infaunal density biomass and bioturbation in the sediments of the arctic ocean abstract little is known about the benthic communities of the arctic ocean s slope and abyssal plains here we report on benthic data collected from box cores along a transect from alaska to the barents abyssal plain during the arctic ocean section of 1994 we determined 1 density and biomass of the polychaetes foraminifera and total infauna 2 concentrations of potential sources of food pigment concentration and percent organic carbon in the sediments 3 surficial particle mixing depths and rates using downcore 210pb profiles and 4 surficial porewater irrigation using nabr as an inert tracer metazoan density and biomass vary by almost three orders of magnitude from the shelf to the deep basins e g 47 403 individuals m 2 on the chukchi shelf to 95 individuals m 2 in the barents abyssal plain water depth is the primary determinant of infaunal density explaining 39 of the total variability potential food concentration varies by almost two orders of magnitude during the late summer season e g the phaeopigment concentration integrated to 10 cm varies from 36 16 mg m 2 on the chukchi shelf to 0 94 mg m 2 in the siberia abyssal plain but is not significantly correlated with density or biomass of the metazoa most stations show evidence of particle mixing with mixing limited to 3 cm below the sediment water interface and enhanced pore water irrigation occurs at seven of the nine stations examined particle mixing depths may be related to metazoan biomass while enhanced pore water irrigation beyond what is expected from diffusion alone appears to be related to total phaeopigment concentration the data presented here indicate that arctic benthic ecosystems are quite variable but all stations sampled contained infauna and most stations had indications of active processing of the sediment by the associated infauna

groundwater processes sandplain seeps and interactions with regional aquifer systems in south western australia abstract groundwater systems were studied in the 4200 ha east belka catchment in a dryland farming area 300 km east of perth w a to determine the cause of sandplain seeps detailed investigations were carried out on a 200 ha hillslope to determine the characteristics of a shallow aquifer system responsible for the salinization of previously productive agricultural soils the impact of the shallow aquifer on the regional system was investigated a shallow less than 8 m perched perennial aquifer was encountered in the deep sandplain materials groundwater discharge of about 1000 kl year 1 from the perched aquifer maintained saline soils across a 5 ha sandplain seep perching is due to the decreased permeability geometry and silicification of the top of the mottled and pallid zones and the convergence of perched ground waters near the seep slug test measurements suggest that the sandplain soils have a relatively low hydraulic conductivity 0 15 m day 1 water qualities in the perched aquifer ranged from brackish to saline 3000 8000 mg l 1 tds peaking in the salt affected area 12 000 mg l 1 tds high nitrate and cl br ratios occur in the shallow aquifer and in the regional ground water beneath the sandplain seep recharge to the deep aquifer takes place throughout the catchment but is greatest beneath the sandplain seep where a perennial groundwater mound occurs recharge to the regional aquifer was estimated to be 6 to 15 mm year 1 increasing to between 20 and 60 mm year 1 beneath the seep by contrast less than 0 3 mm year 1 is able to leave the catchment as regional groundwater flow water levels in the deep bores are consequently rising by 0 05 to 0 25 m year 1 recharge to the deep aquifer beneath the seep and low groundwater gradients create the potential for groundwater flow to take place beneath the topographic divide and towards the adjoining catchment however as the vertical flux to the aquifer is two orders of magnitude greater than the horizontal flow ground waters are effectively impounded within the catchment

late quaternary spatial and temporal variability in arctic deep sea bioturbation and its relation to mn cycles changes in intensity and composition of bioturbation and trace fossils in deep sea settings are directly related to changes in environmental parameters such as food availability bottom water oxygenation or substrate consistency because trace fossils are practically always preserved in situ and are often present in environments where other environmental indicators are scarce or may have been compromised or removed by diagenetic processes the trace fossils provide an important source of paleoenvironmental information in regions such as the deep arctic ocean detailed analysis of x ray radiographs from 12 piston and gravity cores from a transect spanning from the makarov basin to the yermak plateau via the lomonosov ridge the morris jesup rise and the gakkel ridge reveal both spatial and temporal variations in an ichnofauna consisting of chondrites nereites phycosiphon planolites scolicia trichichnus zoophycos as well as deformational biogenic structures the spatial variability in abundance and diversity is in close correspondence to observed patterns in the distribution of modern benthos suggesting that food availability and food flux to the sea floor are the most important parameters controlling variations in bioturbation in the arctic ocean the most diverse ichnofaunas were observed at sites on the central lomonosov ridge that today have partially ice free conditions and relatively high summer productivity in contrast the most sparse ichnofauna was observed in the ice infested region on the lomonosov ridge north of greenland since primary productivity and therefore also the food flux at a certain location is ultimately controlled by the geographical position in relation to ice margin and the continental shelves temporal variations in abundance and diversity of trace fossils have the potential to reveal changes in food flux and consequently sea ice conditions on glacial interglacial time scales down core analysis reveal clearly increased abundance and diversity during interglacial interstadial intervals that were identified through strongly enhanced mn levels and the presence of micro and nannofossils warm stages are characterized by larger trace fossils such as scolicia planolites or nereites while cold stages typically display an ichnofauna dominated by small deep penetrating trace fossils such as chondrites or trichichnus the presence of biogenic structures in glacial intervals clearly show that the arctic deep waters must have remained fairly well ventilated also during glacials thereby lending support to the hypothesis that the conspicuous brown layers rich in mn which are found ubiquitously over the arctic basins are related to input from rivers and coastal erosion during sea level high stands rather than redox processes in the water column and on the sea floor however the x ray radiograph study also revealed the presence of apparently post sedimentary diagenetically formed mn layers which are not directly related to mn input from rivers and shelves these observations thus bolster the hypothesis that the bioturbated brownish mn rich layers can be used for stratigraphic correlation over large distances in the arctic ocean but only if post sedimentary diagenetic layers can be identified and accounted for in the mn cycle stratigraphy

shallow slope failures in clays as a result of decreased evapotranspiration subsequent to forest clearing in the kaministiquia river valley near thunder bay ontario shallow ground movements are common on the grassy slopes whereas the forested slopes generally appear stable these slope failures may

deep arid system hydrodynamics 1 equilibrium states and response times in thick desert vadose zones 1 quantifying moisture fluxes through deep desert soils remains difficult because of the small magnitude of the fluxes and the lack of a comprehensive model to describe flow and transport through such dry material a particular challenge for such a model is reproducing both observed matric potential and chloride profiles we propose a conceptual model for flow in desert vadose zones that includes isothermal and nonisothermal vapor transport and the role of desert vegetation in supporting a net upward moisture flux below the root zone numerical simulations incorporating this conceptual model match typical matric potential and chloride profiles the modeling approach thereby reconciles the paradox between the recognized importance of plants upward driving forces and vapor flow processes in desert vadose zones and the inadequacy of the downward only liquid flow assumption of the conventional chloride mass balance approach our work shows that water transport in thick desert vadose zones at steady state is usually dominated by upward vapor flow and that long response times of the order of 104 105 years are required to equilibrate to existing arid surface conditions simulation results indicate that most thick desert vadose zones have been locked in slow drying transients that began in response to a climate shift and establishment of desert vegetation many thousands of years ago

temporal variability in phytodetritus and megabenthic activity at the seabed in the deep northeast atlantic we report a ten year study of the abundance and activity of megabenthos on the porcupine abyssal plain northeast atlantic together with observations on the occurrence of phytodetritus at the deep sea floor 4850 m using the southampton oceanography centre time lapse camera system bathysnap we have recorded a radical change in the abundance and activity of megabenthos between the two periods of study 1991 1994 and 1997 2000 in 1991 1994 the larger megabenthos occurred at an abundance of c 71 6 ha and were dominated by large holothurians in addition there were very substantial populations of smaller megabenthic ophiuroids c 4979 ha together the total megabenthos are estimated to track over some 17 cm2 m2 d exploiting 100 of the surface of the seabed in c 2 5 years in 1997 2000 the larger megabenthos increased to an abundance of c 204 ha and were joined by exceptional numbers of a small holothurian species amperima rosea 6457 ha and ophiuroids principally ophiocten hastatum 53 539 ha the total megabenthos population was tracking at an estimnated rate of c 247 cm2 m2 d exploiting 100 of seabed in just 6 weeks coincident with these increases in the abundance and activity of the megabenthos there were apparently no mass depositions of aggregated phytodetritus to the seabed in the summers of 1997 1999 mass occurrences of phytodetritus had been noted during the summer months of the three years previously studied 1991 1993 and 1994 with covering between 50 and 96 of the sediment surface there is a statistically significant p 0 02 negative correlation between maximum extent of this seabed cover of phytodetritus and seabed tracking by megabenthos additional studies lampitt et al progr ocean 50 2001 indicate that there were no substantial changes in surface ocean primary productivity in export flux or in the composition of the flux that might otherwise account for the apparent absence of observable concentrations of phytodetritus during the summers of 1997 1999 we postulate that the marked increase in megabenthic tracking activity resulted in the removal via consumption disaggregation burial etc of the bulk of the incoming phytodetrital flux during these years a simple conceptual model based on the apparent phytodetrital fluxes observed in 1991 and 1993 suggests that the megabenthos tracking rates estimated for 1997 1999 are sufficient to account for near total removal of this flux however we are not able to estimate other processes removing phytodetritus i e other elements of the benthos that may also have increased between 1991 1994 and 1997 1999 other independent studies e g ginger et al progr ocean 50 2001 of flux constituents support the possibility that just a few species of megabenthos e g a rosea and o hastatum could well have consumed a major proportion of the incoming flux and so substantially modified the composition of the organic matter available to other components of the benthos

salinity trends in the wheatbelt of western australia results of water and salt balance studies from cuballing catchment abstract a study of water and salt balances within a first order catchment in the western australian wheatbelt has shown that the salt load in the main surface drainage comes largely from groundwater discharging upstream from the basement highs and dykes that extend across the surface drainage and conductive channels within the regolith although salt fall from rainfall is about 2 0 g m 2 year 1 cl the stream load ranges from 180 to 850 g m 2 year 1 with an out input ratio of 100 425 salt storage in the catchment varies from 900 4000 g m 2 in the top 3 m to 27 000 71 000 g m 2 in the 3 15 m depth range and 5000 21 000 g m 2 below 15 m groundwater discharge calculated using br and cl as tracers for the groundwater component fluctuates between 20 and 40 of streamflow stream salinity during the last 3 years was below the long term average this is attributed to a reduction in groundwater discharge caused by low rainfall during this period the downward displacement and leaching of salt stored in the regolith indicates that if groundwater levels continue to rise the quantity and salinity of groundwater discharge will continue to increase causing further rises in stream salinity

disturbances of temperature depth profiles due to surface climate change and subsurface water flow 2 an effect of step increase in surface temperature caused by forest clearing in southwest western australia a series of type curves is presented for estimating vertical groundwater fluxes under the condition of a step increase in surface temperature the depths of minimum groundwater temperature in temperature depth profiles are used as an indicator of the magnitude of the downward groundwater fluxes the type curve method has been applied to the subsurface thermal regime observed in experimental catchments in the collie river basin in southwest western australia to estimate the vertical groundwater fluxes under the condition of surface warming caused by land cover change from forest to agriculture the groundwater fluxes obtained from the type curves and the depths of minimum groundwater temperature in temperature depth profiles agree well with the values obtained from the other studies

changes in streamflow components following logging and regeneration in the southern forest of western australia two small experimental catchments were established in the south west of western australia to study the effects of logging and subsequent regeneration on the mechanism of streamflow generation following a six year pre treatment calibration period 1976 1981 one catchment march road was logged and reforested in 1982 and the other april road south remained as a control logging resulted in an increase in groundwater levels and subsequently groundwater discharge area the deep permanent groundwater levels in the valley and upslope areas rose until 1986 and then began to decline the maximum rise was 5 m in the upslope areas the duration of shallow intermittent groundwater system perched on underlying clay was extended from 2 3 months in winter before logging to 5 6 months after logging the shallow groundwater level rose in the valley and began to discharge at the ground surface in 1986 logging resulted in an increase in streamflow the maximum increase 18 of annual rainfall was in 1983 one year after logging the increase in streamflow was due to a substantial decrease in interception and evapotranspiration increased recharge to the shallow groundwater system decreased soil moisture deficit and consequently an increase in throughflow the increase in base flow was about twice that of quick flow the changes in streamflow and its components in the subsequent years were closely related to the groundwater discharge area most of the quick flow was generated as saturation excess overland flow from the groundwater discharge area in the valley the expansion of the groundwater discharge area increased soil moisture content higher groundwater level and the presence of the shallow groundwater system for the extended periods were responsible for the process of streamflow generation

