anoxia controlled by relative sea level changes an example from the mississippian barnett shale formation abstract a continuous core drilled in the barnett shale formation fort worth basin texas united states a remarkable example of paleozoic organic rich sediments deposited in a narrow inland seaway was analysed by means of sedimentological geochemical and biostratigraphic data as the influence of sea level fluctuations on benthic anoxia in ancient seas is still poorly understood our work aims to shed light on the control exerted by relative sea level variations on the paleoceanographic processes that drove fine grained sediment deposition organic matter dispersal and preservation during the sedimentation of the barnett shale formation using spectral gamma ray log a large second order sequence modulated by a total of thirteen third order sequences was inferred third order relative sea level cycles modulated the level of restriction of the basin through time alternating pulses of bottom water oxygenation and relatively more efficient watermass circulation with times of sluggish bottom water and stagnation which controlled the facies stacking pattern and organic matter preservation in particular relatively increased stagnation occurred during lowstand phases while relatively reduced restriction was principally associated with transgressive and highstand systems tracts with more efficient bottom current circulation on a larger scale second order eustatic cycles played a crucial role in determining the paleoceanographic and depositional processes responsible for anoxia during the early phase of sea level rise the pre existing topography was flooded establishing the conditions for a shallow strongly restricted anoxic basin during the second order regression the basin experienced increased isolation with bottom water stagnation and deep water renewal of 6000 years anoxia terminated abruptly corresponding to the eustatic sea level rise associated with the beginning of a new second order sequence therefore the barnett shale formation represents a significant example of the complex interplay between sea level controlled basin physiography and local paleoceanographic conditions

the metal oxide fraction of pelagic sediment in the equatorial north pacific ocean a source of metals in ferromanganese nodules abstract pelagic sediment recovered at domes site a in the equatorial north pacific 151 w 9 15 n consists of a surface homogeneous layer approximately 10 cm thick overlying a strongly mottled layer that is lighter in color the radiolarian composition of both units is quaternary in areas where this sediment was only a few centimeters thick the underlying sediment was early tertiary clay mineralogy and major oxide composition of the two quaternary sediments are uniform their similarity to continental shale suggests that the sediment has a terrigenous source clay mineralogy and major oxide composition of the tertiary sediment also are uniform although they differ markedly from the quarternary sediment in contrast to the major oxides concentrations of mn co cu and ni soluble in hydroxylamine hydrochlorideacetic acid are strongly different in the surface and subsurface quaternary sediment mn and ni exhibit pronounced depletions in the subsurface sediment ni slightly more than mn cu is also depleted in the subsurface sediment but less than mn it is also depleted in the subsurface tertiary sediment whereas the mn concentration remains high concentration of co relative to mn increases into the subsurface quaternary sediment to a constant co mn ratio of 3 10 2 the trivalent ree the ree exclusive of ce and fe exhibit little down core variation distribution of elements in these sediments is closely related to their concentration in associated surface ferromanganese nodules the nodules are of two distinct types those from the area where the quaternary sediment is relatively thick have mno2 as the dominant manganese mineral the ratios of ni mn cu mn and fe mn in these nodules approximate the corresponding ratios of the soluble fraction of surface sediment todorokite is the dominant mineral of nodules recovered from areas where the quaternary sediment is thin relatively high cu mn ni mn and low fe mn ratios of these nodules mirror differences between the soluble fraction of surface and subsurface quaternary sediment these compositional trends of sediment and nodules at domes site a reflect a diagenetic origin for the todorokite nodules and a predominantly hydrogenous origin for the mno2 nodules

the distribution of fe in the antarctic circumpolar current abstract the large scale distributions of dissolved and total fe in surface and deep waters of the antarctic circumpolar current exhibit strong relationships with hydrography and biological processes the mean dissolved fe concentrations are low in surface waters of the antarctic circumpolar current 0 31 0 49 nm with a minimum of 0 17 nm and higher averaging 1 11 9 nm in the polar frontal region enhanced dissolved surface water concentrations in the polar frontal region are attributed to input from the continental shelf and coincide with phytoplankton spring blooms of large diatoms the effects of sea ice melting and iceberg melting on the fe concentrations were relatively small dissolved deep water concentrations 400 m in the antarctic circumpolar current ranged from 0 4 to 2 8 nm circumpolar deep water has relatively high dissolved fe concentrations in the polar frontal region 0 4 2 8 nm compared with deep waters further to the south 0 6 1 1 nm similarly total dissolvable unfiltered fe concentrations in the upper circumpolar deep water tend to decrease southward from the polar frontal region in the lower circumpolar deep water total dissolvable fe concentrations are higher than in the upper circumpolar deep water due to the existing nepheloid layer and sources on the mid atlantic ridge dissolved and total dissolvable fe concentrations in the antarctic bottom water are higher than those of other water masses in the antarctic circumpolar current consistent with the nepheloid layer as well as diagenetic input from shelf sediments the high nutrient low chlorophyll areas of the antarctic ocean and northeast pacific ocean have different major fe input sources of similar magnitude in the antarctic circumpolar current upward transport of fe is the main input source whereas in the north pacific ocean aerosols are the dominant source

rare earth element concentrations and nd isotopes in the southeast pacific ocean 1 three vertical profiles of rare earth element concentrations and nd isotopic compositions have been measured in the remote southeast pacific ocean the three stations represent contrasting environments the oligotrophic center of the gyre station gyr the transition zone east of the south tropical front station egy and the peru chile upwelling marked by a pronounced oxygen minimum station upx rare earth concentrations display nutrient like vertical profiles except at upx where surface waters are enriched at this station nd isotopic compositions are clearly more radiogenic than in the open ocean suggesting that boundary exchange process is releasing lithogenic rare earth element from the volcanic andes unexpected radiogenic values end reaching 3 7 are also observed at 2000 m at station gyr in the upper circumpolar deep water that commonly have end values around 6 exchange processes related to hydrothermal activity are suspected to produce this increase in end in the vicinity of the east pacific rise these results provide some guidance for higher resolution studies planned in this region by the international geotraces program

anoxic vs dysoxic events reflected in sediment geochemistry during the cenomanian turonian boundary event cretaceous in the umbria marche basin of central italy abstract one of the most spectacular expressions of global oceanic anoxic events oaes of the cretaceous is the livello bonarelli of central italy deposited during the cenomanian turonian boundary event ctbe or oae2 at around 93 5 ma at furlo in the umbria marche basin in italy the bonarelli consists of approximately 1 m of c org rich shales interbedded with radiolarian rich layers and contrasts sharply with the extensive over and underlying siliceous limestones several minor c org rich intervals herein termed black levels average thickness 4 5 cm are interbedded within the scaglia bianca beneath the bonarelli x ray fluorescence and icp ms analyses show that these sediments consist of different mixing systems with three end members 1 sio 2 caco 3 scaglia bianca 2 average shale caco 3 black levels and 3 average shale sio 2 bonarelli given the sharp lithologic contacts and the little geochemical mixing between the groups these are thought to represent rapid switching events between sedimentary modes major element concentrations are generally low except for si and p owing to dilution by silica up to 96 and carbonates as al normalised ratios for elements such as ti or zr taken as proxies for higher energy environments are close to average shale values excess sio 2 is most likely linked to biogenic processes rather than quartz element al ratios of ti mg k rb and zr are fairly constant pointing to a mostly homogeneous source area the black levels and bonarelli are characterised by lower mg al ratios compared to the scaglia bianca sediments suggesting variability in chlorite input which could be linked with short term sea level drops indicated by ti al ratios the bonarelli sediments are severely depleted in mn which is indicative of oxygen depleted bottom water conditions and an open marine environment while the black levels appear to have been deposited in a much more restricted setting a model involving partial physical isolation of the furlo site by a sill coupled to omz variations by extra basinal forcing mechanisms is proposed to account for these conflicting data based on re mo ratios the bonarelli sediments were deposited under varying oxygen depletion levels from suboxic to anoxic while re mo ratios in the black levels show deposition under less oxygen deficient conditions most minor elements many of them redox sensitive or sulphide residing are strongly enriched in the c org rich sediments further documenting the absence of oxygen and potential availability of hydrogen sulphide in the water column at times while high zn concentrations suggest elevated submarine hydrothermal activity during this time interval ba is also present in very high concentrations up to 1 4 with an average weighed concentration of 0 6 for the entire bonarelli and is probably indicative of high paleoproductivity in this area this is further supported by high p concentrations hinting at nutrient availability at this site

the biogeochemistry of aluminum in the pacific ocean abstract vertical distributions and horizontal surface transects of dissolved and particulate al at several locations in the pacific ocean are presented here concentrations of dissolved al in the pacific range from 0 3 to 5 nmol kg in the surface waters from 0 1 to 1 nmol kg in mid depths and from 0 5 to 2 nmol kg in the deep waters from these data and published data from other regions it is evident that al has a unique oceanic chemistry relative to that of other metals external sources and rapid particle scavenging throughout the water column are the major controls on dissolved al distributions in the oceans vertical profiles generally exhibit a surface maximum a mid depth minimum and increasing concentrations toward the sediment water interface this suggests two sources of dissolved al one to the surface waters and one to the deep waters concentrations of dissolved al in surface waters are lowest within the eutrophic low salinity california current 0 3 1 nmol kg and increase westwardly into the subtropical gyre of the north pacific 5 nmol kg values in the south pacific gyre are fivefold lower these horizontal trends indicate that the primary source of dissolved al to the surface waters of the central pacific is from eolian input dissolved al supplied by rivers to the eastern north pacific appears to be rapidly scavenged in estuaries and or the highly productive coastal region the source of dissolved al to the deep waters is not known but could be due to a flux out of the sediments or a remineralization process suspended particulate al concentrations increase with depth at all stations and decrease with distance from the ocean boundary surface values range from 1 5 nmol kg near shore to 0 3 nmol kg in the central gyres of the pacific deep water concentrations range from 22 nmol kg near shore to 4 nmol kg in the north pacific central gyre and decrease to 1 3 nmol kg in the south pacific central gyre observed distributions indicate that suspended particulate al varies with the intensity of bottom sediment resuspension and the horizontal mixing of the resulting nepheloid layer out from ocean boundary regions particle residence times estimated are consistent with other reported values

