a methodology for the study of the relation between coastal cliff erosion and the mechanical strength of soils and rock masses abstract a methodology is proposed to make approximate estimates of the destructive force of waves at the bottoms of cliffs where no accurate bathymetric data are available by means of correlation between the erosion rate of rocky coasts and the mechanical strength of soils and rock masses the correlation used makes it possible to obtain a linear semi logarithmic expression between the long term average erosion rate from an engineering standpoint of coasts consisting of different lithologies wave energy and the uniaxial compressive strength of soils and rock masses forming the cliffs the uniaxial compressive strength of soils consisting of landslide debris was measured using a pocket penetrometer and the rock mass index rmi method was used for rock masses these methods were chosen after critical analysis of the methodologies currently available the proposed approach was tested in the cilento area of southern italy and in particular along a 6 km stretch of coast typified by rock masses and landslide debris that are particularly susceptible to erosion this coastline is exposed to south westerly waves which in deep water reach significant heights between 1 and 3 m and significant wave periods between 4 and 7 s estimates of the coastal erosion rates were made by studying the variations especially in restricted headland areas occurring over two time spans 30 and 45 years respectively by comparing topographic maps and aerial photographs taken at different times these comparisons give approximate indications of retreats of 15 m over the time span of 30 years average erosion rate of 0 5 m year 1 and of 35 m over the time span of 45 years average erosion rate of ca 0 8 m year 1 these data do have a local significance but clearly show how quick these processes sometimes are lastly the study of a notch incised by wave action on a concrete sea wall built to protect a terrace made it possible to quantify the impact of erosion on concrete it was possible to obtain rmi values through field observations furthermore it was possible to obtain the constants of the hoek and brown failure criterion using rmi on the basis of rmi values the rock masses studied were defined as moderately strong to strong and according to the hoek and brown criterion as poor to fair a semilogarithmic linear relation was found between the strength of landslide debris rock masses and concrete as well as their respective long term erosion consequently a rough estimate of the destructive force of waves ca 24 mpa was calculated this value is given by the product of the mean value of their hydraulic pressure for a non dimensional constant which in turn takes into account the sandy pebbly beach sediment at the foot of the cliffs that acts as an abrasive on the rock mass

iron and manganese diagenesis in deep sea volcanogenic sediments and the origins of pore water colloids abstract volcanogenic sediments are typically rich in fe and mn bearing minerals that undergo substantial alteration during early marine diagenesis however their impact on the global biogeochemical cycling of fe and mn has not been widely addressed this study compares the near surface 0 20 cm below sea floor cmbsf aqueous no 3 and solid phase reactive fe distributions between two volcanogenic sediment settings 1 a deep sea tephra rich deposit neighbouring the volcanically active island of montserrat and 2 mixed biosiliceous volcanogenic sediments from abyssal depths near the volcanically inactive crozet islands archipelago shallow penetration of o2 aq into montserrat sediments was observed 5 cmbsf and largely controlled by the oxidation of organic matter dissolved fe and mn distributions in montserrat pore waters were lowest in the surface oxic layer 0 3 m fe 32 m mn with maxima 20 m fe 200 m mn in the upper 1 15 cmbsf unlike montserrat fe and mn in crozet pore waters were ubiquitously partitioned between 0 2 m and 0 02 m filtrations indicating that the pore water distributions of fe and mn in the traditionally termed dissolved size fraction are dominated by colloids with respective mean abundances of 80 and 61 plausible mechanisms for the origin and composition of pore water colloids are discussed and include prolonged exposure of crozet surface sediments to early diagenesis compared to montserrat favouring nano particulate goethite formation and the elevated dissolved si concentrations which are shown to encourage fine grained smectite formation in addition organic matter may stabilise authigenic fe and mn in the crozet pore waters we conclude that volcanogenic sediment diagenesis leads to a flux of colloidal material to the overlying bottom water which may impact significantly on deep ocean biogeochemistry diffusive flux estimates from montserrat suggest that diagenesis within tephra deposits of active island volcanism may also be an important source of dissolved mn to the bottom waters and therefore a source for the widespread hydrogenous mnox deposits found in the caribbean region

quantifying he fluxes from the mantle using multi tracer data assimilation a global coarse resolution ocean model previously fitted to geostrophic shear estimates and to data of 10 hydrographic parameters and tracers has been used to simulate the 3he and 4he distribution

mechanisms controlling dissolved iron distribution in the north pacific a model study mechanisms controlling the dissolved iron distribution in the north pacific are investigated using the biogeochemical elemental cycling bec model with a resolution of approximately 1 in latitude and longitude and 60 vertical levels the model is able to reproduce the general distribution of iron as revealed in available field data surface concentrations are generally below 0 2 nm concentrations increase with depth and values in the lower pycnocline are especially high in the northwestern pacific and off the coast of california sensitivity experiments changing scavenging regimes and external iron sources indicate that lateral transport of sedimentary iron from continental margins into the open ocean causes the high concentrations in these regions this offshore penetration only appears under a scavenging regime where iron has a relatively long residence time at high concentrations namely the order of years sedimentary iron is intensively supplied around continental margins resulting in locally high concentrations the residence time with respect to scavenging determines the horizontal scale of elevated iron concentrations budget analysis for iron reveals the processes by which sedimentary iron is transported to the open ocean horizontal mixing transports sedimentary iron from the boundary into alongshore currents which then carry high iron concentrations into the open ocean in regions where the alongshore currents separate from the coast most prominently in the northwestern pacific and off of california