the biodiversity and biogeography of komokiaceans and other enigmatic foraminiferan like protists in the deep southern ocean we present a survey of komokiaceans and other relatively large stercomata bearing testate protists presumed to be foraminifera based on extensive ship board sorting of samples collected at 13 sites depth range 1820 4930 m in the weddell sea and two sites in the se atlantic cape and aguilas basins north of the antarctic convergence during the andeep iii expedition thirty nine species occurred in the weddell sea and a further 11 in the se atlantic basins of these 50 species 35 are undescribed we assign with a greater or lesser degree of certainty 26 and 13 species to the komokiacean families komokiidae and baculellidae respectively and another 2 to the komokiacea incertae sedis we include in the baculellidae an undescribed species in which very fine hair like fibres similar to those seen in some species currently included in this family arise from the segments that make up the chain like test a further 11 chain like species lack these fibres and we therefore exclude them from the komokiacea a final group of species includes a mixture of different forms some of which exhibit komokiacean like features these assemblages were most diverse at abyssal sites in the central weddell sea 27 30 species per site above 4000 m 1 8 species were present at individual sites and only two species normanina conferta and septuma brachyramosa occurred at depths 2000 m one of these n conferta was the most widely distributed species occurring at 11 stations south of the antarctic convergence as well as the aguilas basin many 31 61 of the southern ocean andeep species are recognised in the north atlantic and 6 were previously described from the central north pacific our results suggest that some komokiacean and chain like species are widely distributed at abyssal depths in the oceans they also support other evidence that many undescribed komokiacean species exist and highlight some of the difficulties involved in defining the morphological limits of this difficult taxon

slope and deep sea abundance across scales southern ocean isopods show how complex the deep sea can be how animals are distributed in the world s largest surface environment the deep sea is poorly understood the andeep antarctic benthic deep sea biodiversity colonisation history and recent community patterns iii cruise probed richness and abundance of one group peracarid crustaceans isopods amphipods cumaceans tanaidaceans mysidaceans as a model of deep sea fauna across southern ocean so sites analysis of samples from the andeep cruises reveals so isopods to be highly abundant rich and endemic as many other taxa in the region are known to be samples taken across three spatial scales include sites tens hundreds and thousands of kilometers apart sites stretching from the southern cape basin south atlantic to continental antarctica and including depths from 1030 to 5000 m across these spatial scales we investigated ecological success abundance of peracarids at order family and species levels remarkably no significant relationship was found between abundance and spatial scale at any taxonomic level that is the variability in abundance at major regional scale is no different to that across just tens of kilometres most taxa were represented in only a few samples but we suggest most inhabitants of the deep weddell sea environment to be very patchy rather than rare separate plots of family genus and species abundance by sample number revealed this to be true nearly all genera and species are an order of magnitude more abundant than background levels in just one or two samples our isopod and amphipod samples reveal the atlantic sector of the so one of the most dynamic and important regions influencing the global deep sea environment to be highly complex our study suggests that at least with regard to the study taxa and area the typical comparisons of regions that are made by ecologists miss the scale at which crucial ecological variability happens even without ice scours creating topographical complexity as on the shelf the deep weddell sea is clearly complex at scales smaller than that measured to date

polychaetes of the deep weddell and scotia seas composition and zoogeographical links a preliminary analysis of polychaetes from box core samples taken in the drake passage the weddell sea and the scotia arc resulted in novel albeit partial information about deep sea communities in the southern ocean similarities were found with deep sea fauna worldwide on the generic level and with adjacent basins on species level polychaetes unlike other taxa apparently have wide geographical ranges in addition the well known phenomenon of eurybathy in the southern ocean may have to be reconsidered as there are indications that the shelf fauna is eventually replaced by deep sea species the only difference to temperate oceans being the greater depth of the faunal shift the general structure of the communities in the deep southern ocean resembles that of other deep sea basins in the low density combined with a high number of species per station

chloride as a signature indicator of soil textural and hydrologic stratigraphies in variable charge deep profiles soil properties that influence water movement through profiles are important for determining flow paths reactions between soil and solute and the ultimate destination of solutes this is particularly important in high rainfall environments for highly weathered deep profiles we hypothesize that abrupt changes in the distribution of the quotient qt silt sand clay reflect the boundaries between textural units or textural ts and hydrologic hs stratigraphies as a result qt can be used as a parameter to characterize ts and as a surrogate for hs secondly we propose that if chloride distributions were correlated with qt under non limiting anion exchange then chloride distributions can be used as a signature indicator of ts and hs soil cores to a depth of 12 5 in were taken from 16 locations in the wet tropical johnstone river catchment of northeast queensland australia the cores belong to nine variable charge soil types and were under sugarcane saccharun officinarum s production which included the use of potassium chloride for several decades the cores were segmented at i m depth increments and subsamples were analysed for chloride ph soil water content theta clay silt and sand contents selected bores were capped to serve as piezometers to monitor groundwater dynamics depth incremented qt theta and chloride correlated each individually significantly with the corresponding profile depth increments indicating the presence of textural hydrologic and chloride gradients in profiles however rapid increases in qt down the profile indicated abrupt changes in ts suggesting that qt can be used as a parameter to characterize ts and as a surrogate for hs abrupt changes in chloride distributions were similar to qt suggesting that chloride distributions can be used as a signature indicator of qt ts and hs groundwater data indicated that chloride distributions depended at least partially on groundwater dynamics providing further support to our hypothesis that chloride distribution can be used as a signature indicator of hs copyright c 2005 john wiley sons ltd

methane generated pockmarks on young thickly sedimented oceanic crust in the arctic vestnesa ridge fram strait acoustic backscatter imagery in the fram strait between greenland and spitzbergen reveals a 1 3 km wide 50 km long belt of 50 pointlike backscatter objects decorating the 1300 m deep crest of vestnesa ridge a 1 2 km thick sediment drift possibly underlain by a transform parallel oceanic basement ridge crustal ages 3 14 ma a 3 5 khz seismic reflection profile indicates that at least some objects are pockmarks 100 200 m in diameter and 10 20 m deep the pockmarks possibly also mud diapirs may have been formed by evolution of methane generated by the decomposition of marine organic matter in the vestnesa ridge sediment drift the ridge may be underlain by an anticlinal carapace of methane hydrate calculated to be 200 300 m thick comparable to the hydrate thickness measured just to the south the rising methane would collect in the ridge crest trap intermittently escaping to the sea floor this hypothesis is supported by multichannel evidence for bright spots and bottom simulating reflectors in the area the pockmark belt may also be located above a transcurrent fault sediment slumps on the flanks of vestnesa ridge and northeast of molloy ridge may have been triggered by plate boundary earthquakes and facilitated by methane hydrates

iceberg discharges into the north atlantic on millennial time scales during the last glaciation high resolution studies of north atlantic deep sea cores demonstrate that prominent increases in iceberg calving recurred at intervals of 2000 to 3000 years much more frequently than the 7000 to 10 000 year pacing of massive ice discharges associated with heinrich events the calving cycles correlate with warm cold oscillations called dansgaard oeschger events in greenland ice cores each cycle records synchronous discharges of ice from different sources and the cycles are decoupled from sea surface temperatures these findings point to a mechanism operating within the atmosphere that caused rapid oscillations in air temperatures above greenland and in calving from more than one ice sheet

live stained deep sea benthic foraminiferans in the western weddell sea trends in abundance diversity and taxonomic composition along a depth transect entire live foraminiferal assemblages i e including soft walled species were analysed using replicate subcores 3 45 cm2 surface area 0 1 cm layer 63 m fraction from multiple corer samples collected along a transect 1100 5000 m water depth of the continental slope and rise and adjacent abyssal plain to the east of the antarctic peninsula foraminiferans usually accounted for 61 83 of all meiofaunal organisms mean densities were highest 576 individuals indiv 10 cm 2 at 2100 m water depth and declined to 240 indiv 10 cm 2 at 5000 m although there was considerable variability between replicates at some stations e g 304 333 1090 indiv 10 cm 2 at 2100 m foraminiferan and metazoan meiofaunal densities were broadly coherent across the depth range sampled a total of 158 live foraminiferal species was recognized assemblages were most diverse on the lower slope with species numbers peaking at 3100 m and the fisher diversity index at 3100 4100 m monothalamous taxa increased in relative abundance from 8 at 1100 m to 33 at 4975 m and there was a corresponding decrease in the proportion of calcareous taxa from 65 to 16 on the continental slope 1100 3100 m the most abundant hard walled species were epistominella exigua adercotryma glomeratum alabaminella weddellensis and stetsonia hovarthi in the deeper samples 4100 5000 m a glomeratum became the dominant hard walled species important soft walled species included tinogullmia riemanni and bathyallogromia weddellensis in some samples from 1100 and 2100 m more than a third of the live assemblage was hidden within phytodetrital aggregates species such as e exigua a weddellensis and t riemanni were concentrated within these microhabitats many of the weddell sea species are typical bathyal and abyssal forms well known from the north atlantic and elsewhere the phytodetrital assemblages are strikingly similar to those reported from abyssal sites in the north atlantic our observations suggest that there are close faunal links between the deep water faunas of the weddell sea and those of other oceanic regions perhaps mediated by thermohaline circulation

distribution of environmental chloride in relation to subsurface hydrology abstract chloride distributions in 32 deeply weathered profiles up to 39 m deep were used to investigate the subsurface hydrology typical of the saline landscapes of the south west of western australia studies took place in two forested areas of differing rainfall and landform to compare the processes of water movement a steady state model of water and chloride movement which included the effects of diffusion was used to estimate vertical soil water flux density q w from observed concentrations of chloride these patterns of water flow were compared to the physical properties of the profiles a great deal of variability was found between profiles and there was a marked difference in the magnitude of q w between the areas of different rainfall however consistent patterns of subsurface water movement can be identified thin coarse textured surface soils are well leached by rainfall but in the clayey unsaturated zone below vertical soil water flux densities are very small due to the uptake of water by the eucalyptus forest where rainfall was 800 mm yr 1 q w was typically of the order 0 4 mm yr 1 and in the area of 1150 mm yr 1 rainfall q w was 2 5 mm yr 1 rates of recharge to groundwater estimated from chloride concentration in the saturated zone were as much as two orders of magnitude greater than q w above the water table it is concluded that preferred water flow in structural and textural heterogeneities within the regolith is the dominant mechanism of recharge the preferred flow paths are distributed throughout the landscape but only constitute a small proportion of it

