scholarly journals Optically stimulated luminescence and isothermal thermoluminescence dating of high sensitivity and well bleached quartz from Brazilian sediments: from Late Holocene to beyond the Quaternary?

2016 ◽  
Vol 46 (suppl 1) ◽  
pp. 209-226 ◽  
Author(s):  
André Oliveira Sawakuchi ◽  
Vinicius Ribau Mendes ◽  
Fabiano do Nascimento Pupim ◽  
Thays Desiree Mineli ◽  
Ligia Maria Almeida Leite Ribeiro ◽  
...  
Keyword(s):  
Late Holocene ◽  
High Sensitivity ◽  
Equivalent Dose ◽  
Optically Stimulated Luminescence ◽  
Osl Dating ◽  
Fluvial Sediments ◽  
Dose Distributions ◽  
Age Limit ◽  
Sediment Mixture

ABSTRACT: The development of optically stimulated luminescence (OSL) dating of sediments has led to considerable advance in the geochronology of the Quaternary. OSL dating is a well established technique to determine sediment burial ages from tens of years to few hundred thousand years. Recent studies have shown that Quaternary sediments of Brazil are dominated by quartz grains with high luminescence sensitivity, allowing the determination of precise and reliable OSL burial ages. In this paper, we show examples of OSL dating of quartz aliquots and single grains from different regions in Brazil, including young coastal-eolian Late Holocene (< 100 years) to Late Pleistocene (~ 150 ka) fluvial sediments. We discuss the OSL data and ages of sediments from carbonate and terrigenous (distributary and tributary systems) fluvial depositional contexts in Brazil. Most of the studied fluvial sediments show equivalent dose distributions with low to moderate dispersion, suggesting well bleached sediments. The comparison between aliquot and single grain data suggests that high overdispersion in equivalent dose distributions of some samples is more related with sediment mixture due to bioturbation than with incomplete bleaching during transport. Well bleached fluvial sediments contrast with the poor bleached pattern usually described for fluvial sediments in the literature. A large part of the fluvial sedimentary record in Brazil is older than the age limit for quartz OSL dating using blue light stimulation. Thus, isothermal thermoluminescence (ITL) dating protocols were tested for dating of fluvial sands from the Xingu River (eastern Amazonia). The studied sample can recover reliable equivalent doses up to 1600 Gy using the ITL 310oC signal. Therefore, this signal would be suitable to extend the age limit of quartz luminescence to the whole Quaternary or beyond (> 2 Ma) in the low dose rate (0.5 - 1.0 Gy/ka) environments typical for Brazilian sediments.

scholarly journals Expectations of scatter in equivalent-dose distributions when using multi-grain aliquots for OSL dating

2011 ◽  
Vol 38 (4) ◽  
pp. 424-431 ◽  
Author(s):  
Alastair Cunningham ◽  
Jakob Wallinga ◽  
Philip Minderhoud
Keyword(s):  
Dose Rate ◽  
Equivalent Dose ◽  
Osl Dating ◽  
Dose Distributions ◽  
Sensitivity Distribution ◽  
Minimum Age ◽  
Single Grain ◽  
Counting Statistics ◽  
Partial Bleaching

AbstractIn the OSL dating of sediment, the scatter in equivalent dose (D e) between grains is almost always larger than would be expected due to counting statistics alone. Some scatter may be caused by insufficient (partial) bleaching of some of the grains prior to deposition. In order to date partially bleached sediment, it is essential to estimate the amount of scatter caused by other processes (e.g. grain-to-grain variability in the natural dose rate). Measurements of such scatter are performed at the single-grain level; by contrast, most OSL dating is performed on multi-grain subsamples, for which grain-to-grain scatter is reduced through averaging.Here we provide a model for estimating the expected scatter (i.e. excluding that caused by partial bleaching) for multi-grain aliquots. The model requires as input the single-grain sensitivity distribution, the number of grains in the sub-samples, and the expected scatter at the single-grain level, all of which can be estimated to an adequate degree. The model compares well with measured values of scatter in D e, determined using aliquots of various sizes, and can be used to help produce a minimum-age D e from multi-grain subsamples that is consistent with single-grain data.

scholarly journals Molluscan communities in Late Holocene fluvial deposits as an indicator of human activity: A study in Podhale basin in South Poland

2013 ◽  
Vol 32 (1) ◽  
Author(s):  
Witold Paweł Alexandrowicz
Keyword(s):  
Late Holocene ◽  
Environmental Changes ◽  
Fluvial Sediments ◽  
Human Settlement ◽  
Anthropogenic Pressures ◽  
Fluvial Deposits ◽  
History Of ◽  
Wide Scale

AbstractThe localities of Late Holocene fluvial sediments in the Podhale basin were subjected to malacological analysis. Two types of mollusc communities were found in these formations. The first type is characterized by a high proportion of species typical of open environments such as the zones of wide valleys. The predomination of shade-loving taxa is typical of the second type which is mainly associated with narrow, V-shaped type valleys. Malacological analysis allowed characterization of these communities and reconstruction of environmental changes over the last few hundred years. Particular attention was paid to the reconstruction of the history of human settlement in the Podhale region and its impact on the transformation of the environment. This impact resulted in massive deforestation and the introduction of wide-scale farming and pastoral practices. Application of this malacological analysis enabled the determination of the anthropogenic pressures, and changes in their intensity, over the last few hundred years.