hydrothermal vents as a kinetically stable source of iron sulphide bearing nanoparticles to the ocean hydrothermal vents emit metals such as iron to the ocean a chemical analysis of hydrothermal fluids suggests that up to 10 of the iron is present as stable iron bearing nanoparticles

iron manganese and lead at hawaii ocean time series station aloha temporal variability and an intermediate water hydrothermal plume trace metal clean techniques were used to sample hawaii ocean time series hot station aloha on seven occasions between november 1998 and october 2002 on three occasions full water column profile samples were obtained on the other four occasions surface and near surface euphotic zone profiles were obtained together with three other published samplings this site may have been monitored for dissolved 0 4 or 0 2 m fe more frequently than any other open ocean site in the world low fe concentrations 2500 m the concentrations we observe 0 4 0 5 nmol kg 1 are significantly lower than some other deep north pacific stations but are similar to values that have been reported for a station 350 miles to the northeast we attribute these low deepwater values to transport of low fe antarctic bottom water into the basin and a balance between fe regeneration and scavenging in the deep water near surface waters have higher fe levels than observed in the lower euphotic zone significant temporal variability is seen in near surface fe concentrations ranging from 0 2 0 7 nmol kg 1 we attribute these surface fe fluctuations to variable dust deposition biological uptake and changes in the mixed layer depth this variability could occur only if the surface layer fe residence time is less than a few years and based on that constraint it appears that a higher percentage of the total fe must be released from north pacific aerosols compared to north atlantic aerosols surprisingly significant temporal variability and high particulate fe concentrations are observed for intermediate waters 1000 1500 m these features are seen in the depth interval where high 3he from the nearby loihi seamount hydrothermal fields has been observed the total fe 3he ratio implies that the hydrothermal vents are the source of the high and variable fe the vertical profile of mn at aloha qualitatively resembles other north pacific mn profiles with surface and intermediate water maxima but there are some significant quantitative differences from other reported profiles the 0 4 m mn concentration is highest near the surface decreases sharply in the upper 500 m then shows an intermediate water maximum at 800 m and then decreases in the deepest waters these concentrations are higher than observed at a station 350 miles to the northeast that shows similar vertical variations it appears that there is a significant mn gradient throughout the water column from hot towards the northeast compared to the first valid oceanic pb data for samples collected in 1976 pb at aloha in 1997 1999 shows decreases in surface waters and waters shallower than 200 m pb concentrations in central north pacific surface waters have decreased by a factor of 2 during the past 25 yr from 65 to 30 pmol kg 1 surface water pb concentrations in the central north atlantic and central north pacific are now comparable we attribute the surface water pb decrease to the elimination of leaded gasoline in japan and to some extent by the u s and canada we attribute most of the remaining pb in pacific surface waters to asian emissions more likely due to high temperature industrial activities such as coal burning rather than to leaded gasoline consumption a 3 year mixed layer time series from the nearby hale aloha mooring site 1997 1999 shows that there is an annual cycle in pb with concentrations 20 higher in winter months this rise may be created by downward mixing of the winter mixed layer into the steep gradient of higher pb in the upper thermocline pb concentrations double between the surface and 200 m from 200 m to the bottom pb concentrations decrease to levels of 5 9 pmol kg 1 near the bottom for most of the water column thermocline and deepwater pb concentrations do not appear to have changed significantly during the 23 yr interval

hydrothermal contribution to the oceanic dissolved iron inventory mineral dust and marine sediment resuspension are generally considered the primary sources of the nutrient iron to the oceans numerical model results suggest that iron released by hydrothermal activity is also an important source of dissolved iron particularly in the southern ocean iron limits phytoplankton growth and hence the biological carbon pump in the southern ocean1 models assessing the impacts of iron on the global carbon cycle generally rely on dust input and sediment resuspension as the predominant sources2 3 although it was previously thought that most iron from deep ocean hydrothermal activity was inaccessible to phytoplankton because of the formation of particulates4 it has been suggested that iron from hydrothermal activity5 6 7 may be an important source of oceanic dissolved iron8 9 10 11 12 13 here we use a global ocean model to assess the impacts of an annual dissolved iron flux of approximately 9 108 mol as estimated from regional observations of hydrothermal activity11 12 on the dissolved iron inventory of the world s oceans we find the response to the input of hydrothermal dissolved iron is greatest in the southern hemisphere oceans in particular observations of the distribution of dissolved iron in the southern ocean3 chever et al manuscript in preparation bowie et al manuscript in preparation can be replicated in our simulations only when our estimated iron flux from hydrothermal sources is included as the hydrothermal flux of iron is relatively constant over millennial timescales14 we propose that hydrothermal activity can buffer the oceanic dissolved iron inventory against shorter term fluctuations in dust deposition