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

chemosynthetic mussels at a brine filled pockmark in the northern gulf of mexico a large 540 square meters bed of bathymodiolus n sp mytilidae bivalvia rings a pool of hypersaline 121 35 practical salinity units brine at a water depth of 650 meters on the continental slope south of louisiana the anoxic brine dissolved oxygen 0 17 milliliters per liter contains high concentrations of methane which nourishes methanotrophic symbionts in the mussels the brine which originates from a salt cored diapir that penetrates to within 500 meters ofthe sea floor fills a depression that was evidently excavated by escaping gas the spatial continuity of the mussel bed indicates that the brine level has remained fairly constant however demographic differences between the inner and outer parts of the bed record small fluctuations

interpretation of soil features produced by ancient and modern processes in degraded landscapes v development of saline sulfidic features in non tidal seepage areas abstract saline sulfidic soils are usually associated with tidal flushing zones however less developed saline sulfidic soils have recently been identified in non tidal seepage and marsh areas strongly affected by waterlogging dryland salinity and erosion in the mediterranean climatic region 600 mm per annum winter rainfall maximum of the mt lofty ranges south australia a conceptual sub model is developed to explain the formation of these saline sulfidic soils by using data from detailed pedological mineralogical hydrological and physico chemical investigations the following three saline sulfidic features were recognised both within the subsurface soil layers and on the soil surface i black sulfidic materials ii iron rich gelatinous precipitates and iii salt iron crusts the abundance of these features and their distribution in relation to each other were used to establish a chronological order of formation for each saline sulfidic feature specific minerals e g pyrite framboids ferrihydrite and schwertmannite were identified and their conditions of formation e g eh and ph established their development is closely associated with two water flow systems a rising saline sulfatic groundwater aquifer and the seasonal discharge of fresh water via a perched water table the conceptual sub model shows how these two water flow systems and three biomineralization processes lead to the formation of these saline sulfidic marsh soils it illustrates how the following three main conditions control the formation of these non tidal saline sulfidic marsh soils i the development of aquic and saline conditions throughout the solum ii the accumulation of organic matter from which fe and s reducing oxidising bacteria derive their energy and iii a continuous supply of fe and s in groundwater aquifers in the mt lofty ranges such conditions are due to rising saline sulfatic groundwater tables following land clearing since european settlement and contemporary weathering of pyrite lenses in the underlying rock

spatial distribution of diverse cold seep communities living on various diapiric structures of the southern barbados prism three sectors of the south barbados prism between 1000 and 2000 m depth were explored by the french submersible nautile chemosynthesis based benthic communities were discovered on several structures affected by diapirism including mud volcanoes domes and an anticlinal ridge the communities are associated with the expulsion of methane rich fluids which is a wide spread process in the area these communities are dominated by large bivalves and vestimentiferans which harbour chemoautotrophic symbiotic bacteria the symbiotic bivalves include two species of mytilidae and one of vesicomyidae with dominance of a methanotrophic mussel cartography of the benthic communities interpretation of thermal measurements and observation of sedimentary patterns have been used to define the life habits of each of the three species of symbiotic bivalves each species has a characteristic preference for different conditions of edaphic and fluid flow the dominant methanotrophic mussel appears to require high velocity vents and hard substratum the vesicomyids and the other species of mussel are able to take up sulfide from the sediments and so are associated with low seepages but also require soft sediment the three bivalve species are assumed successively to colonize the top of a diapiric ridge in a succession related to the temporal evolution of fluid flow and sedimentation the composition of the bivalve assemblages their densities and biomasses all differ between the several mud volcanoes and domes studied and these parameters are thought to be related to the spatial and temporal variations of fluid expulsion through the structures and the lithification processes linked to fluid expulsion one very active dome is at present colonized by an exceptionally large and dense population of the methanotrophic mussel in contrast communities in another area on the domes and volcanoes that are currently inactive were colonized by only a few living vesicomyids and mussels both associated with sulfur oxydizing bacteria and there were numerous empty shells the densities and biomasses of symbiotic bivalves were far greater in the area studied than in a deeper mud volcano field on the same prism that had been studied previously this is consistent with a report that methane production is greater in the southern region of this accretionary prism than in the northern numerous non symbiotic organisms were observed in and around the areas of the seeps some are endemic to the seep communities including some gastropods and shrimps others are either colonists or vagrants from the surrounding deep sea floor filter feeders were very abundant and some of these like the serpulids and large sponges may also be dependent on the chemosynthetic production faunistic composition of both symbiotic and non symbiotic taxa of the assemblages around these cold seeps is closely related to that reported for communities living on hydrocarbon seeps in the gulf of mexico

lateral moisture flow beneath a sandy hillslope without an apparent impeding layer part of a small drainage basin on the sevilleta national wildlife refuge about 25 km north of socorro nm was intensively instrumented with soil monitoring equipment to estimate natural ground water recharge soil moisture data were analysed with special attention to characterizing the influence of topography on the direction of vadose water flow paths in fine to medium aeolian sand moisture content data were obtained by the neutron scattering technique and hydraulic head data were obtained using tensiometers in addition tracer experiments were conducted on a sandy hillslope to delineate the flow paths of vadose water the results indicate that there is a strong lateral component to unsaturated flow on a hillslope even in the absence of apparent sublayers of much lower permeability darcian calculations estimate the long term steady deep flux beneath a concave location to be about 4 per cent of an assumed mean annual precipitation of 20 cm the deep soil water flux downward varied by several orders of magnitude during the 17 month period of record

evolutionary pathways among shallow and deep sea echinoids of the genus sterechinus in the southern ocean antarctica is structured by a narrow and deep continental shelf that sustains a remarkable number of benthic species the origin of these species and their affinities with the deep sea fauna that borders the continent shelf are not clear to date two main hypotheses have been considered to account for the evolutionary connection between the faunas 1 either shallow taxa moved down to deep waters submergence or 2 deep sea taxa colonized the continental shelf emergence the regular sea urchin genus sterechinus is a good model to explore the evolutionary relationships among these faunas because its five nominal species include antarctic and subantarctic distributions and different bathymetric ranges phylogenetic relationships and divergence times among sterechinus species were established using the coi mitochondrial gene by assuming a molecular clock hypothesis the results showed the existence of two genetically distinct main groups the first corresponds exclusively to the shallow water antarctic species s neumayeri while the second includes all the other nominal species either deep or shallow antarctic or subantarctic within the latter group s dentifer specimens all formed a monophyletic cluster slightly divergent from all other specimens which were mixed in a second cluster that included s agassizi from the continental shelf of argentina s diadema from the kerguelen plateau and s antarcticus from the deep antarctic shelf these results suggest that the deeper water species s dentifer and s antarcticus are more closely related to subantarctic species than to the shallow antarctic species s neumayeri thus for this genus neither the submergence nor emergence scenario explains the relationships between antarctic and deep sea benthos at least in the weddell quadrant the observed genetic pattern suggests an initial separation between antarctic and subantarctic shallow species and a much later colonization of deep water from the subantarctic region probably promoted by the geomorphology of the scotia arc

predictive modelling of management options for the control of dryland salinity in a first order catchment in the wheatbelt of western australia abstract a prototype flow model has been developed for cuballing catchment using modflow the results of the simulations showed that in a first order catchment the management strategies most likely to arrest salinity were reforestation and pumping the study confirmed that complete reforestation would arrest groundwater discharge and lead to the restoration of salinized land within the catchment it also showed that replanting the top 25 of the catchment was sufficient to reverse the salinity trend by reducing groundwater discharge to an acceptable level drainage along the main stream line was also effective in reducing groundwater levels in the unconfined aquifer and constrained the discharge in the area adjacent to the stream the simulations also showed that pumping reduced groundwater pressures in both the unconfined and confined aquifers a single windmill discharging at a rate ranging from 15 to 25 m 3 day 1 was sufficient to reduce water levels in the unconfined aquifer by more than 5 m and in the confined aquifer by more than 10 m however the pumping well must be correctly located in the catchment the preferred location is in highly transmissive areas with adequate aquifer thickness and upstream from geological structures restricting groundwater flow in western australia these areas are usually along drainage lines and within discharge areas

organic carbon isotope geochemistry of clayey deposits and their associated porewaters southern alberta abstract the organic carbon cycle of slowly permeable clayey glacial till deposits in the western interior great plains southern alberta was investigated by examining the relationship between solid organic matter som in the till sediments and dissolved organic carbon doc in the till porewaters geochemically the tills can be divided into two distinct zones an upper oxidized low som till zone and a lower unoxidized high som till zone till porewaters in both zones are characterized by high doc contents radiocarbon dating and comparison of som and doc fractions suggest doc in the deep unoxidized zone originated during deglaciation and is probably representative of groundwater ages in this till zone in the oxidized zone doc originates from variable mixtures of soluble organic matter emplaced during deglaciation and cretaceous age coal fragments in this till zone som in the upper till zone was mainly oxidized to co 2 gas during lowered water table conditions of the altithermal climatic period the subsurface production of fossil co 2 gas has serious implications for using the conventional dissolved inorganic carbon dic 14 c groundwater dating method in these clayey till porewaters

simple predictions of maximum transport rate in unsaturated soil and rock 1 in contrast with the extreme variability expected for water and contaminant fluxes in the unsaturated zone evidence from 64 field tests of preferential flow indicates that the maximum transport speed vmax adjusted for episodicity of infiltration deviates little from a geometric mean of 13 m d a model based on constant speed travel during infiltration pulses of actual or estimated duration can predict vmax with approximate order of magnitude accuracy irrespective of medium or travel distance thereby facilitating such problems as the prediction of worst case contaminant traveltimes the lesser variability suggests that preferential flow is subject to rate limiting mechanisms analogous to those that impose a terminal velocity on objects in free fall and to rate compensating mechanisms analogous to le chatlier s principle a critical feature allowing such mechanisms to dominate may be the presence of interfacial boundaries confined by neither solid material nor capillary forces

radiocarbon in dissolved organic carbon a possible groundwater dating method case studies from western canada this paper explores the feasibility of using 14c in dissolved organic carbon doc as an alternative isotopic ground water dating method two hydrogeologically contrasting groundwater systems were tested the cretaceous age milk river aquifer and low permeability organic rich wisconsinan age prairie tills in southern alberta canada comparisons of radiocarbon data were made between doc fractions dissolved inorganic carbon dic and several dic geochemical age correction models along well defined flow paths the data presented demonstrate that 14c dating of doc fractions can indeed provide an alternative method for determining isotopic groundwater ages under suitable conditions however detailed information may be required regarding 1 the geologic nature of the aquifer and its flow system 2 the isotopically conservative behavior of doc 3 the initial 14c activity of doc in recharge and 4 the effect of bacterial redox processes on the 14c activity of doc in the milk river aquifer doc 14c ages were successfully used to estimate groundwater residence times as well as to further refine input parameter assumptions for the dic method in the prairie tills doc 14c ages were used to establish a maximum age for the pore waters in an environment where the dic method is especially problematic

water movement through a thick unsaturated zone underlying an intermittent stream in the western mojave desert southern california usa previous studies indicated that small amounts of recharge occur as infiltration of intermittent streamflow in washes in the upper mojave river basin in the western mojave desert near victorville california these washes flow only a few days each year after large storms to reach the water table water must pass through an unsaturated zone that is more than 130 m thick results of this study done in 1994 1998 show that infiltration to depths below the root zone did not occur at control sites away from the wash at these sites volumetric water contents were as low as 0 01 and water potentials measured as the combination of solute and matric potentials using a water activity meter were as negative as 14 000 kpa water vapor movement was controlled by highly negative solute potentials associated with the accumulation of soluble salts in the unsaturated zone highly negative matric potentials above and below the zone of maximum solute accumulation result from movement of water vapor toward the highly negative solute potentials at that depth the 18o and d delta oxygen 18 and delta deuterium isotopic composition of water in coarse grained deposits plots along a rayleigh distillation line consistent with removal of water in coarse grained layers by vapor transport beneath oro grande wash water moved to depths below the root zone and presumably to the water table about 130 m below land surface underneath oro grande wash volumetric water contents were as high as 0 27 and water potentials measured as matric potential using tensiometers were between 1 8 and 50 kpa on the basis of tritium data water requires at least 180 260 years to infiltrate to the water table clay layers impede the downward movement of water seasonal changes in water vapor composition underneath the wash are consistent with the rapid infiltration of a small quantity of water to great depths and subsequent equilibration of vapor with water in the surrounding material it may be possible to supplement natural recharge from the wash with imported water recharge to the wash may be advantageous because the unsaturated zone is not as dry as most areas in the desert and concentrations of soluble salts are generally lower underneath the wash

hillslope parameter estimation using the inverse procedure abstract the parameter identification process referred to as the inverse method has been applied at the hillslope scale to quantify the hydrologic characteristics of two catchments in western australia the physically based numerical model hills was used despite the limitations imposed by using a model which of necessity contains several simplifying assumptions in contrast to the high level of complexity within the soil profile an encouraging level of representation is achieved it has also been shown that water level data from shallow wells provide a promising method for determination of the average or effective values of vertical and horizontal hydraulic conductivity soil porosity and rates of evaporation the model has also provided an estimate of the various sources of stormflow surface subsurface ground water that occurs during and after a rainstorm

