scholarly journals A sedimentation study of St. Ana Lake (Romania) applying the 210Pb and 137Cs dating methods

2011 ◽  
Vol 38 (2) ◽  
pp. 93-100 ◽  
Author(s):  
Robert Begy ◽  
Alida Timar-Gabor ◽  
Janos Somlai ◽  
Constantin Cosma
Keyword(s):  
Sedimentation Rates ◽  
210Pb And 137Cs ◽  
137Cs Dating ◽  
210Po Activity ◽  
210Pb Activity ◽  
Dating Methods ◽  
Calculated Mass ◽  
Dating Method ◽  
High Resolution Gamma Spectrometry ◽  
Good Agreement

AbstractThe biggest problem with most lakes that have no contact with other water sources and are being charged by precipitation is the massive eutrophication. The aim of this work was to determine the sedimentation rate in order to evaluate the progress of eutrophication for St. Ana Lake (Ciomad Mountain near the Băile Tuşnad in Harghita County (Romania)). The concentration of 210Pb was determined by means of high resolution gamma spectrometry as well as derived from 210Po activity which was measured through alpha spectrometry; values obtained are in good agreement. For the excess 210Pb activity values between 4.0±0.5 Bq/kg and 218±20 Bq/kg have been found. As an alternative method, the 137Cs dating method was applied as well. Calculated mass sedimentation rates are in the range of 0.06±0.01 to 0.32±0.05 g/cm2 year with a mean of value of 0.15±0.02 g/cm2 year. Linear sedimentation rates yielded much higher sedimentation values (between 0.5±0.1 and 7.9±0.7 cm/year with a mean of 2.4±0.6 cm/year), due to the predominant organic matter composition and the long suspension time of the sediment. This is an indication for the process of eutrophication which will probably lead to the transformation of the lake into a peat bog.

scholarly journals Sedimentation rates in the Lake Qattinah using 210Pb and 137Cs as geochronometer

2014 ◽  
Vol 41 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Eskander Alhajji ◽  
Iyas Ismail ◽  
Mohammad Al-Masri ◽  
Nouman Salman ◽  
Mohammad Al-Haleem ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Past Century ◽  
Sedimentation Rates ◽  
Accumulation Rates ◽  
210Pb And 137Cs ◽  
The Past ◽  
Activity Concentrations ◽  
210Pb Activity ◽  
Constant Rate ◽  
210Pb Method

Abstract The constant rate of supply (CRS) of excess 210Pb model was successfully applied to assess 210Pb data of two sediment cores from the lake Qattinah, Syria. Gamma spectrometry was used to determine 137Cs and 210Pb activity concentrations. The bottom of the cores was 210Pb-dated to years 1907 and 1893. The accumulation rates were determined using 210Pb method and found to vary similarly in both cores from 0.10 ± 0.01 to 3.78 ± 0.57 kg m−2 y−1 during the past century. 137Cs was used as an in-dependent chronometer. The two distinct peaks observed on the 137Cs record of both cores, corresponding to 1965 and 1986, have allowed a successful validation of the CRS model.

Determination of recent sedimentation rates and pattern in Lake Naini, India by 210Pb and 137Cs dating techniques

1999 ◽  
Vol 51 (1) ◽  
pp. 97-105 ◽  
Author(s):  
U. Saravana Kumar ◽  
S.V. Navada ◽  
S.M. Rao ◽  
Rm.P. Nachiappan ◽  
Bhishm Kumar ◽  
...  
Keyword(s):  
Sedimentation Rates ◽  
210Pb And 137Cs ◽  
137Cs Dating

The determination of sedimentation rates in Lake Ontario using the 210Pb dating method

1978 ◽  
Vol 15 (3) ◽  
pp. 431-437 ◽  
Author(s):  
John G. Farmer
Keyword(s):  
Sedimentation Rate ◽  
Lake Ontario ◽  
Sedimentary Basins ◽  
210Pb Dating ◽  
Sedimentation Rates ◽  
Surface Mixing ◽  
Dating Method ◽  
210Pb Dating Method

The 210Pb dating method has been applied successfully to the determination of recent sedimentation rates at four sites distributed among the three major sedimentary basins (Niagara, Mississauga and Rochester) of Lake Ontario. Following correction for effects due to compaction of the sediments, mean sedimentation rates ranging from 0.02 cm/year at the periphery of the Mississauga basin to 0.11 cm/year in the Niagara and Rochester basins were determined. Allowance for compaction reduced the non-compaction-corrected sedimentation rates by 20–35%. Neither 210Pb nor fallout 137Cs profiles indicated surface mixing of sediment sufficient to noticeably affect the calculated sedimentation rates. At all four sites, the sedimentation rate seems to have remained constant during the last 100–150 years.