the assessment of rock slope instability along the khosh yeylagh main road iran using a systems approach the slope instability is connected to a large diversity of causative and triggering factors ranging from inherent geological structure to the environmental conditions thus assessment and prediction of slope failure hazard is a difficult and complex multi parametric problem in contrast to the analytic approaches the systems approaches are able to consider infinite number of affecting parameters and assess the interactions of each couple of the parameters in the system this paper presents a complete application of the rock engineering systems approach in prediction of the instability potential of rock slopes in 15 stations along a 20 km section of the khosh yeylagh main road iran as the case study of the research in this research the main objective has been defining the principal causative and triggering factors responsible for the manifestation of slope instability phenomena quantify their interactions obtain their weighted coefficients and calculate the slope instability index which refers to the inherent potential instability of each slope of the examined region the final results have been mapped to highlight the rock slopes susceptible to instability finally as a preliminary validation on the utilization of systems approach in the study region the stability of investigated rock slopes were analyzed using an empirical method and the results were compared the comparisons showed a rather good coincidence between the given classes of two methods

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

geomorphology of soft clastic rock coasts in the mid western adriatic sea abruzzo italy abstract we present the first detailed overall study on the rock coasts in the central adriatic sea abruzzo italy which is one of the few cases of a coast with clastic soft rocks in the entire mediterranean area the coast is composed of cliffs with small beaches coastal slopes with or without a contiguous coastal plain and intervening low lying coasts it is developed on the eastern seaward side of a wide plateau and mesa landscape shaped on an early middle pleistocene clay sand sandstone conglomerate marine sequence covered by late pleistocene holocene continental deposits the study focuses on the overall coast and on eight specific sites combining i dem 2 m cell lidar derived analysis and geological geomorphological surveys of the emerged and submerged areas for the cliff coastal slope characterization ii the results of u th 14c sediment dating and archaeological and palaeontological attributions for constraining the coastal evolution and iii aerial photo time series 1954 2013 time span analysis for the recent cliff retreat assessment the overall features of the cliffs and coastal slopes were defined in terms of their morphology lithology tectonic setting landforms and geomorphological processes whereas the analysis of late pleistocene holocene continental deposits and landform distribution defined and constrained the evolution of the coastal system this enabled us to define eight different types of coastal cliffs slopes meaningful for clastic soft rock coasts the coastal types were defined in terms of i lithology 15 cliffs on marine sandstone 15 cliffs on marine conglomerate 3 cliffs on continental deposits 43 coastal slopes on clay sand sandstone conglomerate sequences ii morphostructural setting i e clay sandstone conglomerate interface elevation and iii of state of activity 3 8 active cliffs 13 8 inactive cliffs 15 9 palaeocliffs 43 of inactive and locally reactivated landslides on coastal slopes variable retreat rates were also defined from retreat measurements over a 60 year time span ranging from 0 15 m yr to 1 m yr and were found to be induced by episodic and localized cliff recession processes and connected to combined wave cut and gravity induced slope processes the assessment of coastal and gravity induced geomorphological processes combined with the analysis and dating of the continental deposits allowed us to define the late pleistocene to present evolution and timing and the evolutionary mechanisms of the main coastal types of soft rock coasts they are connected to wave cut and gravity induced erosion cycles on cliffs and to large rotational ancient landsliding with local recent reactivations on coastal slopes for the different coastal types the expected hazard conditions were outlined

chemical characteristics of newly discovered black smoker fluids and associated hydrothermal plumes at the rodriguez triple junction central indian ridge abstract the chemical characteristics of hydrothermal fluids in the indian ocean have been revealed for the first time a hydrothermal field called the kairei field including active black smoker chimneys was discovered by rov kaiko dives at 25 19 17 s 70 02 40 e 2450 m depth on the southwestern flank of an off axis knoll located 15 miles north of the rodriguez triple junction central indian ridge after detailed tow yo surveys of the hydrothermal plume distribution the temperature of the fluid expelled from the most active chimney was almost stable 359 360 c throughout three successive days of fluid sampling the endmember fluid has a chemical composition similar to the hydrothermal fluids sampled from sediment starved mid ocean ridges in the pacific and the atlantic oceans suggesting typical interactions between hot fluid and mid ocean ridge basalts in the subseafloor reaction zone

