scholarly journals Modern isotope hydrology and controls on δD of plant leaf waxes at Lake El'gygytgyn, NE Russia

2013 ◽  
Vol 9 (1) ◽  
pp. 335-352 ◽  
Author(s):  
K. M. K. Wilkie ◽  
B. Chapligin ◽  
H. Meyer ◽  
S. Burns ◽  
S. Petsch ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Winter Precipitation ◽  
Mean Value ◽  
Great Promise ◽  
Plant Leaf ◽  
Hydrologic Processes ◽  
Leaf Waxes ◽  
Lake El’Gygytgyn ◽  
Alkanoic Acids ◽  
Hydrogen Isotope Ratios

Abstract. Stable isotope data from lipid biomarkers and diatom silica recovered from lake sediment cores hold great promise for paleoclimate and paleohydrological reconstructions. However, these records rely on accurate calibration with modern precipitation and hydrologic processes and only limited data exist on the controls on the δD values for n-alkanoic acids from plant leaf waxes. Here we investigate the stable isotopic composition of modern precipitation, streams, lake water and ice cover, and use these data to constrain isotope systematics of the Lake El'gygytgyn Basin hydrology. Compound-specific hydrogen isotope ratios determined from n-alkanoic acids from modern vegetation are compared with modern precipitation and lake core top sediments. Multi-species net (apparent) fractionation values between source water (precipitation) and modern vegetation (e.g., ϵwax/precip mean value is −107 ± 12‰) agree with previous results and suggest a consistent offset between source waters and the δD values of alkanoic acids. We conclude that although there may be some bias towards a winter precipitation signal, overall δD values from leaf wax n-alkanoic acids record annual average precipitation within the El'gygytgyn Basin. A net fractionation calculated for 200-yr-integrated lake sediments yields ϵ30/precip = −96 ± 8‰ and can provide robust net "apparent" fractionation to be used in future paleohydrological reconstructions.

scholarly journals Modern isotope hydrology and controls on δD of plant leaf waxes at Lake El'gygytgyn, NE Russia

2012 ◽  
Vol 8 (4) ◽  
pp. 3719-3764 ◽  
Author(s):  
K. M. K. Wilkie ◽  
B. Chapligin ◽  
H. Meyer ◽  
S. Burns ◽  
S. Petsch ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Winter Precipitation ◽  
Mean Value ◽  
Great Promise ◽  
Arid Environments ◽  
Hydrologic Processes ◽  
Leaf Wax ◽  
Stable Isotopic ◽  
Lake El’Gygytgyn ◽  
Hydrogen Isotope Ratios

Abstract. Stable isotope data from lipid biomarkers and diatom silica recovered from lake sediment cores hold great promise for paleoclimate and paleohydrological reconstructions. However, these records rely on accurate calibration with modern precipitation and hydrologic processes. Here we investigate the stable isotopic composition of modern precipitation, streams, lake water and ice cover, and use these data to constrain isotope systematics of the Lake El'gygytgyn basin hydrology. Compound specific hydrogen isotope ratios determined from modern vegetation are compared with modern precipitation and lake core top sediments. Multi-species net (apparent) fractionation values between source water (precipitation) and leaf wax lipids (mean value is −105 ± 13‰) agree with previous results in arid environments and provide a basis for application of this proxy downcore. We conclude that although there may be some bias towards winter precipitation signal, overall leaf wax lipids record annual average precipitation within the El'gygytgyn Basin.

scholarly journals Quantitative and qualitative constraints on hind-casting the formation of multiyear lake-ice covers at Lake El'gygytgyn

2013 ◽  
Vol 9 (3) ◽  
pp. 1253-1269 ◽  
Author(s):  
M. Nolan
Keyword(s):  
Water Exchange ◽  
Sediment Cores ◽  
Ice Cover ◽  
Lake Ice ◽  
Ice Growth ◽  
Temperature Reduction ◽  
Air Temperatures ◽  
Lake El’Gygytgyn ◽  
Oxygen Conditions ◽  
Multiyear Ice