solubility of fe iii in seawater abstract recently kuma et al k kuma j nishioka k matsunaga controls on iron iii hydroxide solubility in seawater the influence of ph and natural organic chelators limnol oceanogr 41 1996 396 407 made some careful measurements of the solubility of fe iii in uv and non uv irradiated seawater as a function of ph 5 8 they showed that organic compounds can increase the solubility 32 65 at ph 8 1 apparently due to the formation of fe iii organic complexes in this paper i have examined how these results can be quantified using a speciation model for fe iii the results indicate that the effect of ph 2 9 on coastal and open ocean waters by kuma et al and the earlier filtration measurement of byrne and kester r h byrne d r kester solubility of hydrous ferric oxide and iron speciation in sea water mar chem 4 1976 255 274 can be adequately represented by considering the formation of feoh2 and fe oh 2 using the hydrolysis constants k 1 10 2 62 k 2 10 6 0 determined by millero et al f j millero w yao j aicher the speciation of fe ii and fe iii in natural waters mar chem 50 1995 21 39 the solubility measurements kuma et al 1996 on unaltered coastal and open ocean waters appear to require the consideration of the formation of fe oh 30 k 3 10 13 3 10 14 3 a more careful look at these measurements indicates that the curvature between ph 7 and 8 can be attributed to the formation of complexes of fe3 with organic ligands fel model speciation calculations ph 6 8 yield total ligand concentrations of l t 1 2 nm and 0 17 nm for unaltered coastal and open ocean waters respectively assuming k fel 1021 these estimates are in good agreement with the values found for ocean waters by voltammetric methods the model calculations for the solubility of fe iii 0 2 nm at ph 8 1 and 0 6 nm at ph 7 65 are in good agreement with measured open ocean surface 0 2 nm and deep waters 0 6 nm determined by various workers since these calculations are strongly dependent upon the total fe and organic ligand concentrations in the waters future studies should include solubility and voltammetric measurements on the same sample to clarify these relationships

the manganese nodules of the kane gap east atlantic indicators of sedimentation erosion changes manganese nodules from the kane gap a deep sea channel connecting the sierra leone and gambia basins off west africa were investigated chemically and dated by10be along cross sections comparing the nodule structure with the stratigraphy of the related sediments the following conclusions are drawn concerning the sedimentation processes during the last 4 to 6 106 years the growth of the nodules started about 4 to 4 5 ma before present during or near to the end of a period of erosion on a fossil free probably miocene sediment during the first phase of only a few hundred thousandyears the nodules grew very quickly 7 to 18 mm ma fe rich hydrogenetic material formed the internal sections of the nodules during this time slowing down of the bottom currents resulting in deposition of thin sediment covers for short intervals caused the character of the nodules to change to a more diagenetic composition the growth rates were reduced to about 1 to 2 mm ma the time of slowing is roughly 3 to 4 ma bp

hydrothermal manganese plumes in the mid atlantic ridge rift valley the concentration of dissolved manganese in sea water can be used as a chemical tracer of hydrothermal activity on the underlying sea floor here we present vertical profiles of seawater manganese concentrations above the rift valley of the mid atlantic ridge mar the values obtained indicate the presence of plumes that are presently active generated by hydrothermal vents in the rift valley these plumes are confined to the rift valley and do not spill over into the adjacent deep ocean basins differences between them suggest that there are at least five hydrothermal sources along this 1 700 km long section of mid ocean ridge

geochemical cycles in sediments deposited on the slopes of the guaymas and carmen basins of the gulf of california over the last 180 years sediments deposited on the slopes of the guaymas and carmen basins in the central gulf of california were recovered in two box cores q mode factor analyses identified detrital clastic carbonate and redox associations in the elemental composition of these sediments the detrital clastic fraction appears to contain two source components a more mafic component presumably derived from the sierra madre occidental along the west coast of mexico and a more felsic component most likely derived from sedimentary rocks mostly sandstones of the colorado plateau and delivered by the colorado river the sediments also contain significant siliceous biogenic components and minor calcareous biogenic components but those components were not quantified in this study redox associations were identified in both cores based on relatively high concentrations of molybdenum which is indicative of deposition under conditions of sulfate reduction decreases in concentrations of molybdenum in younger sediments suggest that the bottom waters of the gulf have became more oxygenated over the last 100 years many geochemical components in both box cores exhibit distinct cyclicity with periodicities of 10 20 years the most striking are 20 year cycles in the more mafic components e g titanium particularly in sediments deposited during the 19th century in that century the titanium cycles are in very good agreement with warm phases of the pacific decadal oscillation implying that at times of greater influx of titanium rich

statistical evaluation of elemental concentrations in shallow marine deposits cretaceous lusitanian basin abstract the elemental geochemistry of ancient shallow marine carbonates represents an often underexplored archive of paleoenvironmental change and diagenetic pathways complex multi parameter datasets from a lithologically heterogeneous sedimentary succession in the southern part of the lusitanian basin ericeira portugal are presented and interpreted the section comprises marly carbonate and sandstone rich coastal marine deposits of early albian to early cenomanian age principal component analysis of bulk elemental abundance ca mg sr fe and mn lead to define four geochemical clusters based on common elemental attributes siliciclastics and dolomitized limestones facies yield evidence for significant diagenetic alteration but still preserve information on paleoshoreline position mixed carbonate siliciclastics and limestone facies bear evidence for relative sea level position and relevant paleoclimatic information in their elemental record accordingly mid albian mixed carbonate siliciclastic deposits present variable degrees of continental influx specifically a sharp increase of fe and mn concentrations in relation to continental input is in agreement with periods of enhanced hydrological cycling and increased weathering on adjacent emerged lands the progressive transition towards more marine conditions is accompanied by higher ca and sr content and represented by limestone facies corresponding to a higher sea level position during late albian to early cenomanian times moreover this facies records a trend towards warmer and more arid conditions early diagenetic stabilization and or dissolution of aragonite into low mg calcite can account for major elemental variations including higher sr content strongly coupled with ca content along with lower mg fe and mn concentrations data shown here provide solid evidence that the statistical analysis of the elemental record of ancient marine deposits when combined with conventional sedimentology and thin section petrography allow for elaborate conclusions on their depositional environment and diagenetic pathways cored wells and facies specific reservoir properties can be addressed by these methodologies able to detect and quantify changes in patterns both industry and academy can therefore benefit from approaching such a complex interplay

regulation of algal blooms in antarctic shelf waters by the release of iron from melting sea ice during summer 1995 96 we measured iron in the water column and conducted iron enrichment bottle incubation experiments at a station in the central ross sea 76 30 s 170 40 w first in the presence of melting sea ice and 17 days later in ice free conditions we observed a striking temporal change in mixed layer dissolved iron concentrations at this station from 0 72 2 3 nm with sea ice present to 0 16 0 17 nm in ice free conditions these changes were accompanied by a significant drawdown in macronutrients and an approximate doubling of algal diatom biomass our incubation experiments suggest that conditions were iron replete in the presence of sea ice and iron deficient in the absence of sea ice we surmise that bioavailable iron was released into seawater from the melting sea ice stimulating phytoplankton production and the biological removal of dissolved iron from the mixed layer until iron limited conditions developed these observations suggest that the episodic release of bioavailable iron from melting sea ice is an important factor regulating phytoplankton production particularly ice edge blooms in seasonally ice covered antarctic waters

the effects of continental margins and water mass circulation on the distribution of dissolved aluminum and manganese in drake passage a total of 232 samples were analyzed for concentrations of dissolved aluminum al and manganese mn in drake passage both al and mn were extremely low similar to 0 3 and 0 1 nm respectively in the surface layer of the middle drake passage most likely due to limited input and biological uptake scavenging elevated al 14 nm and mn 2 nm over the south american continental shelf are related to land run off whereas elevated concentrations 1 nm and 2 nm respectively near the antarctic peninsula are most likely related to sediment re suspension re suspension of sedimentary particles and pore waters influences the distribution of al and mn over the continental slopes on both sides of drake passage the influence of the continental margins and accumulated dust input potentially explains the higher al observed eastward in the atlantic section of the southern ocean in the northern drake passage elevated al similar to 0 8 nm and mn similar to 0 3 nm near the seafloor are most likely the result of bottom sediment re suspension by the relatively strong currents in the deep southern drake passage sediment re suspension associated with the inflow of weddell sea deep water appears to cause elevated al 1 nm and mn similar to 0 4 nm in the deep northern drake passage north atlantic deep water brings in elevated al and southeast pacific deep slope water brings in the signature of pacific hydrothermal vents elevated mn and delta he 3 were correlated in this water layer and are most likely originating from the volcanically active ridges in the pacific ocean

