arsenic contamination in groundwater from parts of ambagarh chowki block chhattisgarh india source and release mechanism arsenic contamination in tube well water in ambagarh chowki block central india is restricted to local areas confined within the n s trending dongargarh rift zone affected areas are preferentially located in acid volcanics close to shear zones and also in granites dug wells even in severely contaminated areas generally have as concentration 10 g l but in kaurikasa area several tube wells and dug wells are severely polluted weathered rocks and soils are also enriched in as from severely contaminated areas as preferentially occurs in iron enriched soil and similarly altered biotite chlorite in granite as sorbed in hydrated iron oxide hfo that preferably occurs in acid leachable fraction and possibly as coatings on kaolinite illite and goethite in soil or as coatings and along cleavage traces on weathered biotite and chlorite reductive dissolution of hfo released sorbed as to groundwater and enriched it in fe pyrite in volcanic and shear zone rocks although locally as bearing is a minor source of as in groundwater

continental oceanic crustal transition off southwest africa more than 1 426 mi 2 300 km of 48 trace 12 fold seismic reflection profiles were used to examine the nature of the continent ocean boundary off southwest africa south of the orange river faulted blocks which we interpret as rifted continental crust can be traced seaward to the 3 km isobath the transition to oceanic basement occurs in a zone 19 to 25 mi 30 to 40 km wide beneath the continental rise although structural details are obscured by a thick seaward dipping wedge of pre aii pre late early cretaceous overburden oceanic crust at the presumed contact is not older than magnetic anomaly m9 126 to 121 m y b p north of the orange river a pronounced hinge in continental crust correlates with magnetic anomaly g of rabinowitz 1976 seaward of the hinge a complex fault block terrane is evident oceanic basement can not be traced with any certainty landward of anomaly m4 intracontinental stretching and associated volcanism appear to have been important in the early history of the cape basin rifting and local dike intrusion may explain the presence of some lineated magnetic anomalies previously attributed to sea floor spreading related extrusives form at least part of the pre aii wedge just seaward of the hinge zone our interpretation of the seismic data suggests that the initiation of normal spreading in the cape basin postdates by 4 to 9 m y the valanginian age derived from prevailing plate tectonic reconstructions of the south atlantic

mineralogy and geochemistry of the clay fraction of sediments from the namibian continental margin and the adjacent hinterland the continental shelf off namibia can be divided into two sectors at latitude 18 40 s based on the distinctive morphologies of the two regions and on differences in composition of their surficial sediments the kunene shelf is narrow shallow and covered mainly by terrigenous sediment whereas the walvis shelf is wide deep and supports predominantly biogenic sediment the walvis shelf also possesses a number of distinguishing features its outer region has a concave profile which is attributed to upbuilding of the inner shelf during periods of lowered sea level its inner region is covered by an extensive belt of diatomaceous mud parallel to the coast the seaward and landward flanks of this deposit differ in lithology due mainly to the advanced state of dissolution of opal in deep water and to the influx of aeolian terrigenous detritus especially illite close to shore long belts of terrigenous mud extend southwards from both the kunene and orange rivers the currents responsible for transporting this sediment are poleward directed tongues of the angola benguela front in the north and mixed poleward moving south atlantic central water in the south the kunene river carries more smectite to the sea than the much larger orange the distribution of clay minerals on the continental shelf follows that of the adjacent hinterland with smectite and to a lesser extent kaolinite being significant in the north and illite predominating in the south along the upper slope the concentrations of smectite and kaolinite increase due to their importation from the kunene river by poleward directed antarctic intermediate water the geochemical character of riverine clays reflects the rock types exposed in each of the drainage basins compared with marine sediments these clays are enriched in eight of the fourteen elements investigated namely al fe mg co mn pb rb and zn in contrast the offshore element distribution patterns show little resemblance to the patterns of individual drainage basins clays in the marine sediments are enriched relative to the river sediments in ca k cd ni and sr five lithofacies recognized in the unconsolidated marine sediments are based on the relative proportions of opal calcium carbonate phosphorite glauconite and terrigenous components average element concentrations of individual lithofacies are enriched relative to the river clays in cd diatomaceous facies ca cd ni and sr calcareous and facies k and ni slightly glauconitic facies cd and sr terrigenous facies regionally the clay fractions of unconsolidated marine sediments contain high concentrations of al fe mg k mn and rb on the kunene margin due to aluminosilicates being imported by the kunene river ca and sr reach high values on the walvis outer margin in response to upwelling along the coast maximum concentrations of cd are associated with diatomaceous mud on the walvis inner shelf cu ni and zn reach high levels at a few spot locations where organic matter morg has suffered little dilution from other components especially opal and pb is concentrated with glauconitic sediment on the kunene shelf semi consolidated sediments are exposed intermittently on the outer margin they provide evidence that the palaeoclimate became much drier in post miocene times but in the north this picture is complicated by the introduction of sediment from the kunene river during the late tertiary palaeo oceanographic evidence suggests that the northern part of the study area experienced a concomitant decrease in productivity while in the southern part productivity increased

holocene geochronology of a continentalshelf mudbelt off southwestern africa the holocene lithostratigraphy and geochronology of sediments on an inner continental shelf mud belt off the west coast of southern africa is presented based on a study of seven large gravity cores numerous grab samples and two vibracores two distinctive sections of the mudbelt have been identie ed the northern section is associated with the orange river prodelta and is dominated by laminated clay rich sediments while the southern section off namaqualand is associated with more homogeneous muds ams radiocarbon ages of 31 samples from these cores are problematic due to the absence of expected modern material at the sediment ocean interface and numerous age reversals and inconsistencies in some of the cores possible mechanisms to explain the apparently anomalously old surface and near surface samples are suggested most likely expla nations appear to lie in a combination of sediment retrieval problems the periodic loss of e ne particulate organic carbon from within the water column the sampling of possible relic sediments and most likely of all the incorporation into the sediments of 14 c depleted terrigenous organic matter the age reversals are especially evident in the laminated sediments and the entrainment of old carbon from the terrestrial source of these sediments is offered as the most parsimonious explanation stable carbon isotope analyses and a single lumi nescence age support the contention that radiocarbon date inconsistencies are a consequence of terrestrial inputs of carbon which is non contemporaneous with the actual time of sedimentation in studies of offshore accumulations of terrigenous material the marine derived organic fraction may therefore prove a more reliable measure of radiocarbon chronology

distinguishing potential sources of arsenic released to groundwater around a fault zone containing a mine site arsenic as contamination in groundwater in mineralized areas typically results from the oxidation of as rich sulfide minerals in aquifers from hydrothermal alteration of geothermal systems or as a result of anthropogenic influences such as mining activity the primary goal of this study was to determine the spatial and temporal variance in as concentrations in shallow groundwater in a mineralized area and to identify the main as source controlling the concentration patterns to this end a combination of a geostatistical technique for space time modeling of as concentrations and a numerical simulation which models the transport of as in groundwater is implemented a study site in north sulawesi sulawesi island indonesia was selected as it was suitable for investigating the importance of fault lines and metal mining on as contamination initially stable isotope analysis was used to ascertain the groundwater source and the mixing mechanism of the shallow and deep groundwater geostatistical modeling revealed consistent general patterns of as concentrations during the past 10 years with high concentrations found along a nw se axis by matching the geostatistical results with the distributions of as concentrations obtained through transport modeling the deep seated hydrothermal system along the fault zone was found to be the major as source wastewater from the mine was also observed to be a local as source another important influence on the as concentration pattern was a river which acted as a boundary to separate the groundwater systems into two regions

late quaternary sedimentary environments and landforms in the ganges delta abstract late quaternary sediments deposited since the lowest stand of sea level during the last glacial maximum in the ganges delta and its surrounding region were classified into five units according to their sedimentary facies these are the lowest unit of sandy gravels the lower unit of sand with a few gravels and the middle upper and uppermost units consisting mainly of sand and silt with occasional peat layers the contact between the lower and middle units is fairly sharp and the upper part of the lower unit is oxidized in some places this suggests a period of subaerial exposure after the deposition of the lower unit during the low stand of sea level about the time of the last glacial maximum rivers in the ganges delta and its surrounding region dissected the surfaces of the region and deposited the lowest unit on the valley floors the lower unit was deposited over the lowest unit during an early stage of the post glacial transgression between ca 12 000 yr bp and 10 000 yr bp the surface of the delta was slightly dissected and the top of the lower unit was weathered and oxidized following this period the middle and upper units of alluvial or deltaic sand and silt with occasional peat were deposited the coastline in the early holocene retreated towards the central part of the present ganges delta in the middle and late holocene the silt and clay with occasional peat layers of the uppermost unit indicate that the lowland gradually became marshy and poorly drained as the rate of transgression became slower

palaeoenvironmental and diagenetic control of the mineralogy of upper cretaceous lower tertiary deposits of the central palaeo andean basin of bolivia potosi area abstract a study involving mainly x ray diffraction of the mineralogy of upper cretaceous and lower tertiary deposits aroifilla chaunaca el molino santa lucia and cayara formations of the andean basin in the bolivian eastern cordillera is presented this work refines environmental reconstructions based on previous sedimentological studies in the potosi basin the results including the clay mineralogy show that the sediments were deposited in a lacustrine system which suffered large variations of water level and groundwater influence the siliciclastic sediments are characterized either by abundant feldspars or analcime suggesting a perennial volcanoclastic influence tuff layers in the santa lucia formation support this interpretation the great diversity of clay minerals identified reflects both detrital influences and diagenetic overprinting although diagenetic changes are common in this sedimentary series it is still possible to identify the nature of detrital supply illite and illite smectite mixed layer clays constitute the background clay sedimentation and reflect predominantly arid climate this had already been deduced from sedimentogical and geochemical investigations however detrital kaolinite occurs in a 40 m thick interval of the el molino formation which probably embraces the k t boundary and reflects more humid conditions further work is necessary to locate more precisely this boundary in the absence of accurate biostratigraphical markers authigenic clays are also recognized in the sandstones in the basal part of the cayara formation kaolinite developed authigenically in the tuff layers of the santa lucia formation well crystallized authigenic smectite characterizes the clay fraction in addition chlorite replaces smectite in limestones beds of the el molino formation which were deposited in evaporitic environments the clay assemblages including illite and chlorite at base of the stratigraphic column aroifilla and chaunaca formations probably results from the replacement of smectitic minerals either by chlorite or illite where depth of burial reached more than 2000 m

