sterols as biogeochemical markers in pliocene sediments and their potential application for the identification of marine facies abstract several calcarenite samples from mezapos area south peloponnesus greece have been studied biochemically by extracting the sterols trapped during the sedimentation the results have shown that specific compounds deposited in pliocene sediments can be preserved far up to ca 3 000 000 years these markers therefore provide an indication of marine facies and may be used to determine the limit of a marine transgression

alkalinity dynamics in an unacidified alpine lake sierra nevada california gem lake a small unacidificd high elevation lake in the sierra nevada undergoes an annual cycle of low alkalinity between 30 and 40 pcq liter during the ice free season and high alkalinity 240 peq liter in fall and winter both ph and alkalinity decrease drastically up to one unit for ph and 200 peq liter for alkalinity during spring snowmelt but chemistry of the snow snowmelt and runoff indicate that the declines in alkalinity are due to dilution rather than acidification the hydraulic residence time in the lake incrcascs from about 135 d in winter to 7 d during snowmclt high alkalinity water is simply flushed from the lake and replaced by water with an ionic composition very near that of the snowmclt runoff increases in alkalinity in fall and winter can be accounted for by the rates of weathering in the watershed a mass balance approach is used to reconstruct weathering reactions in the basin it suggests that the lake receives both surface runoff with the weathering products of the hydrolysis of granodiorite minerals to kaolinite and deep water from subterranean circulation with the products of granodiorite weathering to both kaolinitc and smectite the relative importances of low alkalinity surface runoff and high alkalinity groundwater to the recharge of the lake are proposed as factors controlling the seasonal bicarbonate concentration of the lake

processes regulating the solute concentrations of snowmelt runoff in two subalpine catchments of the sierra nevada california geochemical processes regulating solute concentrations in snowmelt runoff were investigated for the snowmelt periods of 1992 and 1993 in two subalpine catchments in sequoia national park california the catchments 0 5 and 0 2 ha have 10 and 25 soil coverage respectively the remaining area is exposed granodiorite bedrock mineral weathering was the major source of solutes in runoff calcium export in excess of stoichiometric plagioclase weathering was attributed to dry deposition and the weathering of mafic minerals and disseminated calcite cation exchange was important in the regulation of k and increased base cation export in response to rain on snow events and libr tracer sulfate fluxes were attributed to snowpack elution and so4 desorption after the beginning of melt the selective retention of li during tracer experiments suggests that acid neutralizing capacity is linked to soil stocks along convoluted flow paths and is not necessarily compromised in areas of sparse soil cover

controls on surface water chemistry in the upper merced river basin yosemite national park california surface water draining granitic bedrock in yosemite national park exhibits considerable variability in chemical composition despite the relative homogeneity of bedrock chemistry other geological factors including the jointing and distribution of glacial till appear to exert strong controls on water composition chemical data from three surface water surveys in the upper merced river basin conducted in august 1981 june 1988 and august 1991 were analysed and compared with mapped geological hydrological and topographic features to identify the solute sources and processes that control water chemistry within the basin during baseflow water at most of the sampling sites was dilute with alkalinities ranging from 26 to 77 pequiv i alkalinity was much higher in two subcatchments however ranging from 51 to 302 pequiv 1 base cations and silica were also significantly higher in these two catchments than in the rest of the watershed concentrations of weathering products in surface water were correlated to the fraction of each subcatchment underlain by surficial material which is mostly glacial till silicate mineral weathering is the dominant control on concentrations of alkalinity silica and base cations and ratios of these constituents in surface water reflect the composition of local bedrock chloride concentrations in surface water samples varied widely ranging from 1 to 96 pequiv 1 the annual volume weighted mean chloride concentration in the merced river at the happy isles gauge from 1968 to 1990 was 26 pequiv l which was five times higher than in atmospheric deposition 4 5 pequiv l suggesting that a source of chloride exists within the watershed saline groundwater springs whose locations are probably controlled by vertical jointing in the bedrock are the most likely source of the chloride sulphate concentrations varied much less than most other solutes ranging from 3 to 14 pequiv 1 concentrations of sulphate in quarterly samples collected at the watershed outlet also showed relatively little variation suggesting that sulphate may be regulated to some extent by a within watershed process such as sulphate adsorption

molecular organic matter in speleothems and its potential as an environmental proxy abstract organic matter preserved in speleothems has considerable potential to record changes in the surrounding environment particularly in the overlying vegetation here we review three types of organic matter analysis relevant to speleothems organic fluorescence lipid biomarker analysis and amino acid racemisation organic matter luminescence provides a useful non destructive and rapid method for assessing dissolved organic matter quantity and quality while biomarker analysis amino acids and lipids has the potential to provide a more detailed signal related to specific parts of the surrounding ecosystem such as the dominant vegetation regime and bacterial activity amino acid analysis has yet to prove demonstrably useful in stalagmites due to the inability to characterise the sources of proteinaceous matter however the small but increasing body of work on lipid biomarker analysis in stalagmites has shown that a wide variety of recognisable biomarkers are preserved over long periods of time 100 ka can be recovered at temporal resolutions of