Middle–Late Holocene earthquake history of the Gyrtoni Fault, Central Greece: Insight from optically stimulated luminescence (OSL) dating and paleoseismology

2016 ◽  
Vol 687 ◽  
pp. 14-27 ◽  
Author(s):  
Ioannis M. Tsodoulos ◽  
Konstantinos Stamoulis ◽  
Riccardo Caputo ◽  
Ioannis Koukouvelas ◽  
Alexandros Chatzipetros ◽  
...  
Keyword(s):  
Late Holocene ◽  
Optically Stimulated Luminescence ◽  
Osl Dating ◽  
Central Greece ◽  
History Of

scholarly journals First note on marine-like cementation of Late Holocene beachrock, Iznik Lake (Turkey)

2012 ◽  
Vol 39 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Ahmet Erginal ◽  
Nafiye Kiyak ◽  
Muhammed Ozturk ◽  
Erdinc Yigitbas ◽  
Mustafa Bozcu ◽  
...  
Keyword(s):  
Fresh Water ◽  
Late Holocene ◽  
Optically Stimulated Luminescence ◽  
Osl Dating ◽  
First Report ◽  
Climatic Optimum

Abstract Micro-fabric characteristics and optically stimulated luminescence (OSL) dating results are presented to discuss the controlling agents and timing of beachrock cementation on the fresh-water Iznik Lake shoreline. The beachrocks are made up of grain-supported polygenic conglomerate containing 20.42% carbonate with encrusted grains, basically as micrite coatings, isopachous aragonite rims, cryptocrystalline void fills and meniscus bridges. The optical ages of twelve samples yielded ages that range from 4.226±0.569 ka on the lowermost beds to 0.706±0.081 on the uppermost. This is the first report of precipitation of marine-like cements in Iznik Lake. The abundant aragonite-dominated cement is likely indicative of precipitation-prone dry evaporative conditions from the climatic optimum to the last millennia.

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

Determination of Selected Phthalates in Some Commercial Cosmetic Products by HPLC-UV

2020 ◽  
Vol 23 (10) ◽  
pp. 1010-1022
Author(s):  
Emrah Dural
Keyword(s):  
High Performance ◽  
Phthalate Esters ◽  
High Sensitivity ◽  
Hplc Method ◽  
Cosmetic Products ◽  
Limit Of Quantification ◽  
Nail Polish ◽  
Accuracy And Precision ◽  
Butyl Phthalate

Aim and scope: Due to the serious toxicological risks and their widespread use, quantitative determination of phthalates in cosmetic products have importance for public health. The aim of this study was to develop a validated simple, rapid and reliable high-performance liquid chromatography (HPLC) method for the determination of phthalates which are; dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), di(2- ethylhexyl) phthalate (DEHP), in cosmetic products and to investigate these phthalate (PHT) levels in 48 cosmetic products marketing in Sivas, Turkey. Materials and Methods: Separation was achieved by a reverse-phase ACE-5 C18 column (4.6 x 250 mm, 5.0 μm). As the mobile phase, 5 mM KH2PO4 and acetonitrile were used gradiently at 1.5 ml min-1. All PHT esters were detected at 230 nm and the run time was taking 21 minutes. Results: This method showed the high sensitivity value the limit of quantification (LOQ) values for which are below 0.64 μg mL-1 of all phthalates. Method linearity was ≥0.999 (r2). Accuracy and precision values of all phthalates were calculated between (-6.5) and 6.6 (RE%) and ≤6.2 (RSD%), respectively. Average recovery was between 94.8% and 99.6%. Forty-eight samples used for both babies and adults were successfully analyzed by the developed method. Results have shown that, DMP (340.7 μg mL-1 ±323.7), DEP (1852.1 μg mL-1 ± 2192.0), and DBP (691.3 μg mL-1 ± 1378.5) were used highly in nail polish, fragrance and cream products, respectively. Conclusion: Phthalate esters, which are mostly detected in the content of fragrance, cream and nail polish products and our research in general, are DEP (1852.1 μg mL-1 ± 2192.0), DBP (691.3 μg mL-1 ± 1378.5) and DMP (340.7 μg mL-1 ±323.7), respectively. Phthalates were found in the content of all 48 cosmetic products examined, and the most detected phthalates in general average were DEP (581.7 μg mL-1 + 1405.2) with a rate of 79.2%. The unexpectedly high phthalate content in the examined cosmetic products revealed a great risk of these products on human health. The developed method is a simple, sensitive, reliable and economical alternative for the determination of phthalates in the content of cosmetic products, it can be used to identify phthalate esters in different products after some modifications.

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