and freshwater and subsequently used to determine palaeosalinities in the middle to late miocene st margarethen zollhaus section upper sarmatian mactra zone pannonian a succession of three gastropod assemblages indicates changing environmental conditions from a limnic fluviatile to littoral mudflat and a sublittoral marine environment several shells of the main representatives of the three assemblages potamides hartbergensis hilber granulolabium bicinctum brocchi potamides disjunctus sowerby and additionally shells of lymnaea sp a typical freshwater gastropod and pomatias conicus a terrestrial gastropod were taken for stable isotope analyses oxygen and carbon isotope data of the freshwater endmember are distinctively lower 18 o 4 5 13 c 9 than of the marine endmembers 18 o 2 2 13 c 2 3 in contrast to the expected intermediate isotopic composition between the freshwater and marine environment the shells of supposed brackish environments have higher 18 o values than the shells of the marine environment these higher 18 o values are explained by evaporation which affected the protected areas of riverine to lacustrine environments and small pools on mudflats formerly considered to be the habitats of the brackish assemblages thus the oxygen and carbon isotope data extend the already existing palaeoenvironmental information

landscape geochemistry retrospect and prospect 1990 at present the terms environmental geochemistry and applied geochemistry are poorly defined in english in fact they usually mean just what a particular geochemist or geochemist s wishes them to mean there is a less common term landscape geochemistry which describes a holistic scientific discipline aimed at the geochemistry of the environment although little known outside the u s s r the basics of landscape geochemistry were first described more than 60 a ago since then landscape geochemistry has had a history pertinent to all scientists who participate in environmental geochemistry today this review traces the evolution of landscape geochemistry and related disciplines over the past 90 a and shows how they all relate to the development of modern environmental geochemistry worldwide in landscape geochemistry the term landscape refers to both the horizontal stratification of land e g into terrestial bog and aquatic ecosystems which co exist in an area of country and to the vertical stratification within these units e g into vegetation soils etc in these respects landscape geochemistry resembles landscape ecology which is currently a discipline of growing importance in environmental science landscape geochemistry differs from landscape ecology because it focuses attention on all aspects of the behaviour of chemical entities e g isotopes elements and ions in both living and dead matter in landscapes of all kinds from the viewpoint of general geochemistry landscape geochemistry focusess on the interaction of the lithosphere with the hydrosphere atmosphere and biosphere this holistic approach provides a common theoretical background for both pure and applied environmental geochemistry worldwide an important aspect of landscape geochemistry particularly pertinent to environmental geochemistry in the non soviet world today is that the subject provides a link between modern exploration geochemistry and modern environmental science including geochemistry historically landscape geochemistry stems from the russian school of landscape science this developed from the ideas of v v dokuchaev 1846 1903 around the turn of the century concepts unique to landscape geochemistry were first described in the 1920s by one of dokuchaev s students b b polynov 1867 1952 a i perel man 1909 a student of polynov began to teach landscape geochemistry at moscow university in 1952 since then the subject has become firmly established as the focus for fundamental and applied environmental geochemistry in the u s s r this review traces the development of landscape geochemistry from its origins around 1920 until 1990 the volume of literature pertinent to the review is voluminous for this reason attention is usually focused on the basic concepts and principles of landscape geochemistry and related scientific disciplines readers who require more detailed information on subjects covered in this review should consult the references cited the review is organized in four parts the first three trace the historical development of landscape geochemistry and related disciplines in three time periods these are 1 pre 1950 2 between 1950 and 1980 and 3 1980 1990 part 4 uses paradigms to summarize the historical evolution of landscape geochemistry and indicates how a global landscape geochemistry might develop in the future