interactions between perched and saprolite aquifers on a small salt affected and deeply weathered hillslope a small hillslope was chosen to investigate the role of throughflow as a mechanism responsible for the movement of soil water and solutes towards a saline seep and as a source of recharge to a permanent regional aquifer at depth the hydraulic properties chemical characteristics and physical responses of both systems were studied on a deeply weathered salt affected hillslope additional data were also obtained from other sites in south western australia regional groundwater flow occurred in a variably textured deeply weathered material in which the hydraulic conductivity varied from 0 001 to 0 14m day 1 perched groundwater flow throughflow occurred in the higher permeability 1 5 m day 1 near surface soil materials throughflow occurred throughout winter contributing approximately 530 m3 of fresh 160 mg l 1 cl water to a saline seep by contrast the deep aquifer discharged approximately 1100 m3 of waters with salt concentrations of 2000 6000 mg l 1 cl recharge and discharge rates to and from the deep aquifer were estimated to be of the order of 5 20 mm a 1 and 50 300 mm a 1 respectively saturated conditions existed throughout winter within the seep and the immediately adjacent non saline area with up to 60 per cent of the hillslope soils becoming saturated after major rainfall events 20 mm day 1 in the mid slopes in particular along a central depression saturation of the shallow soils caused macropore channel recharge to take place through the clay textured subsoils water level responses suggest that approximately 25 30 per cent of annual recharge occurred from one storm studied in september 1984 recharge through macropore channels is a significant mechanism in the concave slope areas on the hillslope throughflow was found to be a major source of water but not salt contributing to the saline seep in general the contribution of throughflow was found to decrease further inland at other sites studied however at inland sites where perennial perched aquifers have developed in deep sands saline areas have been caused by throughflow and not by deep aquifer discharge

co occurrence patterns of ice rafted dropstones and brachiopods in the middle permian wandrawandian siltstone of the southern sydney basin southeastern australia and palaeoecological implications the ecological significance of ice rafted dropstones in present day glacial marine benthic environments has received considerable attention from ecologists but similar studies based on the geological records of dropstones and associated fossils are rare in this study we report statistically significant co occurrences of ice rafted dropstones with brachiopod shells in multiple stratigraphic horizons at multiple sites from the middle permian wandrawandian siltstone of the southern sydney basin in southeastern australia we analysed the distribution patterns of both dropstones and brachiopod dominated fossil assemblages by using a quadrat based sampling method and spatial point pattern analysis it was revealed that the co occurrences of ice rafted dropstones and brachiopod shells are not random rather they demonstrate statistically significant and stratigraphically recurring associations that are here interpreted to represent dropstone associated brachiopod dominated palaeoecological communities in these recurring palaeocommunities the presence of ice rafted dropstones is considered to have added habitat complexity and heterogeneity to the benthic environment especially suited to the settlement of brachiopods in addition the sinking of dropstones from floating ice masses through the water column to the silty seafloor is interpreted to have enriched the nutrient and oxygen supply to the benthic environment further aiding the flourishing and maintenance of a diverse and stable marine benthic fauna supplementary material original data collection supplementary material 1 and spatial point pattern analysis results of rest quadrats supplementary material 2 are available at https doi org 10 6084 m9 figshare c 4101743

the causes of waterlogging in shallow soils and their drainage in southwestern australia abstract sandy loam topsoils overlying sandy clay subsoils on hillslopes in southwestern australia are often waterlogged the relative importance of soil landform climatic and drainage factors on waterlogging intensity was assessed from 1984 to 1986 the sew 30 index was used to quantify waterlogging intensity as measured in 162 shallow wells in five subcatchments waterlogging is caused by the development of a perched watertable on the subsoil clay gravel within the soil profile reduces the porosity and thus the water storage capacity of the soil waterlogging intensity is low where topsoils are deeper than about 0 6 m where the soil profile has an a 2 horizon with high hydraulic conductivity up to 7 8 m day 1 and the site is sloping facilitating lateral flows the hydraulic conductivity of the b horizon can change by as much as two orders of magnitude over a 10 m lateral distance the sites most susceptible to waterlogging have subsoils with a hydraulic conductivity less than 0 003 m day 1 and topsoils which are less than 0 4 m thick susceptible soils became waterlogged in early winter after rainfall exceeded pan evaporation by just 50 mm whereas others remained well drained even in the wettest years q 0 2 5 10 3 m 2 day 1 per m cross section of the soil is a critical value of transmission capacity that induces severe waterlogging in these catchments

paleosols as deep regolith implications for ground water recharge across a loessial climosequence abstract thick loess deposits consisting of paleosol sequences comprise the deep regolith of the palouse region in eastern washington and northern idaho ground water is the principal water supply for the palouse basin yet recharge mechanisms and rates through this regolith are poorly understood forecasting the sustainability of the water supply has been hampered because models that predict ground water recharge are complicated by deep regolith that has complex stratigraphy and in some instances multiple buried hydraulically restrictive horizons to assess water movement pore water cl and 18o distributions were measured to 6 m depths in three catchments representing a climosequence across the basin and interpreted using catchment and basin wide stratigraphic relationships vertical facies between dense and soft horizons coincide with variations in cl in the eastern basin pore water cl ranged from 15 to 150 mg l and increased with depth in addition shifts in isotopic signature of oxygen in pore water coincide with cl rich horizons and suggest long pore water residence times in contrast cl in the central and western basin ranges from 1 to 15 mg l and changes little with depth tracer profiles illustrate three major hydrostratigraphic units in the basin 1 uplands with relatively homogeneous regolith that has short pore water residence times 2 uplands with heterogeneous regolith that has long pore water residence times and 3 valleys with heterogeneous regolith that display dynamic hydraulic processes regional relationships between deep regolith and surface soils were established in order to use the ssurgo database to estimate the spatial extent of each hydrostratigraphic unit the degree of paleosol development mimics that of contemporary sola across the climosequence results indicate that recharge is less than 3 mm year 1 in 33 of the study area where precipitation is greatest and regolith is heterogeneous recharge increases to 10 mm year 1 in 37 of the study area where regolith is homogeneous valley positions having active hydraulic regimes constitute 10 of the basin

groundwater recharge through a heavy textured soil abstract this study was undertaken to outline the character of groundwater movement through the unsaturated and saturated zones of a glacial till using natural tritium a testhole was cored to a depth of 17 4 m below ground surface in southern alberta canada and 55 samples were collected from the cores at 0 3 m intervals the soil water was distilled from each sample and analyzed for natural tritium and the soil samples were analyzed for particle size distribution the upper 3 m of the stratigraphic section consists of coarse to heavy textured interbedded lacustrine deposits these units are underlain by a heavy textured weathered till the study site is a zone of groundwater recharge with the water table at 9 m below ground surface tritium data can be used to show that water which entered the subsurface environment from ground surface after 1953 has migrated to the lacustrine till contact via intergranular seepage and fracture flow and that fractures are transmitting post 1953 recharge water to depths within the underlying slowly permeable unsaturated and saturated till in addition diffusion of tritium from the fractures into the adjacent matrix material appears to occur both above and below the water table

small scale distribution of deep sea demersal nekton and other megafauna in the charlie gibbs fracture zone of the mid atlantic ridge abstract videotapes from manned submersibles diving in the area of the charlie gibbs fracture zone of the mid atlantic ridge were used to investigate the distribution of fishes large crustaceans epifaunal and sessile organisms and environmental features along a series of transects submersibles mir 1 and mir 2 conducted paired dives in an area of mixed sediment and rock beginning depth ca 3000 m and on a large pocket of abyssal like sediments depth ca 4000 m in the shallower area the submersibles passed over extremely heterogeneous terrain with a diversity of nekton epifaunal forms and sessile forms in the first pair of dives mir 1 rose along the mid atlantic ridge from 3000 to 1700 m while mir 2 remained near the 3000 m isobath nekton seen in these relatively shallow dives included large and small macrourids genus coryphaenoides shrimp infraorder penaeidea halosauropsis macrochir aldrovandia sp antimora rostrata and alepocephalids the last two were more characteristic of the upper areas of the slope reached by mir 1 as it rose along the mid atlantic ridge to depths less than 3000 m distributions of some forms seemed associated with depth and or the presence of hard substrate sessile organisms such as sponges and large cnidaria were more likely to be found in rocky areas the second pair of dives occurred in an abyssal area and the submersibles passed over sediment covered plains with little relief and many fewer countable organisms and features the most evident of these were holes mounds small cerianthid anemones small macrourids and the holothurian benthodytes sp a few large macrourids and shrimp also were seen in these deeper dives as well as squat lobsters munidopsis sp sponges and larger cnidaria were mostly associated with a few small areas of rocky substrate holes and mounds showed distributions suggesting large scale patterning over all dives most sessile and epifaunal forms showed clumped distributions however large holothurians and large nekton often had distributions not significantly different from random

impact of geologic heterogeneity on recharge estimation using environmental tracers numerical modeling investigation this paper presents a numerical modeling approach for assessing the impacts of geologic heterogeneity on groundwater recharge estimates derived from environmental tracers common to many of the environmental tracer methods used to infer recharge in arid environments is an assumption of one dimensional vertical downward flow of water and solutes however in recent years there has been a growing recognition that fluid flux rates through geologic materials can be spatially variable owing to heterogeneities in porous media properties previous studies have suggested that local flow directions are dependent upon the stratigraphic and sedimentologic characteristics of the medium and may not be vertical even when application of water at the surface is spatially uniform and hydraulic gradients are vertical consequently environmental tracer movement will also be spatially variable and the one dimensional assumption invoked to interpret unsaturated environmental tracer concentration profiles may be unrealistic two different numerical simulation experiments were performed to investigate the problems with using environmental tracers to infer recharge the first involves simulation of flow and tracer transport through heterogeneous flat lying media and the second considers dipping layered anisotropic media the results of these simulations show that recharge inferred using environmental tracer methods is also highly spatially variable and that recharge estimates obtained by tracer profiles tend to overestimate recharge and should be considered accurate only to within an order of magnitude particularly in situations with significant media heterogeneity consequently recharge estimates obtained from tracer profiles should be critically evaluated with regard to impacts of spatially variable flow

brief interstadial events in the santa barbara basin ne pacific during the past 60 kyr the instability of the northern hemisphere glacial climate over the past 100 kyr has been revealed by at least 20 brief warm interstadial episodes called dansgaard oeschger events recorded in greenland ice cores1 3 and in north atlantic sedimentary records4 5 a few of these events have been recognized elsewhere6 8 here we describe a record of ocean oxygenation and circulation from the santa barbara basin in the northeast pacific ocean which correlates well with the greenland ice core records we see 19 of the 20 dansgaard oeschger events in the form of laminated sediments deposited under anoxic conditions and we can correlate at least 16 of these with the 17 ice core interstadials of the past 60 kyr thus these short term events were not restricted to the north atlantic region the events had substantial ecological and oceanographic effects in the santa barbara basin including changes in benthic faunal populations and in the age and composition of bottom waters similar ventilation changes have been seen in the gulf of california9 10 suggesting that these changes may have been widespread and synchronous along the northeast pacific margin these results suggest sensitivity of broad areas of the ocean atmosphere cryosphere system to short term climate change

