gis assisted inverse geochemical modeling for plausible phase transfers in aquifers a geographical information system gis assisted approach that couples a groundwater flow model and an inverse geochemical model is presented to quantify the phase mole transfers between two points on the flow path within a groundwater system it is used to investigate the plausible phase transfers in the unconfined aquifer of mehsana district of gujarat state india x ray diffraction analysis of soil samples is carried out for mineral characterization the groundwater flow field is simulated using modflow and flow paths used for inverse geochemical modeling are traced using pmpath a particle tracking algorithm the plausible phase mole transfers in the flow path are quantified using phreeqc geochemical code the different scenarios generated by inverse modeling routine are used as input to the geochemical model and simulation runs are taken as forward models the obtained results are compared to the target solution chemistry by using the square of the pearson product moment correlation coefficient results reveal that the groundwater is undersaturated with anhydrite carbon dioxide gas fluorite gypsum halite jarosite k and siderite it is oversaturated with aragonite calcite dolomite ferrihydrite goethite and hematite results further reveal that calcite is precipitating while dolomite gypsum carbon dioxide and fluorite are dissolving together with ion exchange in the flow path

chemical composition of rainfall and groundwater in recharge areas of the bet shean harod multiple aquifer system israel the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining from a regional multiple aquifer system comprising two different carbonate and two basalt aquifers as well as deep seated reservoirs of confined brines this paper the first of two describes the hydrochemistry of the groundwater bodies related to this multiple aquifer system the paper deals with the chemical composition of rain falling on natural recharge areas the chemical contribution of the aquifer rocks and the chemical evolution of groundwaters in the upper flow courses of all aquifers of this regional system the methodology applied is based on the determination of major dissolved ions and on the examination of their ratios and changes along the upper flow paths rain water falling on natural recharge areas has an average chlorinity of 12mgl 1cl and a calcium bicarbonate composition caused by dust borne terrigenous material this rain water salinity decreases with distance from the sea shore fresh groundwaters flowing through the different aquifers may be identified and differentiated by their characteristic salinity levels and ionic ratios groundwaters flowing through carbonate aquifers are identified by different salinity levels and by distinct rmg rca ratios reflecting dolomite calcite ratios in aquiferr rocks the groundwaters of the two basalt aquifers have typical cation assemblages and high na and mg2 concentrations far in excess of those typical of the recharging rainfall groundwater in the upper flow courses of all aquifers investigated is deficient in so2 4 and k relative to recharging rain water

new isotopic evidence for the origin of groundwater from the nubian sandstone aquifer in the negev israel the geochemistry and isotopic composition h o s osulfate c sr of groundwater from the nubian sandstone kurnub group aquifer in the negev israel were investigated in an attempt to reconstruct the origin of the water and solutes evaluate modes of water rock interactions and determine mean residence times of the water the results indicate multiple recharge events into the nubian sandstone aquifer characterized by distinctive isotope signatures and deuterium excess values in the northeastern negev groundwater was identified with deuterium excess values of 16 which suggests local recharge via unconfined areas of the aquifer in the negev anticline systems the d 18 oh2o and d 2 h values 6 5 and 35 4 of this groundwater are higher than those of groundwater in the sinai peninsula and southern arava valley 7 5 and 48 3 that likewise have lower deuterium excess values of 10 based on the geochemical differences between groundwater in the unconfined and confined zones of the aquifer a conceptual geochemical model for the evolution of the groundwater in the nubian sandstone aquifer has been reconstructed the isotopic composition of shallow groundwater from the unconfined zone indicates that during recharge oxidation of pyrite to so4 d 34 sso4 13 d 18 oso4 7 7 and dissolution of caco3 87 sr 86 sr 0 70787 d 13 cdic 3 7 occur in the confined zone of the aquifer bacterial so4 reduction removes a significant part of dissolved so 2

present day south american climate abstract this paper documents the main features of the climate and climate variability over south america on the basis of instrumental observations gathered during the 20th century it should provide a modern reference framework for paleoclimate research in south america targeting high resolution proxies over the past few centuries several datasets suitable for present day climate research are first described highlighting their advantages as well as their limitations we then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans in particular the diversity of precipitation temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large scale circulation caused by the andes cordillera the contrasting oceanic boundary conditions and the landmass distribution similarly the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence as some regions are more influenced by large scale phenomena rooted in the tropical oceans while others are more influenced by high latitude phenomena the impact of these large scale phenomena over south america is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields we have included a discussion on the seasonality and long term stability of such impacts and complemented our general description by an updated review of the literature on climate variability over specific regions

late quaternary palynology in marine sediments a synthesis of the understanding of pollen distribution patterns in the nw african setting abstract after a review of the first steps in marine palynology we show that the understanding of the northwest african setting is crucial to evaluate the potential of marine palynological studies elsewhere we studied distribution patterns of pollen grains in recent marine sediments off nw africa and were able to clearly relate patterns to modern pollen source areas vegetation belts and operating transport systems wind belts and ocean currents in particular patterns of quercus artemisia chenopodiaceae amaranthaceae ephedra gramineae and wet forest trees are very indicative of the position of the vegetation belts on the adjacent continent aeolian pollen transport is carried out by the northeast trade winds and the african easterly jet aej in the rain forest belt transport of pollen and fern spores also occurs by rivers a detailed comparison between recent pollen rain samples from terrestrial and marine sites between 21 and 12 n showed that the latitudinal range of vegetation belts is clearly reflected in the pollen samples of both environments a migration of the southern border of the sahara is reflected by the changing ratio between chenopodiaceae amaranthaceae pollen from the desert and gramineae pollen from the savannah belt distribution patterns of pollen for 9000 and 18 000 14 c yr bp last glacial maximum time slices based on pollen records from eleven marine cores between portugal and the gulf of guinea show significant latitudinal migrations of vegetation belts but a stable position of the main wind trajectories the aej had a stable position around 21 n the belt with trade winds had a stable position from morocco southwards changing vigour of the trade winds is clearly reflected by the patterns of isopollen contours and by changes in pollen influx records

late quaternary vegetation and climate of southern tierra del fuego vegetation and climate over approximately the past 13 000 yr are reconstructed from fossil pollen in a 9 4 m mire section at caleta robalo on beagle channel isla navarino 54 56 s 67 38 w southern tierra del fuego fifty surface samples reflecting modern pollen dispersal serve to interpret the record chronologically controlled by nine radiocarbon dates fossil pollen assemblages are empetrum gramineae gunnera tubuliflorae zone 3b 13 000 11 850 yr b p gramineae empetrum assorted minor taxa zone 3a 11 850 10 000 yr b p nothofagus gramineae tubuliflorae polypodiaceae zone 2 10 000 5000 yr b p nothofagus empetrum zone 1b 5000 3000 yr b p and empetrum nothofagus zone 1a 3000 0 yr b p assemblages show tundra under a cold dry climate zone 3 followed by open woodland zone 2 as conditions became warmer and less dry and later with greater humidity and lower temperatures by closed forest and the spread of mires zone 1 comparisons drawn with records from antarctica new zealand tasmania and the subantarctic islands demonstrate broadly uniform conditions in the circumpolar southern hemisphere the influences of continental and maritime antarctic air masses were apparently considerable in tierra del fuego during cold late glacial time whereas holocene climate was largely regulated by interplay between maritime polar and maritime tropical air