preliminary trace element analysis of arsenic in nepalese groundwater may pinpoint its origin arsenic contamination of groundwater used as drinking water in south asia poses a serious health threat to the inhabitants living on alluvial plains of the himalayan foreland of countries like bangladesh india nepal and myanmar although the geological and geochemical conditions favoring the release of the highly poisonous contaminant from the sediments hosting the groundwater are meanwhile quite well understood there is still a significant debate about the origin of arsenic the sediments forming a huge proportion of the terai lowlands of nepal aquifers are derived from two main sources i sediments deposited by large rivers that erode the upper himalayan crystalline rocks and ii weathered meta sediments carried by smaller rivers originating in the siwalik foothills adjacent to the terai in this article a so far underestimated source of as is discussed the peraluminous leucogranites found ubiquitously in the nepal himalaya the relationship between the trace elements analyzed in the groundwater in the terai and trace elements found in such felsic rocks reflect the origin of the arsenic in the high himalayas of nepal in addition to the high concentration of as a striking feature is the presence of the lithophile trace elements like li b p mn br sr and u in the groundwater the mentioned elements point to a felsic initial source like metapelites or leucogranites all rocks showing a high abundance of especially b p and as as well as cd and pb

geochemistry and mineralogy of surface pyritic tailings impoundments at two mining sites of the iberian pyrite belt sw spain two pyritic tailings impoundments located in two mining areas of the iberian pyrite belt cueva de la mora and minas de riotinto zarandas were selected to asses their potential environmental impact mineralogical xrd diffraction study physico chemical characterization colour particle size ph acid base account total fe as cu pb and zn as well as a speciation study by means of a seven step sequential extraction procedure were performed in superficial 0 20 cm tailings samples arsenic and metal contents in soils around the tailings impoundments were also studied zarandas dam a reclaimed impoundment which has been limed partially topsoiled and planted has supported and allowed the growth of pine trees and other plants for many years the surface of this impoundment can be considered very acid but nonacid forming although total as and metal concentrations were relatively high it is not possible to conclude that the zarandas tailings have polluted the surrounding soils tailings in cueva de la mora showed high total and easily mobilizable concentration of toxic elements the net neutralization potential was strongly negative as a consequence of the acid generation caused by the sulphide oxidation the presence of secondary acid generating minerals and the absence of neutralizing materials coquimbite and rhomboclase efflorescences formed during the mediterranean dry summers on the surface of this impoundment contained very high levels of soluble as cu and zn that were easily dissolved and released to the running water in the first rains of autumn

acid mine drainage at cerro rico de potosi i unabated high strength discharges reflect a five century legacy of mining intensive mining and processing of ag sn pb and zn ores have occurred in various locations within and around the city of potosi bolivia since 1545 surface and subsurface waters stream sediments and soils are contaminated with various ecotoxic metals in the headwaters of the economically vital yet highly impacted upper rio pilcomayo watershed previous studies have documented downstream trace metal contamination however not addressed specific sources the amd discharges identified in this study help link downstream pollution to primary origins the majority of amd would be considered high strength due to metal concentrations and acidity orders of magnitude greater than typical amd discharges from both operating and abandoned portals as well as tailings related deposits displayed a high degree of heterogeneity with total metal concentrations ranging from 0 11 to 7480 0 022 to 889 0 0006 to 65 3 0 001 to 310 0 12 to 72 100 0 3 to 402 0 012 to 34 8 and 0 24 to 19 600 mg l of al as cd cu fe mn pb and zn respectively net acidity and ph ranged from 10 to 246 000 mg l as caco3 equivalent and 0 90 6 94 standard units respectively data were gathered during two sampling events centered around the most extreme periods of the dry and wet seasons of one water year loadings to local streams were marginally greater for most metals in the wet season if observed loadings are historically representative cerro rico amd has contributed thousands of tonnes of ecotoxic metals to the upper rio pilcomayo over the last five centuries metal and hydrogen ion concentrations in the majority of amd sampled were several orders of magnitude above discharge limits set by the bolivian government yet no action has historically or contemporarily been taken

slumps canyons and related features on the continental margin off east london se africa sw indian ocean abstract bathymetric and seismic reflection surveys in the natal valley east of east london show that the most important factors in the neogene development of the outer continental margin have been large scale slumping and penecontemporaneous canyon formation slope wasting and allochthonous mass movements have shifted the foot of the continental slope up to 25 km basinward and have constructed extensive continental rise lobes shelf break breaching by canyon heads is considered an important factor in transferring sediment entrained in the agulhas current from the continental shelf to the deep ocean basin a preliminary sediment budget suggests that the continental rise lobes could have been constructed during the last 2 69 m y following an episode of massive slumping

fluvial landsculpting and the fractal dimension of topography abstract quantitative models of landform development can help us to understand the evolution of mountains and regional topography and the effects of tectonic motions and climate on landscape including its fractal geometry this paper presents a general and powerful three dimensional model of fluvial erosion and deposition at hill to mountain range scale the model works by accumulating the effects of randomly seeded storms or floods precipitons that cause diffusional smoothing then move downslope on digital topography grids that erode portions of elevation differences that transport a slope limited amount of eroded material and that deposit alluvium when their sediment carrying capacity is exceeded the iteration of these simple and almost linear rules produce very complicated simulated landscapes demonstrating that complex landscapes do not require complex laws each process implemented in the model is affected differently by changes in horizontal scale erosion a scale free process roughens topography at all wavelengths this roughening is balanced by diffusive processes scaling as 1 l 2 at short wavelengths and deposition scaling scaling as 1 l 2 at long wavelenghts such a mixture of scale free and scale dependent processes can produce multifractal behavior in the models the fractal dimension of the model topography is much more sensitive to climatic variables than to tectonic uplift landscape evolution may be fractal but it does not seem to be chaotic analysis of topography of areas in southern arizona using variograms shows approximately fractal behavior with mean fractal dimension around 2 2 2 3 departures from an exact fractal relatioship imply that the topography is in detail multifractal the fractal dimension at short wavelengths is less than that at long wavelengths this variation could either be caused by the relative strengths of diffusive and erosional processes shaping the topography or a result of changes in climatic or tectonic conditions still preserved in the landscape

delineation of arsenic contaminated zones in bengal delta india a geographic information system and fractal approach groundwater extracted from shallow aquifers in the bengal delta is contaminated with arsenic the fluviodeltaic process that creates aquifers ironically extends its role to also contaminating them with arsenic the arsenic distribution maps show a spatial association of arsenic contaminated wells with palaeo cut off abandoned channels weight on evidences analysis indicates that the zones of contamination occur around palaeo channels within a corridor of 500 700 m that contains most of the contaminated wells these corridors are interpreted to be the zone of channel shifting contaminated wells represent point fractal geometry that can be separated into isolated points and clusters clusters occur within the zone of channel shifting as obtained by weight on evidences analysis isolated points occur within floodplain or back swamp areas clusters and isolated point fractals are interpreted to reflect the process of arsenic release into groundwater the migration of biomass within the permeable sandy domain of channel deposits is proposed to be the predominant process in generating clusters the isolated points represent restricted biomass spreading in less permeable clay silt dominated floodplains

acid mine drainage at cerro rico de potosi ii severe degradation of the upper rio pilcomayo watershed ag pb sn and zn ores have been intensively mined and processed at cerro rico de potosi bolivia since 1545 acid mine drainage amd and mineral processing plant effluent are prime sources of water contamination in the headwaters of the upper rio pilcomayo watershed streams receiving amd drainage from the slopes of cerro rico and surrounding landscapes were sampled during the dry july august 2006 and wet march 2007 seasons of one water year in stream waters contained total metal concentrations of up to 16 mg l as 4 9 mg l cd 0 97 mg l co 1 100 mg l fe 110 mg l mn 4 1 mg l pb and 1 500 mg l zn with ph ranging from 2 8 to 9 5 amd impacted streams contained elevated concentrations of the same major ecotoxic constituents present in amd discharges at concentrations orders of magnitude greater than in those streams unimpacted by amd many of the amd impacted water bodies are more degraded than class d of the bolivian receiving water body criteria rendering them unfit for domestic or agricultural use natural attenuation is insufficient to render waters safe for use however some of these waters are currently being utilized for irrigation and livestock watering the data indicate that historic and current mining activities have transformed these key natural resources into potential human and environmental health hazards