hydraulic properties of groundwater systems in the saprolite and sediments of the wheatbelt western australia hydraulic properties of deeply weathered basement rocks and variably weathered sedimentary materials were measured by pumping and slug test methods results from over 200 bores in 13 catchments and eight pumping test sites across the eastern and central wheatbelt of western australia were analysed measurements were made in each of the major lithological units and emphasis placed on a ubiquitous basal saprolite aquifer comparisons were made between alternative drilling and analytical procedures to determine the most appropriate methods of investigation aquifers with an average hydraulic conductivity of 0 55 m day 1 occur in variably weathered cainozoic sediments and poorly weathered saprolite grits 0 57 m day 1 these aquifers are separated by an aquitard 0 065 m day 1 comprising the mottled and pallid zones of the deeply weathered profile locally higher values of hydraulic conductivity occur in the saprolite aquifer although after prolonged periods of pumping the values decrease until they are similar to those obtained from the slug test methods hydraulic conductivities measured in bores drilled with rotary auger rigs were approximately an order of magnitude lower than those measured in the same material with bores drilled by the rotary air blast method wheatbelt aquifers range from predominantly unconfined cainozoic sediments to confined saprolite grit aquifer the poorly weathered saprolite grit aquifer has moderate to high transmissivities 4 50 m2 day 1 and is capable of producing from less than 5 to over 230 kl day 1 of ground water which is often of a quality suitable for livestock yields are influenced by the variability in the permeability of isovolumetrically weathered materials from which the aquifer is derived the overlying aquitard has a low transmissivity 1 m2 day 1 especially when deeply weathered indurated and silicified the transmissivity of the variably weathered sedimentary materials ranges from less than 0 5 m2 day 1 to over 10 m2 day 1 depending on the texture of the materials and their position within the landscape higher transmissivity zones may occur as discrete layers of coarser textured materials the salinity of the saprolite and sedimentary aquifers ranges from less than 2000 mgl 1 to greater than 250000 mgl 1 total dissolved solids tds depending on position within the landscape secondary soil salinization develops when groundwater discharge occurs from either saprolite or sedimentary aquifers

submarine pingoes indicators of shallow gas hydrates in a pockmark at nyegga norwegian sea complex pockmarks up to 300 m wide and 12 m deep are located in the nyegga area in the norwegian sea bathymetric data and direct visual documentation and sampling with rovs remotely operated vehicles have shown that these pockmarks contain abundant methane derived authigenic carbonate rocks furthermore geochemical results and the finding of seep associated organisms including tubeworms and bacteria shows that the pockmarks are still active fluid flow locations hovland m svensen h forsberg c f johansen h fichler c fossa j h jonsson r rueslatten h 2005 complex pockmarks with carbonateridges off mid norway products of sediment degassing marine geology 218 191 206 here we report the discovery of localized pingo like sediment mounds up to 1 m high and 4 m wide they occur inside one of the nyegga complex pockmarks g11 all of the seven structures we investigated have four characteristics in common 1 they have a positive topography rounded mounds and cones 2 they are partly covered in bacterial mats indicating ongoing fluid flow 3 they are partly covered in a carpet of small living tubeworms polychaetes which utilize methane 4 they have distinct corrosion pits on their surfaces indicating fluidization and point source corrosion of the covering sediments probably caused by localized sub surface hydrate dissociation we interpret the features as true submarine pingoes formed by the local accumulation of hydrate ice below the sediment surface it is inferred that the pingoes are formed as documented hydrocarbon gases methane ethane propane and butane migrate upwards through distinctive sub surface channels or conduits inside the pockmark we suggest that these submarine hydrate pingoes manifest the exact locations where fluid flow through the seafloor is currently active and that they can therefore be used as small scale indicators of active seepage

basin geomorphological controls on the mechanism of recharge and discharge and its effect on salt storage and mobilization comparative study using geophysical surveys abstract downhole electromagnetic em profiles have been used to study the salt distribution in four catchments in the wheatbelt of western australia the good correlation r 2 0 7 0 9 obtained by relating the apparent conductivity profiles measured by the downhole em with salt profiles from soil cores enabled estimation of the salt storage in the uncored wells the salt distribution was compared with ground conductivity surveys using em31 and em34 instruments in three catchments and with an input aerial electromagnetic survey aem in a fourth catchment the study revealed the presence of five types of apparent electrical conductivity profiles eca which are correlated with the basin geomorphological units the conductivity profiles are 1 low eca recharge profile 2 subsurface peak discharge profile 3 two bulge profiles a single bulge accumulation weathering profile and a split aquifer development profile 4 reduced bulge leaching profile 5 high eca irregular palaeochannel profile the salt distribution showed a systematic increase in salinity from the watersheds to the valleys with salinity increasing upstream of geological structures the salt distribution was found to be controlled by the geomorphologic properties of the basins which control the hydrological and hydrogeological processes and by the recharge discharge mechanisms which influence salt mobilization and accumulation

the canada basin 1989 1995 upstream events and far field effects of the barents sea 1 the effects of upstream events on southern canada basin waters were examined using physical and geochemical data collected at one location between 1989 and 1995 these events included atlantic layer warming relocation of the atlantic pacific water mass boundary and increased ventilation of boundary current waters early signals of change in the canada basin first appeared in 1993 along the continental margin and by 1995 were evident in the basin interior and farther downstream differences in physical and geochemical properties nutrients oxygen 129i and cfcs were observed between 150 and 1600 m of the water column by 1995 the boundary between pacific and atlantic origin water was shallower and atlantic origin water occupied more of the canada basin water column atlantic origin lower halocline water was colder and more ventilated fram strait branch water was colder fresher and more ventilated and barents sea branch water was warmer fresher more ventilated and occupied a larger volume of the water column than in previous years water mass analysis showed that the composition of atlantic origin water in the canada basin in 1995 included 20 more water from the barents sea two related events upstream appear to be the source of this change an atmospheric regime shift in 1989 that increased cyclonic circulation a transition unprecedented within the latter half of the 20th century in magnitude geographic reach and apparent oceanographic impacts and a large volume of dense water flowed from the barents sea to the arctic ocean between 1988 and 1989 these two phenomena illustrate the close relationship between atmospheric and oceanic events whose combined influence was evident 6 years later and 5100 km downstream in the canada basin at depths 1000 m

preferred water flow and localised recharge in a variable regolith abstract the mechanisms of water flow and recharge to groundwater were investigated in a deep clayey regolith in southwest western australia a 700 m2 area was intensively studied for a period of two years vertical distributions of natural chloride in thirteen profiles up to 31 m deep were used to estimate the distribution of vertical soil water flux density in the 16 m unsaturated zone and rates of recharge to groundwater groundwater dynamics were monitored using ten single and four multilevel piezometers the regolith showed marked heterogeneity over horizontal and vertical distances of only a few metres this resulted in complex patterns of water and solute movement through the profiles over most of the experimental area vertical water flux density below 5 m in the unsaturated zone was from 2 2 to 7 2 mm yr 1 however within a relatively small portion of the site vertical soil water flux density was 50 100 mm yr 1 throughout the unsaturated zone this flux more closely matched the apparent rate of recharge to groundwater the area of preferred flow is apparently due to a discontinuity within the regolith a groundwater mound was seen to develop below the localised recharge area within 12 14 h of intense rainstorms and then dissipated over a period of 2 4 days

penetration of the 1990s warm temperature anomaly of atlantic water in the canada basin 1 penetration of the 1990s warm temperature anomaly wta of the fram strait branch of atlantic water fsbw in the canada basin is described using available temperature salinity and velocity data the core temperatures of fsbw show distinct pathways over the chukchi borderland advective velocities of the fsbw are well correlated with bottom topography the resulting multifarious pathways over the chukchi borderland act to modulate and substantially increase the time scale of wta spreading and advancement further downstream two wta tongues are observed one tongue followed the beaufort slope and along this pathway the core temperatures of fsbw decreased rapidly the depth integrated value of heat content remained near constant however suggesting enhanced vertical mixing the second tongue debouched from the northern tip of the northwind ridge and spread eastward into the deep canada basin suggesting a complex recirculation structure within the beaufort gyre index terms 4532 oceanography physical general circulation 4536 oceanography physical hydrography 4512 oceanography physical currents citation shimada k f mclaughlin e carmack a proshutinsky s nishino and m itoh 2004 penetration of the 1990s warm temperature anomaly of atlantic water in the canada basin geophys res lett 31 l20301

water recharge and solute transport through the vadose zone of fractured chalk under desert conditions this study focuses on water flow and solute migration through unsaturated fractured chalk in an arid area the chalk underlies a major industrial complex in the northern negev desert where groundwater contamination has been observed four dry drilling holes were bored through the vadose zone core and auger samples collected at 30 to 50 cm intervals were used for chemical and isotopic analyses enabling the construction of the following profiles 1 a tritium profile to estimate the rate of water flow through the unsaturated zone 2 oxygen 18 and deuterium profiles to assess the evaporation of water at land surface before percolation and in the upper part of the vadose zone after infiltration and 3 chloride and bromide profiles as tracers for inert solutes and pollutants the tritium and bromide profiles showed the rate of infiltration through the unsaturated matrix to be very slow 1 6 11 cm yr the chemical and isotopic data from the core holes suggested that the pore water changes characteristics with depth close to land surface the pore water is strongly evaporated 18o 5 94 and highly concentrated 29 meq cl 100 g rock but changes gradually with depth to amore dilute concentration 4 meq cl 100 g rock and isotopically depleted composition 18o 4 4 closer to the isotopic composition of precipitation and groundwater nearby monitoring wells have shown anthropogenic contribution of heavy metals organic compounds and tritium nativ and nissim 1992 a conceptual model is proposed in which a small portion of the rainwater percolates downward through the matrix while a larger percentage of the percolating water moves through preferential pathways in fractures the water flowing through the fractures penetrates the matrix across the fracture walls where it increases the tritium concentrations depletes the stable isotopic composition and dilutes the salt concentrations the observed rapid downward migration of tritium and heavy metals through the profuse fractures makes the chalk inefficient as a hydrologic barrier

thin and thinner sea ice mass balance measurements during sheba 1 as part of a large interdisciplinary study of the surface heat budget of the arctic ocean sheba we installed more than 135 ice thickness gauges to determine the sea ice mass balance while installing these gauges during the fall of 1997 we found that much of the multiyear ice cover was only 1 m thick considerably thinner than expected over the course of the yearlong field experiment we monitored the mass balance for a wide variety of ice types including first year ice ponded ice unponded ice multiyear ice hummocks new ridges and old ridges initial ice thicknesses for these sites ranged from 0 3 to 8 m and snow depths varied from a few centimeters to more than a meter however for all of their differences and variety these thickness gauges sites shared a common trait at every site there was a net thinning of the ice during the sheba year the thin ice found in october 1997 was even thinner in october 1998 the annual cycle of ice thickness was also similar at all sites there was a steady increase in thickness through the winter that gradually tapered off in the spring this was followed by a steep drop off in thickness during summer melt and another tapering in late summer and early fall as freeze up began maximum surface melting was in july while bottom ablation peaked in august combining results from the sites we found an average winter growth of 0 51 m and a summer melt of 1 26 m which consisted of 0 64 m of surface melt and 0 62 m of bottom melt there was a weak trend for thicker ice to have less winter growth and greater net loss for the year however ice growth was also impacted by the snow depth considerable variability was observed between sites in both accretion and ablation the total accretion during the 9 month growth season ranged from zero for thick ridged ice to more than a meter for young ice ponds tended to have a large amount of surface melting while ridges had considerable bottom ablation

the brigalow catchment study revisited effects of land development on deep drainage determined from non steady chloride profiles summary a large area of woodland in the brigalow bioregion in semi arid central queensland was cleared for agriculture from the 1960s to the 1980s to assess the risk of salinity associated with land clearing soil chloride cl was monitored at the brigalow catchment study bcs in brigalow acacia harpophylla scrub a cropped catchment and a pasture catchment before and after clearing in 1982 the monitoring sites include three landscape positions two on clay soils and one on a sodic duplex sodosol within each catchment an earlier report of deep drainage using the early soil cl profiles and steady state and transient chloride sodics mass balance was revisited after a further 13 yr and four more sampling times profile cl mass changed little in 18 4 yr at scrub sites justifying the use of native vegetation sites to represent pre clearing cl for paired cleared sites steady state cl mass balance cmb gave deep drainage of 0 13 0 34 mm yr for nine pre clearing scrub sites large losses of soil cl occurred under cropping and smaller losses occurred under pasture transient cmb gave average deep drainage of 59 and 32 mm yr for crop and pasture catchments respectively during the development phase 1981 1983 when the land was bare following clearing of native vegetation and prior to establishment of crops or pastures in the 16 7 yr following establishment of agricultural land uses 1983 2000 transient cmb gave average deep drainage of 19 8 range 3 3 50 and 0 16 2 2 to 1 4 mm yr respectively in crop and pasture catchments the drainage rate under pasture was similar to that under brigalow scrub in the cropped catchment drainage for modern farming systems less tillage more summer opportunity crops was about half that of older farming systems wheat summer fallow more tillage less stubble retention drainage was greater for the sodosol than for the clay soils under cropping deep drainage occurred under cropping even though the soils are considered to have low permeability and the climate is semi arid with potential evaporation exceeding rainfall on average in all months increased drainage at cropped sites has driven a clear exponential loss of soil cl as predicted by the transient cmb theory one cropped site is at or near a new steady state and the others will reach a new steady state 50 200 yr after clearing the leachate is saline with an average cl concentration of 7000 mg l and would salinised any groundwater it entered the salinity risk associated with the drainage is not well understood as yet and will depend on local hydrogeological conditions which are poorly mapped in the fitzroy effects of these losses of salts on sodicity soil structure and permeability should also be investigated