the yarkon taninim groundwater basin israel hydrogeology case study and critical review abstract the late albian turonian judea group carbonate aquifer is one of the most important resources of fresh groundwater in the northern negev and in the central part of israel over three decades ago various hydrological hydrochemical hydrometeorological and geological aspects of this aquifer were thoroughly investigated and served to build up the professional background and data base for the management of this resource notwithstanding the accumulating structural hydrogeological and hydrochemical evidence the conceptual hydrogeological model of the yarkon taninim basin which constitutes the western part of the judea group aquifer has neither been questioned nor updated therefore the existing and accepted model of this basin should in the best case only depict general features and trends the present review critically examines the main hitherto accepted hydrogeological conventions points out puzzling and contradictory phenomena and emphasizes questionable issues although the present review deals with problems related to a specific groundwater basin the methods and effort for breaking long established conventions may serve as an example for similar situations in other places in which water resources are managed according to long established concepts and traditions without being periodically revised and reassessed in view of accumulating knowledge

three late quaternary pollen diagrams from southern patagonia and their palaeoecological implications abstract diagrams of fossil pollen in three deposits postdating glacial recession of the last ice age provide an account of late glacial and holocene vegetation and palaeoclimate in southern patagonia sites are mires located along the estrecho de magallanes at punta arenas 53 09 s 70 57 w and puerto del hambre 53 36 s 70 55 w and an intermittent lake some 300 km to the north at torres del paine 50 59 s 72 40 w chronostratigraphy is controlled by 20 radiocarbon dates the oldest site puerto del hambre covering close to 16 000 years charcoal from the sites and carbonate torres del paine as well as tephra layers and an instance of marine incursion puerto del hambre supply additional data of interpretive value accompanying the fossil pollen records is a reference survey of modern pollen fallout from 43 surface sample localities late glacial vegetation during deglaciation consisted mostly of tundra dominated by communities of empetrum acaena gunnera and tubuliflorae compositae under a relatively cold dry climate nothofagus although present in numbers initially at puerto del hambre did not expand until the close of the late glacial at punta arenas expansion of nothofagus was episodic occurring during apparent warmer intervals of the last three millennia of steppe tundra holocene vegetation is depicted at first as a patchwork of nothofagus woodland and steppe subject to climate of relative warmth and limited moisture except at torres del paine where moisture levels were apparently higher than at sites to the south closed nothofagus forest communities subsequently are best developed in the late holocene under a climate with generally cooler wetter parameters fire believed to be caused mostly by palaeoindians has had an important role in shaping vegetation sequences in the holocene formidable however in the development of vegetation are the latitudinal displacements variable intensities of atmospheric conditions caused by shifting storm tracks of the southern westerlies

full glacial late glacial palaeoclimate of the southern andes evidence from pollen beetle and glacial records palaeoecological studies carried out in the chilean lake district and chilotan archipelago 41 43 s record full glacial and late glacial pollen assemblages beginning just after 21000 and beetle assemblages after 18000 both sets extending until 10000 14c yr bp pollen records indicate that subantarctic parkland the vegetation of the early millennia of record changed after about 14000 yr bp to become open woodland and later north patagonian evergreen forest assemblages of plants and beetles responding more or less in unison to a strong rise in temperature 6 c behaved in accord at around 14000 until 13000 12500 yr bp the beetle fauna displaying a marked increase in obligate forest types during full glacial conditions 17400 16100 and 15300 and 14400 yr bp and in the late glacial interval after about 13000 yr bp however climate evidently coerced populations dissimilarly the pollen sequence showing an increase in plant taxa indicative of colder climate whereas the beetle fauna underwent little or no variation contrasting climate modes implied by plants and beetles may be attributed to differential responses to apparent low order temperature changes 2 3 c

chemical assessment of dam water irrigation effects on groundwater qualities in bigherd plain fars province iran in this study the effect of irrigation by dam water in bigherd area fars province iran on groundwater quality 1 and 3 years after dam construction was investigated to conduct this study the major ion concentrations including hco3 ca2 mg2 na k so4 2 and cl and water levels in ten water wells and the dam reservoir were measured during two periods june 2009 and june 2011 analyzed by factor analysis and plotted in water quality charts the results of factor analysis show that most of the dissolved ions including mg2 ca2 so4 2 cl and hco3 particularly in 2009 were mainly originated from carbonate and evaporitic formations as well as from the playa lake factor 1 in 2011 elevated salinity levels were found to be mainly related to intense evaporation during irrigation that are proportional to na and k concentrations factor 2 and depend on the type of crop and irrigation method it was also found that the surface waters from deeper origins had less of an effect on groundwater recharge compared to upstream carbonate aquifers

pollen distribution in marine surface sediments from chilean patagonia abstract southern south america is the only mid to high latitude continental landmass in the southern hemisphere and therefore represents one of the key areas to recover terrestrial records for the study of past and future climate variability at these latitudes during cruise md 159 of r v marion dufresne cores were taken off the chilean coast from 40 to 55 s in the open ocean and the fjords pollen spectra of 32 core top samples illustrate the relationships between pollen distribution in the sampled marine sediments and their transport from the vegetation onshore pollen concentrations show two distinct gradients 1 a north to south gradient controlled by latitudinal vegetation changes and by westerly winds and 2 from the fjords to the open ocean a gradient clearly controlled by wind fluvial inputs and pollen diagenesis linked to the distance from the coast and water depth the distribution of pollen percentages in these marine surface sediment samples reflects the local vegetation from the nearby continental area consequently pollen analyses from older sediments in these marine cores will be reliable tools to reconstruct past vegetational changes

sedimentary organic matter preservation a test for selective degradation under oxic conditions the authors report here a test of the hypothesis that the extent of organic matter preservation in continental margin sediments is controlled by the average period accumulating particles reside in oxic porewater immediately beneath the water sediment interface oxygen penetration depths organic element compositions and mineral surface areas were determined for 16 sediment cores collected along an offshore transect across the washington continental shelf slope and adjacent cascadia basin individual amino acid sugar and pollen distributions were analyzed for a 11 to 12 cm horizon from each core and sup 14 c based sediment accumulation rates and stable carbon isotope compositions were determined from depth profiles within a subset of six cores from representative sites sediment accumulation rates decreased and dissolved o sub 2 penetration depths increased offshore along the sampling transect as a result oxygen exposure times oet increased seaward from decades mid shelf and upper slope to more than a thousand years outer cascadia basin organic contents and compositions were essentially constant within individual sediment cores but varied consistently with location in particular organic carbon surface area ratios decreased progressively offshore and with increasing oet three independent compositional parameters demonstrated that the remnant organic matter in farther offshore sediments is more degraded both concentrationmore and compositional patterns indicated that sedimentary organic matter exhibits a distinct and reproducible oxic effect oet helps integrate and explain organic matter preservation in accumulating continental margin sediments and hence provides a useful tool for assessing transfer of organic matter from the biosphere to the geosphere less