arsenic toxicity of groundwater in parts of the bengal basin in india and bangladesh the role of quaternary stratigraphy and holocene sea level fluctuation arsenic toxicity in groundwater in the ganges delta and some low lying areas in the bengal basin is confined to middle holocene sediments dissected terraces and highlands of pleistocene and early holocene deposits are free of such problems arsenic rich pyrite or other arsenic minerals are rare or absent in the affected sediments arsenic appears to occur adsorbed on iron hydroxide coated sand grains and clay minerals and is transported in soluble form and co precipitated with or is scavenged by fe iii and mn iv in the sediments it became preferentially entrapped in fine grained and organic rich sediments during mid holocene sea level rises in deltaic and some low lying areas of the bengal basin it was liberated subsequently under reducing conditions and mediated further by microbial action intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater this practice has induced groundwater flow mobilizing phosphate derived from fertilizer as well as from decayed organic matter which has promoted the growth of sediment biota and aided the further release of arsenic however the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the ganges floodplains upstream of rajmahal thus arsenic toxicity in the groundwater of the bengal basin is caused by its natural setting but also appears to be triggered by recent anthropogenic activities

arsenic and other drinking water quality issues muzaffargarh district pakistan abstract in 49 samples of groundwater sampled in muzaffargarh district of south western punjab central pakistan concentrations of as exceeded the world health organisation provisional guideline value and united states environmental protection agency usepa maximum contaminant level mcl of 10 g l 1 in 58 of samples and reached up to 906 g l 1 in this semi arid region canal irrigation has lead to widespread water logging and evaporative concentration of salts has the potential to raise as concentrations in shallow groundwater well above 10 g l 1 in fact in rural areas concentrations stay below 25 g l 1 because as in the oxic shallow groundwater and in recharging water is sorbed to aquifer sediments in some urban areas however shallow groundwater is found to contain elevated levels of as the spatial distribution of as rich shallow groundwater indicates either direct contamination with industrial or agricultural chemicals or some other anthropogenic influence geochemical evidence suggests that pollutant organics from unconfined sewage and other sources drives reduction of hydrous ferric oxide hfo releasing sorbed as to shallow groundwater the situation is slightly less clear for seven wells sampled which tap deeper groundwater all of which were found with 50 g l 1 as here as concentrations seem to increase with depth and differing geochemical signatures are seen suggesting that as concentrations in older groundwater may be governed by different processes other data on parameters of potential concern in drinking water are discussed briefly at the end of the paper

hypsometry of divergent and translational continental margins of southern africa abstract flattenings that may be shelves formed by marine erosion deposition or by slump masses are present on continental margins of southern africa that border both the atlantic and indian oceans breaks in slope indicated along sounding lines suggest that a shallow terrace of the atlantic margin has been warped downward from depths of about 130 m southward to about 200 m and a deeper terrace lies between depths of about 150 m to about 440 m examination of contours and hypsometry areas measured between depth contours show widespread flattenings at about 65 and 95 m on the indian ocean margin and 125 155 and 190 m along the atlantic margin seismic profiles indicate that some of these and other more local flattenings are on slump blocks and thus are not correlatable for long distances an additional complication is that sediment introduced by rivers is transported alongshore by wave induced and oceanic bottom currents and that their deltas are ephemeral

nonequilibrium geomorphic processes and deterministic chaos abstract disequilibrium is a common if not dominant condition in geomorphology and other environmental sciences because disequilibrium in a system implies a time lag time steps and time delays in simple deterministic equations may reflect process and such equations have been shown to result in chaos after examining some models of hillslope and catchment development we present an oversimplified model of a hillslope in which we calculate the elevation of a point at time t 1 as a function we consider both linear and nonlinear terms of the difference in elevation between it and the next uphill and downhill points at time t we show how this simple hillslope model will not produce chaos under one set of limiting conditions that do not include nonlinearity but without proof we note that in most conditions the hillslope mode is so similar to other models in which chaos arises because of disequilibrium that chaotic behavior is a likely possibility a formulation wherein the time step is in a weathering and or erosion coefficient rather than the elevation is also proposed

unabated acid mine drainage from cerro rico de potosi bolivia uncommon constituents of concern impact the rio pilcomayo headwaters intensive mining and processing of the polymetallic sulfide ore body of cerro rico de potosi bolivia has occurred since 1545 leading to severe degradation of surface and subsurface waters stream sediments and soils at the headwaters of the economically vital yet highly impacted rio pilcomayo previous studies have documented extremely elevated concentrations of a limited suite of metals in local waterways from acid mine drainage amd terrestrial and in stream tailings and ore processing plant discharges however contamination from a wider variety of ecotoxic metals metalloids was considered likely due to the highly mineralized polymetallic nature of the ore body to screen for this broader range of ecotoxic elements in amd and receiving streams data were gathered during two sampling events timed for the most extreme periods of the dry and wet seasons of one water year concentrations of ag b ba mo sb se sn and v in amd and receiving streams were greater than bolivian discharge limits and receiving water body guidelines as well as international agricultural use standards locally results indicate that contamination from mining cerro rico has a larger scope than previously thought and underscore the importance of remediation globally the results raise the possibility that other mining regions could have unquantified hazards from overlooked ecotoxic elements and that screening for a broader range of contaminants may be warranted

geo genic arsenic contamination in the kerman cenozoic magmatic arc kerman iran implications for the source identification and regional analysis kerman cenozoic magmatic arc kcma is located in the southeastern part of the central iranian volcano plutonic copper belt arsenic contamination from geo genic source is one of the most important environmental concerns in this area the main objective of this study was to determine the role of geothermal related activities in the arsenic contamination for this purpose the old and active geological indicators of the geothermal activities were investigated through the quaternary travertine deposits and the present hydrothermal warm springs respectively results showed that arsenic is highly concentrated ranged mainly from 12 400 to 90 500 mg kg in the reddish brown deposits of the travertine rocks arsenic showed geochemical association with co cu mo sb tl se fe and mn in these samples yukonite ca7fe3 12 aso4 10 oh 2015h2o a rare ca ferric arsenate hydrous mineral was the only as bearing mineral identified in the reddish brown deposits of the travertine rocks arsenic concentration in the hydrothermal warm springs 38 c ranged from 15 900 to 30 500 g l the dominant form was as h3aso30 hydrothermal contaminated waters also were characterized by na cl type and high values of ec 11 400 s cm tds 8300 mg l b 42 700 g l li 3000 g l fe 900 g l sb 82 8 g l and si 47 000 g l and natural anomalies of cs mn mo rb se and tl the obtained hydro geochemical results are similar to those reported in the literature for worldwide hydrothermal waters although natural attenuation processes such as adsorption co precipitation or mixing dilution reduce most of the arsenic contamination from hydrothermal source but some urban and rural communities are still depending on the arsenic contaminated waters with arsenic concentrations higher than recommended values for drinking or irrigation a subject that increases the risk of arsenic related diseases in some areas of the kerman province

the supply and accumulation of silica in the marine environment rivers and submarine hydrothermal emanations supply 6 1 1014g sio2 yr to the marine environment approximately two thirds of the silica supplied to the marine environment can be accounted for in continental margin and deep sea deposits siliceous deep sea sediments located beneath the antarctic polar front convergence account for over a fourth 1 6 1014g sio2 yr of the silica supplied to the oceans deep sea sediment accumulation rates beneath the polar front are highest in the south atlantic with values as large as 53cm kyr during the last 18 000 yr siliceous sediments in the bering sea sea of okhotsk and subarctic north pacific accumulate 0 6 1014g sio2 yr or 10 of the dissolved silica input to the oceans the accumulation of biogenic silica in estuarine deposits removes a maximum of 0 8 1014g sio2 yr although estuarine silica versus salinity plots indicate extensive removal of riverine silica from surface waters the removal rates must be considered as maximum values because of dissolution of siliceous material in estuarine sediments and bottom waters siliceous sediments from continental margin upwelling areas e g gulf of california walvis bay or peru chile coast have the highest biogenic silica accumulation rates in the marine environment 69 g sio2 cm2 kyr despite the rapid accumulation of biogenic silica upwelling areas account for less than 5 of the silica supplied to the marine environment because they are confined laterally to such small areas

effect of acid mine drainage on a karst basin a case study on the high as coal mining area in guizhou province china acid mine drainage amd is a common pollution in mining areas due to the oxidation of pyrite and associated sulfide minerals at mines tailings and mine dumps elevated metals fe mn al and metalloids as hg in amd would deteriorate the local aquatic environment and influence the water supply a carbonate basin with deposits of high arsenic coal in xingren county southwestern china was chosen to study the behavior of as and other chemical constituents along a river receiving amd heavy metals fe mn and major ions such as ca2 mg2 cl so42 in surface water and as in sediment and surface water were analyzed it was found that high concentrations of so42 1 324 7 560 mg l and fe 369 1 472 mg l in surface water were mainly controlled by the interactions between water and rocks such as the oxidation of pyrite in the local coal seams precipitation and adsorption of iron minerals although ubiquitous carbonate minerals in the bedrock and the riverbeds low ph 3 water was maintained until 2 km downstream from the amd source due to the fe hydro oxide minerals coating on the surface of carbonate minerals to restrain the neutralization of acidic water moreover the formation of fe hydro oxide precipitations absorbed as was dominated the attenuation of as from water to sediment whereas the dilution also played an important role in decrease of as in river water

the pallacos of cerro rico de potosi bolivia a new deposit type pallacos are a new kind of ore deposit and are described here in detail for the first time they are found on the flanks of the cerro rico de potosi bolivia the world s largest silver deposit fundamentally pallacos are gravels whose clasts contain sufficient disseminated silver so as to be bulk minable the silver bearing clasts originated from the summit of cerro rico and are composed of dacite porphyry or air fall tuffs or arkosic sands of the caracoles formation that have been altered to vuggy silica or jasperoid analysis of facies bedforms depositional textures and clast sizes and percentages suggests that there are two types of pallacos each with a different depositional mechanism one kind the huacajchi type formed from multiple water transported debris flows the other kind the potosina type is interpreted as catastrophic landslides metal zoning clast alteration style and silver grade vary between the two pallaco types