quaternary soil salinity events and australian vegetation history abstract a late quaternary history of australian soil salinization is produced by comparing chenopodiaceae and casuarina pollen curves although salinity development varied between sites its occurrence was generally associated with arid phases and when high rainfall or high sea level caused regionally high groundwater tables soil salinization contributed to the shift from casuarina to eucalyptus dominance of interglacial sclerophyll vegetation the deposition of saline sediments deflated from the murray basin seems more likely than aboriginal burning to have caused the decline of casuarina at lake george soil salinization probably resulted in other vegetation changes and must be taken into account in environmental reconstructions the renewed increase in soil salinity caused by european land use practices and an associated decline in casuarina are evident in the pollen records of many sites

methane cold seeps as biological oases in the high arctic deep sea cold seeps can support unique faunal communities via chemosynthetic interactions fueled by seabed emissions of hydrocarbons additionally cold seeps can enhance habitat complexity at the deep seafloor through the accretion of methane derived authigenic carbonates mdac we examined infaunal and megafaunal community structure at high arctic cold seeps through analyses of benthic samples and seafloor photographs from pockmarks exhibiting highly elevated methane concentrations in sediments and the water column at vestnesa ridge vr svalbard 79 n infaunal biomass and abundance were five times higher species richness was 2 5 times higher and diversity was 1 5 times higher at methane rich vestnesa compared to a nearby control region seabed photos reveal different faunal associations inside at the edge and outside vestnesa pockmarks brittle stars were the most common megafauna occurring on the soft bottom plains outside pockmarks microbial mats chemosymbiotic siboglinid worms and carbonate outcrops were prominent features inside the pockmarks and high trophic level predators aggregated around these features our faunal data visual observations and measurements of sediment characteristics indicate that methane is a key environmental driver of the biological system at vr we suggest that chemoautotrophic production enhances infaunal diversity abundance and biomass at the seep while mdac create a heterogeneous deep sea habitat leading to aggregation of heterotrophic conventional megafauna through this combination of rich infaunal and megafaunal associations the cold seeps of vr are benthic oases compared to the surrounding high arctic deep sea

understanding sub surface solute distributions and salinization mechanisms in a tropical coastal floodplain groundwater system summary the burdekin coastal floodplain aquifer is a tropical groundwater system exploited for irrigated agriculture that has exhibited increases in groundwater salinity since regular monitoring was introduced in the 1960s evapotranspiration of irrigation water displacement of unsaturated zone solutes enhanced mixing with relict seawater and seawater intrusion are mechanisms considered to explain the observed increase the floodplain aquifer is comprised of complex successions of quaternary terrigenous and marine sediments hosting groundwater with cl concentrations from 50 000 mg l the lowest salinity groundwater is found adjacent to the burdekin river and within palaeochannels dissecting the floodplain cl concentrations no 3 cl mass ratios 0 1 indicate the fresh groundwater originates from vertical infiltration of rainwater and irrigation water entrained with agricultural nitrogen through the coarse grained palaeochannel sediments na cl ratios similar to the burdekin river indicate that lateral discharge from the river channel to the floodplain aquifer also accounts for the distribution of low salinity groundwater tidal and near shore marine sediments deposited during pleistocene and holocene high sea level stands host highly saline groundwater cl 20 000 80 000 mg l up to 15 km inland in many areas of the floodplain nested piezometer locations reveal older more saline water at depth na and cl concentrations of more than 8000 floodplain groundwater samples collected over a 40 yr period fall on a mixing line between river water fresh groundwater and modern relict seawater indicating that intermediate salinity waters have evolved over time through varying degrees of mixing between the two end member compositions temporal trends in na and cl concentrations indicate that increases in groundwater salinity across the floodplain are primarily due to this mixing process and that evapotranspiration from irrigated crops and displacement of unsaturated zone solutes has had less of an effect this salinization process which includes displacement of relict seawater within the aquifer and seawater intrusion is likely exacerbated by extraction from 1400 production bores and enhanced recharge across the floodplain halting and reversing the ongoing groundwater salinization will require a mixture of setting and meeting local and regional groundwater targets water table depths and groundwater quality and where needed implementing appropriate deep drainage and drainage disposal management strategies

characterizing the hydrogeology of a complex clay rich aquitard system using detailed vertical profiles of the stable isotopes of water abstract high resolution 1d profiles of the stable isotopes of porewater 2h and 18o obtained by direct porewater equilibration of core samples were used to identify hydrogeologic zones in a thick complex till aquitard system in saskatchewan canada detailed 1d isotope profiles revealed the presence of three distinct hydrogeological zones an upper 5 10 m an intermediate 10 30 m and a lower 30 62 5 m till zone the upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity k the lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers the curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion we show that high resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles i e 2h and 18o analyses of water samples and k determinations further the direct equilibration approach overcomes the problem of piezometer leakage in low k aquitards

benthic foraminiferal biodiversity response to a changing arctic palaeoclimate in the last 24 000 years investigations on the benthic foraminiferal fauna of sediment cores from the eurasian basin arctic ocean continental margin reveal well correlated biodiversity maxima and minima during the last 24 kyrs the temporal variable biodiversities observed at the core sites on a large scale reflect the palaeoclimatic evolution of the high northern latitudes herein sediments deposited during interglacials and interstadials reveal highest species richness whereas glacials and stadials are documented by lower species numbers in high resolution core ps2837 different periodicities in species richness in sediments from the late weichselian and holocene can be detected biodiversity periodicities of 1 57 kyrs and 0 76 kyrs characterize sediments of the late weichselian whereas with the retreat of glacial ice sheets and shorter seasonal ice coverage holocene sediments reveal shorter periodicities of 1 16 kyrs and 0 54 kyrs with the establishment of modern hydrographic conditions at about 4000 bp 4 kyrs a significant increase in the amplitudes of species richness can be observed although sediments deposited during warmings reveal highest species richness we doubt that water temperature determines the abundance and distribution of most benthic foraminifera in the arctic ocean we rather suggest that the temporal variabilities in species richness reflect changes in the availability of food which in the arctic ocean mainly depends on extend and duration of seasonal sea ice retreat in the study area the latter one besides the seasonal varying insolation is essentially determined by the advection rates and temperature of atlantic water entering the arctic ocean via the west spitsbergen current because both flowrate and temperature of the west spitsbergen current were increased during interstadials and interglacials a predominantly indirect influence of palaeotemperature on the biodiversity of benthic foraminifera is suggested yet rare species like atlantic species may indeed have a temperature sensitive metabolism 2007 elsevier b v all rights reserved

response of input and output of water and chloride to clearing for agriculture five small forested catchments in the collie river basin in southwest western australia were instrumented to quantify the changes in the input and output of salt and water when land use changed from forest to agriculture the paired catchment approach was used with two adjacent catchments located in high rainfall 1200 mm yr 1 and a group of three located in a lower 800 mm yr 1 rainfall area the treatment of complete clearing was applied to one catchment in the high rainfall zone and to about half of one catchment in the lower rainfall zone after three years of calibration with the uncleared control catchments strategies of partial clearing were applied to the third catchment in the lower rainfall zone the catchment pairs were found to be well matched the yield of water and salt increased immediately after clearing in the higher rainfall catchment streamflow increased about four times to 48 of rainfall salt load increased to fifteen times the mean saltfall measured as chloride ion of 7 g m 2 yr 1 direct runoff increased fourfold to 16 of yearly streamflow due partly to the progressive increase in the area of soil saturated to the surface the perched groundwater system was the major source 77 in 1983 of streamflow though it was the route rather than the source of increased salt to the stream the mottled and pallid clay profile was the dominant source of salt transported by the deep groundwater system into the perched aquifer streamflow became perennial in the first postclearing year absolute increases in streamwater and salt output from partially cleared catchments in the lower rainfall location were about an order of magnitude less than for the higher rainfall catchment though the relative increases were similar the three catchments were found to be accumulating salt in the cleared catchments the rising potentiometric surface would establish a saline groundwater discharge zone in the valley and a net export of salt in all treated catchments reduced interception results in increased water availability at the soil surface for stormflow and infiltration the reduction in transpiration had an added effect in increasing recharge to groundwater a new equlibrium for water had not been achieved eight years after clearing but was estimated to precede the new salt equilibrium

global deep sea extinctions during the pleistocene ice ages the dark near freezing environment of the deep oceans is regarded as one of the most stable habitats on earth and this stability is generally reflected in the slow turnover rates extinctions and appearances of the organisms that live there by far the best fossil record of deep sea organisms is provided by the shells of benthic foraminifera protista a little known global extinction of deep sea benthic foraminifera occurred during the pleistocene ice ages in the southwest pacific it caused the disappearance of at least two families 15 genera and 48 species 15 25 of the fauna of dominantly uniserial elongate foraminifera with distinctive apertural modifications these forms progressively died back and became extinct during glacial periods in the late pliocene to middle pleistocene ca 2 5 0 6 ma most extinctions occurred between 1 0 and 0 6 ma at the time of the middle pleistocene climatic revolution this first high resolution study of this extinction event indicates that it was far more significant for deep sea diversity loss than previously reported 10 species the middle pleistocene extinction was the most dramatic last phase of a worldwide decline in the abundance of these elongate forms a phase that began during cooling near the eocene oligocene boundary and continued during the middle miocene clearly these taxa declined when the world cooled but the reason is yet to be resolved

mechanisms responsible for streamflow generation on a small salt affected and deeply weathered hillslope this paper considers the contributions of overland flow throughflow and deep seepage to the generation of streamflow in a salt affected deeply weathered landscape runoff mechanisms on a small hillslope in south western australia were dependent on the extent and development of variable source areas in winter streamflow generation was controlled by returnflow saturation overland flow and throughflow in summer post ponding infiltration excess and saturation overland flow dominated the extent of the variable source area and the magnitude of streamflow were due to antecedent soil moisture rainfall and slope morphology concave hillslope sections accumulated soil moisture due to both saturated and unsaturated lateral flow processes throughflow provided the mechanism and vehicle for solute movement from the groundwater discharge area to the stream however discharge from the deep aquifer was the primary mechanism responsible for soil salinity and maintaining the core of the variable source area estimates of throughflow which only take account of soil water movement and disregard returnflow will underestimate the magnitude of throughflow

marine airborne salts applied to trace evapotranspiration local recharge and lateral groundwater flow in western australia concentrations of dissolved cl br so4 na k ca and mg in ground waters of six study areas in the flat wheatbelt of western australia revealed a variations of several orders of magnitude of ion concentrations 40 63 000 mg c11 1 in ground waters encountered in wells 2 46 m deep b variations exceeding an order of magnitude in the salinity observed in depth profiles of individual wells c positive linear correlations between the concentrations of cl br na and mg observed in all the study areas and similar correlations also with ca k and so4 in part of these areas d marine like relative ionic concentration abundances of cl br na and mg in the six study areas and of ca k and so4 in part of the areas e concentrations of the various ions distinctly below saturation with halite br containing salts or gypsum observations of this nature are shown to provide a powerful tool to establish a lack of fractionation between the marine ions during the atmospheric transport b salt input dominated by marine airborne salts c operation of evapotranspiration from the regolith in calculable degrees that vary from one surface cell to another d lack of salt phases in the aquifer materials e dominance of local vertical recharge over remote lateral recharge f infiltration of active recharge through preferred pathways in the aerated zone g storage of ground water in local compartments h amount of annual recharge in each unit of area and i hydrochemical maturity of the local hydrological system rise of water tables as a result of forest clearing produces a different flow regime for water and solutes the depth of the aerated zone is drastically reduced saline interstitial water is mobilized from the aquifer the former aerated zone and previously productive land becomes degraded by excessive soil salinities