the fault pattern in the northern negev and southern coastal plain of israel and its hydrogeological implications for groundwater flow in the judea group aquifer abstract on the basis of a broadly expanding data base the hydrogeological properties of the judea group sequence in the northern negev and southern coastal plain of israel have been reassessed the updated subsurface model is based on data derived from water and oil wells and on recent large scale geophysical investigations a new regional pattern of the reassessed geological through the subsurface of the study area has been revealed in view of the reassessed geological and hydrological subsurface setting it appears that the judea group aquifer should not be regarded as one continuous and undisturbed hydrological unit owing to the occurrence of regional faults its subaquifers are locally interconnected these subaquifers which contain mainly high quality water are juxtaposed as a result of faulting against kurnub group sandstones containing brackish paleowater the latter group is faulted against late jurassic formations containing highly saline groundwater in the beer sheva area the judea group aquifer is vertically displaced against the senonian and eocene mt scopus and avdat groups which also contain brackish and saline water in the southern coastal plain major faults locally dissect also the pleistocene kurkar group facilitating inflow of mg rich groundwater deriving from judea group dolomites the new geological evidence and its hydrogeological implications provide new solutions for previously unexplained salinization phenomena

late holocene marine productivity changes in northern patagonia chile inferred from a multi proxy analysis of jacaf channel sediments abstract a multi proxy approach based on organic organic carbon alkenones and c n and inorganic geochemical proxies biogenic opal inorganic carbon fe ti and ca preserved in the sediments of the jacaf channel cf7 pc33 44 21 s 72 58 w 510 m water depth chilean fjords yields evidence of major past productivity fluctuations in accordance with climatic changes over the last 1800 years the downcore record clearly shows two productivity climate modes the first period prior to 900 cal yr bp is characterized by decreased marine productivity and a reduced continental signal pointing to diminished precipitation and runoff in contrast the second period between 750 cal yr bp and the late 1800s top of core is illustrated by elevated productivity and an increased continental signal suggesting higher precipitation and runoff both time intervals are separated by a relatively abrupt transition of 150 years which roughly coincides with the beginning of the little ice age the increased content of freshwater diatoms and chrysophyte cysts that characterize the last 200 years of the latter mode coincides with a significant decrease in the carbonate content of the sediment together they further indicate increased terrigenous contributions and decreased marine carbonate productivity at the end of the little ice age the correspondence between our record and other paleoclimate studies carried out in south america and antarctica demonstrates that the chilean fjord area of northern patagonia is not just sensitive to local climatic variability but also to regional and possibly global variability

late quaternary vegetation of southern isla grande de chiloe chile late glacial holocene forest history of southern isla chiloe latitude 43 10 s was reconstructed on the basis of pollen analysis in three profiles laguna soledad laguna chaiguata puerto carmen prior to 12 500 yr b p pollen records are dominated by plant taxa characteristic of open habitats zone i from 12 500 yr b p to the present tree species predominate in the pollen records zones ii v between 12 500 and 9500 yr b p ombrophyllous taxa nothofagus podocarpus nubigena myrtaceae fitzroya pilgerodendron and drimys are frequent in all pollen diagrams suggesting a wetter and colder climate than the present between 9000 and 5500 yr b p valdivian forest elements such as nothofagus dombeyi type weinmannia and eucryphia caldcluvia dominate indicating a period of drier and warmer climate from 5500 yr b p onward the expansion of mixed north patagonian subantarctic forest elements and the increased frequence of tepualia suggest increased rainfall and temperatures oscillating around the modern values the change from open to forest vegetation ca 12 500 yr b p probably represents the most pronounced climatic change in the record and can be interpreted as the glacial postglacial transition in the study area

chemical evolution of saline waters in the jordan dead sea transform and in adjoining areas the ca mg relationship in groundwaters strongly points to the overall dolomitization and local albitization the mg ca ratios reveal two trends by which saline waters develop increase of mg ca ratio by evaporation and decreasing mg ca ratios due to dolomitization and albitization br cl vs na cl ratios demonstrate that albitization does not play a major role which leaves dolomitization to be the main source for decreasing mg ca ratios in saline waters in the eastern and southern region of lake kinneret salinization occurs by mixing with a ca mg molar ratio 1 dominates which developed by the albitization of plagioclase in abundant mafic volcanics and the dolomitization of limestones the most saline groundwater of the tabgha fuliya and tiberias clusters could be regional derivatives of at least two mother brines in diluted form one is represented by ha on water the other is a na rich brine of the zemah type additionally a deep seated ca dominant brine may ascend along the fractures on the western side of lake kinneret which is absent on the eastern side groundwaters of the lower jordan valley are chemically different on both sides of the jordan river indicating that the exchange of water is insignificant all saline waters from the dead sea and its surroundings represent a complex mixture of brines and precipitation and local dissolution of halite and gypsum many wells of the arava araba valley pump groundwater from the upper cretaceous limestone aquifer the origin of the water is actually from the lower cretaceous kurnub group sandstones groundwater drawn from the quaternary alluvial fill either originates from kurnub group sandstones eilat 108 yaalon 117 or from altered limestones of the judea group the origin of these waters is from floods flowing through wadis incised into calcareous formations of the judea group on the other hand as a result of step faulting hydraulic contact is locally established between the kurnub and the judea groups aquifers facilitating the inter aquifer flow of the confined kurnub paleowater into the karstic formations of the judea group two periods of neogene brine formation are considered the post messinan inland lagoon resulting in drying up of the sdom sea and the evaporation of the pleistocene samra lake which went further through the stage of lake lisan to the present dead sea for the first period major element hydrochemistry suggests that the saline waters and brines in the jordan dead sea arava valley transform evolved from the gradual evaporation of an accumulating mixture of sea ground and surface water due to the precipitation of carbonates gypsum and halite such an evaporating primary water body was strongly enriched in mg br and b and shows high molar ratios of br cl b cl and mg ca but low na cl ratios the development of the br cl ratio is chemically modelled showing that indeed brine development is explicable that way along with the evaporation brine evaporites formed which are leached by infiltrating fresh water yielding secondary brines with na cl ratios of 1 when primary brines infiltrated the sub surface they were subjected to mg ca exchange in limestones dolomitization and to chloritization and albitization in basic igneous rocks turning them into ca cl brines these tertiary brines are omnipresent in the rift the brines of the late lisan and dead sea were generated by evaporating drainage waters which leached halite gypsum and carbonates from the soil and from the sub surface all these brines are still being flushed out by meteoric water resulting in saline groundwaters this flushing is regionally enhanced by intensive groundwater exploitation in variable proportions the neogene and late lisan lake and recent dead sea brines have to be considered as the most serious sources of salinization of groundwaters in the rift deep seated pre sdom brines cannot strictly be excluded but if active they play a negligible role only

chemical and isotopic 87sr 86sr δ18o δd constraints to the formation processes of red sea brines abstract about twenty deeps filled with hot brines and or metalliferous sediments are located along the red sea axis these brines present a well suited framework to study the hydrothermal activity in such a young ocean the present study outlines the results of a geochemical approach combining major trace element and isotopic oxygen hydrogen strontium analyses of brines in six of the deeps to evaluate different processes of brine formation and to compare the evolution of each deep important heterogeneities in temperature salinity hydrographic structure and chemistry are recorded each brine having its own characteristics the intensity of hydrothermal circulation varies among the deeps and ranges from being strong atlantis ii and nereus to weak port soudan and even to negligible valdivia and suakin and it varies along the entire red sea axis these observations do not favour a unique formational model for all of the brines for example the brines of the suakin deep appear to have been formed by an old sea water which dissolved evaporite beds without significant fluid circulation and hydrothermal input while others such as atlantis ii or nereus deeps appear to be dominated by hydrothermal influences a striking feature is the absence of a relationship between the position of the deeps along the axis and their evolutionary maturity