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

the assessment of rockfall hazard at the base of talus slopes fragmental rockfall is characterized by the independent movement of individual rock fragments after detachment from a rock face the continued operation of the process leads to the accumulation of talus slopes on talus slopes the rockfall shadow extends beyond the base of the talus and consists of scattered boulders that have run out beyond the base of the slope the landing probability of boulders in the shadow is examined return periods of the order of 1000 years relative to a house site are typical rockfall behaviour particularly with respect to run out into the shadow can be assessed using geological evidence empirical methods physical modelling and computer based analytical models an empirical minimum shadow angle of 27 5 i e the angle between the distal limit of the shadow and the top of the talus slope is suggested and would be useful in rockfall vulnerability studies at the base of talus slopes as a first approximation to shadow limits it is preferable to the use of the rockfall fahrb

dissolved iron in the arctic ocean important role of hydrothermal sources shelf input and scavenging removal arctic ocean waters exchange with the north atlantic and thus dissolved iron dfe in the arctic has implications for the global fe cycle we present deep water 250 m dfe concentrations of the central arctic ocean nansen amundsen and makarov basins the dfe concentration in the deep waters varies considerably between these basins with the lowest dfe concentrations 0 2 0 4 nm in the makarov basin higher concentrations similar to 0 45 nm in the amundsen basin and highest concentrations similar to 0 6 0 7 nm in the nansen basin atlantic input from the shelf seas and slopes enhances the dfe concentration in the nansen basin moreover hydrothermal activity at the gakkel ridge causes a significant and widespread enrichment of dfe in the eurasian basins at a depth of 2000 3000 m below this maximum the important role of scavenging and absence of input sources are reflected in a strong relation with dissolved mn dmn and in very low 3000 m amundsen and makarov basins the depth profiles of dfe in the arctic ocean notably in the makarov basin deviate from the dfe distribution pattern observed in other parts of the world ocean

hydrothermal plumes at the rodriguez triple junction indian ridge water column anomalies of light transmission mn fe al and ch4 concentrations were searched in the central southeastern and southwestern indian ridge segments centered on the rodriguez triple junction rtj 25 32 s 70 02 e for the purpose of locating hydrothermally active areas in july to august 1993 we found an active zone in the central indian ridge segment 25 18 20 s approximately 12 miles north of the rtj where significant hydrothermal plumes were observed at 2 200 2 400 m depth intensive tow yo observations using a ctd rosette multi sampling system equipped with a transmissometer revealed that the plumes show temporal as well as spatial variations discrete water samples within the plumes were enriched in mn fe and ch4 with maximum concentrations of 9 8 nm 40 2 nm and 3 3 nm respectively judging from the spatial and chemical characteristics of the plumes especially from transmission anomalies andc h4mn ratios we speculate that the hydrothermal venting site might be not in the rift valley but on the eastern off axis zone several miles distant from the rift valley

estimation of clay content in soil based on resistivity modelling and laboratory measurements the determination of clay content in near surface formations is crucial for geotechnical hydrogeological and oil contamination studies we have developed a technique for estimating clay content that consists of the minimization of the difference between the theoretically calculated and measured soil resistivities as a function of water salinity to calculate the resistivity we used a model that takes into account the electrochemical processes in the clay micropores the experimental measurements of soil resistivity were performed on soil samples completely saturated by brines at different concentrations of nacl salt in the range 0 6 100 g l to obtain the resistivity versus salinity curve the parameters obtained with this curve inversion are the clay content the total porosity and the cation exchange capacity to verify the new technique we determined clay concentrations of artificial mixtures of calibrated sand and clay the relative mean error in the clay content does not exceed 20 for a 5 fitting error of the resistivity versus salinity curves such evaluations allow the correct separation of the main lithological groups sand sandy loam loam and light medium and heavy clay we applied this technique to estimate the petrophysical parameters of soils clay content porosity and cation exchange capacity at various sites in mexico the results improved the interpretation of the vertical electrical soundings the lithological soil characterization and the delineation of oil contaminated areas

hydrothermal sediments are a source of water column fe and mn in the bransfield strait antarctica short sediment cores were collected from 1100 m water depth at the top of hook ridge a submarine volcanic edifice in the central basin of the bransfield strait antarctica to assess fe and mn supply to the water column low temperature hydrothermal fluids advect through these sediments and in places subsurface h2s is present at high enough concentrations to support abundant sclerolinum sp an infaunal tubeworm that hosts symbiotic thiotrophic bacteria the water column is fully oxic and oxygen penetration depths at all sites are 2 5 cmbsf pore water fe and mn content is high within the subsurface ferruginous zone max 565 mol fe l 1 3 7 cmbsf 14 18 times higher than values measured at a nearby background site of equivalent water depth diffusion and advection of pore waters supply significant fe and mn to the surface sediment sequential extraction of the sediment demonstrates that there is a significant enrichment in a suite of reactive authigenic fe minerals in the upper 0 5 cm of sediment at one site characterised by weathered crusts at the seafloor at a site with only minor authigenic mineral surface enrichment we infer that leakage of pore water fe and mn from the sediment leads to enriched total dissolvable fe and mn in bottom waters an eh sensor mounted on a towed package mapped a distinct eh signature above this coring site which is dispersed over several km at the depth of hook ridge we hypothesise that the main mechanism for fe and mn efflux from the sediment is breach of the surface oxic layer by the abundant sclerolinum sp along with episodic enhancements by physical mixing and resuspension of sediment in this dynamic volcanic environment we propose that hook ridge sediments are an important source of fe and mn to the deep waters of the central basin in the bransfield strait where concentrations are sustained by the benthic flux and fe is stabilised in the water column as either colloidal phases or ligand bound dissolved species entrainment of this water mass into the drake passage and thereby the antarctic circumpolar current could provide a significant metal source to this hnlc region of the southern ocean if mixing and upwelling occurs before removal of this metal pool to underlying sediments sediment covered volcanic ridges are common within rifted margins and may play a previously overlooked role in the global fe cycle