simple permeability model for natural granular media a previously published pore scale model provides a simple analytic expression relating the permeability of a natural granular media to its porosity this model is quantitatively accurate at high to intermediate porosities it is based on two independent parameters porosity and average grain size at low porosities however the model is unable to capture the experimentally observed trends percolation provides a natural description of the pore closure evident in sedimentary media at low porosities the use of percolation concepts provides the necessary input to predict the permeability in the porosity range where pore blocking occurs thus a simple analytic model utilizing an experimental value for the percolation threshhold is derived for the permeability of sandstones and calcite aggregates over the full range of porosity

application of a chemical leach technique for estimating labile particulate aluminum iron and manganese in the columbia river plume and coastal waters off oregon and washington in order to determine the total concentration of bioavailable trace metals in seawater measurement of both the dissolved and labile particulate fractions is necessary comparison of labile particulate metal concentrations from various researchers is limited because of differing definitions of the fraction that is potentially available to phytoplankton on a time frame of generations a comparison experiment was conducted on coastal and riverine suspended particulate matter to determine the difference between several commonly used techniques that operationally define the labile particulate trace metal fraction furthermore we compared two leach techniques for surface transect samples from within the columbia river plume and water offshore of oregon and washington united states the particulate trace metal concentration in the leachate was determined by high resolution inductively coupled plasma mass spectrometry from this comparison one chemical leach was chosen to best define the labile particulate fraction of al fe and mn a weak acid leach 25 acetic acid at ph 2 with a mild reducing agent 0 02 m hydroxylamine hydrochloride and a short heating step 10 min 90 95 c this leach was applied to three surface transects within the columbia river plume these coastal waters were found to be rich in labile particulate trace metals that are directly delivered from the columbia river and indirectly supplied via resuspension from upwelling over a broad continental shelf

hafnium and neodymium isotopes in seawater and in ferromanganese crusts the element perspective abstract hafnium and nd isotopes are increasingly used as paleoceanographic proxies comparing the mantle crust array and the seawater array in plots of e hf vs e nd it has been observed that for a given e nd value the corresponding e hf value is higher for seawater than it is for terrestrial rocks while this difference had initially been explained by significant hydrothermal input of mantle hf into seawater the currently favoured explanation is incongruent weathering of continental rocks producing radiogenic riverine hf input we here address this topic from the perspective of the behaviour of these two elements in seawater and in ferromanganese fe mn crusts we distinguish between a truly dissolved and a dissolved hf and nd pool the latter being comprised of truly dissolved and colloid bound colloidal hf and nd while there exists a hydrothermal pathway for colloid bound dissolved mantle hf into the oceans there is in marked contrast to nd no important riverine pathway for colloidal or truly dissolved continental hf owing to their respective chemical speciation in seawater there exists truly dissolved nd in the ocean while the amount of truly dissolved hf is insignificant neodymium is in exchange equilibrium between local seawater and both the hydrous fe and mn oxides hydrogenetic fe mn crusts are composed of due to continuous ad and desorption there is continuous isotopic re equilibration and the isotopic composition of nd in a fe mn crust reflects that of truly dissolved nd in local ambient seawater in contrast hf is only associated with the hydrous fe oxides on which it forms surface precipitates that do not exchange with seawater due to this lack of isotopic re equilibration the isotopic composition of hf in a fe mn crust is the average of that of all the hf scavenged during the lifetime of the hydrous fe oxide particles since the hf bearing hydrous fe oxides in a fe mn crust do not form from local ambient seawater at the crust s growth site but are advected as colloids or fine particles their hf isotopic composition depends on the origin and migration pathway of these colloids hence while nd isotopes in fe mn crusts provide reliable information on truly dissolved nd in local ambient seawater hf isotopes rather indicate the origin and pathway of hydrous fe oxide colloids and might differ from truly dissolved hf in local ambient seawater this may explain the occasional decoupling of nd and hf isotopes in fe mn crusts and supports the notion of a significant hydrothermal mantle signal of hf in seawater

an overview of dissolved fe and mn distributions during the 2010 2011 u s geotraces north atlantic cruises geotraces ga03 abstract high resolution dissolved fe dfe and dissolved mn dmn distributions were obtained using a trace metal clean rosette during the geotraces ga03 zonal transect cruises usgt10 and usgt11 across the north atlantic ocean this manuscript provides a general overview of the dfe as well as dmn and dissolved al dal distributions that reveal several fe inputs at varying depths across the study region elevated dfe concentrations correlate with elevated dal concentrations in the surface waters of the subtropical gyre indicating a significant atmospheric source of fe in contrast there is no apparent significant dust source for mn in the subsurface waters dfe maxima are a result of the remineralization process as revealed by their correspondence with dissolved oxygen minima within the oxygen minimum the ratio of dfe to apparent oxygen utilization aou is lower than would be expected from the measured fe content of surface water phytoplankton suggesting that a significant amount of dfe that is remineralized at depth 63 90 is subsequently scavenged from the water column the rate of remineralization which is based on the slope of dfe aou plot is similar across a wide area of the north atlantic in addition to the remineralization process sedimentary inputs are apparent from elevated dmn signals in the eastern basin particularly near the african coast in the western basin sedimentary input is also occurring along the advective flow path of the upper labrador sea water ulsw as ulsw transits along the north american continental shelf region the largest dfe anomaly 68 nm which also corresponds to a dmn anomaly up to 33 nm is seen in the neutrally buoyant hydrothermal plume sampled over the mid atlantic ridge and that signal is visible for 500 km to the west of the ridge

new geochemical constraints on the paleocene eocene thermal maximum dababiya gssp egypt the paleocene eocene thermal maximum petm shows an extraordinary drop in the 13c of carbonate and organic matter across the globe suggesting massive release of 13c depleted carbon dioxide into the ocean and atmosphere over a very short time interval probably 20ky we report a geochemical and mineralogical study of 106 samples spanning the most expanded petm at the dababiya global stratotype standard section and point gssp near luxor egypt the field and laboratory observations reveal that the deposition occurred in a submarine channel extended laterally about 200 m with the deepest part 0 88 m at the designated gssp although all bio zones are present stable isotope records of both carbonate and organic carbon show decreases starting 0 6 m below the paleocene eocene boundary peb and culminating at the erosion surface a persistent shift in 15norg values to near zero reflects a gradual increase in bacterial activity high ti k and zr and low si contents at the peb coincide with increased kaolinite contents which suggests intense chemical weathering under more humid conditions at the petm onset two negative ce anomalies indicate intervals of anoxic conditions during the lower and middle petm base and top of zone e1 the first anoxic event is represented by a negative ce anomaly high v c rand v v ni ratios negative mn and an abundance of idiomorphic pyrite crystals that indicate anoxic to euxinic conditions the anoxic event middle petm is marked by high u mo v fe and abundant small sized 2 5 m pyrite framboids increased cu ni and cd at the same level suggesting anoxic conditions linked to high surface water productivity above this interval oxic conditions returned as indicated by the precipitation of phosphorus and barium these data reveal an expanded petm interval marked by intense weathering as a crucial parameter during the recovery phase

the contrasting biogeochemistry of iron and manganese in the pacific ocean abstract vertical and horizontal distributions of dissolved and suspended particulate fe and mn and vertical fluxes of these metals obtained with sediment traps were determined throughout the pacific ocean in general dissolved fe is low in surface and deep waters 0 1 to 0 7 nmol kg with maxima associated with the intermediate depth oxygen minimum zone 2 0 to 6 6 nmol kg vertical distributions of dissolved mn are similar to previous reports exhibiting a surface maximum a subsurface minimum a mn maximum layer coincident with the oxygen minimum zone and lowest values in deep waters near shore removal processes are more intense for dissolved fe than for dissolved mn dissolved mn in the surface mixed layer remains elevated much farther offshore than dissolved fe elevated near surface dissolved mn concentrations occur in the north pacific equatorial current suggesting transport from the eastern boundary near surface mixed layer dissolved mn concentrations are higher in the north pacific gyre reflecting enhanced northern hemisphere aeolian sources residence time estimates for the settling of refractory paniculate fe and mn from the upper water column are 62 220 days fe and 105 235 days mn in contrast residence times for the scavenging of dissolved fe and mn are 2 13 years fe and 3 74 years mn scavenging residence times for dissolved mn based on horizontal mixing in the surface mixed layer of the northeast pacific are 0 4 years nearshore to 19 years 1000 km offshore there is no evidence for in situ fe redox dissolution within sub oxic waters in the eastern tropical north pacific dissolved fe appeared to be controlled by dissolution from sub oxic sediments with oxidative scavenging in the water column or upper sediment layers however in situ mn dissolution within the oxygen minimum zone was evident

fluvial and hydrothermal input of manganese into the arctic ocean abstract a total of 773 samples were analysed for dissolved manganese mn in the arctic ocean aboard r v polarstern during expedition ark xxii 2 from 28 july until 07 october 2007 from tromso norway to bremerhaven concentrations of mn were elevated in the surface layer with concentrations of up to 6 nm over the deep basins and over 20 nm in the laptev sea the general distribution of mn through the water column is consistent with previous studies but there are differences in the absolute concentrations that are most likely related to differences in sample area sampling and filtration the elevated concentrations of mn in the surface layer are related to fresh water input this was visible in the strong negative correlations observed between dissolved mn and salinity the correlation between mn and salinity and the correlation between mn and the quasi conservative trace water mass tracer po4 showed fluvial and melt water input and the pacific and atlantic origin of the surface waters a large portion of the mn delivered by the arctic rivers is removed in the shelf seas and does not pass into the central basins most likely a benthic flux is at the origin of the elevated concentrations of mn near the sediments in the barents and kara seas these elevated concentrations of mn apparently affected the deep basins as well as maxima in the concentrations of mn were observed that corresponded with lowered transmission over the continental slope a maximum in the concentration of mn in the deep basin corresponded with anomalies in light transmission potential temperature and dissolved iron confirming the hydrothermal origin the hydrothermal plume was observed throughout the nansen basin and over the deep gakkel ridge around 2500 m depth and a smaller plume was observed around 3200 m the concentration of mn at the mn maximum around 2500 m depth decreased exponentially consistent with a first order scavenging model the concentrations of mn were extremely low in the deep makarov basin 0 05 nm and slightly higher in the eurasian basin 0 1 nm outside the influence of the hydrothermal activity