a review of the source behaviour and distribution of arsenic in natural waters the range of as concentrations found in natural waters is large ranging from less than 0 5 g l 1 to more than 5000 g l 1 typical concentrations in freshwater are less than 10 g l 1 and frequently less than 1 g l 1 rarely much higher concentrations are found particularly in groundwater in such areas more than 10 of wells may be affected defined as those exceeding 50 g l 1 and in the worst cases this figure may exceed 90 well known high as groundwater areas have been found in argentina chile mexico china and hungary and more recently in west bengal india bangladesh and vietnam the scale of the problem in terms of population exposed to high as concentrations is greatest in the bengal basin with more than 40 million people drinking water containing excessive as these large scale natural as groundwater problem areas tend to be found in two types of environment firstly inland or closed basins in arid or semi arid areas and secondly strongly reducing aquifers often derived from alluvium both environments tend to contain geologically young sediments and to be in flat low lying areas where groundwater flow is sluggish historically these are poorly flushed aquifers and any as released from the sediments following burial has been able to accumulate in the groundwater arsenic rich groundwaters are also found in geothermal areas and on a more localised scale in areas of mining activity and where oxidation of sulphide minerals has occurred the as content of the aquifer materials in major problem aquifers does not appear to be exceptionally high being normally in the range 1 20 mg kg 1 there appear to be two distinct triggers that can lead to the release of as on a large scale the first is the development of high ph 8 5 conditions in semi arid or arid environments usually as a result of the combined effects of mineral weathering and high evaporation rates this ph change leads either to the desorption of adsorbed as especially as v species and a range of other anion forming elements v b f mo se and u from mineral oxides especially fe oxides or it prevents them from being adsorbed the second trigger is the development of strongly reducing conditions at near neutral ph values leading to the desorption of as from mineral oxides and to the reductive dissolution of fe and mn oxides also leading to as release iron ii and as iii are relatively abundant in these groundwaters and so4 concentrations are small typically 1 mg l 1 or less large concentrations of phosphate bicarbonate silicate and possibly organic matter can enhance the desorption of as because of competition for adsorption sites a characteristic feature of high groundwater as areas is the large degree of spatial variability in as concentrations in the groundwaters this means that it may be difficult or impossible to predict reliably the likely concentration of as in a particular well from the results of neighbouring wells and means that there is little alternative but to analyse each well arsenic affected aquifers are restricted to certain environments and appear to be the exception rather than the rule in most aquifers the majority of wells are likely to be unaffected even when for example they contain high concentrations of dissolved fe

geothermal spring causes arsenic contamination in river waters of the southern tibetan plateau china large numbers of as enriched geothermal springs are distributed at the southern tibetan plateau and their influence on river water is still not clear lhasa river and its tributary duilong qu located at downstream of the largest geothermal spring of the tibetan plateau were selected for sampling during monsoon and non monsoon seasons dissolved trace elements b cr ni cu zn as cs ba and u were measured in river water samples by icp ms the results show that due to contribution of geothermal spring as levels of duilong qu 205 6 g l and lhasa river 12 7 g l were higher during non monsoon season than that of who guideline for drinking water 10 g l accordingly as level of river water was lower during the monsoon season than that of the non monsoon season due mainly to dilution process therefore although tibetan rivers are generally considered as free of contamination geothermal springs cause as contamination of river water at some local regions and may harm the local residents further research is needed in other parts of the plateau to determine whether as level of groundwater of the related region is high

hydrogeochemical characteristics of streams with and without acid mine drainage impacts a paired catchment study in karst geology sw china summary a paired catchment study was used to assess hydrochemical characteristics of streams in amd acid mine drainage impacted and non amd impacted catchments in a karstic region sw china the catchments shared similar geology slope aspect area and climate but different land use since one encompassed mining activities as a result hydrogeochemical characteristics of the amd impacted water were dominantly controlled by oxidation of pyrite while that of non amd impacted were influenced by water rock reactions it is also coincident with the source of 34 s so4 in both waters upstream unit ion fluxes of the amd impacted catchment for ca mg h fe and so 4 were 17 g m 2 yr 2 g m 2 yr 0 0002 g m 2 yr 17 g m 2 yr and 136 g m 2 yr respectively while unit ion fluxes of the non amd impacted catchment were much lower than that of the amd impacted catchment along the flow fluxes of h ca mg fe and so 4 decreased in the amd impacted water but increased in the non amd impacted water the observation was coincident with variations of ion concentrations in both waters along the flow supported by phreeqc modeling of minerals such as goethite jarosite ss melanterite scorodite calcite and dolomite it suggests that the transport of constituents of interest except for ca and mg is dramatically different in these catchments results provide important information on karst system response to amd together with the baseline data to understand the degree and type of impairment

evaluation of arsenic sorption and mobility in stream sediment and hot spring deposit in three drainages of the tibetan plateau abstract enrichment of arsenic as in sediment 12 227 mg kg in the upstream tributaries of the indus and brahmaputra rivers originating from the tibetan plateau where hot springs were abundant has been found sandy sediment samples from the nu salween river lantsang mekong river and jinsha yangtze river also originating from the tibetan plateau were collected in july 2012 and were found to contain 6 8 mg kg to 30 5 mg kg as average17 3 6 5 mg kg n 12 deposits collected within 1 m of two hot springs in changdu tibet displayed significantly higher as levels 263 7 mg kg in ld 2 with 65 quartz and 101 8 mg kg in nud 1 with 82 calcite to evaluate the valence states of as and also the phases responsible for sorption x ray absorption spectroscopy xas was employed to analyze the two hot spring deposits and three river sediment samples coarse sand nud 6 as 14 6 mg kg fine sand nud 4 as 17 8 mg kg and silty sand ld 1 as 30 5 mg kg the x ray absorption near edge spectrum xanes data indicate that 70 of as from 3 samples in the nu salween river drainage nud 1 nud 4 and nud 6 is as v or arsenate with the rest being as 0 or as fe sulfides the proportion of as v is 90 for 2 samples in the lantsang mekong river drainage ld 1 and ld 2 linear combination fit of the iron extended x ray fine structure spectrum exafs show that 3 samples from the nu salween river contain 20 ferrihydrite and 10 goethite without any hematite being detected but 2 samples from the lantsang mekong river contain

role of quaternary stratigraphy on arsenic contaminated groundwater from parts of middle ganga plain up bihar india late quaternary stratigraphy and sedimentation in the middle ganga plain mgp uttar pradesh bihar have influenced groundwater arsenic contamination arsenic contaminated aquifers are pervasive within narrow entrenched channels and flood plains t0 surface of fine grained grey to black coloured argillaceous organic rich holocene sediments newer alluvium contaminated aquifers are often located close to distribution of abandoned or existing channels and swamps the pleistocene older alluvium upland terraces t2 surface made up of oxidized yellowish brown sediments with calcareous and ferruginous concretions and the aquifers within it are free of arsenic contamination mgp sediments are mainly derived from the himalaya with minor inputs from the peninsular india the potential source of arsenic in mgp is mainly from the himalaya the contaminated aquifers in the terai belt of nepal are closely comparable in nature and age to those of the mgp arsenic was transported from disseminated sources as adsorbed on dispersed phases of hydrated iron oxidea and later on released to groundwater mainly by reductive dissolution of hydrated iron oxide and corresponding oxidation of organic matter in aquifer strong reducing nature of groundwater is indicated by high concentration of dissolved iron 11 06 mg l even within the arsenic affected areas dugwells are found to be arsenic safe due to oxyginated nature

late mesozoic and tertiary sediment supply to the eastern cape basin se atlantic and palaeo drainage systems in southwestern africa isopach asymmetry and sediment component changes in dsdp cores from the se atlantic orange basin support the hypothesis of major drainage system changes in sw africa during late cretaceous cenozoic time this involved alternations in the use of the 28 s modern orange river and 31 s modern olifants river exit points across the western escarpment by rivers carrying run off from the upper orange vaal catchment areas as well as radical re organizations of internal drainage geometry it is postulated that during late cretaceous times the 28 s exit was used with the middle orange river following a course in the interior well to the south up to 150 km of its modern channel sediment discharge rates from this river were relatively high at least 10 106 m3 yr 1 and resulted in rapid advancement of the continental margin sediment prism west of the mouth by large scale slumping the palaeogene orange vaal river exit was via the 31 s escarpment crossing and during the later part of this period the cape canyon was cut across the continental shelf and slope a significant reduction in sediment discharge to 2 0 106 m3 yr 1 suggests that the lower tertiary climate for sw africa was drier than that of late cretaceous times however aridity did not commence until late miocene times when the orange vaal discharge had switched back to the 28 s exit modern sediment discharge rates 6 5 106 m3 yr 1 are relatively high and reflect soil erosion caused by agricultural activity the two major alterations in exit point of the orange vaal late cretaceous early tertiary and late oligocene early miocene are related to periods of low sea level which promoted river capture adjacent to the western escarpment an additional factor in the first course change may have been the disruption of the middle orange channel by late cretaceous igneous intrusions less important internal reorganizations of the drainage system are postulated in late miocene pleistocene times economic implications for offshore diamond distribution are briefly mentioned