nature and origin of sedimentary clasts associated with mud volcanoes in the nile deep sea fan relationships with fluid venting abstract during the last 10 years several marine geological geophysical surveys conducted on the nile deep sea fan have provided much new information about the large fluid seepage phenomenon which characterizes this passive margin segment among the data more than 60 sediment cores have been recovered in this area rock clasts were collected from eight of them as well as during deep sea dives notably in the area of isis osiris and amon mud volcanoes in few areas especially in the western and the north eastern provinces of the nile fan some clasts consist of crust fragments resulting from cementation of muddy sediment by precipitation of high mg calcite these clasts correspond to a simple cementation of the mud by precipitation of high mg calcite as a consequence no obvious textural or faunal difference with the ambient matrix mud can be observed these clasts are made of autochthonous crusts derived from microbial anaerobic oxidation of methane and release of bicarbonate and sulphide in the surrounding pore water these clasts also lack aragonite in most of the other cases menes caldera isis osiris and amon mud volcanoes allochthonous clasts characterized by low mg calcite cement siderite or dolomite mixed with expelled mud outcrop on the seafloor nannofossils have allowed us to date some of these clasts most of the ages range from pliocene to pleistocene one clast is lower cretaceous in age the lithological facies often indicate coastal or deltaic environments some clasts are closely linked to an evaporite rich environment halite gypsum and analcime they all provide useful information on the nature of buried sedimentary series covering the margin their presence on the seafloor is due to the expulsion of a pressurized mixture of sediment water and gas this process is believed to have used pre existing tectonic conduits

tracing the origin of salts in groundwater by sr isotopic composition the crystalline complex of the southern sinai egypt abstract the source of the salts in the groundwater from the arid crystalline complex of the southern sinai has been traced by the sr isotopic composition of the waters and their major chemical components twelve water sources with salinity ranging between 200 and 450 mg l 1 were analyzed the salts are composed of 30 na k and ci and 70 ca sr mg so 4 and hco 3 the 87 sr 86 sr ratio of the waters is in the range of 0 7087 0 7100 with an average of 0 7090 0 0003 the 87 sr 86 sr ratio in the basement rocks acid igneous and metamorphic is generally higher than 0 71 even low rb sr minerals have values of 0 72 assuming sr in the water genetically accompanies ca the major constituent of the carbonate fraction the low 87 sr 86 sr ratio excludes the possibility that this fraction originated from dissolution of country rock a mixing model between ancient carbonates and the crystalline country rock for sr in the groundwater is rejected it is suggested that the chemical composition of the water is mainly controlled by aerosols originating from beach sands aragonite of recent reef debris and sabkha sediments halite gypsum anhydrite aragonite and mg calcite from the coastal plains of the sinai thus under the present conditions chemical weathering is a process practically negligible the sr isotopic composition of the waters rejects the possibility that the air borne dust in the region is derived from cretaceous tertiary marine sediments in egypt and lybia

pollen distribution in marine sediments from the south eastern indonesian waters abstract pollen analysis on box core sediments from the south eastern indonesian waters provide information on trends in pollen transport and on pollen distribution in the marine surface sediments pollen and at a lower rate pteridophyta spore concentration values tend to decrease with increasing distance from the shoreline as a result pteridophyta percentages tend to increase with increasing distance from the shoreline mangrove pollen shows very little export from its distribution area while pollen from the mid upper montane group shows a substantial export from its onshore distribution area in general despite the complex nature of vegetation patterns and pollen transport in this region the onshore distribution of individual taxa and major vegetation types is well reflected in the pollen distribution in the marine sediments

chemical composition of rainwater and floodwaters in the negev desert israel abstract rain and floodwater were sampled by self sealing samplers scattered over the area of two drainage basins in the negev desert of israel the sampling was carried out during the winters of 1978 1981 water was analyzed for the following ions ca2 mg2 na k hco 3 cl and so2 4 the chemical type of the rain and floodwater as well as the total quantities of salts precipitated and drained out from the basins were investigated the chemical characteristics of the rainwater falling in the negev resemble those of rainwater in northern israel but the absolute quantities of ions are smaller the total quantities of salts introduced into the basin were found to be larger than the quantities of salts drained out by the floods the chemical composition of the floodwater was found to be governed by the lithology of the drainage basin and not by the initial chemical characteristics of the rain from which it was derived

radiolaria and pollen records from 0 to 50 ka at odp site 1233 continental and marine climate records from the southeast pacific abstract site 1233 drilled during leg 202 of the ocean drilling program provides a detailed record of marine and continental climate change in the southeast pacific and south american continent splits from over 500 samples taken at 20 cm intervals for quantitative analysis of radiolarian and pollen populations yield a temporal resolution of 200 400 years in each sample 39 pollen taxa and 40 radiolarian species and genera were evaluated age control is provided by 25 ams 14c dates lamy f kaiser j ninnemann u hebbeln d arz h w stoner j 2004 science 304 1959 1962 multivariate statistical analyses of these data allow us to conclude the following 1 during the past 50 ka the region of the central chile coast is not directly influenced by polar water from the antarctic region 2 changes in ocean conditions off central chile during this time interval primarily reflect north south shifts in the position of the south pacific transition zone 3 changes in chilean vegetation reflect comparable latitudinal shifts in precipitation and the position of the southern westerlies 4 the first canonical variate of radiolarian and pollen records extracted from site 1233 are remarkably similar to each other as well as to temperature records from the antarctic which suggests that marine and continental climate variability in the region is tightly coupled at periods longer than 3000 years 5 the phase coupling of these climate records which lead variations of continental erosion based on iron abundance at the same site are consistent with a hypothesis that erosion is linked to relatively long i e few thousand years response times of the patagonian ice sheet and thus is not a direct indicator of regional climate

the chemical evolution of kurnub group paleowater in the sinai negev province a mass balance approach abstract the chemical evolution of the kurnub group paleowater was studied starting from rainwater in recharge areas of the sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer this was achieved by investigating the chemical composition of groundwater ionic ratios degrees of saturation with common mineral species normative analysis of dissolved salts and by modeling of rock water interaction and mixing processes occurring along groundwater flow paths the initial groundwater composition used is from the nakhel well in sinai it evolves from desert rainwater percolating through typical kurnub group lithology in sinai this rainwater dissolves mainly gypsum halite and dolomite together with smaller amounts of marine aerosol and k feldspar at the same time it precipitates calcite sio 2 smectite and degasses co 2 between the area of nakhel and the northern negev the chemistry of kurnub group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas small amounts of feldspars and of dolomite cement in sandstones eroded from the arabo nubian igneous massif of sinai and organic degradation derived co 2 concomitantly there is precipitation of calcite smectite sio 2 and probably analcime characteristic of sediments in continental closed basins north of the negev the kurnub group fluids are diluted and altered by mixing with judea group aquifer groundwaters on the e there is mixing with residual brines from the water body ancestral to the dead sea prior to discharge into the arava valley rock water interaction indicated by netpath and phreeqc modeling is in agreement with lithology and facies changes previously observed in the kurnub group sequence