understanding hydrological processes in a highly stressed granitic aquifer in southern india the results of a study evaluating the recharge discharge conditions of an unconfined stressed granitic aquifer situated in a semi arid region of andhra pradesh southern india are presented over the last three decades excessive withdrawal of groundwater has drastically lowered the water table to the bedrock the watershed studied was divided into four zones based on geomorphology and hydrogeological conditions using environmental chloride data pertaining to groundwater soil depth profiles and some hydrogeologic and hydrochemical observations a recharge model for the watershed was developed the model revealed that the bulk of the vertical recharge in the western elevated land occurs through preferred pathways and that a small fraction occurs through the soil matrix in addition the watershed has a poor hydrogeologic fabric as indicated by the small range of matrix flow recharge 1 to 1 5 of rainfall among the four zones the dominating preferential flow was high 16 of the annual average rainfall in the valley fills but decreased to 5 5 5 in the plains furthermore although the bulk of the recharge occurs vertically considerable lateral movement of groundwater down the slope indicates that sequential hydrochemical changes occur distinct geomorphological features that exist in the watershed support the proposed model situations similar to those described above may exist in numerous watersheds in the granitic hard rock region therefore information obtained from investigations conducted in this watershed can aid in the development of plans enabling the sustainable exploitation of watersheds that have not yet been developed as well as implementation of appropriate rainwater conservation measures in over exploited watersheds copyright 2009 john wiley sons ltd

review on soil water isotope based groundwater recharge estimations groundwater recharge estimations are necessary for sustainable management of groundwater resources among various hydraulic hydrogeological and hydrological approaches tracer methods are proposed to improve groundwater recharge estimations soil water isotope based estimates of groundwater recharge rates were developed in the 1960s and have been applied in more than 40 studies reviewed within this manuscript this comprehensive review research distinguishes three fundamental research approaches 1 labelling method with tritium or deuterium which can be used to trace unsaturated zone water movement 2 tracing soil water movement using a seasonal signal of stable isotopes in precipitation mainly applied in humid zones and 3 interpretation of an evaporation signal that impacts soil water stable isotope composition mainly applicable in arid and semiarid regions more recently advances in soil water extraction and analytical methods allow a higher sampling resolution and in situ measurements of soil water stable isotopes analytical advances may strengthen and improve the applicability of stable isotope methods for quantitative recharge we present compare and discuss studies of unsaturated zone isotope profiles with an emphasis on necessary prerequisites such as a substantial thick porous sedimentary layer or negative influences through high clay and silt contents or dry soil conditions copyright 2015 john wiley sons ltd

cenozoic deep sea benthic foraminifers tracers for changes in oceanic productivity from late middle eocene through earliest oligocene high latitude regions cooled and by the end of the period continental ice sheets existed in antarctica diversity of planktonic microorganisms declined and modern groups of terrestrial vertebrates originated coeval faunal changes in deep sea benthic foraminifers have been related to cooling of deep waters and increased oxygenation cooling however occurred globally whereas species richness declined at high latitudes and not in the tropics the late eocene and younger lower diversity high latitude faunas typically contain common epistominella exigua and alabaminella weddellensis opportunistic phytodetritus exploiting species that indicate a seasonally fluctuating input of organic matter to the sea floor we speculate that the species richness gradient and increase in abundance of phytodetritus exploiting species resulted largely from the onset of a more unpredictable and seasonally fluctuating food supply especially at high latitudes

distribution source and evolution of nitrate in a glacial till of southern alberta canada this paper addresses the distribution origin and controls upon nitrate in a 30 km2 area of the interior great plains region of southern alberta canada high concentrations of nitrate 100 mg l 1 no 3 n occurred in several isolated enclaves below the water table in brown weathered till nitrate concentrations of over 300 mg l 1 n were encountered in groundwater samples collected from these enclaves low nitrate concentrations 1 1 mg l 1 no 3 n were also encountered in the weathered till upgradient and downgradient of the nitrate enclaves groundwater samples collected from the underlying grey nonweathered till and bedrock had no 3 n concentrations of 1 1 mg l 1 through the application of geochemical no 3 n and nh 4 n studies environmental isotope studies tritium microbial analyses nitrifiers and laboratory experiments it was shown that the high nitrates found in the weathered till are the result of the oxidation of ammonium present within the tills it is postulated that this oxidation occurred during the holocene epoch when water tables were much lower than present day levels 5 18 m and 2 m below ground respectively through the use of eh measurements the enumeration of denitrifying bacteria and laboratory experiments the potential for denitrification was shown to exist below the present day water table in the weathered till as well as in the nonweathered till and bedrock isotopic data showed that less denitrification may be occurring within the nitrate enclaves than in adjacent downgradient areas

climatic controls on diffuse groundwater recharge in semiarid environments of the southwestern united states 1 although there is no diffuse groundwater recharge at many semiarid sites evidence for diffuse recharge exists at some locations where mean annual precipitation is much less than mean annual potential evapotranspiration particularly where soils are coarse and rainfall variable is substantial we investigate the climatic controls on diffuse recharge using a one dimensional variably saturated flow model the model is driven by a stochastic parameterization of climate that includes storm size distribution and seasonality of precipitation p and potential evapotranspiration pet constrained by data from 536 weather stations in the southwestern united states storm size distribution and seasonality determine the frequency and duration of intervals when p exceeds pet which controls the flux of water past the root zone for coarse soils climates with large infrequent storms yield recharge when exceeds 0 4 compared with 0 7 for a typical climate recharge through fine soils is insensitive to storm size and occurs at 0 8 seasonality has a stronger influence on recharge than storm size distribution and the effects are similar for coarse and fine soils recharge is relatively insensitive to rainfall seasonality in contrast the typical pet annual cycle lowers of the recharge threshold by 0 3 the relative timing of p and pet maxima is critical recharge occurs at values that are lower by 0 2 when the rainy season occurs during winter instead of summer over the range of climate and soils examined values at the recharge threshold varied from 0 2 to 0 7 therefore and alone are insufficient to predict where recharge will occur

a younger thinner arctic ice cover increased potential for rapid extensive sea ice loss 1 satellite derived estimates of sea ice age and thickness are combined to produce a proxy ice thickness record for 1982 to the present these data show that in addition to the well documented loss of perennial ice cover as a whole the amount of oldest and thickest ice within the remaining multiyear ice pack has declined significantly the oldest ice types have essentially disappeared and 58 of the multiyear ice now consists of relatively young 2 and 3 year old ice compared to 35 in the mid 1980s ice coverage in summer 2007 reached a record minimum with ice extent declining by 42 compared to conditions in the 1980s the much reduced extent of the oldest and thickest ice in combination with other factors such as ice transport that assist the ice albedo feedback by exposing more open water help explain this large and abrupt ice loss

hydro environmental status and soil management of the river nile delta egypt the sea level rise has its own bearing on the coastal recession and hydro environmental degradation of the river nile delta attempts are made here to use remote sensing to detect the coastal recession in some selected parts and delineating the chemistry of groundwater aquifers and surface water which lie along south mid northern and coastal zone of the nile delta eight water samples from groundwater monitoring wells and 13 water samples from surface water were collected and analyzed for various hydrochemical parameters the groundwater samples are classified into five hydrochemical facies on hill piper trilinear diagram based on the dominance of different cations and anions facies 1 ca mg na hco3 cl so4 type i facies 2 na cl hco3 type ii facies 3 na ca mg cl type iii facies 4 ca na mg cl hco3 type iv and facies 5 na mg cl type v the hydrochemical facies showed that the majority of samples were enriched in sodium bicarbonate and chloride types and which reflected that the sea water and tidal channel play a major role in controlling the groundwater chemical composition in the quaternary shallow aquifers with a severe degradation going north of nile delta also the relationship between the dissolved chloride cl mmol l as a variable and other major ion combinations in mmol l were considered as another criterion for chemical classification system the low and medium chloride groundwater occurs in southern and mid nile delta classes a and b whereas the high and very high chloride classes d and c almost covers the northern parts of the nile delta indicating the severe effect of sea water intrusion other facets of hydro environmental degradation are reflected through monitoring the soil degradation process within the last two decades in the northern part of nile delta land degradation was assessed by adopting new approach through the integration of glasod fao approach and remote sensing gis techniques the main types of human induced soil degradation observed in the studied area are salinity alkalinity sodicity compaction and water logging on the other hand water erosion because of sea rise is assessed multi dates satellite data from landsat tm and etm images dated 1983 and 2003 were used to detect the changes of shoreline during the last two decades the obtained results showed that the eroded areas were determined as 568 20 acre meanwhile the accreted areas were detected as 494 61 acre during the 20 year period

a new chloride leaching approach to the estimation of diffuse recharge following a change in land use abstract a new approach has been developed to estimate the increase in groundwater recharge following land use modification the approach uses the degree of leaching of chloride to quantify soilwater drainage below the root zone which ultimately leads to groundwater recharge it is more general than similar previously reported techniques for analysing transient chloride profiles to infer recharge rates and hence has wider application we have applied the technique to a field situation in southern australia where clearing of native vegetation for agricultural production leads to large increases in groundwater recharge the examples serve to demonstrate the technique and some of the practical difficulties in the application of solutes techniques to recharge estimation

benthic macrofauna and megafauna assemblages in the arctic deep sea canada basin abstract the benthic component of an interdisciplinary expedition on icebreaker uscg healy analyzed box core samples and seafloor photographs to quantify deep sea assemblages in the canada basin and chukchi borderland area soft bottom metazoan macrofauna 250 m were collected with 33 box cores at 11 stations ranging from 817 to 3961 m water depth in the high arctic canada basin from 28 june to 25 july 2005 megabenthic epifauna was quantified with a digital camera platform suspended 2 89 2722 ind m 2 and total biomass ranged from 0 2 to 1 6 g wet weight 0 06 m 2 2 macrofauna diversity numbered between 8 and 55 taxa per station abundance biomass number of taxa and diversity indices of macrofauna declined significantly with water depth polychaetes crustaceans and bivalves dominated the macrofaunal densities biomass and species numbers the megafauna visible in the seabed photographs was assigned to a total of 67 provisional taxa the lowest taxon count per station was 11 and the highest was 51 at the pockmark station epifauna abundance was also highest in this pockmark mean 5 8 ind m 2 and generally lower at deepest stations 0 1 0 9 ind m 2 but was skewed by large numbers of the holothuroid kolga hyalina epifauna observed in the center of the pockmark was significantly different from all other station groups but did not include known chemosynthetic fauna or bacterial mats multivariate analysis indicated that station groupings chukchi slope canada basin abyss and the chukchi cap were significantly different in community composition in the macrofauna box corer samples but could not be similarly distinguished as such in the epifauna photographs

environmental isotope hydrology of salinized experimental catchments deuterium oxygen 18 tritium and chloride concentrations were used in three salinized experimental catchments to gain insight into the mechanism of solute concentration and flow processes in the saturated and unsaturated zones the three experimental catchments were studied because of their location in different rainfall regions their status with respect to clearing of native vegetation and with respect to secondary salinization two uncleared catchments have average annual rainfalls of approximately 820 and 1220 mm respectively the third cleared catchment has an annual rainfall of 650 750 mm this catchment was in an advanced state of secondary salinization and displayed large areas of saline groundwater discharge with halite encrustation at the ground surface the stable isotope compositions of the solution phase in solute bulge profiles in the unsaturated zone showed a close agreement with the amount weighted mean isotopic composition of rainfall and only surficial evidence of isotopic enrichment due to evaporation evaporation from the soil surface plays a minor role as a mechanism of solute concentration in the unsaturated zone the dominant process of solute concentration in the unsaturated zone was ion exclusion during uptake of water by tree roots which was evidently a solute but not isotope fractionating process tritium analyses of unsaturated zone water and grondwater indicated movement of recent recharge to 7 10 m depth at the low rainfall site but over the full depth of the 15 m unsaturated zone at the higher rainfall site the variability in 18o and 2h values of groundwaters was used in association with chloride concentrations to provide information on mixing characteristics of groundwaters within the catchments