episodic lake acidification in the sierra nevada california seven high altitude headwater catchments were studied from 1990 to 1994 to evaluate susceptibility to episodic acid neutralizing capacity anc depression dilution decreasing base cation concentrations was the primary factor in anc depression during snowmelt accounting for 75 to 97 of the anc reduction in lakes where acidification increasing anion concentrations was noted nitrate and sulfate were equally important during the first half of snowmelt while sulfate dominated the latter half a linear model based on the relationship between minimum and fall overturn anc for the lakes in our study estimated that none of the 114 lakes sampled during the 1985 epa western lakes survey had been episodically acidified anc 0 modifications of the model were used to predict that approximately 6 and 10 of sierran lakes will become episodically acidified with increases in nitrate and sulfate deposition of 50 and 150 respectively no lakes will be chronically acidified with these depositional increases

granite weathering and the sensitivity of alpine lakes to acid deposition lake chemical data from the national surface water survey nsws were corrected for the effects of regional atmospheric deposition and then used to evaluate the role of weathering in supplying base cations silica sulfate and alkalinity to surface waters in alpine vs subalpine and in glaciated vs unglaciated granitic terrane of the western and southeastern united states thermodynamic models idealized reaction stoichiometry and multivariate regression involving solutes and geographic variables indicate that irreversible weathering can largely account for lake chemistry by contrast relatively minor roles are played by reversible ion exchange in soils and sediments terrestrial bioaccumulation and transformations in lakes the regional patterns in lake acidity components no so4 doc co3 and statistical relationships between acidity and base cations demonstrate that rock weathering is limited by acid inputs in many alpine catchments prior to fall overturn the empirical success of the henriksen alkalinity model depends on a high ca na weathering ratio the latter increases with increasing physical disturbance of the catchment iuvenility hence under natural circumstances attains a maximum as a result of on going or recent glaciation the henriksen model fails in geochemically old terrane where cation losses accompanying silicate weathering attain steady state proportions

sterols as biogeochemical markers results from ensemble e of the stalagmitic floor grotte du lazaret nice france abstract four samples of stalagmitic flowstone ensemble e from the grotte du lazaret were studied biochemically by extracting the sterols trapped in the calcite matrix the analysis of these compounds has provided information about the type of vegetation that existed during the formation of this stratum between 120 000 and 70 000 bp in order to understand further fossilisation mechanisms of the sterols we compared these results with the results from a modern site at meudon similarly we studied some samples from quarry of meudon in which speleothem is at the present time in formation in addition the mineralogical analysis of the samples revealed the presence of crystalline structures analogous to those observed in a recent site this comparison provided information about the formation mechanisms of these crystalline systems and the environment associated with ensemble e between 120 000 and 70 000 bp

major ion chemistry and sensitivity to acid precipitation of sierra nevada lakes most alpine and subalpine lakes of the sierra nevada california are very dilute weakly buffered calcium bicarbonate waters seventy three lakes selected to lie in basins representative of sierran bedrocks were sampled in the summers of 1981 and 1982 and have a median alkalinity of 50 eq 1 1 range 5 1137 and a ph of 7 range 5 7 9 4 the alkalinity of sierran lakes cannot be predicted from altitude basin area or lake area the concentrations of sulfate calcium or alkalinity in lake waters are positively correlated with the percent areal coverage of volcanic or calcareous rocks in the basins the lakes are not acidified but are extremely sensitive to increases in acidity of atmospheric precipitation

radar reflections reveal a wet bed beneath stagnant ice stream c and a frozen bed beneath ridge bc west antarctica digital airborne radar data were collected during the 1987 88 antarctic field season in nine gridded blocks covering the downstream portions of ice stream b 6 km spacing and ice stream c 11 km spacing together with a portion of ridge bc between them an automated processing procedure was used for picking onset times of the reflected radar pulses converting travel times to distances interpolating missing data converting pressure transducer readings correcting navigational drift performing crossover analysis and zeroing remanent crossover errors interpolation between flight lines was carried out using the minimum curvature method maps of ice thickness estimated accuracy 20 m and basal reflection strength estimated accuracy 1 db were produced the ice thickness map confirms the characteristics of previous reconnaissance maps and reveals no new features the reflection strength map shows pronounced contrasts between the ice streams and ridge bc and between the two ice streams themselves we interpret the reflection strengths to mean that the bed of ice stream c as well as that of ice stream b is unfrozen that the bed of ridge bc is frozen and that the boundary between the frozen bed of ridge bc and the unfrozen bed of ice stream c lies precisely below the former shear margin of the ice stream