Characterization of the Chromosomalaac(6′)-Iz Gene of Stenotrophomonas maltophilia

1999 ◽  
Vol 43 (10) ◽  
pp. 2366-2371 ◽  
Author(s):  
Thierry Lambert ◽  
Marie-Cécile Ploy ◽  
François Denis ◽  
Patrice Courvalin
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Type I ◽  
Aminoglycoside Resistance ◽  
Reading Frame ◽  
A Value ◽  
Calculated Mass ◽  
Total Dna ◽  
Good Agreement

ABSTRACT The aac(6′)-Iz gene of Stenotrophomonas maltophilia BM2690 encoding an aminoglycoside 6′-N-acetyltransferase was characterized. The gene was identified as a coding sequence of 462 bp corresponding to a protein with a calculated mass of 16,506 Da, a value in good agreement with that of ca. 16,000 found by in vitro coupled transcription-translation. Analysis of the deduced amino acid sequence indicated that the protein was a member of the major subfamily of aminoglycoside 6′-N-acetyltransferases. The enzyme conferred resistance to amikacin but not to gentamicin, indicating that it was an AAC(6′) of type I. The open reading frame upstream from the aac(6′)-Izgene was homologous to the fprA gene of Myxococcus xanthus (61% identity), which encodes a putative pyridoxine (pyridoxamine) 5′-phosphate oxidase. Pulsed-field gel electrophoresis of total DNA from BM2690 and S. maltophilia ATTC 13637 digested with XbaI, DraI, and SpeI followed by hybridization with rRNA and aac(6′)-Iz-specific probes indicated that the gene was located in the chromosome. Theaac(6′)-Iz gene was detected by DNA-DNA hybridization in all 80 strains of S. maltophilia tested. The MICs of gentamicin against these strains of S. maltophilia were lower than those of amikacin, netilmicin, and tobramycin, indicating that production of AAC(6′)-Iz contributes to aminoglycoside resistance in S. maltophilia.

Radioanalytical assessment of sedimentation rates in Guajará Bay (Amazon Estuary, N Brazil): a study with unsupported 210Pb and 137Cs modeling

2013 ◽  
Vol 299 (1) ◽  
pp. 407-414 ◽  
Author(s):  
Patrícia Andrade Neves ◽  
Paulo Alves de Lima Ferreira ◽  
Márcia Caruso Bícego ◽  
Rubens Cesar Lopes Figueira
Keyword(s):  
Sedimentation Rates ◽  
210Pb And 137Cs ◽  
Unsupported 210Pb ◽  
Amazon Estuary

U-Th vs. AMS 14C dating of shells from the Achenheim loess (Rhine Graben)

2005 ◽  
Vol 176 (3) ◽  
pp. 249-255 ◽  
Author(s):  
Christophe Innocent ◽  
Christine Flehoc ◽  
Francis Lemeille
Keyword(s):  
14C Dating ◽  
Average Value ◽  
Rhine Graben ◽  
Younger Age ◽  
Isochron Diagram ◽  
Dating Method ◽  
Thorium 232 ◽  
Ams 14C Dating ◽  
Good Agreement