fluxes and distribution of dissolved iron in the eastern sub tropical north atlantic ocean aeolian dust transport from the saharan sahel desert regions is considered the dominant external input of iron fe to the surface waters of the eastern sub tropical north atlantic ocean to test this hypothesis we investigated the sources of dissolved fe dfe and quantified dfe fluxes to the surface ocean in this region in winter 2008 surface water dfe concentrations varied between 1 5 nm correlated positively with apparent oxygen utilization aou and showed the importance of organic matter remineralization as an dfe source as a consequence vertical diffusive mixing formed an important fe flux to the surface ocean in this region even surpassing that of a major dust event

meridional distribution of dissolved manganese in the tropical and equatorial pacific abstract the distribution of dissolved mn dmn was studied in the tropical and equatorial pacific along a meridional transect beginning at station aloha 22 45 n 158 w extending southwards to 7 s along 158 w results show that in the surface ocean 6000 km from the continents which suggests that dmn in the deep open ocean is strongly affected by remineralization the dmn aou linear relationship n 37 r 0 87 that we found in this work is consistent with culture studies and can be applied to mn models to reproduce the observed open ocean mn concentrations in deep waters

glacial interglacial co2 change the iron hypothesis several explanations for the 200 to 280 ppm glacial interglacial change in atmospheric co2 concentrations deal with variations in southern ocean phytoplankton productivity and the related use or nonuse of major plant nutrients an hypothesis is presented herein in which arguments are made that new productivity in today s southern ocean 7 4 1013g yr 1 is limited by iron deficiency and hence the phytoplankton are unable to take advantage of the excess surface nitrate phosphate that if used could result in total southern ocean new production of 2 3 1015 g c yr 1 as a consequence of fe limited new productivity holocene interglacial co2 levels preindustrial are as high as they were during the last interglacial 280 ppm in contrast atmospheric dust fe supplies were 50 times higher during the last glacial maximum lgm because of this fe enrichment phytoplankton growth may have been greatly enhanced larger amounts of upwelled nutrients may have been used and the resulting stimulation of new productivity may have contributed to the lgm drawdown of atmospheric co2 to levels of less than 200 ppm background information and arguments in support of this hypothesis are presented

rare earth elements in the nw indian ocean abstract dissolved rare earth element ree distributions have been determined at three stations in the high productivity nw indian ocean nwio upwelling zone dissolved ree distributions within the well oxygenated surface waters and deep portions of the water column are similar to those reported previously from other open ocean locations at depth dissolved ree concentrations are intermediate between those of the atlantic and pacific oceans consistent with the continuous regeneration and enrichment of the strictly trivalent rees in and the progressive oxidative removal of ce from the deep ocean within the mid depth oxygen minimum zone dissolved ree concentrations exhibit a notable enrichment superimposed upon these typical oceanic profiles further dissolved ce concentrations are preferentially enriched within the suboxic horizon compared to the rest of the series indicating the reduction of insoluble ce iv to dissolved ce iii at these depths by analogy with our previous studies of ree distributions in anoxic basins we propose that the more modest enrichments of the strictly trivalent rees observed in the nwio suboxic zone must derive from uptake through scavenging within the well oxygenated portions of the water column and regeneration from sediments and settling particles within the more reducing conditions of the oxygen minimum zone

vertex manganese transport through oxygen minima abstract manganese transport through a well developed oxygen minimum was studied off central mexico 18 n 108 w in october november 1981 as part of the vertex vertical transport and exchange research program refractory leachable and dissolved mn fractions associated with particulates caught in traps set at eight depths 120 1950 m were analyzed particles entering the oxygen minimum had relatively large mn loads however as the particulates sank further into the minimum total mn fluxes steadily decreased from 190 nmol m 2 day 1 at 120 m to 36 nmol m 2 day 1 at 400 m manganese fluxes then steadily increased in the remaining 800 1950 m reaching rates of up to 230 nmol m 2 day 1 at 1950 m manganese concentrations were also measured in the water column dissolved mn levels 1 were consistently observed within the 150 600 m depth interval in contrast suspended particulate leachable mn amounts were especially low at those depths and never exceeded 0 04 nmol kg 1 the combined water column and particle trap data clearly indicate that mn is released from particles as they sink through the oxygen minimum rate of change estimates based on trap flux data yield regeneration rates of up to 0 44 nmol kg 1 yr 1 in the upper oxygen minimum 120 200 m however only 30 of the dissolved mn in the oxygen minimum appears to be from sinking particulate regeneration the other 70 probably results from continental slope release horizontal transport processes dissolved mn scavenges back onto particles as oxygen levels begin to increase with depth scavenging rates ranging from 0 03 to 0 09 nmol kg 1 yr 1 were observed at depths from 700 to 1950 m these scavenging rates result in mn residence times of 16 19 years and scavenging rate constants on the order of 0 057 yr 1 manganese removal via scavenging on sinking particles below the oxygen minimum is balanced by mn released along continental boundaries and transported horizontally via advective diffusive processes manganese appears to be very weakly associated with particulates nevertheless the amounts of mn involved with sinking biogenic particles are large and the resulting fluxes are on the same order of magnitude as those necessary to explain the excess mn accumulating on the sea floor the overall behavior of mn observed in this and other studies strongly suggests some type of equilibrium occurring between dissolved and particulate phases this equilibrium appears to shift in direct or indirect response to dissolved oxygen levels

manganese and iron in indian ocean waters abstract the first vertical profiles of dissolved mn and fe for the nw indian ocean are reported the area is characterized by seasonal upwelling and a broad oxygen minimum zone in intermediate waters the dissolved fe profile exhibits a maximum 5 1 nm in the oxygen minimum zone with low values both in surface waters 0 3 nm and deep waters around 1 nm mn concentrations in the surface waters are elevated 2 0 4 3 nm and decrease rapidly in an offshore direction below the first 25 m concentrations decrease dramatically 0 5 1 3 nm indicating removal by oxidation and particle scavenging further down various mn maxima are observed which can be related to hydrographic features sigma 1 1 intermediate water originating from the red sea lost its dissolved o2 while flowing northward along the omani coast and exhibits a strong mn maximum 4 6 6 5 nm coincident with the deep o2 minimum 2 2 at the two inshore stations in the gulf of oman this is overlain by relatively modest mn maxima 2 7 nm related to arabian gulf overflow water 3 3 finally the strong mn maxima 4 4 5 6 nm in the oxygen minimum zone at the two offshore stations are related to yet another watermass below these various maxima concentrations decrease gradually to values as low as 90 pm at 2000 meters depth towards the seafloor concentrations increase again leading to a modest bottom water maximum 0 7 1 5 nm the overall vertical distributions of mn and fe are strikingly similar also in actual concentrations to those previously reported for the eastern equatorial pacific an area also characterized by an extensive o2 minimum zone

controls on trace metal authigenic enrichment in reducing sediments insights from modern oxygen deficient settings any effort to reconstruct earth history using variations in authigenic enrichments of redox sensitive and biogeochemically important trace metals must rest on a fundamental understanding of their modern oceanic and sedimentary geochemistry further unravelling the multiple controls on sedimentary enrichments requires a multi element approach of the range of metals studied most is known about the behavior of fe mn and mo in this study we compare the authigenic enrichment patterns of these elements with a group whose behavior is not as well defined cd cu zn and ni in three oxygen poor settings the black sea the cariaco basin venezuela and the peru margin these three settings span a range of biogeochemical environments allowing us to isolate the different controls on sedimentary enrichment our approach relying on the covariation of elemental enrichment factors ef defined for element x as efx x al sample x al lithogenic has previously been applied to mo and u to elucidate paleoenvironmental information on for example benthic redox conditions the particulate shuttle and the evolution of water mass chemistry we find two key controls on trace metal enrichment first the concentration of an element in the lithogenic background sediment used in calculating efx controls the magnitude of potential enrichment maximum enrichment factors of 376 and 800 are calculated for mo 1 ppm in detrital sediments and cd 0 3 ppm respectively compared to values not greater than 17 in any setting for the other five metals 45 ppm to 4 5 wt in detrital sediments second there is a relationship between the aqueous concentration of the element in overlying seawater and its degree of enrichment in the sediment we further identify four important processes for delivery of trace metals to the sediment these are 1 cellular uptake especially important for zn and cd 2 interaction co precipitation with sulfide mo cu and cd 3 passive scavenging via the traditional particulate shuttle mo ni and cu and 4 an association with the benthic fe redox shuttle mn ni finally we summarize the oceanic mass balance of cd and mo and place the first constraints on the contribution of reducing sediments to the oceanic mass balance of cu zn and ni we show that reducing sediments are the ultimate repository for up to half the total output flux of these elements from the oceanic dissolved pool