u series dates for stalagmitic flowstone e riss wurm interglaciation at grotte du lazaret nice france abstract several samples of stalagmitic flowstone ensemble e at grotte du lazaret nice france were dated by u series isotopes the results show that this speleothem began to grow about 130 000 yr b p and continued to about 70 000 yr b p coinciding almost exactly with the last interglaciation isotope stage 5 even though ensemble e is not in direct stratigraphic relation with the cave deposits this study shows that the acheulian artifacts industry and fauna within lazaret are older than the riss wurm interglaciation

organic proxies in speleothems new developments advantages and limitations abstract research into organic matter in speleothems has progressed recently to encompass new analytical approaches and applications which offer increased potential in areas such as palaeo temperature reconstruction and high resolution palaeo environmental records from the quaternary here we review three major areas of relevance for future work in the field the origin transport and transformation of the organic matter which is ultimately preserved in speleothems the types of proxies currently available for use or in development and their advantages and issues and the recently developed prospect of high resolution organic matter records derived from the analysis of organic trace elements complexes the continuing extension of work in these research areas offers excellent potential for organic speleothem proxies to grow as a valuable tool in palaeoenvironmental research

geochemical response to variable streamflow conditions in contaminated and uncontaminated streams 1 seasonal variations in stream inorganic geochemistry are not well documented or understood we sampled two mining impacted and two relatively pristine streams in western montana over a 12 month period collecting samples every 4 weeks with supplemental sampling at least weekly during spring runoff we analyzed all samples for dissolved operationally defined as 0 2 m and total recoverable concentrations generally the trace elements al as cu fe mn and zn did not correlate linearly with streamflow while the major elements e g ca k and mg did suspended sediment total recoverable metals and h followed clockwise hysteresis rotations driven by short term flushing events during the very early stages of spring runoff mining impacted sites had higher concentrations of many trace elements than did relatively pristine sites one of the mining impacted sites exhibited strong geochemical responses to spring rain events in the basin the results underscore the need to sample streams frequently during changing hydrologic and climatic conditions in order to accurately monitor surface water quality and to determine solute and particulate loads both contaminant and noncontaminant

composition and sources of lipid compounds in speleothem calcite from southwestern oregon and their paleoenvironmental implications we analyzed speleothem calcite from the oregon caves national monument southwestern oregon to determine the preservation distribution concentrations and sources of aliphatic lipid compounds preserved in the calcite maximum speleothem growth rate occurs during interglaciations and minimum during glacial intervals concentrations of the total lipid compounds range from 0 5 to 12 9 g g 1 they increase at times of low speleothem growth rate suggesting dilution whereas the apparent accumulation rate of lipid compounds tends to be highest during times of fastest speleothem growth rate such increased accumulation generally corresponds to times of warm interglacial climate suggesting either a greater source of organic materials during interglacial times and or greater efficiency of compound capture during more rapid calcite growth aliphatic lipid compounds include homologous n alkanoic acids n alkanols and methyl n alkanoates and sterols with concentrations ranging from 0 3 to 7 8 g g 1 0 4 to 1 1 g g 1 0 5 to 9 6 g g 1 and 0 1 to 2 7 g g 1 respectively minor amounts of branched methyl n alkanoates and dimethyl n alkanedioates are also present the high concentrations of methyl n alkanoates are the result of esterification reactions of free fatty acids in alkaline solutions with high ph values associated with the dripping cave waters the distribution patterns and geochemical parameters and indices indicate that the major sources of the aliphatic lipids involved leaching from higher plants and microbial residues derived from the soil zone above the cave system the estimated percentage of microbial inputs ranged from 42 to 90 of the total lipids and also showed an increase in accumulation during warm climates these well preserved lipid compounds in speleothem calcite could be used as biomarkers for paleoenvironmental study

the role of disseminated calcite in the chemical weathering of granitoid rocks accessory calcite present at concentrations between 300 and 3000 mg kg 1 occurs in fresh granitoid rocks sampled from the merced watershed in yosemite national park ca usa loch vale in rocky mountain national park co usa the panola watershed ga usa and the rio icacos puerto rico calcite occurs as fillings in microfractures as disseminated grains within the silicate matrix and as replacement of calcic cores in plagioclase flow through column experiments using de ionized water saturated with 0 05 atm co2 produced effluents from the fresh granitoid rocks that were dominated by ca and bicarbonate and thermodynamically saturated with calcite during reactions up to 1 7 yr calcite dissolution progressively decreased and was superceded by steady state dissolution of silicates principally biotite mass balance calculations indicate that most calcite had been removed during this time and accounted for 57 98 of the total ca released from these rocks experimental effluents from surfically weathered granitoids from the same watersheds were consistently dominated by silicate dissolution the lack of excess ca and alkalinity indicated that calcite had been previously removed by natural weathering the extent of ca enrichment in watershed discharge fluxes corresponds to the amounts of calcite exposed in granitoid rocks high ca na ratios relative to plagioclase stoichiometries indicate excess ca in the yosemite loch vale and other alpine watersheds in the sierra nevada and rocky mountains of the western united states this ca enrichment correlates with strong preferential weathering of calcite relative to plagioclase in exfoliated granitoids in glaciated terrains in contrast ca na flux ratios are comparable to or less than the ca na ratios for plagioclase in the subtropical panola and tropical rio icacos watersheds in which deeply weathered regoliths exhibit concurrent losses of calcite and much larger masses of plagioclase during transport limited weathering these results indicate that the weathering of accessory calcite may strongly influence ca and alkalinity fluxes from silicate rocks during and following periods of glaciation and tectonism but is much less important for older stable geomorphic surfaces