Abstract Shells extracted from loess deposits at Achenheim (Rhine Graben) have been investigated for AMS 14C and for U-Th dating by the isochron method on single shells. The two chronometers provide results that are not in agreement : the obtained 14C date is 38 ka B.P. In contrast, U-Th results provide much older ages. The 238U/232Th –230Th/232Th isochron diagram gives an age of 69 kyr, whereas a slightly younger age of 64 kyr is derived from the other, 234U/232Th – 230Th/232Th, diagram. 234U/238U ratios have not been found to vary from a shell to another : the average value is 1.199, slightly higher than radioactive equilibrium. For both isochrons, the Y-axis intercept is slightly negative, which indicates that there is no evidence for a significant detrital component. Thorium 232 that is present in the shells is probably incorporated in the material. The negative intercepts suggest that the two ages have been probably “aged” resulting from a slight mobilisation of uranium. By constraining the Y-axis intercepts at 0, ages that are in good agreement from one to another, can be calculated at 60.9 kyr and 60.4 kyr, respectively. In both cases, the statistical quality of the alignment is only slightly deteriorated. Since U-Th ages are in agreement with stratigraphic data, in contrast to the 14C date, one may believe that they date the end of early diagenesis, with uranium trapping. In contrast, the AMS 14C date is either thought to reflect analytical limitations of AMS 14C dating for such type of material, or to date a younger geologic event. In this latter case, a possible hypothesis is that this event has triggered the slight opening of the 238U – 234U system. In any case, this study demonstrates once again that surface formations often tell such complex stories that only one single dating method cannot usually be sufficient to describe precisely these histories. Instead, informations derived from different independent chronometers have to be compared.

Sedimentation rates in Bera Lake (Peninsular Malaysia) using 210Pb and 137Cs radioisotopes

2013 ◽  
Vol 17 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Mohammadreza Gharibreza ◽  
John Kuna Raj ◽  
Ismail Yusoff ◽  
Zainudin Othman ◽  
Wan Zakaria Wan Muhamad Tahir ◽  
...  
Keyword(s):  
Peninsular Malaysia ◽  
Sedimentation Rates ◽  
210Pb And 137Cs ◽  
Bera Lake

scholarly journals Multiple Dating of a Long Flowstone Profile

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 503-509 ◽  
Author(s):  
Mebus A Geyh ◽  
G J Hennig
Keyword(s):  
Growth Rate ◽  
West Germany ◽  
Spin Resonance ◽  
Dating Methods ◽  
Growth History ◽  
Order Of Magnitude ◽  
History Of ◽  
Dating Method ◽  
Closed Systems ◽  
Glacial Periods

Dense speleothem samples are considered as closed systems and are, therefore, possibilities for any dating method. Four dating methods (14C, U/Th, paleomagnetism, and electron spin resonance = ESR) were used for samples up to 1,000,000 yr old and taken along a vertical flowstone profile in the Heggen cave in West Germany. Also δ18O and δ13C analyses were carried out.The reliability of the results of each method is dependent on the diagenetic processes that took place during the complex growth history of the flowstone. Speleothem growth was interrupted during glacial periods. During interglacial periods, at least the stalagmite growth rate was greater by one order of magnitude than during interstadial periods. During the periods of low interstadial growth rate various processes might have changed the 14C, 18O, and 13C concentrations, leaching might have removed uranium, recrystallization might have moved thorium several centimeters, and increased content of radon in the cave might have exaggerated the accumulated dose (AD) at the speleothem surface. As a result, 14C ages may be too small and U/Th as well as ESR data may be too large.

Empirical formula for mass excess of heavy and superheavy nuclei

2016 ◽  
Vol 31 (28) ◽  
pp. 1650162 ◽  
Author(s):  
H. C. Manjunatha ◽  
B. M. Chandrika ◽  
L. Seenappa
Keyword(s):  
Empirical Formula ◽  
Superheavy Nuclei ◽  
Mass Excess ◽  
Hartree Fock ◽  
Heavy And Superheavy Nuclei ◽  
Polynomial Fit ◽  
Calculated Mass ◽  
Model Independent ◽  
Experimental Values ◽  
Good Agreement

A new empirical formula is proposed for mass excess of heavy and superheavy nuclei in the region Z = 96–129. The parameters of the formula are obtained by making a polynomial fit to the available theoretical and experimental data. The calculated mass excess values are compared with the experimental values and other results of the earlier proposed models such as finite range droplet model (FRDM) and Hartree–Fock–Bogoliubov (HFB) method. Standard deviation of calculated mass excess values for each atomic number is tabulated. The good agreement of present formula with the experiment and other models suggests that the present formula could be used to evaluate the mass excess values of heavy and superheavy nuclei in the region 96[Formula: see text][Formula: see text][Formula: see text]Z[Formula: see text][Formula: see text][Formula: see text]129. This formula is a model-independent formula and is first of its kind that produces a mass excess values with the only simple inputs of only Z and A.

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