geochemical evolution of groundwater in a basaltic aquifer based on chemical and stable isotopic data case study from the northeastern portion of serra geral aquifer sao paulo state brazil summary groundwater from the fractured basalt serra geral aquifer sga represents an important source for water supply in northeastern sao paulo state brazil groundwater flow conditions in fractured aquifers hosted in basaltic rocks are difficult to define because flow occurs through rock discontinuities the evaluation of hydrodynamic information associated with hydrochemical data has identified geochemical processes related to groundwater evolution observed in regional flowpaths sga groundwaters are characterized by low tds with ph varying from neutral to alkaline two main hydrochemical facies are recognized ca mg hco 3 and na hco 3 types primarily the geochemical evolution of sga groundwater occurs under co 2 open conditions and the continuous uptake of co 2 is responsible for mineral dissolution producing bicarbonate as the main anion and calcium and magnesium in groundwater ion exchange between smectites na and ca beidelites seems to be responsible for the occurrence of na hco 3 groundwater toward the rio grande in the northern portion of the study area there is mixing between sga groundwater and water from the sandstones of the guarani aquifer system as evidenced by the chemical and isotopic composition of the groundwater inverse mass balance modeling performed using netpath xl produces results in agreement with the dissolution of minerals in basalt feldspars and pyroxenes associated with the uptake of atmospheric co 2 as well as the dissolution of clay minerals present in the soil kaolinite precipitation occurs due to the incongruent dissolution of feldspars while si remains almost constant due to the precipitation of silica the continuous uptake of co 2 under open conditions leads to calcite precipitation which in addition to ion exchange are responsible by ca removal from groundwater and an increase in na concentrations down the flow gradientco 2 is subject to closed conditions where the basalts are covered by the sediments of bauru group or associated with deeper isolated discontinuities a decrease in the amount of dissolution of labradorite and augite is observed associated with precipitation of carbonates and kaolinite stable isotope ratios of sga groundwater vary from 37 8 to 61 3 vsmow for 2 h vsmow and 5 7 to 8 9 vsmow for 18 o indicating temporal variations in climatic conditions during recharge

definition of groundwater flow patterns by environmental tracers in the multiple aquifer system of southern arava valley israel abstract the present paper describes a model for identification and semi quantitative evaluation of the different water bodies replenishing groundwater in the southern arava rift valley the potential sources of recharge into the alluvial aquifer of the valley were assessed by multivariable cluster analysis of environmental tracers such as dissolved ions and stable isotopes this data was also used to determine the flow pattern to the valley and within its alluvial aquifer to the natural outlet of the red sea spatial variations in the chemical compositions of groundwater and of their isotopic ratios are explained as the result of differential rates of replenishment of various water bodies flowing to the arava the alluvial aquifer of the southern arava valley is recharged by the following water bodies 1 lateral subsurface flow caused by infiltration of water from flash floods occurring in the neighbouring mountain massifs 2 upward and lateral groundwater flow from sandstone and carbonate aquifers in the negev and edom mountains and 3 leakage from deep seated brine reservoirs a complete groundwater flow pattern based upon hydrological hydrochemical and isotopic data is presented in a compartmental configuration

temperature and precipitation record in southern chile extended to 43 000 yr ago southern chile 41 56 s in the belt of westerly winds receives mostly heavy precipitation reaching 8 500 mm yr 1 near 50 s and decreasing northwards and southwards from this latitude to 1 500 mm mean january summer temperatures near sea level along the latitudinal gradient are 8 16 c refs 1 2 dense rain forest covers much of the region to 48 s south to cape horn magellanic moorland prevails and rain forest becomes limited modern pollen measured in surface samples reflects the distribution of plant species in the vegetation we have now applied regression equations relating present day pollen to temperature and precipitation to fossil pollen data at taiquemo to assess climatic conditions during the quaternary the results extend our previous record of the past 16 000 yr at alerce3 beyond the lateglacial to 43 000 yr bp for the 27 000 yr interval they show mean january temperatures of 10 12 c and mean annual precipitation centred around 1 000 mm except during the time span of 31 000 43 000 yr bp when amounts increased to 4 000 mm in general fluctuations correspond to the isotopic climatic reconstruction in antarctica4 and to changes inferred from pollen data at comparable latitudes in tasmania5 8 and new zealand9 10

the last glacial holocene transition in southern chile warming at the last glacial termination in the north atlantic region was interrupted by a period of renewed glacial activity during the younger dryas chronozone ydc the underlying mechanism of this cooling remains elusive but hypotheses turn on whether it was a global or a north atlantic phenomenon chronological sedimentological and palaeoecological records from sediments of small lakes in oceanic southern chile demonstrate that there was no ydc cooling in southern chile it is therefore likely that there was little or no cooling in southern pacific surface waters and hence that ydc cooling in the north atlantic was a regional rather than global phenomenon

quantitative assessment of the flow pattern in the southern arava valley israel by environmental tracers and a mixing cell model abstract this paper demonstrates the implementation of a novel mathematical model to quantify subsurface inflows from various sources into the arid alluvial basin of the southern arava valley divided between israel and jordan the model is based on spatial distribution of environmental tracers and is aimed for use on basins with complex hydrogeological structure and or with scarce physical hydrologic information however a sufficient qualified number of wells and springs are required to allow water sampling for chemical and isotopic analyses environmental tracers are used in a multivariable cluster analysis to define potential sources of recharge and also to delimit homogeneous mixing compartments within the modeled aquifer six mixing cells were identified based on 13 constituents a quantitative assessment of 11 significant subsurface inflows was obtained results revealed that the total recharge into the southern arava basin is around 12 52 10 6 m 3 year 1 the major source of inflow into the alluvial aquifer is from the nubian sandstone aquifer which comprises 65 75 of the total recharge only 19 24 of the recharge but the most important source of fresh water originates over the eastern jordanian mountains and alluvial fans

chilean and southeast pacific paleoclimate variations during the last glacial cycle directly correlated pollen and δ18o records from odp site 1234 abstract joint pollen and oxygen isotope data from ocean drilling program site 1234 in the southeast pacific provide the first continuous record of temperate south american vegetation and climate from the last 140 ka located at 36 s 65 km offshore of concepcion chile site 1234 monitors the climatic transition zone between northern semi arid summer dry winter wet climate and southern year round rainy cool temperate climate dominance of onshore winds suggests that pollen preserved here reflects transport to the ocean via rivers that drain the region and integrate conditions from the coastal mountains to the andean foothills down hole changes in diagnostic pollen assemblages from xeric lowland deciduous forest characterized by grasses herbs ferns and trees such as deciduous beech nothofagus obliqua mesic valdivian evergreen forest including conifers such as the endangered prumnopitys andina and subantarctic evergreen rainforest comprised primarily of southern beech n dombeyi reveal large rapid shifts that likely reflect latitudinal movements in atmospheric circulation and storm tracks associated with the southern westerly winds during glacial intervals mis 2 4 and 6 rainforests and parkland dominated by nothofagus moved northward into the region at the mis 6 5e transition coeval with the rapid shift to lower isotopic values rainforest vegetation was rapidly replaced by xeric plant communities associated with mediterranean type climate an increased prominence of halophytic vegetation suggests that mis 5e was more arid and possibly warmer than mis 1 although rainforest pollen rises again at the end of mis 5e lowland deciduous forest pollen persists through mis 5d and 5c into mis 5b substantial millennial scale variations occur in both interglacial and glacial regimes attesting to the sensitivity of the southern westerly belt to climate change comparison of the cool mesic n dombeyi rainforest assemblage from site 1234 with 18 o in the byrd ice core shows that on time scales longer than 10 ka cool moist conditions in central chile were coherent with and occurred in phase with antarctic cooling this is also likely at millennial scales although rainforest pollen lags antarctic cooling with exponential response times of about 1000 years which plausibly reflects the ecological response time to regional climate change