geochemical study of arsenic and other trace elements in groundwater and sediments of the old brahmaputra river plain bangladesh the geochemical study of groundwaters and core sediments from the old brahmaputra plain of bangladesh was conducted to investigate the distribution of arsenic and related trace elements groundwaters from tube wells are characterized by ph of 6 4 7 4 dissolved oxygen do of 0 8 1 8 mg l ca contents of 5 50 mg l and fe contents of 0 2 12 9 mg l arsenic concentrations ranged from 8 to 251 g l with an average value of 63 g l a strong positive correlation exists between as and fe r2 0 802 p 0 001 concentrations in groundwater the stratigraphic sequences in the cores consist of yellowish silty clays at top passing downward into grayish to yellowish clays and sands the uppermost 3 m and lower parts from 13 to 31 m of the core sediments are oxidized average oxidation reduction potential orp 170 and 220 mv respectively and the orp values gradually become negative from 3 to 13 m depths 35 to 180 mv indicating that anoxic conditions prevail in the shallow aquifers of the brahmaputra plain age determinations suggest that clay horizons at 10 m depth were deposited at around 2 000 and 5 000 years bp 14c ages during the transgressive phase of sea level change elevated concentrations of as pb zn cu ni cr and v are present in the silts and clays probably due to adsorption onto clay particles significant concentrations of as occur in black peat and peaty sediments at depths between 9 and 13 m a strong positive correlation between as and fe was found in the sediments indicating as may be adsorbed onto fe oxides in aquifer sediments

qualitative chaos in geomorphic systems with an example from wetland response to sea level rise the spatial and temporal complexity of earth surface processes and landforms and the presence of deterministic chaos in many fundamental physical processes provide reasons to suspect chaos in geomorphic systems a method is presented to assess the likelihood of chaotic behavior in a geomorphic system the method requires identification of the fundamental system components their positive negative or negligible influences on each other and the relative strength or magnitudes of these links based on this information the method can classify geomorphic systems as stable and nonchaotic unstable and potentially chaotic or unstable and generally chaotic positive self enhancing feedback is a key diagnostic of the likelihood of chaotic behavior a sample application of the method to the problem of coastal marsh response to sea level rise is provided which shows the marsh to be unstable if changes in vegetation cover are partly dependent on vegetation density the system is generally chaotic if marsh veg

the chaotic characteristics of landslide evolution a case study of xintan landslide a new method based on the chaos theory is used to assess the evolution process of a slope system the method is applied to the xintan landslide and the results show 1 the slope movement is a complex process of the slope going in and out of the stable and chaotic state 2 the method reveals the evolution process of the slope pointing to the slope failure while the observed movement shows a simple monotonic increase with time 3 the method is not sufficiently mature to precisely predict the time of failure but it has potential for improvement with further research and more field data for analysis

duration of magmatic hydrothermal and supergene activity at cerro rico de potosi bolivia new high precision 40ar 39ar dating of sanidine and biotite from two rhyolitic domes and an ignimbrite combined with existing fission track data and a hydrothermal sericite age suggests that the world class ag deposit at cerro rico was emplaced during a protracted period of magma related hydrothermal activity beginning at 13 77 0 03 ma and continuing for at least 0 2 m y this may have been sustained by a large single injection or repeated injections of fractionated ag enriched magma into a high level magma chamber k ar dating of alunite indicates that supergene oxidation had begun by about 13 5 ma soon after dome emplacement and progressed semicontinuously for at least 7 5 m y this oxidation while not leading to significant enrichment has significantly enhanced the economic viability of the disseminated part of the orebody

sources of lead in the san cristobal pulacayo and potosi mining districts bolivia and a reevaluation of regional ore lead isotope provinces new lead isotope data on ores crustal rocks and leachates of crustal rocks combined with data in the literature provide important new constraints on the sources of ore metals in southwest to south central bolivia including the very large recently discovered silver zinc deposit at san cristobal the pulacayo polymetallic district and the giant potosi silver tin base metal deposit lead isotope ratios of ores and igneous rocks from the san cristobal deposit and from paleozoic and cretaceous sedimentary rocks are compared with published data on high grade middle proterozoic metamorphic basement rocks these data constrain the major source of lead and by inference of other ore metals at san cristobal to be the metamorphic basement rocks leaching experiments on samples of paleozoic and cretaceous sedimentary rocks show that the easily leachable lead from these rocks is much less radiogenic than the whole rock compositions however lead isotope ratios of both whole rocks and leachates of these upper crustal rocks are too radiogenic for them to be major sources of ore lead at san cristobal lead isotope ratios of ores from pulacayo and potosi are similar to each other and lie within the range of paleozoic and cretaceous sedimentary whole rock compositions leaching of pb from the sedimentary rocks cannot explain the isotopic compositions of the pulacayo and potosi ores and the isotopic homogeneity of the potosi ores also argues against mixing of lead from diverse sources in the hydrothermal system lead from the sedimentary rocks may have been incorporated by magmatic assimilation followed by extraction of ore metals from the resulting magma lead isotope ratios of san cristobal ores are different from those of pulacayo potosi and other deposits to the east but resemble the compositions of ores and volcanic rocks in western bolivia on this basis we identify a new ore lead isotope province extending from san cristobal northward across the eastern altiplano and into southern peru this province is coincident with but smaller than the extent of the proposed arequipa antofalla metamorphic basement craton the degree of incorporation of ore metals from the metamorphic basement appears to depend on the timing and or location of the mineralizing event ore deposits in the northern part of province iv formed before the thickening of andean crust beginning around 20 ma and incorporated minor amounts of metals from the metamorphic basement younger deposits farther to the south contain major to dominant components of basement lead

intensive pre incan metallurgy recorded by lake sediments from the bolivian andes the history of pre columbian metallurgy in south america is incomplete because looting of metal artifacts has been pervasive here we reconstruct a millennium of metallurgical activity in southern bolivia using the stratigraphy of metals associated with smelting pb sb bi ag sn from lake sediments deposited near the major silver deposit of cerro rico de potosi pronounced metal enrichment events coincide with the terminal stages of tiwanaku culture 1000 to 1200 a d and inca through early colonial times 1400 to 1650 a d the earliest of these events suggests that cerro rico ores were actively smelted at a large scale in the late intermediate period providing evidence for a major pre incan silver industry

subsidence control on river morphology and grain size in the ganga plain the ganga plain represents a large proportion of the current foreland basin to the himalaya the himalayan sourced waters irrigate the plain via major river networks that support approximately 10 percent of the global population however some of these rivers are also the source of devastating floods the tendency for some of these rivers to flood is directly linked to their large scale morphology in general the rivers that drain the east ganga plain have channels that are perched at a higher elevation relative to their floodplain leading to more frequent channel avulsion and flooding in contrast those further west have channels that are incised into the floodplain and are historically less prone to flooding understanding the controls on these contrasting river forms is fundamental to determining the sensitivity of these systems to projected climate change and the growing water resource demands across the plain here we present a new basin scale approach to quantifying floodplain and channel topography that identifies areas where channels are super elevated or entrenched relative to their adjacent floodplain we explore the probable controls on these observations through an analysis of basin subsidence rates sediment grain size data and sediment supply from the main river systems that traverse the plain yamuna ganga karnali gandak and kosi rivers subsidence rates are approximated by combining basement profiles derived from seismic data with known convergence velocities results suggest a more slowly subsiding basin in the west than the east grain size fining rates are also used as a proxy for relative subsidence rates along the strike of the basin the results also indicate higher fining rates and hence subsidence rates for given sediment supply in the east by integrating these observations we propose that higher subsidence rates are responsible for a deeper basin in the east with perched low gradient river systems that are relatively insensitive to climatically driven changes in base level in contrast the lower subsidence rates in the west are associated with a higher elevation basin topography and entrenched river systems recording climatically induced lowering of river base levels during the holocene

factors controlling shelf sediment dispersal along the southeast african continental margin abstract four major factors control sediment dispersal along the southeast african continental margin 1 morphology of the upper continental margin 2 wave regime and wind driven circulation 3 influence of the agulhas current and 4 sediment supply these factors interact on various scales to produce a unique regional sediment dispersal pattern the continental shelf is very narrow and the adjacent slope extremely steep the shelf platform is interrupted by a number of structural offsets and locally the shelf break is dissected by numerous submarine canyons the nearshore zone down to about 60 m waterdepth is dominated by a high energy swell regime and in most places is underlain by a thin wedge of sandy sediment this wedge appears to have achieved dynamic equilibrium with the prevailing energy regime and additional sediment is rapidly dispersed and fed into a sandstream situated on the central shelf where the agulhas current dominates sediment transport along some parts of the coast the sediment wedge is dammed behind a drowned coastal dune ridge within the sandstream sediment is transported alongshelf until a structural offset is reached where sediment spills over the shelf break four major localities for off shelf transport are recognized between maputo and port elizabeth most of the suspended load appears to be expelled from the system without being deposited on the shelf in the lee of each offset a clockwise gyre is developed which produces return flow currents capable of moving sediment northward thereby creating bedload partings in the vicinity of these partings depositional features are observed that are similar to those normally associated with tidal regimes e g bedforms migrating in opposite directions most of the bedload sediment entering the system is eventually deposited in well defined sinks situated in the lee of structural offsets this model applies only to inter glacial high sea level situations accompanied by strong western boundary flow of the agulhas current

evaluation of hydrogeochemical processes in the pleistocene aquifers of middle ganga plain uttar pradesh india evaluation of major ion chemistry and solute acquisition process controlling water chemical composition were studied by collecting a total of fifty one groundwater samples in shallow 25 m in the varanasi area hydrochemical facies mg hco3 dominated in the largest part of shallow groundwater followed by na hco3 and ca hco3 whereas ca hco3 is dominated in deep groundwater followed by mg hco3 and na hco3 high as concentration 50 g l is found in some of the villages situated in northeastern parts i e adjacent to the concave part of the meandering ganga river of the varanasi area arsenic contamination is confined mostly in tube wells hand pump within the holocene newer alluvium deposits whereas older alluvial aquifers are having arsenic free groundwater geochemical modeling using wateq4f enabled prediction of saturation state of minerals and indicated dissolution and precipitation reactions occurring in groundwater majority of shallow and deep groundwater samples of the study area are oversaturated with carbonate bearing minerals and under saturated with respect to sulfur and amorphous silica bearing minerals sluggish hydraulic conductivity in shallow aquifer results in higher mineralization of groundwater than in deep aquifer but the major processes in deep aquifer are leakage of shallow aquifer followed by dominant ion exchange and weathering of silicate minerals