the geochemistry of manganese in the northeast pacific ocean off washington1 2 water collected along a transect normal to the coast of washington was analyzed for dissolved co 4 pm and total dissolvable manganese tdm the vertical profiles exhibit the same general features observed elsewhere in the pacific but a horizontal section of the transect shows that concentrations increase markedly toward the continental margin a surface maximum ranging from 0 57 nmol kg in offshore waters to 5 24 over the continental slope is probably due to fluvial inputs especially from the columbia river another possible source is the upwelling of manganeseenriched bottom water over the shelf horizontal gradients are also observed in the oxygen minimum as manganese concentrations decrease from 4 75 nmol kg l near the continental slope to 0 7 1 in open ocean water porewater and solid phase data suggest that manganese is being actively remobilized under reducing conditions in the slope sediments and is diffusing into the overlying seawater at a rate sufficient to balance losses by vertical mixing and particulate scavenging two stations on opposite sides of the juan de fuca ridge have deep concentration maxima that are almost certainly due to injections of hydrothermal vent fluid along the ridge

the trace metal composition of suspended particles in the oceanic water column near bermuda trace metal partitioning between seawater and particles both suspended and sinking must be determined to understand and model oceanic trace metal scavenging processes in order to improve the oceanic particulate trace metal data base a newin situ pump was developed and deployed to collect suspended particles from 0 4000 m in the sargasso sea near bermuda these particles were analyzed for al fe mn co zn cu ni cd and pb major particulate carrier phases were estimated from ca opaline si and p cd is the only trace element of this group with a particulate maximum in near surface waters the other metals have low particulate concentrations mol l in near surface waters and increase with depth into the upper thermocline particulate al and fe are then uniform with depth below about 1000 m until increasing in the bottom nepheloid layer the remaining elements mn co zn cu ni and pb decrease from the mid thermocline values to lower and relatively uniform concentrations in deep waters the similarities among the vertical profiles for these metals suggest that authigenic mn oxides influence their uptake from the dissolved pool although an important or dominant role for other host phases specifically particulate organic matter is not ruled out by the data mean intermediate and deep water concentrations are al 3600 fe 1200 mn 146 co 1 5 zn 7 4 cu 15 ni 6 0 cd 0 06 and pb 2 1 pmol l these particulate al and mn values agree with previous measurements in this region but the other elements are lower by a factor of 3 fe co to 30 zn suggesting that earlier data were compromised by contamination the suspended metal data are used in a simple steady state two flux model to evaluate the role of suspended particles in determining the vertical flux of metals in the sargasso sea the model calculations indicate that removal of suspended particles in the deep 500 m water column contributes less than half of the total deep flux for all of the elements investigated except for cd this result implies that uptake of these metals onto particles in the deep central ocean is a minor factor in their oceanic mass balance if this finding is generally true for oligotrophic ocean environments whole ocean residence times for these elements must be governed largely by processes occurring either in near surface waters or at ocean margins

trace metals in contemporary and seventeenth century galapagos coral records of seasonal and annual variations we report trace element calcium ratios for modern cuca mnca cdca and pbca and seventeenth century cuca mnca and pbca specimens of pavona clavus collected in the galapagos islands these data include the first reliable measurements of cuca ratios in coralline aragonite we estimate that the ratio of cuca in the lattice to that in seawater i e the effective distribution coefficient is 0 3 lower than the value of 1 observed for several other divalent elements we estimate the effective distribution coefficient for mn is 1 distribution coefficients in coral aragonite for 8 divalent metals are near unity despite different ionic radii and chemical speciation in seawater investigation of where these substituents are incorporated in the aragonite lattice is clearly warranted in a modern hood island coral quarter annually sampled from 1964 73 cuca ratios decrease twofold from the late 1960s to early 1970s mnca and cdca ratios vary seasonally with upwelling and the generic el nino the el nino southern oscillation enso events of 1965 1969 and 1972 are marked by suppression of cdca ratios by about 2 5 nmol mol while the mnca ratio is highest during the strong 1972 enso pbca ratios were relatively constant throughout this period from the cuca record of a seventeenth century urvina bay coral annually sampled from 1600 1725 and the estimated cu distribution coefficient surface seawater cu concentrations at galapagos during the seventeenth century were similar to present day at 0 7 1 4 nmol kg estimated pb concentrations were lower at 5 20 pmol kg and mn concentrations were slightly higher at 1 6 2 8 nmol kg

biogeochemical processes at the sediment water interface in a northeastern atlantic abyssal locality porcupine abyssal plain abstract temporal and spatial variability in the composition of suspended particulate material spm was found at a northeastern atlantic abyssal locality on the porcupine abyssal plain at a depth of 4850 m total spm was distinctly higher in july 1997 than in march april 1997 and october 1996 the 20 m of water immediately overlying the seabed was strongly influenced by resuspension and the suspended particulate matter was enriched with iron and manganese two water distinct layers which were characterized by being enriched with spm fep mnp and alp were encountered during all sampling periods at depths of 4000 m and 4800 m the enrichment of spm with biogenic elements such as ba ca and sr implies it has a high biogenic content increases were observed in the concentrations of these biogenic elements throughout the sampling period which indicates that the biogenic content of the spm was steadily increased spm content and element aluminum ratios increased in the spring and summer of 1997 compared to autumn 1996 probably as a result of increases in primary productivity coincidental increases in near bottom current velocities and possibly other processes such as increases in bacterial activity and bioturbation authigenic formation of solid phases of fe and mn were also influencing the spatial variability chemical reactions involving organic carbon and oxygen which lead to the incorporation of iron and manganese in various forms into sediments were deduced it is proposed that there was formation of lepidocrocite feooh in the presence of organic carbon and oxygen and also that iron may also have been transformed into fe2o3 re precipitation of fe and mn is strongly enhanced by their enrichment in the spm in the bottom waters the sediments predominantly consist of biogenic carbonates and can be characterized as foraminiferal ooze the proportion of these biogenic carbonates proved to be higher in the more recent sediments either as result of recent increases in total primary productivity or because of carbonate dissolution within the subsurface sediments parallel increases of mn fe and carbonates in the sediment layers supports the idea that the metallic ions are being adsorbed on to calcite surfaces rather than being co precipitated in the carbonate phases reprecipitation of iron and manganese in other solid phases with the involvement of organic carbon corg in the oxygen penetration zone is suggested

iron and macronutrients in california coastal upwelling regimes implications for diatom blooms the supply of iron relative to that of the macronutrients nitrate phosphate and silicic acid plays a critical role in allowing extensive diatom blooms to develop in coastal upwelling regimes the presence or absence of a broad continental shelf influences the supply of iron the iron input to central california upwelling waters varies spatially and can be characterized by two end member regimes one end member which includes monterey bay and extending north to pt reyes is an iron replete regime where upwelling occurs over a relatively broad continental shelf that results in waters with high concentrations of dissolved and particulate iron 10 nm entrained together with high concentrations of nitrate and silicic acid in these iron replete regions extensive blooms of large diatoms deplete macronutrient concentrations which results in correspondingly high chlorophyll a concentrations the other end member located to the south of monterey bay off the big sur coast is an iron deplete regime where upwelling is focused offshore of a narrow continental shelf upwelled waters in the big sur region are characterized by low dissolved and particulate iron concentrations 1 nm together with high concentrations of nitrate and silicic acid extremely low iron concentrations unused nitrate and silicic acid and a low abundance of large diatoms characterize surface waters in these iron deplete regions and thus represent coastal upwelling high nutrient low chlorophyll systems limited by the micronutrient iron

the mean and annual cycle of upper layer temperature fields in relation to sverdrup dynamics within the gyres of the atlantic ocean using 28 years of expendable bathythermograph data 1967 1994 we describe the mean and annual cycle of the upper ocean temperature fields in the atlantic from 30 s to 50 n in the context of the basin scale wind driven gyres sverdrup stream function field which provide a framework for describing the oceanographic measurements we examine the circulation field implied by the temperature distributions which are used as a proxy for the field of mass similarities between the temperature and stream function fields increase with depth in the lower to subthermocline depths of the tropical and equatorial gyres the zonal currents form a closed circulation a southeastward boundary current is suggested near and below 150 m that provides closure for the tropical gyre and the equatorial gyre axis is southward of that suggested by the stream function field higher in the water column the north equatorial countercurrent necc may be a surface manifestation of the north equatorial undercurrent neuc where the latter can be interpreted as the southern limb of the tropical gyre because there are large vertical shears in the tropics the equatorial gyre is not clearly indicated in the vertically integrated temperature field but appears below about 200 m here the south equatorial undercurrent seuc can be interpreted as the eastward flowing northern limb of the equatorial gyre and is opposite in direction to the westward flowing south equatorial current above both the neuc and seuc are analagous to currents in the pacific that are governed by non sverdrup dynamics despite the shortcomings of the data the mean annual cycle appears to be relatively stable and we have discounted the possibility that in regions where it represents a significant percentage of the total variance it is changing slowly over the 28 years of record the wind forcing fields which undergo large meridional movements 5 6 of latitude during their annual cycle with some exceptions have essentially no counterpart in gyre movements between their seasonal extremes most of the variability associated with the annual cycle is confined to the upper 300 m greatest variability where ranges exceed 6 c occurs in the northwestern atlantic in late winter and early spring during this time of year south of the gulf stream and below about 100 m water temperatures exhibit a systematic phase lag with depth the next largest area of variability where ranges can also exceed 6 c resides in the tropical western basin between the equator and 10 n just below 100 m in the eastern basin ranges decrease and shoal additionally the phase fields are consistent with the intensification and relaxation of the tropical ridge trough system where the necc disappears in march in the west but the necc neuc complex is strongest in september