a new approach to detecting vegetation and land use change using high resolution lipid biomarker records in stalagmites a hundred year stalagmite lipid biomarker record from mechara southeastern ethiopia is presented the record has been recovered at a 10 yr temporal resolution marking the first time this has been achieved in stalagmite biomarker work and providing the first opportunity to investigate the relationship between stalagmite lipid records and hydrological transport lags a vital issue in interpreting palaeoenvironmental signals preserved plant derived n alkanes and n alkanols show clear changes in composition over time relating to known land use changes in the area particularly the expansion of agriculture in the early twentieth century the level of environmental detail provided by this technique combined with the long term chronological framework offered by stalagmites holds significant promise for the investigation of early human environments and their associated climatic and anthropogenic controls

determining soil sources by organic matter epr fingerprints in two modern speleothems organic matter om sources and transfers are critical questions at the crossroad of ecology hydrology and paleoenvironmental studies in karst environments recently chemical or isotopic characterisations of these organic matters have demonstrated their diversity in karst water and speleothems however knowledge of their origin and transfer from soil needs to be improved especially in karst environments where a mosaic of soils occurs here we investigate the applicability of the electron paramagnetic resonance epr signature of om to seek different soil fingerprints in speleothems the positions and the shapes of semiquinone type radical s epr lines are considered as a robust signature of the organic matter through the different compartment of karst ecosystems we demonstrate that the combination of epr lines simulation constitutes a fingerprint that discriminates folic leptosol developed on limestone outcrops from eutric cambisols located in the dolines and topographical depressions we also report the conservation of the thinner om epr lines after a water extraction of the organic matter from soils finally om epr signatures were detected in two different speleothems sampled near each other a stalagmite and a subaqueous flowstone an unexpected two orders of magnitude discrepancy between the free radical concentrations of the subaqueous flowstone and the soils on one hand and the low free radical concentration of the stalagmite samples on the other was ascribed to the kinetics of conformational changes in om occurring during their transfer through karst either in fast or in slow water pathways a folic leptosol fingerprint was found in stalagmite and conversely an eutric cambisol fingerprint was found in the flowstone sample this unexpected difference between the epr signatures of the flowstone sample and stalagmite sample was ascribed to the masking of the leptosol epr signature due to the low concentrations of free radicals in the case of the flowstone sample and to the fact that the epr signature of the stalagmite sample clearly shows the leptosol is the sole source of the om finally the folic leptosol fingerprint remains steady over the last four centuries covered by the stalagmite demonstrating that the source of the om is stable over the growth period strengthening the interest of om entrapped in speleothem for paleoenvironment studies

diel stream geochemistry taylor valley antarctica unlike temperate and polythermal proglacial streams the proglacial streams in taylor valley tv antarctica are derived primarily from glacier surface melt with no subglacial or groundwater additions solute responses to flow reflect only the interaction of glacial meltwater with the valley floor surrounding the stream channel we have investigated the major minor and trace element 24 h variations of two proglacial melt streams andersen creek and canada stream originating from the canada glacier in tv antarctica both streams exhibited diel mid austral summer diurnal flow variation with maximum flow being more than 50 times the minimum flow dissolved 0 4 m major minor and trace solute behaviors through diel periods were strongly controlled by the availability of readily solubilized material on the valley floor and hyporheic biological exchanges anderson creek had generally greater solute concentrations than canada stream because of its greater receipt of eolian sediment andersen creek also acquired greater solute concentrations in the rising limb of the hydrograph than the falling limb because of dissolution of eolian material at the surface of the stream channel coupled with minimal hyporheic biological exchange conversely canada stream had less available eolian sediment but a greater hyporheic biological exchange which preferentially removed trace and major solutes in the rising limb and released them in the falling limb given the dynamic nature of discharge eolian and hyporheic biological processes solute loads in tv streams are difficult to predict copyright 2012 john wiley sons ltd