geological and geochemical examination of arsenic contamination in groundwater in the holocene terai basin nepal geological and geochemical study has been carried out to investigate arsenic contamination in groundwater in nawalparasi the western terai district of nepal the work carried out includes analyses of core sediments provenance study by rare earth elements analyses 14c dating and water analyses results showed that distribution of the major and trace elements are not homogeneous in different grain size sediments geochemical characteristics and sediment assemblages of the arsenic contaminated nawalparasi and uncontaminated bhairahawa area have been compared geochemical compositions of sediments from both the areas are similar however water chemistry and sedimentary facies vary significantly extraction test of sediment samples showed significant leaching of arsenic and iron chemical reduction and contribution from organic matter could be a plausible explanation for the arsenic release in groundwater from the terai sediments

structural setting of the neoarchean terrains in the commonwealth bay area 143 145 e terre adelie craton east antarctica lithological and structural maps from the east commonwealth bay unit ecb terre adelie and georges v land antarctica are presented with a summary of the main structural and metamorphic data obtained in the area the ecb unit is structured during the late archean lower proterozoic at 2 4 2 5 ga with i granulite metamorphism at 9 6 kbar and 850 50 c of lower mid crust and amphibolite metamorphism p 5 kbar t 750 c of the upper crustal levels ii the lower crustal granulites are uplifted and suffered local partial melting and then retrogression into the amphibolite facies at 550 50 c 5 kbar granulites are extruded in the core of a crustal scale anticlinal fold granulites being retrogressed only on the rims of the anticline crustal scale folding along with other structural features results from intense ne sw shortening that prevailed during the late archean orogenic cycle strike slip and extensive motions are only minor in that process iii top to the east thrusting and nappe piling has at least locally occurred under lower amphibolite to greenschist facies conditions finally it seems that iv the paleoproterozoic 1 7 ga structural imprint may have only affected the rims of the archean units the tectonic context observed in the 1 7 ga cape hunter phyllites features mainly e w shortening component and vertical extrusion the eastern mertz and western port martin parts of the archean block were reactivated by localized dextral shearing

arsenic levels in groundwater from quaternary alluvium in the ganga plain and the bengal basin indian subcontinent insights into influence of stratigraphy abstract late quaternary stratigraphy and sedimentation in the ganga alluvial plain and the bengal basin have influenced arsenic contamination of groundwater arsenic contaminated aquifers are pervasive within lowland organic rich clayey deltaic sediments in the bengal basin and locally within similar facies in narrow entrenched river valleys within the ganga alluvial plain these were mainly deposited during early mid holocene sea level rise arsenic was transported from disseminated sources as adsorbed on dispersed phases of hydrated iron oxide these were preferentially entrapped as sediment coatings on organic rich fine grained deltaic and floodplain sediments arsenic was released later to groundwater mainly by reductive dissolution of hydrated iron oxide and corresponding oxidation of sediment organic matter strong reducing nature of groundwater in the bengal basin and parts of affected middle ganga floodplains is indicated by high concentration of dissolved iron maximum 9 35 mg l groundwater being virtually stagnant under these settings released arsenic accumulates and contaminates groundwater the upland terraces in the bengal basin and in the central ganga alluvial plain made up of the pleistocene sediments are free of arsenic contamination in groundwater these sediments are weakly oxidised in nature and associated groundwater is mildly reducing in general with low concentration of iron

fractals in topography application to geoarchaeological studies in the surroundings of the necropolis of dahshur egypt the necropolis of dahshur in northern egypt witnessed human environment interaction on a millennial scale but to an unknown extent the present study aims to decipher ephemeral channel networks which are common landscape features in the surroundings of the necropolis from landforms that were subject to human influence the analysis was carried out on the basis of surface geometry as derived from a digital elevation model dem the hypothesis is tested that the natural fractal patterns of channel networks lead to fractal surface topography when fluvial processes are the main factors for relief evolution therefore the estimated fractal dimension of channel networks is correlated with the fractal dimension of surface topography to determine the mutual functional relationship a high degree of functional relationship within some areas of the dem shows that channel networks are self similar branching trees that imprint their geometry on to surface topography in a scale range of 15 to 190 m a low correlation of fractal patterns of channel network and surface topography in the vicinity of the pyramid district of the necropolis is interpreted as channel beds modified or induced by human impact either due to the usage of the channel beds as transport ways for building material leading to an acceleration of processes like soil erosion or due to direct activities like mining or landscape architecture

river water quality across the himalayan regions elemental concentrations in headwaters of yarlung tsangbo indus and ganges river to study the water quality across the himalayan region a total of 43 river water samples were collected in september 2012 from the yarlung tsangbo brahmaputra indus and ganges basins we measured the common water quality parameters ph ec tds and water temperature and analyzed the element concentrations as cr s sr tl b ba ca al fe k mg mn na rb and ti using icp aes the results show that all the rivers have an alkaline environment with ph from 7 9 to 8 9 tds has a positive relationship with ca and mg concentrations the elemental contents are comparable among the samples from different river basins the enrichment factor of as in river water across himalayas showed a high value at 30 indicating the impacts of anthropogenic activities the river water quality in this region is under the influence of climate change on the glacier melting which will affect the water chemistry and the seasonal discharge of river runoff

a nonlinear dynamical model of landslide evolution a nonlinear dynamical model for the evolution of landslide is proposed the parameters of this model are obtained through an improved iterative algorithm of inversion developed in the paper based on the nonlinear dynamical model and nonlinear dynamical systems nds theory the approaches to determining the lyapunov exponents the predictable timescale and the stability criterion of the evolutional state of landslide are given a case study of the xintan slope is presented to illustrate the capability and merit of the nonlinear dynamical model

a geochemical assessment of the middle and lower mvoti river system kwazulu natal south africa this paper presents one of the first investigations into the geochemical enrichment of the middle and lower mvoti river system chemical elements are naturally present in aquatic sediments but their concentrations tend to rise to potentially toxic levels via both natural and anthropogenic processes this study evaluated the concentrations of aluminum arsenic boron barium cadmium calcium cobalt chromium copper iron lead magnesium manganese molybdenum nickel phosphorous selenium silicon strontium titanium vanadium and zinc using inductively coupled plasma optical emission spectroscopy the levels of elements present were used to assess their spatial distribution within the river and to determine the contamination factors and enrichment factors for each element the pollution load index pli is another contributing parameter that was calculated to determine the degree of pollution at each site the results indicate that the sediments of the mvoti are low to moderately polluted and deteriorating with time average pli value of 5 19 and that a major contributing factor to this contamination is natural sources

geochemical background in soils a linear process domain an example from istria croatia definition of geochemical background in exploration and environmental geochemistry has always been regarded as contingent upon scale and investigated locality but mostly under assumption that hosts of processes that produce the data more or less conform individually to gaussian law of central tendencies recently understanding of pedogenesis as synergetic process being characterized by non linear dynamics renders thermodynamic approach directly applicable in assessment of geochemical thresholds with concepts of linearity and normality set alongside in solving the problems of soil geochemistry seen from this perspective the work is an attempt to relate conceptual fundamentals of non linear dynamical theory to basic statistical methods in order to elucidate the nature and origins of element subpopulations hidden in the original geochemical data from the soils of istrian peninsula western croatia to this purpose the two major groups of soils were selected for analysis depending on the type of bedrock as one of the main soil forming factors geochemical data were subjected to the trimming procedure by which the outliers were removed from the total data collective and attributed to non linear causes precluding simple cause and effect relationships as the sine qua non of gaussian distribution geochemical background is then defined as the normal range of data of the remaining trimmed dataset indicating the thermodynamic branch of the specific soil processes as opposed to outliers being described as dissipative structures

arsenic mobility in fluvial environment of the ganga plain northern india in the northern part of the indian sub continent the gomati river a tributary of the ganga river was selected to study the dynamics of arsenic as mobilization in fluvial environment of the ganga plain it is a 900 km long groundwater fed low gradient alluvial river characterized by monsoon controlled peaked discharge thirty six water samples were collected from the river and its tributaries at low discharge during winter and summer seasons and were analysed by icp ms dissolved as and fe concentrations were found in the range of 1 29 9 62 and 47 84 431 92 g l respectively arsenic concentration in the gomati river water has been detected higher than in its tributaries water and characteristically increases in downstream attributed to the downstream increasing of fe2o3 content sedimentary organic carbon and silt clay content in the river sediments significant correlation of determination r 2 0 68 was also observed between as and fe concentrations in the river water arsenic concentrations in the river water are likely to follow the seasonal temperature variation and reach the level of world health organization s permissible limit 10 g l for drinking water in summer season the gomati river longitudinally develops reducing conditions after the monsoon season that mobilize as into the river water first dissolved as enters into pore water of the river bed sediments by the reductive dissolution of fe oxides hydroxides due to microbial degradation of sedimentary organic matter thereafter it moves upward as well as down slope into the river water column anthropogenically induced biogeochemical processes and tropical climatic condition have been considered the responsible factors that favour the release of as in the fluvial environment of the ganga plain the present study can be considered as an environmental alarm for future as groundwater resources of the ganga brahmaputra delta are seriously affecting the human environment relationship at present