particle dynamics in the rising plume at piccard hydrothermal field mid cayman rise processes active in rising hydrothermal plumes such as precipitation particle aggregation and biological growth affect particle size distributions and can exert important influences on the biogeochemical impact of submarine venting of iron to the oceans and their sediments however observations to date of particle size distribution within these systems are both limited and conflicting in a novel buoyant hydrothermal plume study at the recently discovered high temperature 398 c piccard hydrothermal field mid cayman rise we report optical measurements of particle size distributions psds we describe the plume psd in terms of a simple power law model commonly used in studies of upper and coastal ocean particle dynamics observed psd slopes derived from spectral beam attenuation and laser diffraction measurements are among the highest found to date anywhere in the ocean and ranged from 2 9 to 8 5 beam attenuation at 650 nm ranged from near zero to a rarely observed maximum of 192 m 1 at 3 5 m above the vent we did not find large 100 m particles that would settle rapidly to the sediments instead beam attenuation was well correlated to total iron suggesting the first order importance of particle dilution rather than precipitation or dissolution in the rising plume at piccard our observations at piccard caution against the assumption of rapid deposition of hydrothermal particulate metal fluxes and illustrate the need for more particle size and composition measurements across a broader range of sites globally

subduction zone volcanic ash can fertilize the surface ocean and stimulate phytoplankton growth evidence from biogeochemical experiments and satellite data volcanoes confront earth scientists with new fundamental questions can airborne volcanic ash release nutrients on contact with seawater thereby excite the marine primary productivity mpp and most notably can volcanoes through oceanic fertilization affect the global climate in a way that is so far poorly understood here we present results from biogeochemical experiments showing that 1 volcanic ash from subduction zone volcanoes rapidly release an array of nutrients co limiting algal growth in vast oceanic areas 2 at a speed much faster minute scale than hitherto known and that marine phytoplankton from low iron oceanic areas can swiftly within days utilize iron from volcanic sources we further present satellite data possibly indicating an increase of the mpp due to the seaward deposition of volcanic particulate matter our study supports the hypothesis that oceanic iron fertilization with volcanic ash may play a vital role for the development of the global climate

atmospheric transport of iron and its deposition in the ocean the atmospheric transport of continental weathering products is responsible for much of the mineral material and fe entering the open ocean and is probably the dominant source of nutrient fe in the photic zone in regions where other nutrients are present in high concentrations the flux of fe from the atmosphere may be a limiting factor in primary productivity due to the larger source regions for dust north of the equator 8 times more atmospheric fe is deposited in the northern hemisphere than in the southern hemisphere the mineral aerosol and fe transport and deposition are highly variable due to the episodic nature of dust generation and its transport and deposition processes between 10 and 50 of the total atmospheric fe entering the world ocean appears to dissolve i e it will pass through a 0 4 m pore size filter rapidly when the mineral matter enters the ocean much of the atmospheric fe is present as fe ii apparently produced as a result of photochemical reduction reactions taking place during atmospheric transport this readily soluble fe ii should be available immediately for use as a nutrient by phytoplankton atmospheric transport from the continents is estimated to supply 3 times as much dissolved fe to the oceans as that delivered via rivers

landslide hazard mapping along the coastline of the cilento region italy by means of a gis based parameter rating approach abstract this paper deals with the heuristic approach used for landslide hazard zonation along the coastal slopes and cliffs of the cilento region between agropoli and sapri italy this sector of coastline about 118 km in length is formed mainly of mesozoic carbonates and miocene flysch quaternary marine sandstones together with beach sands also crop out due to the destructive force of the waves the coastline is affected by several landslides mainly rock falls and slides the major geomorphological geological and structural features of about 154 slopes and cliffs have been analysed and several parameters affecting the rock masses were detected and measured these parameters deal with topographical geological geomechanical environmental and wave hydraulic characteristics of the studied area in order to perform the heuristic approach the rock engineering systems res proposed by hudson was adopted with several modifications the main steps of this work were 1 the choice of parameters relevant to landslide hazard zonation 2 the analysis of binary interaction between parameters 3 the weighting of interaction importance 4 the rating assignment to different classes of parameter values and 5 the final computation of an instability index i i a database containing the measured parameters was prepared and using an interaction matrix the outputs were linked into a geographic information system it contains the following elements geological and geomorphological features historical data regarding landslides images and values of i i for the studied slopes and cliffs if new landslides occur or near shore engineered structures are built then the i i values will be automatically upgraded values of the i i were grouped into 3 classes marking low medium and high landslide hazard both carbonatic rock masses and flysch were distinguished with respect to i i values to show the differences in landslide susceptibility in fact rapid but small rock falls can cause more casualties than moderate speed but large slides high landslide hazard affects about 41 of carbonate cliffs and about 53 of slopes in arenaceous marly flysch

