scholarly journals Crustal uplifting rate associated with late-Holocene glacial-isostatic rebound at Skallen and Skarvsnes, Lützow-Holm Bay, East Antarctica: evidence of a synchrony in sedimentary and biological facies on geological setting

2010 ◽  
Vol 7 (3) ◽  
pp. 4341-4384 ◽  
Author(s):  
Y. Takano ◽  
Y. Yokoyama ◽  
J. J. Tyler ◽  
H. Kojima ◽  
M. Fukui ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Fresh Water ◽  
Late Holocene ◽  
Environmental Changes ◽  
Temporal Variations ◽  
East Antarctica ◽  
Rrna Gene ◽  
16S Rrna Gene Analysis ◽  
Isostatic Rebound ◽  
Geological Setting

Abstract. We determined the mean crustal uplifting rate during the late Holocene along the Soya Coast, Lützow-Holm Bay, East Antarctica, by dating a marine-lacustrine transition recorded in lake sediments. We focused on temporal variations in the chemical composition of sediments recovered from Lake Skallen Oike at Skallen and Lake Oyako at Skarvsnes. Both sets of lake sediments record environmental changes associated with a transition from marine to lacustrine (fresh water) settings, as indicated by analyses of sedimentary facies for carbon and nitrogen contents, nitrogen isotopic compositions (15N/14N), and major element concentrations. Changes in the dominant primary producers during the marine-lacustrine transition were also clearly revealed by biogenic Opal-A, diatom assemblages, and gradient gel electrophoresis (DGGE) with 16S rRNA gene analysis. Geochronology based on radiocarbon dating of acid-insoluble organic carbon suggested that the environmental transition from saline to fresh water occurred at 2940±100 cal yr BP at L. Skallen and 1060±90 cal yr BP at L. Oyako. Based on these data and a linear approximation model, we estimated a mean crustal uplifting rate of 3.6 mm yr−1 for the period since the marine-lacustrine transition via brackish condition; this uplift is attributed to glacial-isostatic rebound along the Soya Coast. The geological setting was the primary factor in controlling the emergence event and the occurrence of simultaneous changes in sedimentary and biological facies along the zone of crustal uplift.

Paleoclimatic reconstruction studies in lake sediments: major proxies, technical evolution and database

2020 ◽  
Author(s):  
Paula Bianchini ◽  
Elder Yokoyama ◽  
Luciana Prado
Keyword(s):  
Lake Sediments ◽  
Climate Changes ◽  
Environmental Changes ◽  
Drainage Basin ◽  
Spatial Scales ◽  
Temporal Variations ◽  
Quality Data ◽  
Anthropogenic Factors ◽  
Data Sets ◽  
Geochemical Composition

<p>Paleoclimate studies in different temporal and spatial scales provide important information on long-term statistics required to test hypotheses about climate changes. Comprehensive high-quality data sets and a solid understanding of dynamic climate processes in different temporal variations are essential to evaluate the sensitivity of the climatic system. Moreover, these data sets and dynamic analyses can help to distinguish the variability of natural and anthropogenic factors, reducing uncertainties about the magnitude and impact of future global climate changes. A common way to conduct paleoclimatic studies is through high resolution multiproxy lake sediments. Lake environments have been increasingly used in recent years to infer past fluctuations in climate, and many studies that comprise different locations and timescales demonstrate the great value of lakes as paleoclimatic archives. Because lake sediments are continental indicators sensitive to environmental changes, they can be used to reconstruct climate parameters, such as past rainfall, area management and environmental or limnological lake conditions. Changes of rainfall quantity can be recorded in lake archives by the variation of sedimentary input, which is related to changes in drainage basin and erosion rate. Beside of sedimentary input, lake sediments also exhibit physical and chemical changes in water bodies which, in turn, induce transformation in geochemical composition caused by changes in runoff or other allocated components. Thus, there is a variation in the proxies used in the studies, both in relation to the type of proxy used and the relationship used. In this context, we made a compilation of paleoclimatic studies on lake sediments (about 350 lakes), focusing on the main proxies used. Our study shows that there has been a change in the major proxies used along decades and with the emergence of new analysis techniques. In addition, we notice that lake characteristics (e.g., shape, geomorphological context, formation, etc.) have directly influence the proxies used and the quality of the information obtained. This compilation provides a database with an analysis of several lakes around the world, which can help future works and enable the identification of commonly used proxies according to the different variables that should be used, promoting more objective analyzes.</p>

scholarly journals Diatom analysis of Edku Lake sediments to assess the Late Holocene environmental changes in northern Egypt