dissolved iron speciation in two distinct river plumes and an estuary implications for riverine iron supply dissolved iron fe speciation in the columbia river plume the san francisco bay plume and the columbia river estuary was investigated using competitive ligand exchange adsorptive cathodic stripping voltammetry cle acsv with the added ligand salicylaldoxime a stronger l1 type fe binding ligand class was measured in all surface samples and in the columbia river estuary a weaker l2 type ligand class was present in the far field columbia river plume and the san francisco bay plume but was not observed in the low salinity s 1 4 22 5 waters of the near field columbia river plume or estuary concentrations of total dissolved fe were correlated with the concentrations of the stronger l1 type ligand in nonestuarine s 13 surface samples leachable particulate 0 4 m fe concentrations in the columbia river plume were measured to supplement existing data from the san francisco bay plume there is a large concentration of readily leachable particulate fe in the two plumes yet it is the concentration of ambient l1 type ligands that appears to dictate the concentration of dissolved fe in these waters and consequently the supply of dissolved fe to neighboring coastal waters the correlation between dissolved fe and l1 ligand concentrations in both plume waters as well as in california current and upwelled surface waters suggests that this relationship will persist in other coastal environments and should be considered when evaluating and modeling coastal fe cycling and supply

seasonal cycles of manganese and cadmium in coral from the galapagos islands manganese to calcium ratios in corals from the eastern and western galapagos demonstrate regional differences in seasonal trace metal cycling the variability of trace metal to calcium ratios within the galapagos islands points to their unique geographic setting as a major factor this region is influenced by several major oceanic currents e g the south equatorial current the equatorial undercurrent and the panama or el nino current and by extremely intense upwelling manganese to calcium ratios in a banded coral pavona clavus from isabela island the westernmost island in the galapagos have distinct seasonal cycles for the non el nino southern oscillation enso years 1946 1950 with lower ratios following intensified seasonal upwelling cadmium calcium ratios show less distinct seasonal cycles the near moderate enso event in 1951 is marked by the disruption of seasonal cycles in mnca and cdca ratios in contrast corals from islands further east in the galapagos hood island 1964 1973 linn et al 1990 san cristobal 1965 1979 shen and sanford 1990 have stronger seasonal cdca signals with higher ratios following seasonal upwelling and less distinct seasonal cycles in mnca ratios one half year out of phase with cdca variations average mnca ratios are lower for these corals from locations further east indicating that urvina bay appears to have an additional localized source of mn shen and sanford 1990 in general these regional variations in seasonal trace metal cycling are consistent with coral stable isotope signals and with their geographic locations these variations are important to consider in using coral records to reconstruct and interpret oceanographic events occurring prior to historical records

geochemical behavior of dissolved manganese in the east china sea seasonal variation estuarine removal and regeneration under suboxic conditions to better understand the geochemical cycle of dissolved manganese mn in the east china sea ecs the distribution of dissolved mn across the ecs was investigated during three field studies in 2011 may august and november the concentration of dissolved mn decreased across the ecs with distance from the coast mn rich ecs shelf waters could export to the kuroshio waters and had the potential to influence the northwest pacific ocean as well as the japan sea the kuroshio waters were devoid of dissolved mn so its incursion could be tracked as it entered the ecs continental shelf region approximately 50 m isobath seasonal variations of dissolved mn in the ecs were significant with the highest concentrations occurring in summer dissolved mn in the changjiang estuary was nonconservative and significant quantities were removed by net sorption onto suspended particulate matter a model describing the sorption processes was applied to data for the changjiang estuary regeneration of dissolved mn took place in near bottom waters of the suboxic zone in august 2011 following extensive consumption of oxygen the benthic flux of dissolved mn was estimated based on mn concentrations in the overlying waters and the near bottom waters a preliminary box model was established to develop a dissolved mn budget for the ecs based on the dissolved mn content in the ecs and the total input flux a residence time of 76 350 days for dissolved mn in the ecs was inferred

manganese cerium and iron in the sulu celebes and philippine seas this study was undertaken to investigate trace metals in southeast asian seas that have different hydrographic settings the philippine the celebes and the sulu seas results reveal characteristics of dissolved and leachable manganese dissolved cerium and leachable iron in the water column remarkable increases of mn ce and fe exist at the bottom layer of the water column in the celebes sea the ce mn molar ratios in the bottom waters of the celebes sea are identical to those in the porewaters of the underlying sediment both ce and mn show similar geochemical cycles in these deep waters of the celebes sea in the sulu sea s deep waters the leachable particulate fractions are dominant for fe and mn the residence time of fe in the sulu sea is estimated as 12 years this residence time estimate is very similar to the particle residence time in the water column implying that resuspension of sediment derived particles affects leachable fe distributions in the sulu sea

instability of bottom water redox conditions during accumulation of quaternary sediment in the japan sea the concentrations of cd cr cu mo ni sb u v and zn were measured in early quaternary sediment 1 32 to 1 08 ma from the oki ridge in the japan sea the elements were partitioned between a detrital fraction composed of terrigenous and volcaniclastic aluminosilicate debris and a marine fraction composed of biogenic and hydrogenous debris derived from seawater the most important factors controlling minor element accumulation rates in the marine fraction were 1 primary productivity in the photic zone which largely controlled the flux of particulate organic matter bound minor elements settling through the water column and onto the seafloor and 2 bottom water redox which determined the suite of elements that accumulated directly from seawater this marine fraction of minor elements on oki ridge recorded six periods of high minor element abundance assuming a constant bulk sediment accumulation rate each period lasted roughly 5 000 to 10 000 years with a 41 000 year cycle accumulation rates of individual elements such as cd mo and u suggest sulfate reducing conditions were established in the bottom water during the 10 000 year periods accumulation rates of cr and v during the intervening periods are indicative of less reducing denitrifying conditions interelement ratios for example cu mo v cr and sb mo further reflect bottom water instability such that bottom water redox actually varied from sulfate reducing to denitrifying during the periods of highest minor element accumulation rates it varied from denitrifying to oxidizing during the intervening periods sediment lithology supports these interpretations of the minor element distributions the sediment is finely laminated for several of the periods represented by cd mo and u maxima and weakly laminated to bioturbated for the intervening periods the geochemistry of this sediment demonstrates the unambiguous signal of mo principally but of several other minor elements as well in recording sulfate reducing conditions in bottom water the forcing function that altered their accumulation that is that altered primary productivity and bottom water redox conditions is problematic currently held opinion suggests that o2 depletion was most strongly developed during glacial advances low sea level during such times is interpreted to have enhanced primary productivity and restricted bottom water advection

inorganic geochemistry of the type caradoc series sandbian to middle katian upper ordovician onny valley shropshire uk the geochemistry and petrology of the type section of the caradoc series in the onny valley indicate that it was deposited on a marginal basin continental shelf similar to the western side of the present sea of japan the lower beds form a transgressive regressive sequence in which the rocks become less mature upwards all the coarser sediments above the basal quartzites and conglomerates are greywackes in which the apparent muddy and ferrous matrix is due to the breakdown of unstable minerals and particles higher values of na 2 o and na k ratios are found in the coarser shallow water sandstones of the horderley sandstone formation and decrease markedly in the succeeding beds accompanied by an increase in k 2 o higher values of carbonate corrected and hence related other major and minor elements like sio 2 cao p 2 o 5 mno and most trace elements correlate with the transgressive systems and maximum flooding surfaces of the three sequences recognized where they are related to condensation at those horizons chemical indices of alteration cia suggest that the horderley sandstone formation underwent greater predepositional physical weathering than lower and higher beds which is compatible with the petrography and were deposited during a cool phase within overall warm sandbian katian times trace element ratios suggest an oxic to suboxic depositional environment

tracing ni cu and zn kinetics and equilibrium partitioning between dissolved and particulate phases in south san francisco bay ca using stable isotopes and hr icpms

contribution of resuspended sedimentary particles to dissolved iron and manganese in the ocean an experimental study abstract a number of trace metals play essential roles in marine ecosystem structure and biological productivity until recently it has been argued that phytoplankton access primarily dissolved iron while particulate iron was considered a refractory material with little use biologically and limited interaction with the dissolved pool in order to assess the transfer mechanisms between sediment sourced particulate trace metals and the dissolved pool we conducted a 14 month incubation that reacted resuspended sediments with natural seawater both originating from the kerguelen area keops cruises southern ocean in the dark and at concentrations replicating natural conditions three types of sediments were investigated named biosi biosi ca and basalt mostly composed of i biogenic silica bsio2 ii bsio2 and calcite and iii basaltic fragments respectively the release of dissolved silicon dsi iron dfe and manganese dmn was monitored regularly throughout the incubation as well as living bacteria density and fe organic ligands depending on the origin and composition of the sediment unique dfe and dmn fluxes were observed including a strong decoupling between dfe and dmn the basaltic sediment released up to 1 09 0 04 nmol l 1 of dfe and 0 28 0 09 nmol l 1 of dmn while the biogenic sediments released a higher 3 91 0 04 nmol l 1 and 8 03 0 42 nmol l 1 of dfe and dmn respectively several factors influencing the release and removal of dfe and dmn were discernable at the temporal sampling resolution of the incubation including the structural composition of the sediment bacterial abundance and the formation of manganese oxides the regular sampling over short timescales and the extended sampling over one year proved to be critical to constrain the processes and exchanges that govern the contribution of the particulate to the dissolved pools overall this incubation provides a strong basis for reassessing the role of resuspended sedimentary particles in the marine biogeochemical cycles of fe and mn indeed we show that biogenic silica calcite rich and basaltic particles can contribute substantial dissolved fe and mn to the overlying water column in the future the global extent of this previously overlooked external metal source should be quantified through further process studies and biogeochemical models this article is part of a special issue entitled cycles of trace elements and isotopes in the ocean geotraces and beyond edited by tim m conway tristan horner yves plancherel and aridane g gonzalez