evidence of an extensive spread of hydrothermal dissolved iron in the indian ocean abstract ocean scale transect observations covering the entire water depth enable a comprehensive picture of the chemistry including the circulation and biogeochemical cycling of elements in seawater the large scale investigation of dissolved iron fe took place through the japanese geotraces study and here we report a basin scale full depth section profile of dissolved fe in the indian ocean from the arabian sea to the southern ocean the data clearly shows the hydrothermal fe distributed over 3000 km distance in the deep layer centered at a depth of approximately 3000 m around the central indian ridge segment and a large part of the dissolved fe from the hydrothermal sources was in the real soluble fraction rather than the colloidal fraction in the intermediate water in the north arabian sea another dissolved fe rich water mass existed where fe was enriched by remineralization processes from settling particles and or adjacent reducing sediments and preserved in the suboxic water the basin scale section profile indicates that there are several sources supplying dissolved fe to deep waters such as the hydrothermal sources and terrestrial fe input with a persistent condition in the oxygen minimum zone omz between the northern subtropical section though few fe sources were apparent in the southern ocean combining our size fractionated fe data with numerical modeling study suggests that the fe physical chemical form in seawater differs between the sources and is a key factor for controlling residence time and explaining the large scale distributed hydrothermal fe

variability in oceanic dissolved iron is dominated by the colloidal fraction abstract oceanic surface and deep iron distribution and size fractionation were investigated on three cruises in the sub tropical and tropical atlantic ocean detailed profiles and transects were collected and analyzed for dissolved fe dfe 0 4 m filtered and soluble fe sfe 0 02 m filtered the difference between dfe and sfe is inferred to be the colloidal fraction of fe cfe sfe concentration distributions and profiles showed little variability in the atlantic ocean with slightly lower concentrations of sfe in the upper ocean than the relatively uniform concentrations observed in deep water 0 3 to 0 4 nmol kg in contrast variability in the atlantic dfe was dominated by variability in cfe dfe and cfe followed dust deposition trends and observed surface maxima in dfe profiles were always due to maxima in the cfe fraction where dust deposition and surface dfe were low i e the south atlantic the cfe fraction of dfe was low and frequently negligible in surface waters below the surface maxima in cfe and dfe cfe always decreased to negligible levels at 30 80 m remained low or negligible throughout the pycnocline and increased with depth below the pycnocline at a site located on the edge of the equatorial system 10 n high dfe and cfe concentrations were associated with an oxygen minimum zone omz at depths of 130 to 1100 m deep water dfe and cfe concentrations varied between water masses depending on the source age and path of the water masses dfe in nadw decreased by 30 from the north atlantic to the south atlantic site with most of the decrease due to loss of cfe at the south atlantic site nadw had higher dfe and a higher fraction of cfe than the antarctic water masses

a new cavability index in block caving mines using fuzzy rock engineering system abstract a new cavability index ci for block caving mines is introduced the interaction matrix based on the rock engineering system res that analyzes the interrelationship between the parameters affecting rock engineering activities is used to study rock mass cavability since the value of interaction in the res method is not unique the fuzzy system is used to minimize subjectivity of the weights which are computed in the res method as a result an index is presented to predict the cavability potential of rock masses the palabora mine was selected as a case study and the proposed index was used to rank the three geological units in this mine it was observed that the rock cavability index could suitably predict rock masses condition from caving point of view the newly proposed approach could be a simple but efficient tool in evaluation of the parameters affecting the cavability of rock mass in block caving mines and hence be useful in decision making under uncertainties

methane manganese and helium 3 in newly discovered hydrothermal plumes over the central indian ridge 18 20 s we have investigated newly discovered submarine hydrothermal plumes over the central indian ridge 18 20 s onshore chemical analyses of methane its carbon isotope manganese and helium 3 in seawater samples obtained from the plumes revealed their detailed geochemical characteristics one of the newly discovered hydrothermal plumes located over the western wall of the axial valley at segment 15b 19 33 s called the roger plateau showed constant ch4 mn and ch4 3he ratios throughout the plume the ch4 3he ratio 4 106 and 13c 17 5 are consistent with those of basalt hosted sediment free hydrothermal systems although the ch4 mn ratio 1 is moderately higher these features are thought to indicate a metal depleted fluid chemistry the other hydrothermal field is located within the axial valley at the northern part of the smooth lava plain at segment 16 18 20 s called the dodo great lava plain where several plumes were detected the ch4 mn and ch4 3he ratios showed large variation through the plumes while 13c values were almost constant geochemical characteristics of venting fluid estimated from those of the plumes were apparently high ch4 mn 6 and ch4 3he 60 106 ratios and low 13c values 27 5 suggesting possible influences of several methane input processes to the fluid chemistry