deglacial and postglacial climate history in east central isla grande de chiloe southern chile 43 s abstract palynologic and stratigraphic data from laguna tahui 42 50 s 73 30 w indicate cool temperate and humid conditions there between 14 000 and 10 000 14c yr b p followed by warmer and drier than present conditions between 10 000 and 7000 14c yr b p and subsequent cooling and rise in precipitation over the last 5800 14c yr the thermophilous valdivian trees eucryphia cordifolia and caldcluvia paniculata reached their maximum abundance during the early holocene warm dry phase 10 000 7000 14c yr b p followed by a rise in lake levels and reexpansion of north patagonian conifers starting at 7000 and 5800 14c yr b p respectively variations in the stratigraphic and geographic distribution of temperate rainforests in southern chile suggest multimillennial trends in temperature and westerly activity which are spatially and temporally coherent with paleoclimate records from neighboring regions climate variability at millennial and submillennial time scales may account for the establishment and persistence of fine scale mosaics of valdivian and north patagonian rainforest species in low to mid elevation communities since 5800 14c yr b p

the nubian sandstone aquifer in the central and northern negev israel delineation of the hydrogeological model under conditions of scarce data abstract the cl content of ground water in the central and northern negev ranges between 250 mg 1 1 in the beer sheva area and 1600 mg 1 1 near the egyptian border where the water is also thermal with high concentrations of sulphates and iron during the last few years groundwater resources in the heavily populated beer sheva area have become endangered by a continuing process of salinization in the course of the present work it was found that in the study area ground water flows through a multiple aquifer system including the jurassic lower cretaceous kurnub group and the upper cretaceous judea group aquifers because of the absence of impermeable beds at the boundary between the two groups brackish ground water flows from the kurnub group into the overlying judea group aquifer moreover numerous faults discovered in the subsurface facilitate lateral inflow of kurnub ground water into the judea aquifer by interpreting new lithostratigraphic data from the kurnub group and seismic surveys made in the study area it is shown that the kurnub aquifer extends far beyond the hitherto known boundaries and contains an additional estimated volume of 51 10 9 m 3 of paleowater the limiting factors of its exploitability are groundwater depth and salinity the rational exploitation of the kurnub paleowater may prevent salinization of the overlying judea group aquifer

the interaction of two major old water bodies and its implication for the exploitation of groundwater in the multiple aquifer system of the central and northern negev israel abstract in the beer sheva region of the negev desert the only significant fresh groundwater is contained within the judea group carbonate aquifer it is found that this aquifer holds two distinctly different old water bodies one such groundwater body has evolved in equilibrium with the carbonate aquifer rocks after being recharged during the holocene in the hebron mountains north of the study area at present modern recharge as denoted by the tritium and radiocarbon contents is very minor a subtle piston effect generated by contemporary replenishment is discussed in representative hydrographs in beer sheva wells another groundwater body identified in the judea group aquifer derives from the underlying kurnub group aquifer the regional artesian kurnub group aquifer nubian sandstone contains an older and brackish groundwater body which has been recharged in sinai during pleistocene pluvials faulting in the beer sheva region facilitated hydrologic contact between the two aquifers exploitation of the judea group has released confining pressures and resulted in the intrusion of kurnub group water into the overlying judea group carbonate aquifer this process is most significant in those wells drilled close to major faults where salinity increases with pumping the intruding water originating from the kurnub group sandstone aquifer has not yet equilibrated chemically with the carbonate host the low ph and high temperatures that have been encountered indicate continuing and very recent intrusion in the beer sheva area in the absence of direct significant modern recharge as determined from tritium and 14 c values all waters should be considered as paleowaters that are being mined a complete revision of the hydrologic concept by which the multiple aquifer system can be exploited is required to take into account the fact that the fresh judea group groundwater is actually an old holocene water body intruded by brackish and older pleistocene water along fault zones

high and low latitude climate control on the position of the southern peru chile current during the holocene 1 we reconstructed changes of temperature salinity and productivity within the southern peru chile current during the last 8000 years from a high resolution sediment core recovered at 41 s using alkenones isotope ratios of planktic foraminifera biogenic opal and organic carbon paleotemperatures and paleosalinities reached maximum values at 5500 years ago and thereafter declined to modern values whereas paleoproductivity continuously increased throughout the last 8000 years we ascribe these long term holocene trends primarily to latitudinal shifts of the antarctic circumpolar current acc the concurrence with shifts in the position of the southern westerlies points to a common response of atmospheric and oceanographic circulation patterns off southern chile millennial to centennial scale fluctuations of paleotemperatures and paleosalinities on the other hand lag displacements in the position of the southern westerlies but reveal a significant correlation to short term temperature changes in antarctica indicating a high latitude control of the acc at these timescales

thermochronological evidence of a low angle mid crustal detachment plane beneath the central south island new zealand oblique continental convergence and uplift in the southern alps new zealand is largely accommodated by dextral transpression on the alpine fault however towards the south of the orogen the alpine fault becomes increasingly strike slip despite evidence for high exhumation rates in the pacific plate here we present 41 new apatite and zircon fission track ages to investigate the role of the southern alpine fault in pacific plate exhumation since the miocene through development of a new maximum likelihood fission track age calculation method to overcome extremely low 0 1 ppm 238u concentrations in apatites we estimate the width of the fully reset apatite zone ages 5 ma southeast of the southern alpine fault which has been previously overestimated instead this zone is 30 km wide rather than 60 km we combine our exhumation profile with thermo kinematic modelling to impose constraints on fault kinematics and deformation history the surface cooling age pattern can be well reproduced by exhumation along a listric reverse fault which shallows to a low angle 6 10 mid crustal detachment beneath the southern lakes this structure is comparable to the listric central alpine fault geometry previously constrained by thermo kinematics models to the north of our study region we propose this detachment plane is continuous beneath a large region of central south island and may be acting to accommodate underthrusting of australian crust beneath the pacific plate this article is protected by copyright all rights reserved

antarctic timing of surface water changes off chile and patagonian ice sheet response marine sediments from the chilean continental margin are used to infer millennial scale changes in southeast pacific surface ocean water properties and patagonian ice sheet extent since the last glacial period our data show a clear antarctic timing of sea surface temperature changes which appear systematically linked to meridional displacements in sea ice westerly winds and the circumpolar current system proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore but reveal a variable glacier response time of up to 1000 years which may explain some of the current discrepancies among terrestrial records in southern south america

the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel abstract issar a 1981 the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel in w back and r letolle guest editors symposium on geochemistry of groundwater 26th international geological congress j hydrol 54 285ndash 296 a parallel trend has been found to exist between the isosalinity lines and the isopiezo metric lines in the fossil aquifers of the nubian sandstones in southern israel and the central sinai the flow pattern in these aquifers determines the rate of mixing between paleo seawater and paleo meteoric water this flowpattern is determined by the spatial relations between the nubian sandstone outcrops in the central sinai and the major fault lines of the dead sea and suez rift valleys a cumulative chemical composite diagram in which 18o stable isotope data were plotted makes it possible to classify the water and to trace the ratios in the mixture