hot shale in an ice world paleoceanographic evolution of the northern gondwana margin during the early paleozoic tanezzuft formation tunisia abstract the tanezzuft formation deposited in marine periglacial conditions on the northern gondwana margin during the end of the ice house climate that characterized the lowermost silurian the basal part of this sedimentary sequence is characterized by organic rich facies with locally very high measured total organic carbon toc content up to values greater than 20 while deposition of organic rich sediments during greenhouse time interval is well known deposition of black shales during ice house conditions is poorly documented the extraordinary paleoceanographic conditions that led to the accumulation and preservation of enormous amounts of organic matter in periglacial settings makes this formation an atypical example of black shales deposition the study area is situated on the north african platform in southern tunisia on the northern flank of the ghadames basin petrophysical logs biostratigraphic organic and inorganic geochemical data from nine wells are here integrated with the aim of reconstructing the depositional history of the tanezzuft formation and the role played by organic matter production preservation and dilution through time data indicate that dilution that is depositional style and framework had an important control on lateral and vertical distribution of the c organic rich facies toc and hydrogen index hi maxima are found in correspondence of the main transgressive phases with repetitive stacking patterns strongly associated with source rock properties organic matter production as observed by detailed palynofacies analysis was mainly marine in nature with important contribution by amorphous organic matter leiosphaeridia tasmanaceae and minor amounts of graptolites fragments geochemical data indicate that the organic richest interval hot shale of the tanezzuft formation deposited under severe anoxic conditions that resulted in enhanced organic matter preservation at the sea floor of mod 3d an organic facies modelling software tool by sintef is used in order to reconstruct and quantify the peculiar processes that controlled the exceptional accumulation of organic matter at the time of deposition modelling results indicate that water stratification was the most plausible process that drove organic matter sedimentation under mesotrophic conditions density stratification was probably controlled by the deglaciation phase after the hirnantian glaciation and or by the flooded complex basin physiography that induced an inefficient circulation of the water masses the complete recovery from these extreme paleoceanographic conditions implied progressive processes that took several hundred thousand years

suboxic trace metal geochemistry in the eastern tropical north pacific abstract we analyzed al ti fe mn cu ba cd u mo v and re in water column settling particulate and sediment 0 to 22 cm samples from the intense oxygen minimum zone omz of the eastern tropical north pacific near mazatlan mexico the goal was to determine how the geochemistry of these elements was influenced by suboxic water column conditions and whether the sediments have a unique suboxic geochemical signature the water column was characterized by a mn maximum reaching 8 nmol kg 1 at 400 m concentrations of cu ba cd mo re u and v were unaffected by the low o2 conditions and were comparable to those of the open ocean sinking particles were composed of lithogenic particles of detrital origin and nonlithogenic particles of biogenic origin al ti and fe were mostly at least 79 lithogenic about 75 of the mn was nonlithogenic significant amounts at least 58 of cu ba cd and mo were nonlithogenic sediment geochemistry varied across the continental shelf and slope cadmium u and re have prominent maxima centered at 310 m with 12 3 ppm 10 9 ppm and 68 3 ppb respectively at the core top high values of mo averaging 6 8 ppm and v averaging 90 ppm are seen in omz surface sediment additional down core enrichment occurs for all redox sensitive elements in the top 10 cm for u mo v and re surface sediments are a poor indicator of metal enrichment comparison of the nonlithogenic composition of sediments with sinking particles suggests that direct input of plankton material enriched in metals makes a significant contribution to the total composition especially for cd u and mo we evaluated re mo and cd u ratios as tracers for redox environments rhenium and mo concentrations and re mo ratios do not lead to consistent conclusions concurrent enrichments of re and mo are an indicator of an anoxic depositional environment in contrast high re mo ratios are an indicator of suboxic conditions cadmium is enriched in surface sediments while u has considerable down core enrichment the concentrations of cd and u and the cd u ratio do not follow patterns predicted from thermodynamics though the water column is suboxic these four redox sensitive elements indicate that the sediments are anoxic the implication for paleostudies is that a trace metal sediment signature that indicates anoxic conditions is not necessarily attributable to an anoxic water column

processes controlling the distribution and cycling of manganese in the oxygen minimum zone of the arabian sea abstract vertical and horizontal distributions of dissolved and particulate manganese were investigated in the arabian sea northwestern indian ocean during the 1995 spring intermonsoon period march april us jgofs process cruise 2 tn045 the region is characterized by an intense basin wide oxygen minimum zone omz that strongly influences the manganese distribution in the omz two distinct dissolved mn d mn maxima were observed at depths of 200 300 m and 600 m respectively the latter peak displayed concentration maxima of approximately 6 nanomolar and was largely confined to stations north of 19 n latitude stations n2 n7 this mid depth maximum was associated with the low oxygen core of the omz o 2 saager et al 1989 geochimica et cosmochimica acta 53 2259 2267 this signal was largely absent at stations along the southern transect likely due to oxidative scavenging of d mn to the suspended particulate phase mid depth particulate mn maxima at some southern stations stations s4 s11 appear to be remnants of this feature the upper d mn maximum 200 300 m depth was more widely distributed than the 600 m peak with d mn concentrations of 3 to as high as 8 nm at most stations east of about 62 e longitude the signal was everywhere correlated with the secondary nitrite maximum at stations within the main denitrification zone delineated by naqvi 1991 nepheloid layers presumably bacterial also were associated with this depth interval particulate mn profiles displayed corresponding concentration minima and low mn al and reactive refractory mn ratios for this same depth interval suggesting reductive dissolution of mn oxyhydroxides these observations imply that in situ microbially mediated processes may be the predominant source of d mn in the upper omz while horizontal advection is more important deeper in the water column

chemical reaction rates and entrainment within the endeavour ridge hydrothermal plume the aging of the hydrothermal plume over the endeavour segment of the juan de fuca ridge was estimated by measuring the222rn3he ratio in the plume as it dispersed despite uncertainties in the source function of hydrothermal input it wa determined that the relative sequence of removal from the plume ish2 c 222rn ch4 mn where c is a measure of particle concentration and the mean life of222rn is 5 5 days h2 is removed from the plume within hours of input while mn is not removed within the two week timescale of the radon helium clock entrainment of bottom water within the buoyant plume may introduce additional chemical signatures into the spreading effluent layer over that which would be introduced by hydrothermal discharge alone this is particularly significant for those chemical species which are not greatly enriched in the vent fluids relative to bottom water concentration and which display a nutrient like profile in the deep ocean thus we found that significant fractions of the si and226ra anomalies in the plume were not of hydrothermal origin but were derived from entrained bottom water which has a higher concentration of these elements than ambient water at plume height

geochemistry of suspended particles in the subantarctic and polar frontal zones south of australia constraints on export and advection processes filtered particles from a southern ocean meridional transect from 42 s to 54 s along 142 e off tasmania were studied between surface and 600 m water depth saz 1998 expedition february april 1998 particulate ba sr ca p u th ti al mn light rare earth elements and zr contents were analyzed by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy mesopelagic baxs total ba minus a lithogenic fraction estimated from al contents were higher within the polar front zone pfz in comparison with the northern areas indicating that c export to the intermediate and deep ocean is more important in the pfz average surface uxs versus latitude covaries with mesopelagic baxs contrasting with organic matter proxies such as pp and chlorophyll a this similar behavior suggests that u might be preferentially adsorbed on organic material which subsequently becomes involved with barite precipitation srp and cap contents decrease sharply with depth following total particle content for the northern area 42 47 s surface ce anomaly reflects essentially a lithogenic signature 0 6 ce ce 1 ascribed to the supply from the tasmanian continental shelf suspended matter from surface waters at stations south of 47 s shows an enhanced seawater signature 0 3 ce ce 0 6 in all stations ce anomalies increase with depth toward values close to 1 this is likely due to the increase of lithogenic authigenic ratio of particles with depth rather than redox processes finally an advective event is identified at 45 s below 200 m by a strong increase of lithogenic element contents which affects baxs

atmospheric trace elements at enewetak atoll 2 transport to the ocean by wet and dry deposition the concentrations of trace elements in precipitation and dry deposition are presented for samples collected at enewetak atoll 11 n 162 e during searex experiments in 1979 the concentrations of al sc mn fe co and th in rain are dominated by crustal material and for these elements wet deposition evidently exceeds dry deposition for most of these elements the present rates of atmospheric deposition at enewetak are similar to their mean rate of accumulation in sediments over the past 5 10 000 years suggesting that the air to sea exchange of particles is closely tied to the sedimentary cycle of the mid pacific noncrustal sources govern the concentrations of pb zn cu se and cd in wet and dry deposition samples analyses of dry deposition collected from a flat plastic plate indicate that the amount of material recycled from the sea surface varies markedly between samples and even though these estimates do not necessarily reflect the dry deposition to the ocean surface the results suggest that recycled sea spray often amounts to more than 50 of the total dry deposition of the enriched elements recycled sea spray also makes up a significant fraction of the total wet deposition of the enriched elements the net deposition rates of elements such as cu and zn are greater than or equal to their inputs from vertical mixing but the net deposition of pb clearly exceeds the input from upwelling the current net deposition rates of the enriched elements are also similar to their rates of removal to sediments these results indicate that air sea exchange processes may significantly affect the chemistry of trace metals in the open ocean