Abstract. Analysis of the 3.6 Ma, 318 m long sediment core from Lake El'gygytgyn suggests that the lake was covered by ice for millennia at a time for much of its history and therefore this paper uses a suite of existing, simple, empirical degree-day models of lake-ice growth and decay to place quantitative constraints on air temperatures needed to maintain a permanent ice cover on the lake. We also provide an overview of the modern climatological and physical processes that relate to lake-ice growth and decay as a basis for evaluating past climate and environmental conditions. Our modeling results indicate that modern annual mean air temperature would only have to be reduced by 3.3 °C ± 0.9 °C to initiate a multiyear ice cover and a temperature reduction of at least 5.5 °C ± 1.0 °C is likely needed to completely eliminate direct air–water exchange of oxygen, conditions that have been inferred at Lake El'gygytgyn from the analysis of sediment cores. Once formed, a temperature reduction of only 1–3 °C relative to modern may be all that is required to maintain multiyear ice. We also found that formation of multiyear ice covers requires that positive degree days are reduced by about half the modern mean, from about +608 to +322. A multiyear ice cover can persist even with summer temperatures sufficient for a two-month long thawing period, including a month above +4 °C. Thus, it is likely that many summer biological processes and some lake-water warming and mixing may still occur beneath multiyear ice-covers even if air–water exchange of oxygen is severely restricted.

scholarly journals Simultaneous Determination of Local Cerebral Glucose Utilization and Blood Flow by Carbon-14 Double-Label Autoradiography: Method of Procedure and Validation Studies in the Rat

1986 ◽  
Vol 6 (3) ◽  
pp. 273-285 ◽  
Author(s):  
Myron D. Ginsberg ◽  
David W. Smith ◽  
Mitchell S. Wachtel ◽  
Mayra Gonzalez-Carvajal ◽  
Raul Busto
Keyword(s):  
Validation Studies ◽  
Optimization Procedure ◽  
Mean Value ◽  
Great Promise ◽  
Computer Assisted ◽  
Published Data ◽  
Carbon 14 ◽  
Coefficients Of Variation ◽  
Double Label ◽  
Label Strategy

Validation studies were undertaken to establish a computer-assisted double-label autoradiographic strategy employing [14C]2-deoxyglucose ([14C]2DG) and [14C]iodoantipyrine ([14C]IAP) to measure local CMRglu (LCMRglu) and CBF (LCBF). An organic solvent was used to extract the majority of IAP between first and second film exposures. In contrast to previously published data, all solvents tested produced partial losses of 2DG from tissue, and all allowed 2–6% of IAP to persist even after 5-day washes. Technical-grade chloroform permitted equal retention of unmetabolized and metabolized 2DG. A linear model was established, which was insensitive to the changes in tissue self-absorption that were shown to occur with chloroform extraction. Propagated error in computing tissue [14C]2DG and [14C]IAP was reduced by maximizing IAP extraction (by longer solvent wash times) and by administering 2.5 times as much IAP as 2DG. Fractional 2DG retention was measured in single-label 2DG sections placed on the films, and fractional IAP retention was evaluated by an optimization procedure. With this strategy, double-label values for LCMRglu and LCBF in anesthetized rats agreed with values obtained in matched single-label series to within 5%. The coefficients of variation for the double- and single-label LCMRglu data were virtually identical, whereas the coefficient of variation for double-label LCBF was 1.8 times that of single-label LCBF. The double-label strategy permitted pixel-by-pixel measurement and video display of the LCMRglu/LCBF ratio; the mean value among structures was 0.472 μmol/ml. With proper attention to methodological detail, this double-label strategy shows great promise for routine laboratory application.

scholarly journals Radiocarbon Dating of Pleistocene Fauna and Flora from Starunia, SW Ukraine

Radiocarbon ◽  
2012 ◽  
Vol 54 (01) ◽  
pp. 123-136 ◽  
Author(s):  
T Kuc ◽  
K Różański ◽  
M J Kotarba ◽  
T Goslar ◽  
H Kubiak
Keyword(s):  
Sediment Cores ◽  
Mean Value ◽  
Natural History Museums ◽  
Burial Site ◽  
History Museums ◽  
Minimum Age ◽  
The Mean ◽  
Field Campaigns ◽  
Pleistocene Mammals ◽  
Age Range

