Search results for "Sediment"
showing 10 items of 1648 documents
Farmācijas produktu atliekvielu noteikšana Pēterupes ūdenī, sedimentos, perifitonā un gliemenēs
2018
Farmācijas produktu atliekvielu noteikšana Pēterupes ūdenī, sedimentos, perifitonā un gliemenēs. Grūbe S., zinātniskie vadītāji asoc. prof. Dr. chem. Bartkevičs V., Mg. ķīm. Ikkere L. E. Maģistra darbs, 50 lappuses, 19 attēli, 15 tabulas, 31 literatūras avots. Latviešu valodā. Darba literatūras apskatā ir apkopota vispārīgā informācija par farmācijas produktu atliekvielu nokļūšanu apkārtējā vidē, to ietekmi uz vidi, kā arī apkopoti citu autoru rezultāti par pētāmo savienojumu vērtībām dažādās matricās. Tika izmantoti ūdens, sedimentu, perifitona paraugi no piecām vietām Pēterupē un četri gliemju paraugi no Ķīšupes un Aģupes. Paraugos noteikti 23 analīti – farmācijas produktu atliekvielas no…
The Monte San Nicola section (Sicily) revisited: A potential unit-stratotype of the Gelasian Stage
2022
The Monte San Nicola area (Southern Sicily) offers a spectacular exposure of open-marine sediments that were employed in 1998 for defining the Global Stratotype Section and Point (GSSP) of the Gelasian Stage (Upper Pliocene). After the lowering of the Pliocene/Pleistocene boundary to ca. 2.6 Ma in 2010, the Gelasian GSSP has been redefined as the base of both the Pleistocene Series and the Quaternary Period, which increased its importance and visibility within the scientific community. However, documentation on the Monte San Nicola reference section is still sparse. In the light of its renewed status, we decided to undertake a complete revision of the Gelasian Stage in its type area, in ord…
First characterization of Gamkonora gas emission, North Maluku, East Indonesia
2020
Gamkonora is an active volcano capable of intense manifestations that regularly forced thousands of inhabitants to flee their villages. The most extreme eruption, in 1673, was a VEI 5 event that induced pitch-dark environment over the region. Paradoxically, little is known about Gamkonora volcano and here we present the first gas measurement results obtained in September 2018 using a MultiGAS and a scanning DOAS. Results highlight a relatively small but magmatic gas with a CO2/ST of 3.5, in the range of high-temperature gas emissions from Indonesian volcanoes and H2O/SO2, CO2/SO2, H2S/SO2, and H2/SO2 ratios of 135, 5.6, 0.6, and 0.2, respectively. The daily gas emission budget corresponds t…
Occurrence and concentration of PAHs in clams and sediments of the marine coastal lagoon of Ganzirri (Italy). Extraction, GC-MS analysis, distributio…
2006
The distribution of selected Polycyclic Aromatic Hydrocarbons (PAHs) in surface sediments and clams of marine coastal lagoons, called Ganzirri, located at the Sicilian coast of the, Messina's strait, has been investigated by GC/MS analysis with Selected Ion Monitoring (SIM) mode. The lagoon is characterized by abundant organic detritus, deriving from aquagenic and anthropogenic inputs. Anoxic/reduced conditions of sediments make them a preferential site for uptake and preservation of PAHs. From an eco-toxicological point of view, the aquatic ecosystem investigated appears to be moderately polluted. The investigations have been performed on the 16 PAHs recommended by US-EPA as priority pollu…
GIS-based methodology for mapping and modeling microbialite deposits in high mountain lakes and wetlands of Central Andes (Catamarca, Northwestern Ar…
2022
Modern microbialites in Argentina's Puna (Central Andes) are considered a reliable tool for understanding the evolution of early life on our planet and developing strategies for detecting life on Mars. The morphological, structural and geochemical variations in these deposits, together with their distribution and architecture, are some of the most important parameters for understanding and characterising them. However, the lack of appropriate cartography and/or the high price to access it, added to the complex geological and geomorphological context in this region, complicate a traditional mapping on a good scale of detail. This paper presents a GIS-based methodology for a detailed mapping …
Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition …
2018
Joint International Ocean Discovery Program and International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub impact crater. We present P-wave velocity, density, and porosity measurements from Hole M0077A that reveal unusual physical properties of the peak-ring rocks. Across the boundary between post-impact sedimentary rock and suevite (impact melt-bearing breccia) we measure a sharp decrease in velocity and density, and an increase in porosity. Velocity, density, and porosity values for the suevite are 2900–3700 m/s, 2.06–2.37 g/cm3, and 20–35%, respectively. The thin (25 m) impact melt rock unit below the suevite has velocity measurements…
Rare earth elements and hydrothermal ore formation processes
1992
Abstract The geochemical behaviour of REE is influenced by nearly all important hydrothermal ore formation processes including fluid-rock interactions, fluid precipitations, adsorption and scavenging onto particles, and changes in fluid temperature, pressure, pH, Eh, alkalinity and ligand concentration. Destabilization of REE complexes in response to these physicochemical changes and possible chemical-crystallographic controls determine the concentration and distribution of REE within hydrothermal minerals, mineraloids and amorphous phases. Alteration assemblages of intrusive related mineralisations may exhibit a wide range of REE distributions and REE fractionation trends. The REE distribu…
Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP
2014
© 2014 by The University of Chicago. All rights reserved. A major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ± 150 years before present, forming the YD Boundary (YDB) layer, distributed over 150 million km2 on four continents. In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon. The ND abundances in bulk YDB sediments ranged up to ≈500 ppb (mean: 200 ppb) and…
Occurrence and Genesis of Palygorskite and Associated Clay Minerals in a Pleistocene Calcrete Complex, Sde Boqer, Negev Desert, Israel
1996
AbstractPalygorskite and associated clay minerals have been studied in a Pleistocene calcrete complex from the Negev desert (Sde Boqer, Israel). This complex is divided into five main parts: the chalky and marly bedrock overlain by its weathered product, a brecciated calcrete hardpan; the laminar crust; loess pockets trapped in the calcrete; and the overlying soft surficial soil. The distribution of clay minerals is directly dependent on the position of the sample in the calcrete complex. Smectite is inherited from the bedrock in the calcrete with an aeolian enrichment in loess pockets and upper soft soil. The source of kaolinite is mainly detrital, related to desert dust. Illite is partly …
Weathering Products of a Dismantled Variscan Basement. Minero-Chemical Proxies to Insight on Cretaceous Palaeogeography and Late Neogene Palaeoclimat…
2020
This study compares, for the first time, the mineralogy and geochemistry of two residual-clay deposits in NW Sardinia (Nurra district) that formed at different times in tropical and sub-tropical climates. Both deposits represent palaeosols with deep-weathered residual profiles and overlie Mesozoic carbonate rocks that were deposited on the south European palaeomargin. The older alterite is Cenomanian–Turonian in age and grades upward into a horizon of karstic bauxite, whereas the younger unit occurs within alluvial deposits of Late Neogene age. The Cretaceous palaeosol represents the precursor of the overlying bauxite and formed from unknown sedimentary parent rocks. In contrast, the Messin…