arid hypogene karst in a multi aquifer system hydrogeology and speleogenesis of ashalim cave negev desert israel

late quaternary vegetational and climatic changes in the pampa grassland of argentina abstract the vegetation and climate of the pampa grassland argentina during the late quaternary are reconstructed from pollen recovered from dated stratigraphic sections from arroyo walls and from archaelogical excavations prior to 10 500 yr b p herbaceous psammophytic steppe existed in the central part of the pampa grassland while xerophytic woodland associated with psammophytic and halophytic steppe occurred in the southwestern part of the pampa these types of vegetation and the continental conditions that prevailed in the area of the present day coast 38 s indicate subhumid dry climate and annual precipitation 100 mm lower than present a subsequent change toward a vegetation characteristic of ponds swamps and foodplains or toward environments with locally more effective moisture occurred ca 10 500 yr b p suggesting annual precipitation close to modern levels or a higher availability of water in the central part of the pampa grassland this type of vegetation existed until 8000 yr b p when it was replaced by grassland communities that lasted until 7000 yr b p in the southwestern part of the pampa grassland this vegetation developed before 7000 yr b p and persisted until ca 5000 yr b p sea level higher than the present ca 6200 yr b p is consistent with sharp modification of the vegetation and development of local halophytic communities dominant at 38 s a return to subhumid dry conditions occurred after 5000 yr b p the late holocene vegetation is characterized by pollen assemblages similar to the psammophytic and halophytic communities of the southern pampa grassland associated with communities with more edaphic conditions at the same time at 38 s a sea level regression is suggested by the dominance of fresh water pollen assemblages and micropaleontological remains the trend toward humid temperate conditions ca 1000 yr b p suggested by vertebrate remains characteristic of temperate and humid conditions as well as a very short but dry episode during the 18th century suggested by the geology are not clearly evidenced in the pollen sequences vegetational and climatic changes are explained by the latitudinal shifts and changes in intensity of the southern atmospheric circulation and changes in sea level

inverse geochemical modeling of groundwater evolution with emphasis on arsenic in the mississippi river valley alluvial aquifer arkansas usa summary inverse geochemical modeling phreeqc was used to identify the evolution of groundwater with emphasis on arsenic as release under reducing conditions in the shallow 25 30 m mississippi river valley alluvial aquifer arkansas usa the modeling was based on flow paths defined by high precision 2 cm water level contour map x ray diffraction xrd scanning electron microscopic sem and chemical analysis of boring sediments for minerals and detailed chemical analysis of groundwater along the flow paths potential phases were constrained using general trends in chemical analyses data of groundwater and sediments and saturation indices data minteqa2 of minerals in groundwater modeling results show that calcite halite fluorite fe oxyhydroxide organic matter h 2 s gas were dissolving with mole transfers of 1 40e 03 2 13e 04 4 15e 06 1 25e 01 3 11 and 9 34 respectively along the dominant flow line along the same flow line fes siderite and vivianite were precipitating with mole transfers of 9 34 3 11 and 2 64e 07 respectively cation exchange reactions of ca 2 4 93e 04 mol for na 2 51e 04 mol on exchange sites occurred along the dominant flow line gypsum dissolution reactions were dominant over calcite dissolution in some of the flow lines due to the common ion effect the concentration of as in groundwater ranged from so 4 2 with co precipitation of as into sulfide is the limiting factor controlling dissolved as in groundwater

a pacific hydrographic section at 88 w water property distribution full depth conductivity temperature depth ctd hydrographic measurements with high horizontal and vertical resolution were made in february april 1993 along a line lying at a nominal longitude of 88 w and extending from southern chile 54 s to guatemala 14 n it crossed five major deep basins southeast pacific chile peru panama and guatemala basins east of the east pacific rise vertical sections of potential temperature salinity potential density oxygen silica phosphate nitrate and nitrite are presented to illustrate the structure of the entire water column some features of interest found in the sections are described and an attempt is made to interpret them in terms of the isopycnal property distributions associated with the large scale ocean circulation these features include various near surface waters observed in the tropical and subtropical regions and the fronts that mark the boundaries of these waters the possible importance of salt fingering to the downward salt transfer from the high salinity subtropical water a shallow thermostad pycnostad developed at 16 18 5 c in the subtropical water low salinity surface water in the subantarctic zone west of southern chile large domains of extremely low oxygen in the subpycnocline layer on both sides of the equator and a secondary nitrite maximum associated with a nitrate minimum in these low oxygen domains high salinity low oxygen high nutrient subpycnocline water that is carried poleward along the eastern boundary by the peru chile undercurrent the subantarctic mode and antarctic intermediate waters middepth isopycnal property extrema observed at the crest of the sala y gomez ridge influences of the north pacific and the north atlantic upon deep waters along the section and the characteristics and sources of the bottom waters in the five deep basins along the section

ice age vegetation and climate of subtropical chile abstract vegetation and climate of subtropical chile over the past 50 000 yr are reconstructed from pollen spores and other microfossils contained in a 10 7 m section of lacustrine deposits of laguna de tagua tagua 34 30 s 71 10 w controlled by 14 radiocarbon age determinations five pollen assemblages covering stratigraphic zones in the section represent plants on the upland and species inhabiting the lake basin surface pollen spectra from 58 stations approximately 30 40 s form an adjunct for interpreting past vegetation and climate from the fossil record temperature semi humid woodland of southern beech nothofagus dombeyi type and podocarp prumnopitys andina was apparently established about laguna de tagua tagua during the pleistocene contrasting existing semi arid broad sclerophyllous vegetation the woodland was extensive about the lake at the time of the last glacial maximum 25 000 14 000 yr b p and earlier 43 000 34 000 yr b p pollen from the families chenopodiaceae and amaranthaceae which characterize intervals of the pleistocene centered around 33 000 and 43 000 yr b p and the holocene suggests intervening episodes of relative aridity lake level fluctuations appear to follow the late quaternary climatic pattern implied by pollen assemblage data water in the lake was relatively high during development of southern beech podocarp woodland whereas during intervals of chenopod amaranth dominance lake levels were comparatively low excess precipitation over evaporation which during the pleistocene favored development of woodland of beech and podocarp is attributed to greater storm frequency conditions were apparently governed by strengthening of atmospheric circulation in the belt of southern westerly winds in the late glacial the temperate and more humid ice age climate with limited seasonality underwent transition to a subtropical semi arid mediterranean type that identifies the postglacial fluctuations in intensity of the southern westerlies marked by latitudinal movement of the polar front can account for past vegetation changes at laguna de tagua tagua