New attempts arc presented to determine the age of large Pleistocene mammals excavated at Starunia, ∼130 km southeast of Lviv, Ukraine. This remarkable discovery made at the beginning of the 20th century included a complete carcass of woolly rhinoceros (No. 2), fragments of 3 woolly rhinoceroses (Nos. 1, 3, and 4) and remnants of numerous specimens of other fossil fauna and flora. Although attempts to date paleontological findings from Starunia site go back to the early 1970s, the results obtained before 2006 arc somewhat misleading, mostly due to unresolved contamination problems. Comprehensive cleaning of the samples adopted in the framework of this study was aimed at removal of 2 potential sources of contamination: (i) radiocarbon-free hydrocarbons abundant at the burial site; and (ii) allochthonous organic materials containing contemporary carbon that were used in the past during preservation of the dated specimens. Two types of samples have been analyzed for their14C content in the framework of the present study: (i) fragments of bones and teeth collected from specimens stored or exposed in the Natural History museums in Lviv and Kraków; and (ii) samples of terrestrial macrofossils retrieved from sediment cores obtained during the 2007–2008 field campaigns in the Starunia area.14C analyses of collagen were supplemented by measurements of its elemental C/N ratio and13C/12C and15N/14N isotope ratios. Three14C dates obtained for rhinoceros No. 2 span the age range from 35.3 to 40.0 ka BP, in agreement with the minimum age estimated from macrofossils. The mean value of 37.7 ± 1.7 ka BP falls in the range of ages reported for big Pleistocene mammals from other locations in Europe. The bones of rhinoceros No. 3, which were found in close vicinity to those of rhinoceros No. 2, reveal a14C age of 36.7 ± 0.6 ka BP. The δ15N and δ13C values obtained for collagen extracted from bones and teeth belonging to rhinoceroses Nos. 1, 2, and 3 are in a broad agreement with analogous literature data for large Pleistocene mammals found in other sites in Europe, North America, and Siberia.

scholarly journals A statistical mass-balance model for reconstruction of LIA ice mass for glaciers in the European Alps

2007 ◽  
Vol 46 ◽  
pp. 161-169 ◽  
Author(s):  
Wolfgang Schöner ◽  
Reinhard Böhm
Keyword(s):  
Mass Balance ◽  
Input Data ◽  
Driving Forces ◽  
Winter Precipitation ◽  
Mean Value ◽  
Balance Model ◽  
European Alps ◽  
Seasonal Temperature ◽  
Mass Balance Model ◽  
Linear Regression Models

AbstractStepwise linear regression models were calibrated against the measured mass balance of glaciers in the Austrian Alps for the prediction of specific annual net balance and summer balance from climatological and topographical input data. For estimation of winter mass balance, a simple ratio between the amount of winter precipitation and the measured winter balance was used. A ratio with a mean value of 2.0 and a standard deviation of 0.44 was derived from the sample of measured winter balances. Climate input data were taken from the HISTALP database which offers a homogenized data source that is outstanding in terms of its spatial and temporal coverage. Data from the Austrian glacier inventory were used as topographical input data. From the group of possible predictors summer air temperature, winter precipitation, summer snow precipitation and continentality (as defined from seasonal temperature variation) were selected as climatological driving forces in addition to lowest glacier elevation and area-weighted mean glacier elevation as topographical driving forces. Summer temperature explains 60% of the variance of summer mass balance and 39% of the variance of annual mass balance. Additional factors increase the explained variance by 22% for summer and 31% for annual net balance. The calibrated mass-balance model was used to reconstruct the mass balance of Hintereisferner and Vernagtferner back to 1800. Whereas the model performs well for Hintereisferner, it fails for some sub-periods for Vernagtferner due to the complicated flow dynamics of the glacier.

