fossil diatoms
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Phytotaxa ◽  
2022 ◽  
Vol 530 (3) ◽  
pp. 295-300
Author(s):  
J.P. KOCIOLEK ◽  
A. DANZ

We describe a new species of the diatom genus Grunowia, G. mannii Kociolek & A.Danz, sp. nov., from a Miocene fossil deposit in New Mexico, USA. The species has wide fibulae, a keel that is off-center externally, with distinct proximal raphe ends, both internally and externally. The species is differentiated from others in the genus in the narrow valves that are swollen and rounded in the center. We formally transfer two species from Nitzschia to Grunowia, making the new combinations, Grunowia constricta (Chen & Zhu) Kociolek & A.Danz, comb. nov. and Grunowia pseudosinuata (Hamilton & Laird) Kociolek & A.Danz, comb. nov. We discuss the distribution of the genus over time and space. This report from the Miocene represents the oldest known member of the genus Grunowia in the fossil record.


2021 ◽  
Vol 64 (5) ◽  
pp. VO553
Author(s):  
Luigina Vezzoli ◽  
Claudia Principe ◽  
Chiara Sorbini

At the foothillof Monte Amiata volcano (southern Tuscany, Italy), small extinct lake basins of late Pleistocene age are documented. These lake basins were characterized by the deposition of two very different types of sediment: a) derived from the authigenic precipitation of iron oxides (goethite) and exploited as earth pigments; b) biogenic siliceous sediment composed of fossil diatoms and named diatomaceous earth or diatomite. The lacustrine sediments of Mount Amiata volcano were widely exploited for various applications since ancient times. Literary documents begin in the 16th century, with the descriptions of Cesalpino, Gesner, Agricola, and Imperato. Specific references to the diatomites of Monte Amiata are quoted in the 17th century by Boccone and Bonanno. The quarrying activity was described by Micheli in 1733. During the 18th and 19th centuries, the diatomaceous earths of Monte Amiata are part of the important geological collections of Micheli, Targioni Tozzetti, Baldassarri, Campani, and Tommi. A particular significance has the collection of botanic and ichthyologic fossils collected by Ezio Tongiorgi, and now preserved in the Museum of Natural History of the University of Pisa sited at the Charterhouse of Pisa in the Calci village. These paleontological samples preserve the biological and physical testimonies of the environmental and climatic changes of the late Pleistocene and are now particularly valuable because they are the only remaining evidence of the diatomaceous lacustrine deposits of the paleo-lakes of Monte Amiata. For these reasons, they represent geological materials with a fundamental cultural value.


Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 479
Author(s):  
Lyubov’ Titova ◽  
Abdulmonem Hassan ◽  
Ivan Mikhailov ◽  
Elena Rodionova ◽  
Sergei Rasskazov ◽  
...  

Fossil diatoms are an excellent tool for reconstructing the palaeoenvironmental and palaeogeographic changes involving lacustrine systems. In this work, the diatom content of Pliocene sediments recovered from a core extracted in the Tunka Basin (Baikal Rift Zone, Russia) is described. Revealed by light and scanning electron microscopy, 170 species of diatoms were found. Benthic, alkaliphilic, indifferent, cosmopolitan, and oligosaprobe species predominated. Ecological, geographical, and stratigraphic analysis of diatoms showed two ecozones, differing in taxonomic diversity of species. From the data obtained, palaeoenvironmental conditions of these zone formations have been reconstructed. It was shown that during the period corresponding to sedimentation in Ecozone II, the reservoir was cooler, as suggested by the increase of arctic-alpine taxa. The absence of Baikal Pliocene endemics and the presence of local endemics in the Tunka core indicate that there was no geographical connection between the palaeolake of the Tunka Valley and Lake Baikal during the Pliocene.


2021 ◽  
Vol 9 (6) ◽  
pp. 591
Author(s):  
Mirye Park ◽  
Sang Deuk Lee ◽  
Hoil Lee ◽  
Jin-Young Lee ◽  
Daeryul Kwon ◽  
...  