the hydrochemical evolution of brackish groundwater in central and northern sinai egypt and in the western negev israel summary cretaceous trans boundary aquifers in the central and northern parts of sinai egypt and the negev israel are geographically and geologically both contiguous and continuous hydrogeological and hydrochemical studies of these aquifers with disregard to political boundaries are scarce the lower cretaceous kurnub group aquifer in sinai and the negev hosts paleowater mostly replenished during the pleistocene the objectives of this study are to elucidate the relationship between regional structural elements and the salinization of groundwater in the kurnub group in sinai and further downstream in the negev the stable plateaus in southern sinai and the fold structures in the north continuing into the negev are separated by the w e striking minshara ramon shear zone with the exception of higher salinities in the north the chemical composition of kurnub group groundwater north and south of the shear zone is similar similarly groundwater in the overlying upper cretaceous aquifer differs from kurnub groundwater only within and north of the shear zone and is characterized by higher cl concentrations lower mg rca ratios due to high ca in the calcareous aquifer and by a heavier isotopic signature inverse hydrogeochemical modeling using phreeqc indicates that the increase in salinity of kurnub groundwater within the shear zone and in adjacent areas could be due to two different sources first the salinization process could be the result of mixing with sulfate rich brackish groundwater occurring in jurassic formations which are in fault controlled lateral contact with the kurnub group aquifer second the salinity differences could be from unflushed seawater in the subsurface of the northern sinai and western negev i e possible remnants of the post messinian lower pliocene transgression which penetrated into northern sinai the western negev and the coastal plain of israel both through erosional channels which were incised during the neogene and by flooding over outcrops of permeable formations

saline groundwater in israel its bearing on the water crisis in the country abstract one of the major causes for the deterioration of water quality bearing heavily on the water crisis in israel is the ongoing contamination of its water resources by saline water bodies the present paper reviews the geochemical processes forming saline water lists and explains certain chemical and isotopic parameters which enable understanding these processes and describes the saline groundwater bodies and various salinization phenomena occurring in the country s various aquifers deterioration of groundwater in israel is caused by numerous natural processes such as encroachment of sea water migration of connate highly pressurized brines penetrating into fresh groundwater by subsurface dissolution of soluble salts originating in surrounding country rocks and by water rock interaction in addition to sea water two saline water bodies were identified as the main factors causing salinization of fresh groundwater a ca chloride brines encountered in the jordan dead sea rift valley in various parts of the negev and of the coastal plain and b na chloride saline water identified in the subsurface of the negev and in the southern part of the coastal plain intensive exploitation of groundwater in israel has disturbed the natural equilibrium which prevailed between fresh and saline water the newly established groundwater flow regimes have facilitated the migration of saline water bodies their participation in the active hydrological cycle and the progressive contamination of fresh groundwater these processes which were not anticipated by planners and water resources managers emphasize that large scale groundwater exploitation was undertaken without giving sufficient consideration to the occurrence and subsurface migration of saline water and brines

stable isotopes carbon 14 and hydrochemical composition from a basaltic aquifer in sao paulo state brazil the cretaceous serra geral aquifer sga is contained within one of the largest continental flood basalts in the world reaching a thickness up to 1700 m in the center of the parana basin the sga is one of the most important groundwater reservoirs in northeastern sao paulo state brazil responsible for water supply to cities and agriculture in order to evaluate the geochemical and isotopic evolution of sga as well as to determine the mean residence time a groundwater sampling campaign was carried out over the sga in sao paulo state brazil from january to april 2013 two main hydrochemical facies were recognized ca mg hco3 related to water rock interaction reactions in basaltic outcrop such as mineral dissolution due to atmospheric co2 uptake and alkaline na hco3 groundwater evolved from mixing with groundwater from the underlying guarani aquifer system stable isotope 18o and 2h ratios range from 8 87 to 5 32 vsmow and 61 31 to 31 64 vsmow respectively closely following the gmwl spatial and temporal variations in isotope ratios are associated with the south atlantic convergence zone activities and the type of rain responsible for recharge values for 13c vary from 21 53 to 7 11 vpdb while 14c activities vary from 1 2 pcm to more than 100 pcm presenting a trend to enrichment and decrease in 14c activities westward concordant with the regional groundwater flow direction most recent groundwaters have 13c ratio contents mostly consistent with c3 plants

composition and origin of thermal waters in the gulf of suez area egypt abstract thermal waters with discharge temperatures ranging from 32 to 70 c are being discharged along the gulf of suez egypt from springs and shallow artesian wells a comprehensive chemical and isotopic study of these waters supports previous suggestions that the waters are paleometeoric waters from the nubian sandstone aquifer the chemical and isotopic compositions of solutes indicate possible contributions from tertiary sedimentary aquifer rocks and windblown deposits marine aerosols and or evaporite dust in the recharge area there is no chemical or isotopic evidence for mixing with red sea water gas effervescence from the hammam faraoun thermal water contains about 4 ch4 13c 32 6 and 0 03 he having an isotopic ratio consistent with a mixture of crustal and magmatic he 3he 4he 0 26 re geothermometers for the thermal waters indicate maximum equilibration temperatures near 100 c the waters could have been heated by percolation to a depth of several km along the regional geothermal gradient

modern and late quaternary clay mineral distribution in the area of the se mediterranean sea the present day clay mineral distribution in the southeastern levantine sea and its borderlands reveals a complex pattern of different sources and distribution paths smectite dominates the suspended load of the nile river and of rivers in the near east illite sources are dust bearing winds from the sahara and southwestern europe kaolinite is prevalent in rivers of the sinai in egyptian wadis and in saharan dust a high resolution sediment core from the southeastern levantine sea spanning the last 27 ka shows that all these sources contributed during the late quaternary and that the nile river played a very important role in the supply of clay nile influence was reduced during the glacial period but was higher during the african humid period in contrast to the sharp beginning and end of the african humid period recorded in west african records 15 and 5 5 ka our data show a more transitional pattern and slightly lower nile river discharge rates not starting until 4 ka the similarity of the smectite concentrations with fluctuations in sea surface temperatures of the tropical western indian ocean indicates a close relationship between the indian ocean climate system and the discharge of the nile river

evolution of brackish groundater in a typical arid region northern arava rift valley southern israel brackish groundwater in the northern arava valley south of the dead sea is characterized by salinities up to 4000 mg l this groundwater originates from two main aquifers the first is a relatively shallow aquifer composed of clastic and carbonates of the neogene recent hazeva and arava fill formations the second aquifer occurs usually within a depth of 700 1500 m and is composed of lower cretaceous sandstones of the kurnub group no significant differences could be discerned between the concentrations and ionic ratios of these two main groundwater bodies the chemical evolution of the groundwater is the result of two major processes 1 dissolution groundwater flowing through the kurnub group beyond the boundaries of the arava rift valley and through part of the hazeva and arava fill aquifers is characterized by typical ratios na cl 1 and by ca hco3 so4 0 75 the chemical composition of this groundwater indicates a contribution of salts derived from ancient cacl brines such brines are known to have evolved since the neogene in the arava rift valley they are encountered throughout the whole sedimentary succession in the dead sea and northern arava rift valley area intermixing to various degrees with brackish or fresh groundwater the stratigraphic relation between the brackish and saline groundwater bodies is not consistent usually the less concentrated groundwater overlies the more saline there are however cases of transposition possibly indicating the occurrence of unflushed pockets of cacl brines brackish groundwater derived from the two main aquifers is characterized by an excess of mg and so4 such an excess may have evolved from residual salts precipitated as the result of recent or subrecent fractional evaporation of rain and or floodwater under arid conditions water which precipitated crusts of calcite gypsum and halite became enriched in mg and so4 and to a lesser degree in k and na another possible explanation for the excess mg and so4 is the complete evaporation of surface water resulting in the precipitation of kmg sulphates subsequent dissolution by freshflood water would then preferentially dissolve and mobilize these highly soluble minerals