scholarly journals Leaf waxes in litter and topsoils along a European transect

2016 ◽  
Author(s):  
Imke Schäfer ◽  
Verena Lanny ◽  
Jörg Franke ◽  
Timothy I. Eglinton ◽  
Michael Zech ◽  
...  
Keyword(s):  
Chain Length ◽  
Deciduous Forest ◽  
Soil Depth ◽  
Large Species ◽  
Alkanoic Acid ◽  
Climate Conditions ◽  
Leaf Wax ◽  
Leaf Waxes ◽  
Forest Sites ◽  
Alkanoic Acids

Abstract. Lipid biomarkers are increasingly used to reconstruct past environmental and climate conditions. Leaf wax derived long chain n-alkanes and n-alkanoic acids may have great potential for reconstructing past changes in vegetation, but the factors that affect the leaf wax distribution in fresh plant material, as well as in soils and sediments are not yet fully understood and need further research. We systematically investigated the influence of vegetation and soil depth on leaf waxes in litter and topsoils along a European transect. Our deciduous forest sites are often dominated by the n-C27 alkane and n-C28 alkanoic acid. Conifers produce few n-alkanes, but show high abundances of the C24 n-alkanoic acid. Grasslands are characterized by relatively high amounts of C31 and C33 n-alkanes and C32 and C34 n-alkanoic acids. Chain length ratios thus may allow to distinguish between different vegetation types, but caution must be exercised given the large species-specific variability of chain length patterns. An updated endmember model with a new n-alkane ratio is provided to illustrate, and tentatively account for, degradation effects on n-alkanes.

scholarly journals Changes of Carbon Number of Hydrocarbon Contained in Various Plant Leaf Waxes

1981 ◽  
Vol 19 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Yoshitoshi HIROOKA ◽  
Kimihiko SATO ◽  
Masana SUWANAI
Keyword(s):  
Carbon Number ◽  
Plant Leaf ◽  
Leaf Waxes

scholarly journals Residual Level, Profile and Potential Ecological Risk of Organochlorine Pesticides in Subsurface Sediments from Lakeshore Backfill Site and Lakebed of an Abandoned Oxidation Pond After Desilting for 15 Years

2021 ◽  
Author(s):  
Ya-Fen Wang ◽  
Tao Liu ◽  
JinCan Tang ◽  
ZhiWei Xiong ◽  
LiangChu Song ◽  
...  
Keyword(s):  
Organochlorine Pesticides ◽  
Sediment Cores ◽  
Acid Methyl Ester ◽  
Principal Component ◽  
Potential Ecological Risk ◽  
Mean Value ◽  
Oxidation Pond ◽  
Subsurface Sediments ◽  
Deep Layers ◽  
Agricultural Input

Abstract The occurrence and distribution of 19 organochlorine pesticides (OCPs), together with microbial ester-linked fatty acid methyl ester (EL-FAME) profiles were investigated in sediments from an abandoned oxidation pond of Ya-Er lake, China, which had been heavily polluted by hexachlorocyclohexanes (HCHs) and chlorobenzenes in 1980s. Subsurface sediment samples were taken from five sediment cores along the transect running from lakeshore to lakebed. The concentration of total OCPs ranged from 29.8 to 941.8 ng g-1 dw, with a mean value of 193.3 ng g-1 dw. Hexachlorobenzene (HCB), HCHs and dichlorodiphenyl-trichloroethanes (DDTs) were the three dominant OCP classes, accounting for 26.5%-97.4%, 1.8%-51.5%, and 0.4%-15.5% of the total, respectively. Hot spots of HCB, HCHs and DDTs were detected in 0.9-2.7 m deep layers of the lakeshore, where was one of the dredged sediment backfill sites for in-situ remediation of the oxidation pond in 2002-2004. High potential risks of HCHs and HCB were still indicated. Historical industrial input (27.2%), recent agricultural input (14.7%), and persistent residuals (14.3%) were the three major identified sources of OCPs, using Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR). Redundancy analysis of microbial EL-FAME profiles and nine dominant OCPs revealed that the spatial variation in microbial community structure was significantly corresponded with the OCP composition. This is the first study highlighted the concern on historical industrial inputs of OCPs in subsurface sediments of the lakeshore disposal zone. The findings could help to distinguish the artificial backfill sediments from natural polluted sediments for optimization of further desilting plans.

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