uthpb zircon dating of the 13 8 ma dacite volcanic dome at cerro rico de potosi bolivia abstract the temporal relationship between the extrusion of the miocene dacite volcanic dome at cerro rico de potosi bolivia and the associated ag sn mineralization has an important bearing on the heat and metal sources for this world class mineral deposit the highly altered nature of the volcanic rock however has prevented previous efforts from definitively determining the emplacement age of the dome rather than subsequent episodes of alteration the present study uses u th pb dating of sparse zircon contained in the dacite to demonstrate that at most only several hundred thousand years separate dome emplacement from main stage mineralization the dacite contains a morphologically heterogeneous population of zircon with considerable variation in size shape and color preliminary analyses revealed the presence of a significant component of inherited zircon most likely as older cores that were overgrown by rims during the crystallization of the dacite magma morphological distinctions shape size color within the zircon population provided the basis for separating the zircon into fractions that reduced or enhanced the inherited component in composite grains by analyzing the tips of zircon with very large length to width ratios it was possible to constrain the crystallization age of the dacite to 13 8 0 2 ma the dispersion of data on a concordia diagram indicates at least two ages of inherited zircon one mesozoic associated with yellow grains and another proterozoic associated with colorless grains such xenocrystic components have useful petrogenetic implications for the source and travel path of the magma

the fate of geothermal arsenic in the madison and missouri rivers montana and wyoming geothermal as from yellowstone national park causes high as concentrations 10 370 g l in the madison and missouri rivers in montana and wyoming arsenic transport is largely conservative in the upper basin as demonstrated by the near equivalence of dissolved and total recoverable as concentrations the constancy of as loads and consistent ratios of concentrations of as to conservative geothermal tracers diurnal cycling of as between aqueous and solid phases in response to ph induced changes in sorption equilibria causes small variations of about 10 20 in dissolved as concentrations hcl extractable as concentrations in river and lake sediment in the upper basin are variable depending on position relative to the as rich headwaters and geochemical and physical processes associated with lakes in the lower missouri river large quantities of suspended sediment from tributaries provide sufficient sorption sites for substantial conversion of as from the aqueous phase to the solid phase

synchronous anatexis metamorphism and rapid denudation at nanga parbat pakistan himalaya the nanga parbat haramosh massif of the western himalaya is a north trending half window of indian crust that provides spectacular exposures of precambrian basement gneisses that have been overprinted by himalayan metamorphism we report here petrologic data and u pb dates on zircon and monazite which document that nanga parbat gneisses underwent a pliocene pleistocene episode of high grade metamorphism and anatexis during an interval in which the nanga parbat massif was undergoing rapid denudation at mean rates of 5 mm yr we speculate that by initiating decompression melting this denudation may be at least partly responsible for the anatexis and high grade metamorphism

spatial distribution of trace elements in floodplain alluvium of the upper blackfoot river montana the mike horse mine tailings dam in western montana was partially breached in 1975 due to heavy rainfall and a failed drainage bypass approximately 90 000 tons of metal and arsenic enriched tailings flowed into beartrap creek and the blackfoot river the spatial distribution of trace elements as cd cu mn pb and zn in floodplain alluvium of the upper blackfoot river were examined along 20 transects in the upper 105 river kilometers downstream from the tailings dam trace element concentrations decrease with distance from the failed dam with as reaching background concentrations 15 km from the mike horse dam cd and pb at 21 km cu at 31 km and mn and zn at 37 km distance from the mike horse tailings dam and mine area is the dominating factor in explaining trace element levels with r 2 values ranging from 0 67 to 0 89 maximum floodplain trace element concentrations in the upper basin exceed us epa ecological screening levels for plants birds and other mammals and reflect adverse hazard quotients for exposure to as and mn for atv motorcycle use trace element concentrations in channel bank and bed alluvium are similar to concentrations in floodplain alluvium indicating active transport of trace elements through the river and deposition on the floodplain the fine fraction 2 mm of floodplain alluvium is dominated by sand sized particles 2 0 0 05 mm with cu and mn significantly correlated with silt sized 0 05 0 002 mm alluvium ongoing remediation in the headwaters area will not address metal contamination stored downstream in the channel banks and on the floodplain additionally some trace elements cu mn and zn were conveyed farther downstream than were others as cd pb

trans african drainage system of the sahara was it the nile an exciting result of the first spaceborne radar scans of the eastern sahara has been the recognition of drainage channels buried at depths of several metres below the dry desert sand we relate these observations to the megageomorphological evolution of africa and conclude that the radar river valleys may have been parts of an old nile river system rather than courses cut by a postulated westward flowing trans african drainage system tads extending from the red sea hills to the niger delta

an assessment of soil contamination due to heavy metals around a coal fired thermal power plant in india combustion of coals in thermal power plants is one of the major sources of environmental pollution due to generation of huge amounts of ashes which are disposed off in large ponds in the vicinity of the thermal power plants this problem is of particular significance in india which utilizes coals of very high ash content 55 wt since the thermal power plants and the ash ponds are located in densely populated areas there is potential chance for contamination of soil and groundwater of the surrounding areas from the toxic trace elements in the ash an attempt has been made to study the extent of soil contamination around one of the largest thermal power plants of india located at kolaghat west bengal india chemical analysis of the top soils and the soils collected from the different depth profiles surrounding the ash ponds show that the top soils are enriched in the trace elements mo as cr mn cu ni co pb be v zn which show maximum enrichment 2 5 in the top soils collected from all the soil profiles these elements are also enriched in the pond ash since there are no other sources of industrial effluents it can be said that the enrichment of the trace elements mn co mo cr cu pb zn as ni be v is attributed to their input from ash from the disposal pond the study has been further strengthened by log normal distribution pattern of the elements

migration of cu zn cd and as in epikarst water affected by acid mine drainage at a coalfield basin xingren southwest china epikarst water which is one of the most important water resources in karst mountain areas is extremely sensitive to mining activities acid mine drainage amd with high levels of heavy metals can degrade the water quality a typical coalfield basin was chosen to research the migration process of heavy metals it was found that the chemical compositions of the stream water in the research field were controlled by the dissolution of carbonate rocks or and the weathering and oxidation of pyrite in the mining area excluding a few sites in the mining area as v was dominant species of arsenic in the form of h2aso4 or haso4 2 in the research field based on the mass balance concept it was found that fluxes of as zn cu and cd in water from the mining area site 17 affected by amd were 18 871 281 and 12 kg year 1 respectively also concentrations of cd zn as and cu in the stream water decreased along the flow because these ions deposited from the water to the stream bed as the redistribution processes in environment

changed late quaternary marine environments on atlantic continental shelf and upper slope abstract about 2000 large sediment samples were collected during the early 1960s throughout the continental shelf off the atlantic coast of the united states to establish and map sediment types including sediments relict from times of glacially low and subsequently higher sea levels in about 510 of these samples we found fossil shells of mollusks remaining from environmental conditions different from those at present publications and collections by others contain about 70 additional samples having relict mollusks some of these shells indicate lower sea levels others colder water and still others warmer water than is now present radiocarbon measurements from earlier studies by us and others established the dates of colder water late pleistocene and we made additional measurements to learn the dates of warmer water about 1000 to 2000 yr b p the results show reasonably enough that continental shelves are the sites of relict faunas as well as of sediments that indicate changed and complex environmental histories

a gloria traverse over the marginal fracture zone and continental margin of se africa abstract a geological and physiographical interpretation of nearly 60 000 km 2 of the continental margin of se africa 21 20 e to 31 e has been made using gloria sonographs and seismic and bathymetric records these data have enhanced our understanding of the structural complexity of basement and sedimentary features in particular the marginal fracture ridge mfr which forms part of the agulhas falkland fracture zone affz most of the 500 km long exposed section can be traced in the sonographs and it is concluded that the mfr is not a single lineament but consists of two en echelon basement ridges that overlap by approximately 20 km in the vicinity of the scrutton ridge 23 5 e the latter is an enigmatic basement sliver that may be a narrow upthrust block east of 26 e a major slump and canyon province has been identified in the southwestern part of the natal valley here we record three previously undescribed canyons padrone boesmans and fish and extensive compressional structures in the distal parts of a large slump lobe

sources and controls of arsenic contamination in groundwater of rajnandgaon and kanker district chattisgarh central india summary a high concentration of arsenic as contamination in ground water has been reported in the village of kaudikasa in rajnandgaon district wherein around 10 of the population is suffering from as borne diseases the region does not share any demographic or geological similarity with the sedimentary aquifers of the bengal delta plain in eastern india but represents an igneous terrain with elevated as concentrations in groundwater there is limited information about the source of as in groundwater and its mobility constraints in this area almost all the wells are located in the granitic terrain with pegmatitic intrusions most of these wells are characterized by as concentration above the world health organization who 1999 and the bis bureau of indian standards standards with the highest being found in a well with more than 250 g l of as here we report petrographic studies of the granitic host rock and x ray diffraction results that indicate that altered realgar as4s4 para realgar ass and or tennantite cu12as4s13 are the main mineral that contain as this element is leached during the weathering and water rock interactions microprobe analysis of the altered realgar grains of in pegmatitic intrusions of the host granite indicate 23 27 wt as remote sensing is useful to delineate the source of this contaminant which appears to lie at the intersection of a mineralized nw se and n s lineaments associated with the kotri rift zone these lineaments are structurally controlled as rifting followed by thrusting and other types of faulting caused left lateral displacement of n s kotri lineament along a nw se fault plane showing sinistral shearing this process caused water drainage in the areas to flow along these highly mineralized weak zones thus the water becomes highly contaminated due to leaching of minerals at the intersection of these lineaments clearly visible at two areas of high contamination that lie very near to this intersection over granitic rock the source of as affecting the rajnandgaon district is located in granites that have pegmatitic intrusions likely generated by hydrothermal activity