first active hydrothermal vents on an ultraslow spreading center southwest indian ridge the ultraslow spreading southwest indian ridge is a major tectonic province representing one of the important end member mid ocean ridge types for its very slow and oblique spreading and providing the only known route for migration of chemosynthetic deep sea vent fauna between the atlantic and indian oceans we report the investigation of the first active high temperature hydrothermal field found on any ultraslow mid ocean ridge worldwide located on southwest indian ridge at 37 47 s 49 39 e it consists of three zones extending 1000 m laterally and it is one of four recently discovered active and inactive vent sites within a 250 km long magmatically robust section our results provide the first direct evidence for potentially widespread distribution of hydrothermal activity along ultraslow spreading ridges at least along magmatically robust segments this implies that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities it is surprising that the special vent fauna appear to indicate some complex affinity to those on the central indian ridge southern mid atlantic ridge and the southwest pacific ocean

hydrothermal plumes over the carlsberg ridge indian ocean 1 indian ocean ridges north of the rodriguez triple junction remain poorly explored for seafloor hydrothermal activity with only two active sites confirmed north of 25 s we conducted water column surveys and sampling in 2007 and 2009 to search for hydrothermal plumes over a segment of the carlsberg ridge here we report evidence for two separate vent fields one near 3 42 n 63 40 e and another near 3 41 5 n 63 50 e on a segment that is apparently sparsely magmatic both sites appear to be located on off axis highs at the top of the southern axial valley wall at depths of 3600 m or shallower 1000 m above the valley floor at the 63 40 e site plume sampling found local maxima in light scattering temperature anomaly oxidation reduction potential orp dissolved mn and3he no water samples are available from the 63 50 e site but it showed robust light scattering and orp anomalies at multiple depths implying multiple sources orp anomalies are very short lived so the strong signals at both sites suggest that fluid sources lie within a few kilometers or less from the plume sampling locations although ultramafic rocks have been recovered near these sites the light scattering and dissolved mn anomalies imply that the plumes do not arise from a system driven solely by exothermic serpentinization e g lost city instead the source fluids may be a product of both ultramafic and basaltic gabbroic fluid rock interaction similar to the rainbow and logatchev fields on the mid atlantic ridge

dissolved iron anomaly in the deep tropical subtropical pacific evidence for long range transport of hydrothermal iron abstract dissolved iron profiles along a north south transect along 158 w in the tropical pacific show evidence of two deepwater anomalies the first extends from station aloha 22 78 n to the equator at 1000 1500 m and lies below the maximum apparent oxygen utilization and nutrient n p concentrations the feature is not supported by vertical export processes but instead corresponds with the lateral dilution field of 3 he derived from the loihi seamount hawaii though a sediment source associated with the hawaiian island chain cannot be entirely ruled out the second deeper 2000 3000 m anomaly occurs in tropical south pacific waters 7 s and also does not correlate with the depths of maximum nutrient concentrations or apparent oxygen utilization but it does coincide closely with 3 he emanating from the east pacific rise more than 5000 km to the east we hypothesize that these anomalies represent the long range 2000 km transport of hydrothermal iron residuals stabilized against scavenging by complexation with excess organic ligands in the plume source regions such trace leakage of hydrothermal iron to distal plume regions would have been difficult to identify in most hydrothermal vent mapping studies because low analytical detection limits were not needed for the proximal plume regions these findings suggest that hydrothermal activity may represent a major source of dissolved iron throughout the south pacific deep basin today as well as other regions having high mid ocean spreading rates in the geologic past in particular we hypothesize that high spreading rates along the south atlantic and southern ocean mid oceanic ridges combined with the upwelling ventilation of these distal hydrothermal plumes may have increased ocean productivity and carbon export in the southern ocean assessing the magnitude and persistence of dissolved hydrothermal iron in basin scale deep waters will be important for understanding the marine biogeochemistry of iron and potentially on ocean productivity and climate change during the geologic past

geological analysis and stability assessment of a sea arch in palinuro southern italy abstract the study aims to describe the geological and geostructural layouts of an unstable sea arch located in a very attractive tourist area of southern italy on the basis of ad hoc field surveys and laboratory tests the problems of an in depth geo mechanical characterization of the rock mass are discussed in details and its main strength parameters are derived an indirect assessment of the possible geostatic stress field due to the neotectonic events which affected this sector of apennine range during the last 100 000 years is proposed and validated by means of numerical non linear fe analyses the results suggest that the presence of a lateral thrust acting into the promontory located at the back of the arch is very likely and its effects would agree well with the failures occurred in the past on the arch surfaces it is concluded that any possible intervention should be carefully designed on the basis of the highlighted factors and further investigations