the influence of pore distribution on the hydraulic conductivity of some swedish tills abstract the relationship between pore size distribution and hydraulic conductivity was studied on 42 undisturbed till samples the results show a random pattern in the relationship between the total porosity and the hydraulic conductivity a significant positive correlation was obtained between the hydraulic conductivity and the porosity in the interval 95 30 m whereas no such relationship could be established between the hydraulic conductivity and coarser pores this could be explained by the fissility structure in the till matrix which forms continuous micro fissures about 50 100 m in width whereas the coarser pores are more or less isolated

fluoride dynamics in the granitic aquifer of the wailapally watershed nalgonda district india high concentrations of fluoride up to 7 6 mg l are a recognized feature of the wailapally granitic aquifer of nalgonda district andhra pradesh india the basement rocks provide abundant sources of f in the form of amphibole biotite fluorite and apatite the whole rock concentrations of f in the aquifer are in the range 240 990 mg kg calcretes from the shallow weathered horizons also contain comparably high concentrations of f 635 950 mg kg the concentrations of water soluble f in the granitic rocks and the calcretes are usually low 1 of the total or less but broadly correlate with the concentrations observed in groundwaters in the local vicinity the water soluble fraction of fluoride is relatively high in weathered calcretes compared to fresh calcretes groundwater major ion composition shows a well defined trend with flow downgradient in the wailapally aquifer from na ca hco3 dominated waters in the recharge area at the upper part of the catchment through to na mg hco3 and ultimately to na hco3 and na hco3 cl types in the discharge area in the lowest part the evolution occurs over a reach spanning some 17 km groundwater chemistry evolves by silicate weathering reactions although groundwaters rapidly reach equilibrium with carbonate minerals favouring precipitation of calcite and ultimately dolomite in the lower parts of the watershed this precipitation is also aided by evapotranspiration decreasing ca activity downgradient leads to a dominance of fluorite undersaturated conditions and consequently to mobilisation of f despite the clear downgradient evolution of major ion chemistry concentrations of f remain relatively uniform in the fluorite undersaturated groundwaters most being in the range 3 0 7 6 mg l the rather narrow range is attributed to a mechanism of co precipitation with and or adsorption to calcrete in the lower sections of the aquifer the model may find application in other high f groundwaters from granitic aquifers of semi arid regions

organic matter composition and macrofaunal diversity in sediments of the condor seamount azores ne atlantic in recent years increasing knowledge has been accumulated on seamounts ecology however their sedimentary environments and associated biological communities remain largely understudied in this study we investigated quantity and biochemical composition of organic matter and macrofaunal diversity in sediments of the condor seamount ne atlantic azores in order to test the effect of the seamount on organic matter distribution sediment samples were collected in 6 areas the summit the northern and southern flanks and bases and in an external far field site macrofauna abundance and diversity were investigated on the summit the southern flank and in the far field site the organic matter distribution reflected the complex hydrodynamic conditions occurring on the condor concentrations of organic matter compounds were generally lower on the whole seamount than in the far field site and on the seamount summit compared to flanks and bases a clear difference was also evident between the northern and southern slopes of the condor suggesting a role of the seamount in conditioning sedimentation processes and distribution of food resources for benthic consumers macrofauna assemblages changed significantly among the three sampling sites high abundance and dominance accompanied by low biodiversity characterized the macrofauna community on the condor summit while low dominance and high biodiversity were observed at the flank our results although limited to five samples on the seamount and two off the seamount do not necessarily support the paradigm that seamounts are more biodiverse than the surrounding seafloor however the abundance and biomass functional diversity and taxonomical distinctiveness of the macrofaunal assemblages from the condor seamount suggest that seamounts habitats may play a relevant role in adding to the regional biodiversity

a comparison of recharge estimates to a fractured sedimentary aquifer in south africa from a chloride mass balance and an integrated surface subsurface model the paper describes the use of an integrated surface subsurface modelling approach to estimate recharge to a semi arid karoo aquifer and a comparison of the results with a chloride mass balance on a sub area scale parameters were not calibrated to test the success with which the model can be applied in regions of scarce data the chloride balance suggests a mean annual recharge of 4 5 mm year 1 based on a mean annual rainfall of 460 mm the model predicts 5 8 mm year 1 from a mean annual rainfall of 483 mm during the simulation period recharge was found to be highly variable in space with a positively skewed distribution in time spatial variability was attributed to differences in the distribution of soil moisture content resulting from variations in slope soil texture and depth both methods suggest that recharge is considerably less than the mean of 9 9 mm year 1 estimated from the currently prescribed rainfall recharge relationship for karoo aquifers

spatial variation in seabed temperatures in the southern ocean implications for benthic ecology and biogeography the antarctic seabed has traditionally been regarded as cold and thermally stable with little spatial or seasonal variation in temperature here we demonstrate marked spatial variations in continental shelf seabed temperature around antarctica with the western antarctic peninsula shelf significantly warmer than shelves around continental antarctica as a result of flooding of the shelf by circumpolar deep water from the antarctic circumpolar current the coldest shelf seabed temperatures are in the weddell sea ross sea and prydz bay as a consequence of seasonal convection associated with strong air sea heat fluxes and sea ice formation these waters constitute the dense precursors of antarctic bottom water and can descend down the adjacent slope to inject cold water into the southern ocean deep sea deep sea seabed temperatures are coldest in the weddell sea and are progressively warmer to the east there is a distinct latitudinal gradient in the difference between seabed temperatures on the shelf and in the deep sea with the deep sea warmer by up to similar to 2 k at high latitudes and colder by similar to 2 k around sub antarctic islands these differences have important consequences for benthic ecology and biogeography understanding the evolutionary history of the antarctic marine biota and the impact of regional climate change

paleohydrologic implications of some deep soilwater chloride profiles murray basin south australia abstract a chloride mass balance approach to estimating soilwater ages and paleorecharge rates was tested in an area where considerable paleoclimatic data were available for comparison application of the method to data from four cores of the unsaturated zone taken in the western murray basin showed that the soil water at the base of the chloride build up or bulge associated with the root zone of the native mallee vegetation was emplaced during the last glacial interval at least 20 000 years bp furthermore recharge rates at this time were very low these observations agree with independent paleoclimate evidence that suggest that this time was colder windier and drier results are consistent with the notion that the root zone chloride bulge so typical of the murray mallee region developed in response to aridity that peaked during the last full glacial interval in australia the chloride method is a useful tool in paleohydrology especially when used in concert with other evidence

quantitative investigations of the hydraulic connection between a large reservoir and a buried valley aquifer in southern alberta quantitative investigations including two aquifer tests and development of a three dimensional 3d ground water flow model were required to determine the hydraulic connection between an irrigation reservoir and a buried valley aquifer in southern alberta evidence of seepage was detected in the buried valley aquifer 10 km east of the pine coulee reservoir at the onset of filling in 1999 when the reservoir level exceeded an elevation of 1035 m above sea level a s l concern for an increase in the local water table and the creation of artesian conditions in the aquifer prompted this study to determine the approximate location of a seepage window that appeared to be connecting the reservoir and aquifer observations of hydraulic head in the aquifer during the pumping tests revealed a barrier bound ary when the reservoir level was at an elevation of 1035 m a s l and a recharge boundary condition when the elevation exceeded 1039 m a s l these data were used to calibrate a 3d groundwater flow model which was needed to deter mine the hydraulic properties and approximate location of the leakage zone the quantitative investigation showed that seepage likely occurred through the sideslopes of the flooded coulee rather than through the low permeability coulee floor sediments or the embankment dam further simulations illustrated the expected seepage rates at various reservoir supply levels and the pumping rates required for relief wells installed in the buried valley aquifer to maintain historic aquifer hydraulic head a brief postanalysis indicated that the forecasted pumping rates were only 15 lower than have been required to maintain preconstruction water levels in the buried valley aquifer

diversity in deep sea benthic macrofauna the importance of local ecology the larger scale history and the antarctic abstract high diversity in macrobenthos in the deep sea still lacks satisfactory explanation even if this richness may not be exceptional compared to that in coastal soft sediments explanations have assumed a highly ecologically interactive saturated local community with co existence controlled by either niche heterogeneity or spatio temporal heterogeneity embodying disturbance all have failed to provide convincing support local regional scale biodiversity relationships support the idea of local richness in macrobenthos being predominantly dependent on the larger rather local scale local scale ecological interactions seem unlikely to have overriding importance in co existence of species in the deep sea even for relatively abundant core species with wide distributions variety in observed larger scale pattern and the strong inter regional pattern particularly in the poorly known southern hemisphere seem to have a pluralistic causation these include regional scale barriers and extinctions e g arctic and ongoing adaptive zone re colonisation e g mediterranean along with other historical constraints on speciation and migration of species caused by changes in ocean and ocean basin geometry at the global scale lack of knowledge of the antarctic deep sea for example blocks coherent understanding of latitudinal species diversity gradients we need to reconcile emerging understanding of large scale historical variability in the deep sea environment with massive extinctions among microfossil indicators as recently as the pliocene to results from cladistic studies indicating ancient lineages such as asellote isopods that have evolved entirely within the deep sea the degree to which the great age diversity and high degree of endemism in antarctic shelf benthos might have enriched biodiversity in the adjacent deep seas basins remains unclear basin confluence with the atlantic indian and pacific oceans may have encouraged northwards dispersion of species from and into the deep antarctic basins so that any regional identity is superficial interpretation of the antarctic deep sea as a diversity pump for global deep sea biodiversity may simply reflect re colonisation via basin confluence of northern hemisphere areas impoverished by the consequences of rapid environmental change during the quaternary

effects of forest clearing on groundwater abstract groundwater systems were studied in five catchments 0 8 3 5 km2 over ten years at the end of the third year forest vegetation was totally or partially cleared in three catchments the cleared areas were sown to pasture or crop in accord with conventional agricultural practice for the region permanent aquifers were encountered within a deeply 30 m weathered regolith derived from igneous basement rocks in the higher rainfall catchment pair aquifer boundaries corresponded reasonably well with the surface divide but permanent aquifers were encountered mainly in lower parts of the three catchments in the medium rainfall areas slug test measurements of hydraulic conductivity k varied by more than a factor 100 within a catchment but there was no significant difference between the geometric mean of k in each catchment which varied between 1 4 and 7 6 mm d 1 in the higher rainfall catchments the potentiometric surface under forest normally responded by 1 4 m after each winter wet season this indicates significant seasonal recharge on the basis of the number of piezometers exhibiting this behaviour seasonal recharge was widespread in this area by contrast the seasonal response of the potentiometric surface was rarely more than 1 m under forest in the medium rainfall catchments and at many sites there was no apparent recharge in several years of this study in areas fully cleared for agriculture the potentiometric surface moved upward at more than 2 6 m yr 1 averaged over several years this was equivalent to increased recharge estimated as 6 12 of rainfall depending on the specific yield used for the aquifer the potentiometric surface was observed to rise less rapidly 0 9 m yr 1 in areas subjected to partial clearing groundwater chloride concentrations exhibit no obvious spatial pattern in the catchments probability density functions of the chloride data have similar shapes in the higher and medium rainfall catchment areas with median values of 460 and 1000 mg 1 1 respectively chloride concentrations were essentially constant with time in some piezometers while in others concentrations varied with or without trend recorded changes in time and space are not consistent with the transport equation for solute in an aquifer leading to the conclusion that local variability of solution velocity may be important this is in accord with the observed variability of hydraulic conductivity in these aquifers