Suncheonman Bay, Korea’s most representative estuary, is an invasive coastal wetland composed of 22.6 km2 of tidal flats surrounded by the Yeosu and Goheung Peninsulas. In January 2006, this region was registered in the Ramsar Convention list in Korea, representing the first registered wetland. Estuaries are generally known to have high species diversity. In particular, several studies have been conducted on planktonic and epipelic diatoms as primary producers. Suncheonman Bay has already been involved in many biological and geochemical studies, but fossil diatoms have not been evaluated. Therefore, we investigated fossil diatoms in Suncheonman Bay and introduced sub-fossil diatoms recorded in Korea. One sedimentary core has been extracted in 2018. We identified 87 diatom taxa from 52 genera in the SCW03 core sample. Of these, six species represent new records in Korea: Cymatonitzschia marina, Fallacia hodgeana, Navicula mannii, Metascolioneis tumida, Surirella recedens, and Thalassionema synedriforme. These six newly recorded diatom species were examined by light microscopy and scanning electron microscopy. The ecological habitats for all the investigated taxa are presented.


2021 ◽  
Vol 11 (10) ◽  
pp. 4533
Author(s):  
Angela Sardo ◽  
Ida Orefice ◽  
Sergio Balzano ◽  
Lucia Barra ◽  
Giovanna Romano

Diatoms are unicellular eukaryotic microalgae widely distributed in aquatic environments, possessing a porous silica cell wall known as frustule. Diatom frustules are considered as a sustainable source for several industrial applications because of their high biocompatibility and the easiness of surface functionalisation, which make frustules suitable for regenerative medicine and as drug carriers. Frustules are made of hydrated silica, and can be extracted and purified both from living and fossil diatoms using acid treatments or high temperatures. Biosilica frustules have proved to be suitable for biomedical applications, but, unfortunately, they are not officially recognised as safe by governmental food and medical agencies yet. In the present review, we highlight the frustule formation process, the most common purification techniques, as well as advantages and bottlenecks related to the employment of diatom-derived silica for medical purposes, suggesting possible solutions for a large-scale biosilica production.


2021 ◽  
Vol 55 (1) ◽  
pp. 19-34
Author(s):  
G. V. Kovaleva ◽  
R. M. Gogorev

A study of the Upper Miocene deposits on the Taman Peninsula revealed a new centric diatom Thalassiosira kozyrenkoae Kovaleva et Gogorev. The absence of findings of this species in the modern diatom flora suggests that it is extinct. The species was likely endemic for the Sea of Azov – the Black Sea basin. Single findings of valve fragments in the New Azov layers make it possible to use T. kozyrenkoae as a stratigraphic marker and to estimate the distribution extent of the Neogene sediments from the outcrops. This study will contribute to the more precise identification of the origin of the redeposited fossil diatoms in the Quaternary sediments from the Sea of Azov.


OSEANA ◽  
2019 ◽  
Vol 44 (1) ◽  
pp. 70-87
Author(s):  
Septriono Hari Nugroho

AN OVERVIEW OF DIATOM AND ITS APPLICATIONS ON THE GEOSCIENCE AREA. Diatoms have been being studied in many countries. Diatoms provide a valuable and well-understood means on biomonitoring – one of which is focused on the base of the aquatic foodweb and highly representative of water quality. They are found in most aquatic environments and the sys tematic and taxonomic investigations of modern and fossil diatoms have been supported by numerous stud ies of distributional ecology. Diatom systematics, taxonomy and ecology indeed offer a wide scope of applications - from water quality to environmental monitoring and biostratigraphy as well as on geoscience area. The application of diatom analysis in determining whether drowning was the cause of death has proven to be a valuable tool in forensic science. Furthermore, diatoms can provide a record of environmental conditions because their relationship to water quality and aquatic habitat has been already known, and the diatom cell wall, which is silicified to form a frustule, is well-preserved, easily detectable and occurs in high numbers in sediment and water. However, this should not be limited to simply make an inventory of data: thoughtful ecology and paleo-ecology will assist in predicting the environmental impact of pollution and climate changes.


Author(s):  
Yelena I. Shtyrkova ◽  
Yelena I. Polyakova

The results of fossil diatoms investigation from the deltaic sediments are presented. Samples were obtained from the core DM-1 and two Holocene outcrops from the Damchik region of the Astrakhan Nature Reserve. In the core samples eight periods of sedimentation based on diatom analysis were identified: the sediments formed in shallow freshwater basins and deltaic channels. The samples from the outcrops were investigated in much greater detail.


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