gis based landslide susceptibility mapping for the 2005 kashmir earthquake region abstract the m w 7 6 october 8 2005 kashmir earthquake triggered several thousand landslides throughout the himalaya of northern pakistan and india these were concentrated in six different geomorphic geologic anthropogenic settings a spatial database which included 2252 landslides was developed and analyzed using aster satellite imagery and geographical information system gis technology a multi criterion evaluation was applied to determine the significance of event controlling parameters in triggering the landslides the parameters included lithology faults slope gradient slope aspect elevation land cover rivers and roads the results showed four classes of landslide susceptibility furthermore they indicated that lithology had the strongest influence on landsliding particularly when the rock is highly fractured such as in shale slate clastic sediments and limestone and dolomite moreover the proximity of the landslides to faults rivers and roads was also an important factor in helping to initiate failures in addition landslides occurred particularly in moderate elevations on south facing slopes shrub land grassland and also agricultural land were highly susceptible to failures while forested slopes had few landslides one third of the study area was highly or very highly susceptible to future landsliding and requires immediate mitigation action the rest of the region had a low or moderate susceptibility to landsliding and remains relatively stable this study supports the view that 1 earthquake triggered landslides are concentrated in specific zones associated with event controlling parameters and 2 in the western himalaya deforestation and road construction contributed significantly to landsliding during and shortly after earthquakes

iron ii distribution and oxidation kinetics in hydrothermal plumes at the kairei and edmond vent sites indian ocean deep sea hydrothermal activity cycles the entire volume of the global ocean through deep sea hydrothermal plumes at least every 4 8 103 a a rapid timescale that is comparable to global deep ocean mixing an important process within hydrothermal plumes is the oxidation of dissolved iron discharged with vent fluids leading to the co precipitation of many other vent sourced metals thus modifying gross hydrothermal fluxes to the deep ocean and acting as a net sink in the ocean chemical budgets of certain key tracers here we report direct measurements of dissolved fe ii oxidation rates from two recently discovered indian ocean vent sites that are intermediate between pacific and atlantic values thus demonstrating that the rate of iron oxidation and formation of scavenging fe iii solid phases in hydrothermal plumes varies systematically along the global deep ocean conveyor the average pseudo first order rate constant for the oxidation reaction is 0 303 h 1 and the corresponding half life 2 31 h the rate plots show some curvature however indicating additional processes possibly interactions with organic matter may also influence the net oxidation removal rate different rates of oxidation of iron in hydrothermal plumes in different ocean basins have important implications for the dispersion of produced oxide phases which in turn may impact on uptake of other metals from seawater and deposition into underlying ridge crest and ridge flank sediments

first data on trace metal level and behaviour in two major arctic river estuarine systems ob and yenisey and in the adjacent kara sea russia dissolved and colloidal trace element concentrations cd cu fe ni and pb were determined in the ob and yenisey river estuary systems and in the adjacent kara sea in september 1993 the data show a natural low concentration level of dissolved 0 4 m trace metals cd cu fe ni and pb in the two rivers and in the kara sea as compared to world unpolluted rivers and the central arctic ocean suggesting that the region studied is pristine with respect to trace metals the pathway of trace metals transported from rivers to the ocean seems to be complicated and largely influenced by biogeochemical processes taking place in the estuarine mixing zone colloidal material 104 daltons 0 4 m in addition to its significant contribution to the so called dissolved fraction has been shown to play a fundamental role in determining the behaviour of both conservative and non conservative trace metals during estuarine mixing hence colloids may control to a large extent the fate of dissolved trace metals as well as their net input from the rivers to the kara sea

contributions from glacially derived sediment to the global iron oxyhydr oxide cycle implications for iron delivery to the oceans estimates of glacial sediment delivery to the oceans have been derived from fluxes of meltwater runoff and iceberg calving and their sediment loads the combined total 2900 tg yr 1 of the suspended sediment load in meltwaters 1400 tg yr 1 and the sediment delivered by icebergs 1500 tg yr 1 are within the range of earlier estimates high resolution microscopic observations show that suspended sediments from glacial meltwaters supraglacial and proglacial sediments and sediments in basal ice from arctic alpine and antarctic locations all contain iron oxyhydr oxide nanoparticles which are poorly crystalline typically 5 nm in diameter and which occur as single grains or aggregates that may be isolated or attached to sediment grains nanoparticles with these characteristics are potentially bioavailable a global model comparing the sources and sinks of iron present as oxyhydr oxides indicates that sediment delivered by icebergs is a significant source of iron to the open oceans beyond the continental shelf iceberg delivery of sediment containing iron as oxyhydr oxides during the last glacial maximum may have been sufficient to fertilise the increase in oceanic productivity required to drawdown atmospheric co2 to the levels observed in ice cores

landslide risk assessment prediction of travel distance the geotechnical engineering office of hong kong database of landslides for the period 1984 1993 containing over 3000 landslide records and data for major landslides before this period were made