2017 ◽  
Vol 38 (2) ◽  
pp. 234-247
Author(s):  
Abdelfattah A. Zalat ◽  
Hamza M. Khalil ◽  
Ali S. Ali ◽  
Seham A. El Nagar
Keyword(s):  
Lake Sediments ◽  
Late Holocene ◽  
Environmental Changes ◽  
Diatom Analysis ◽  
Northern Egypt

scholarly journals Microbiome of Odontogenic Abscesses

2021 ◽  
Vol 9 (6) ◽  
pp. 1307
Author(s):  
Sebastian Böttger ◽  
Silke Zechel-Gran ◽  
Daniel Schmermund ◽  
Philipp Streckbein ◽  
Jan-Falco Wilbrand ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Oral Microbiome ◽  
Minor Role ◽  
Rrna Gene ◽  
Sequencing Analysis ◽  
Bacterial Strains ◽  
16S Rrna Gene Analysis ◽  
Odontogenic Infections ◽  
Odontogenic Abscess

Severe odontogenic abscesses are regularly caused by bacteria of the physiological oral microbiome. However, the culture of these bacteria is often prone to errors and sometimes does not result in any bacterial growth. Furthermore, various authors found completely different bacterial spectra in odontogenic abscesses. Experimental 16S rRNA gene next-generation sequencing analysis was used to identify the microbiome of the saliva and the pus in patients with a severe odontogenic infection. The microbiome of the saliva and the pus was determined for 50 patients with a severe odontogenic abscess. Perimandibular and submandibular abscesses were the most commonly observed diseases at 15 (30%) patients each. Polymicrobial infections were observed in 48 (96%) cases, while the picture of a mono-infection only occurred twice (4%). On average, 31.44 (±12.09) bacterial genera were detected in the pus and 41.32 (±9.00) in the saliva. In most cases, a predominantly anaerobic bacterial spectrum was found in the pus, while saliva showed a similar oral microbiome to healthy individuals. In the majority of cases, odontogenic infections are polymicrobial. Our results indicate that these are mainly caused by anaerobic bacterial strains and that aerobic and facultative anaerobe bacteria seem to play a more minor role than previously described by other authors. The 16S rRNA gene analysis detects significantly more bacteria than conventional methods and molecular methods should therefore become a part of routine diagnostics in medical microbiology.

Beryllium isotopes in sediments from Lake Maruwan Oike and Lake Skallen, East Antarctica, reveal substantial glacial discharge during the late Holocene

2021 ◽  
Vol 256 ◽  
pp. 106841 ◽  
Author(s):  
Adam D. Sproson ◽  
Yoshinori Takano ◽  
Yosuke Miyairi ◽  
Takahiro Aze ◽  
Hiroyuki Matsuzaki ◽  
...  
Keyword(s):  
Late Holocene ◽  
East Antarctica ◽  
Beryllium Isotopes ◽  
Glacial Discharge

scholarly journals Late-Holocene landscape evolution and human presence in the northern Danube delta (Chilia distributary lobes)

The Holocene ◽  
2021 ◽  
pp. 095968362110191
Author(s):  
Luminița Preoteasa ◽  
Alfred Vespremeanu-Stroe ◽  
Anca Dan ◽  
Laurențiu Țuțuianu ◽  
Cristian Panaiotu ◽  
...  
Keyword(s):  
Middle Ages ◽  
Economic History ◽  
Late Holocene ◽  
Environmental Changes ◽  
Land Use Changes ◽  
Sedimentary Facies ◽  
The Black Sea ◽  
Danube Delta ◽  
Human Presence ◽  
Historical Texts

This paper documents the Late-Holocene environmental changes and human presence in the northern Danube delta using a multidisciplinary approach that combines geoscientific data with archaeological findings, historical texts, and maps. It follows the formation and progression of the Chilia distributary and the reconfiguration of socioeconomic activities. Sedimentary facies identified on five new cores by changes in texture properties, magnetic susceptibility, geochemistry, and macro- and microfauna composition together with the newly obtained chronology constrain the complex evolution of the Chilia branch as filling in a long-lasting bay and then of a giant lagoon (Thiagola) which covered most of the northern delta since the Old Danube lobe inception (ca. 7500 yrs BP) till modern Chilia development. It initiated during the Greek Antiquity (ca. 2500 yrs ar BP) at the delta apex, while in Roman times (ca. 1800 yrs BP) it pursued its slow flowing into the vast Thiagola Lagoon. The most dramatic transformations occurred in the last 800 years when the river passed east of the Chilia promontory, rapidly went through the present-day Matița-Merhei basin (several decades), and created its first open-sea outlet. Solid discharge increased in two distinct periods, once in the Middle Ages (ca. 750 yrs BP) and then in the Modern Period (ca. 150 yrs BP) due to human-induced land-use changes in the Danube watershed. The chronology of the cultural remains on the pre-deltaic Chilia promontory and the multiproxy analysis of a sediment core retrieved nearby downstream suggest the terrestrial connection of the island with the mainland in ancient times. The hitherto contended issue of the old Thiagola Lagoon and its location are redefined here, as are the original identifications of ancient and medieval toponyms and hydronyms, especially for Chilia-Licostomo, Byzantine, Genoese, Moldavian, Ottoman, and Russian trading point of great importance in the political and economic history of the Black Sea and neighboring regions.

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