formation of ferromanganese crusts on northwest intertropical pacific seamounts electron photomicrography and microprobe chemistry abstract seven ferromanganese crusts from the northwest intertropical pacific seamounts were analyzed for photomicroscopic growth structures microprobe chemistry and ages based on co chronometer growth rate the crusts on the marshall islands seamounts are thick and are divided into phosphatized lower older and nonphosphatized upper younger growth generations the older crust consists of compact laminations and columns impregnated with carbonate fluoapatite cfa whereas the younger crust is characterized by porous botryoids and columns of mno2 and fe oxyhydroxide the crusts on the federated states of micronesia fsm and palau islands seamounts are thin and are often incorporated with inorganic opal a in the uppermost part comprising the younger generation some crusts show scours and fractures although the growth of crusts has been often interrupted by mass failure of slope sediments the crusts on the marshall islands seamounts are estimated to have grown at rate of about 3 mm ma since the middle eocene and to have been phosphatized in the late oligocene during the host seamounts were located beneath the equatorial zone of high productivity prolonged infiltration of the oxygen minimum zone omz water into shallower water older crusts redistributed crust composition by precipitating cfa enriching subsequent amounts of mn and ni and removing some co the younger crust has formed at slower rate about 2 mm ma under the stronger influence of bottom water circulation in the north of the equatorial zone concentrating abundant co in the uppermost part of some crusts siliceous skeletons transform with burial to inorganic opal a and si rich fe oxyhydroxide suggesting that biosilica diagenesis can enhance crust growth

southern california inner basin sediment trap calibration the deployment of particle interceptor traps pits in the three inner basins of the southern california bight santa barbara santa monica and san pedro where preserved laminated bottom sediments occur provides a natural calibration between the parameters determined with the pits and those derived from the historical sedimentary deposits the accumulation rates and chemical composition of the pit materials compare favorably with these recently deposited bottom sediments the ratio of the measured particle collection rate to the sediment accumulation rate for these three basins averaged0 93 0 20 radionuclide 210pb 228th 232th and trace element fe cu zn cd pb compositions of the pit materials and surface sediments agree within generally 30 in each basin an application of pits as a sampling system in an outer basin san nicolas where the sedimentary record has been obscured by bioturbation is also presented to further demonstrate the utility of pits for spatial and temporal studies of various aspects of particle transport and sediment deposition based on the calibration of the pits in the three inner basins we conclude from the comparison of the radionuclide and trace element compositions between the pit materials and surface sediments from the san nicolas basin that recently deposited sedimentary material has been mixed by bioturbation with older material from the last several hundred years excess210pb and the228th 232th activity ratio in the pit material are 6 and 15 times higher than in the surface sediment total pb and1n hno3 leachable pb are 4 and 8 fold higher in the pit material

particulate manganese dynamics in gulf stream warm core rings and surrounding waters of the n w atlantic manganese has been measured in size fractionated paniculate matter profiles obtained by large volume in situ filtration of the upper 1000 m of the n w atlantic as part of the warm core rings experiment wcre in 1982 environments sampled included warm core rings wcr 82b and 82h the entrainment zone at the edge of these rings the slope water surrounding rings and the gulf stream gs and sargasso sea ss from which the rings formed manganese concentrations ranged from 10 pmol kg 1 to 10 000 pmol kg 1 with the extreme values observed in the quasi isolated core waters of wcr 82b and in a tongue of shelf water at the periphery of wcr 82b respectively the majority of the mn was in the 1 53 m particle size fraction and most mn was probably close to 1 m in size mn showed no correlation with major biogenic phases indicating that formation by local biological processes was not an important source instead most paniculate mn present in the waters sampled originated in reducing sediments at the continental margin a manganese budget for the quasi isolated core waters of wcr 82b between february and june 1982 showed that most mn removal was by the aggregation of the small mn oxyhydroxide particles into fecal material followed by sedimentation calculations show that wcrs cause offshore particulate mn transports from the continental margin between 66 w and cape hatteras of 8 5 104 to 14 104 mol d 1 with most derived from the continental shelf only 4 of the shelf derived mn becomes entrained into wcrs and the rest is left to disperse in the slope water or enter the circulation of the gulf stream the wcr induced offshore mn transports may account for a large fraction of the mn flux to sediments on the continental slope and upper continental rise

rare earth major and trace elements in chert from the franciscan complex and monterey group california assessing ree sources to fine grained marine sediments abstract rare earth element ree major and trace element analyses of 77 samples from the mesozoic franciscan complex and miocene monterey group of california usa indicate that magnitudes of the ce anomaly ce ce and total ree abundances sree in these rocks are controlled dominantly by a the amount of included metalliferous material b the amount of direct terrigenous input and c the overall burial rate the relative importance of these individual processes varies across an ocean basin in such a way that ree relative fractionations and sree correspond with its depositional environment our conclusions are supported by an extensive review of published ree data from various river coastal open ocean and ridge influenced waters as well as terrigenous pelagic and metalliferous sediment the chert sequences record deposition in spreading ridge open ocean basin and continental margin environments the relative importance of metalliferous and terrigenous influences and the role of scavenging from seawater may be estimated from a sample s inferred depositional distance km from the spreading ridge the major element chemistry and the stratigraphie context the ce ce values are low 0 29 in the vicinity of spreading ridges and trend to successively higher 1 values with decreasing metalliferous and increasing terrigenous influences other ree indicators ree lu n la n eu eu also respond to metalliferous and terrigenous influences near the spreading ridge chert ree appears determined by burial rate while shale ree responds to metalliferous abundance in open ocean and continental margin environments ree is controlled by sediment exposure time and therefore is related inversely to burial rate ree data are consistent with the major elements fe2o3 mno and al2o3 in reflecting the respective metalliferous and terrigenous sources p2o5 and cao do not vary with ce ce in any environment but cao shows a weak negative correlation with ree trace element trends e g v cr cu ge si rb sr y th u in general can similarly be accounted for in the context of depositional position relative to metalliferous and terrigenous inputs rees in chert appear less affected by post depositional processes than either major or trace elements indicating that rees are better tools for paleoceanographic or tectonic reconstructions that are based on chert chemistry this work complements recent efforts to elucidate the factors determining large scale ree distributions in marine sediments and has direct bearing on previous attempts to use the ce anomaly in older rocks and sediments as a recorder of secular variations and anoxic events in the overlying water column

manganese iron and sulphur cycling on the pakistan margin abstract benthic biogeochemical processes in the oceans oxygen minimum zones omzs are of global significance yet they remain poorly defined here sedimentary manganese iron and sulphur cycling are studied at sites above within and below the omz on the pakistan margin of the arabian sea before and immediately after the southwest monsoon mechanisms and rates of sedimentary mn fe and s cycling demonstrated down slope variation according to the position of the omz no significant seasonal change was evident except at one station on the upper margin where bottom waters became hypoxic during the late to post monsoon sampling due to the shoaling of the upper omz boundary within the omz mn 4 reduction within the water column limited supply of reactive mn to the underlying sediments the majority of reactive mn reaching the sedimentary environment is reduced abiotically via reaction with fe 2 sediments within the omz act as a source of mn 2 to the overlying water below the omz mn 2 is re oxidised within the water column and is deposited on the surface of the underlying sediments manganese is then reduced microbially and re oxidised within the oxygenated surface sediments uniform surface sediment fe al ratios across the margin suggest that fe 3 reduction is lacking within the water column omz in contrast fe is actively cycled within the sediments with fe 3 reduction occurring via dissimilatory pathways an absence of potential fe 2 oxidants within the omz results in an efflux of fe 2 from the sediments to the water column below the omz greater oxidant availability ensures that fe is retained within the sediments measured sulphate reduction rates at all sites across the margin were surprisingly low 0 0 45 mmol m 2 d 1 relative to rates observed on other omz margins the abundance of fe oxides in the sedimentary environment appears to suppress sulphate reduction

manganese fluxes from mississippi delta sediments abstract massive sediment deposition on the mississippi river delta establishes reducing conditions sufficient to bring about mn dissolution in the top millimeters of sediment as a result significant fluxes of dissolved mn pass from the delta sediments to the overlying water column this process is examined by study of chemical partitioning of mn in river particulates and delta sediments and from interstitial water chemistry remobilized mn is actively transported away from the delta area with aluminosilicate detritus thereby providing excess mn to the deep gulf of mexico at the expense of the delta sediments

integrated assessment of the tarut island coast arabian gulf saudi arabia in order to assess pollutants on the tarut island coast saudi arabian gulf 38 coastal sediment samples 40 mollusk specimens and 26 seawater samples were collected for fe cu pb mn cd se as co b cr hg mo and zn analysis using inductively coupled plasma mass spectrometer the analysis indicated that the coastal sediments were enriched polluted and contaminated with as pb cd and hg gastropods were good accumulators for fe cu zn pb mn cd and co while bivalves were good accumulators for se cr and hg the spatial distribution of heavy metals in seawater samples indicated no obvious trend along the studied coast land reclamation dust storms petrochemical industries oil leakage desalination plants and sewage effluents were the significant sources of heavy metal pollutants along tarut coast the comparison between heavy metals in the tarut island coast and other worldwide coasts was emphasized