the significance of large sediment supply active tectonism and eustasy on margin sequence development late quaternary stratigraphy and evolution of the ganges brahmaputra delta abstract borehole data from the ganges brahmaputra delta system unveil an intriguing late quaternary history controlled by immense sediment discharge tectonics and eustasy sea level first intersected a major portion of the lowstand surface 10 000 11 000 cal yr bp marking the onset of sediment trapping and delta growth despite rapid sea level rise 1 cm yr sediment load was sufficient to maintain relative shoreline stability during this time by 7000 cal yr bp accommodation was quickly infilled with slowed sea level rise leading to upstream channel migration and widespread dispersal of sands this forced coastal progradation along the western delta front where the ganges was situated and much of the river s fine grained discharge bypassed the subaerial delta and formed a prograding deltaic clinoform on the shelf concurrently brahmaputra sediments were sequestered to an inland tectonic basin thus starving the adjacent shoreline and leading to transgression along the eastern delta by 5000 cal yr bp the two rivers had migrated or changed course to discharge along the eastern delta shoreline which began to prograde into what is now the modern river mouth estuary present delta configuration appears to have developed by 3000 cal yr bp evolution of the tectonically active ganges brahmaputra g b system reveals important similarities and differences with other deltas overall facies succession follows that of basic models progressing from an alluvial valley to coastal marine delta front to a prograding subaerial delta plain however the timing thickness and controls of these deposits differ immense sediment discharge from the ganges and brahmaputra rivers allowed initial delta growth 2000 3000 yr earlier than the global average despite debouching onto a canyon incised high energy margin subsequently a thick 50 m transgressive systems tract was formed during the early holocene phase of delta aggradation contrasting with extensive shoreline retreat documented along most margins highstand progradation of coastal and shelf sequences ensued by the middle holocene but subsiding inland basins also favored accumulation of a thick to 40 m highstand sequence in the lower floodplains unlike many other delta systems subsidence in the subaerial g b delta is not dominated by compaction but rather by plate driven tectonic processes that generate rates up to 4 mm year overall the huge sediment load tectonic subsidence major seismic events and a nearshore canyon system have led to widespread sediment dispersal and sequence formation across the subaerial delta shelf and deep sea bengal fan throughout the late quaternary

progressive and regressive pedogenesis and complex soil evolution abstract the simultaneous operation of regressive and progressive pedogenetic pathways raises the possibility that soil evolution may exhibit patterns far richer and more complex than increasing development over time this possibility is explored via a numerical model incorporating the relative rates of progressive and regressive pedogenesis and feedbacks between these rates and the degree of soil development this model may exhibit deterministic chaos and sensitive dependence on initial conditions with realistic parameter values variations in profile development in a region of the north carolina coastal plain where soil forming factors are relatively constant is consistent with deterministic chaos chaotic soil evolution suggests that soil development may reflect the interplay between progressive and regressive soil forming processes in addition to or instead of the age of a surface or deposit the former may produce a state of development which is unique to a particular time sensitively dependent on the unknown initial conditions and not simply related to age soils and their genetic signatures as indicators of relative ages and quaternary environments may need to be reinterpreted in this light

the age and thermal history of cerro rico de potosi bolivia cerro rico de potosi bolivia is the world s largest silver deposit and has been mined since the sixteenth century for silver and for tin and zinc during the twentieth century together with by product copper and lead the deposit consists primarily of veins that cut an altered igneous body that we interpret to be a dacitic volcanic dome and its underlying tuff ring and explosion breccia the deposit is compositionally and thermally zoned having a core of cassiterite wolframite bismuthinite and arsenopyrite surrounded by a peripheral lower temperature mineral assemblage consisting principally of sphalerite galena lead sulfosalt and silver minerals the low temperature assemblage also was superimposed on the high temperature assemblage in response to cooling of the main hydrothermal system both the dacite dome and the ore fluids were derived from a larger magmatic hydrothermal source at depth the dome was repeatedly fractured by recurrent movement on the fault system that guided its initial emplacement the dome was extruded at 13 8 0 2 ma 2 based on u th pb dating of zircon mineralization and alteration occurred within about 0 3 my of dome emplacement as indicated by a 40ar 39ar date of 13 76 0 10ma 1 for sericite from the pervasive quartz sericite pyrite alteration associated with the main stage high temperature mineralization the last thermal event able to reset zircon fission tracks occurred no later than 12 5 1 1 ma 1 as indicated by fission tract dating minor sericite and magmatic steam alunite veins were episodically formed around 11 ma and between 8 3 and 5 7 ma the younger episodes occurring at the time of extensional fracturing at cerro rico and wide spread volcanism in the adjacent los frailes volcanic field none of these younger events appear to be significant thermal mineralizing events the exceptionally flat thermal release pattern of 39ar from sericite and the results of the fission tract dating of zircon show that none of the younger events was hot enough and lasted long enough to cause significant loss of ar or annealing of zircon fission tracks u th pb dating of zircon cores indicates a precambrian progenitor for some zircons and ree analyses of dated samples of hydrothermally altered dacite show the presence of a prominent positive eu anomaly which constrains interpretations of the origin and evolution of the magmatic hydrothermal system

nonlinear dynamics and the evolution of relief abstract theories of landscape evolution and available field evidence suggest that topographic relief may increase decrease or remain relatively constant over time the trend depends on the relative balance between endogenic and exogenic forces and or the spatial scale a straightforward mathematical argument shows that when relief generally decreases over time or remains constant landscape evolution is stable and non chaotic chaotic unstable topographic evolution produces divergence where initial elevation differences and subsequent perturbations generally increase over time this leads to or at least towards a conceptual model of landscape evolution this model based on nonlinear dynamical systems nds theory recognizes 10 modes five stable and five chaotic of topographic evolution together these modes can accommodate existing theories and models of landscape evolution no mode can persist indefinitely over geologic time implying that landscapes inevitably undergo phases of increasing and decreasing relief these phases may be quite long because the model can accommodate any observed trend in relief evolution it is not falsifiable and is therefore not proposed as a theory the nds model does have implications with respect to the preservation of planar surfaces the next step is to develop a testable hypothesis

arsenic pollution in groundwater of west bengal india an insight into the problem by subsurface sediment analysis abstract arsenic values in groundwater above the maximum permissible limit of 0 05 mg l have been reported from several areas of the lower delta region of the ganga padma river system it is confined to areas east of hooghly river and to the shallow aquifer arsenic values in sub surface sediments from arsenious water zones are significantly higher than values from safe water zones the major part of the sediments consisting of non magnetic and some feebly magnetic minerals is arsenic free some iron rich clastic minerals like illite biotite chlorite fe coated grains and also the authigenic siderite concretions which together constitute only a small part of the sediments are carriers of arsenic and contribute the element to contaminate groundwater illite biotite and chlorite degenerate to produce iron oxide hydroxide coating on their surface and also on the surface of some other sand particles arsenic is adsorbed on the iron hydroxide coating creating one kind of sink for the element bacteria induced growth of siderite concretions grow initially on these clastic minerals and after attaining bigger size fall off as individual globules arsenic gets adsorbed on these concretions forming a second kind of sink for the element arsenic carrying river water inundates the lower delta at the time of seasonal flood arsenic percolates with the water downwards to the shallow aquifer it gets fixed in the aquifer sediments in the two ways described and is retained in the traps thus formed locally developed reducing condition causes dissolution of iron hydroxide coating on the surface of clastic arsenic traps and also of the siderite concretions this leads to increase in arsenic level in groundwater at these sites a currently active process of creation and periodic enrichment of the arsenic traps followed by their subsequent depletion through desorption and dissolution is suggested to be the reason for arsenic contamination of groundwater in this part of the delta

anthropogenic arsenic menace in delhi yamuna flood plains arsenic one of the most poisonous chemical elements was analyzed in the waters of the host of the 2010 commonwealth games i e new delhi the study revealed shocking outcomes with arsenic concentrations well beyond the safe limits set by who and a maximum concentration up to 180 ppb was found in the groundwater analysis of around 120 water samples collected extensively along the yamuna flood plain showed that more than 55 had arsenic contamination beyond the who limit of 10 ppb the maximum value of arsenic in coal and fly ash from rajghat coal based thermal power plant contained 200 and 3 200 ppb respectively moreover the ore petrography of coal samples shows the presence of arsenopyrite mineral maximum concentration of arsenic contamination is found within a 5 km radius from power plants in the perspective of delhi arsenic contamination is purely anthropogenic due to coal based thermal power plants which had already shown toxic arsenic fluorine and china type coal effects the presence of such power plants in coal field locations e g west bengal and bangladesh could release the arsenic due to combustion in superthermal power plants thus accentuating the arsenic concentration besides the natural arsenic coming from the foreland basins of the himalaya in indian sub continent

characterization of recharge processes in shallow and deeper aquifers using isotopic signatures and geochemical behavior of groundwater in an arsenic enriched part of the ganga plain abstract arsenic concentrations in groundwater extracted from shallow aquifers in some areas of the ganga plain in the states of bihar and uttar pradesh exceed 50 g l 1 and locally reach levels in the 400 g l 1 range the study covered 535 km2 of active flood plain of the river ganga in bihar where a two tier aquifer system has been delineated in a multi cyclic sequence of quaternary sand clay sandy clay and silty clay all 250 m below ground surface the research used isotopic signatures 18o 2 3h 14c and major chemical constituents hco 3 so 4 2 no 3 cl ca 2 mg 2 na k as total of groundwater to understand the recharge processes and groundwater circulation in the aquifers values of 18o and 2 combined with 3h data indicate that the recharge to the as enriched top 40 m of the deposits is modern