scholarly journals Stratigraphy and Sedimentation Rates from Oxygen Isotope Composition, Organic Carbon Content, and Grain-Size Distribution at the Peru Upwelling Region: Holes 680B and 686B

1990 ◽  
Author(s):  
G. Wefer ◽  
P. Heinze ◽  
E. Suess
Keyword(s):  
Grain Size ◽  
Organic Carbon ◽  
Carbon Content ◽  
Oxygen Isotope ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Isotope Composition ◽  
Oxygen Isotope Composition ◽  
Organic Carbon Content ◽  
Sedimentation Rates

Late Quaternary Upwelling Variations in the Eastern Equatorial Atlantic Ocean as Inferred from Dinoflagellate Cysts, Planktonic Foraminifera, and Organic Carbon Content

2000 ◽  
Vol 54 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Christine Höll ◽  
Sylvia Kemle-von Mücke
Keyword(s):  
Organic Carbon ◽  
Atlantic Ocean ◽  
Carbon Content ◽  
Isotope Composition ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Organic Carbon Content ◽  
Equatorial Atlantic ◽  
Northern Summer ◽  
Equatorial Atlantic Ocean

Analysis of multiple proxies shows that eastern equatorial Atlantic upwelling was subdued during isotope stage 5.5, more intense during stages 4, 5.2, 5.4, and 6, and most intense early in stage 2. These findings are based on proxy measures from a core site about 600 km southwest of Liberia. The proxies include total organic carbon content, the ratio of peridinoid and oceanic organic-walled dinoflagellate cyst species, accumulation rates of calcareous dinoflagellates, estimates of sea surface paleotemperatures, the difference in stable oxygen isotope composition between two species of planktonic foraminifera that live at different water depths, and the abundance of the planktonic foraminifera Neogloboquadrina dutertrei. Most of these parameters consistently vary directly or inversely with one another. Slight discrepancies between the individual parameters show the usefulness of a multiple proxy approach to reconstruct paleoenvironments. Our data confirm that northern summer insolation strongly influences upwelling in the eastern equatorial Atlantic Ocean.

scholarly journals Geochemistry of Street Dust in Tyumen, Russia: Influence of Traffic Load

2021 ◽  
Author(s):  
Dmitriy Moskovchenko ◽  
Roman Pozhitkov ◽  
Dzhamilya Ukarkhanova
Keyword(s):  
Particle Size ◽  
Organic Carbon ◽  
Particle Size Distribution ◽  
Carbon Content ◽  
Size Distribution ◽  
Road Dust ◽  
Traffic Load ◽  
Anthropogenic Sources ◽  
Emission Spectrometry ◽  
Organic Carbon Content

Abstract The article presents the results of studying the composition of road dust in Tyumen, a large city in Western Siberia. On roads with different traffic intensities, 50 dust samples were taken, in which the particle size distribution, pH, and organic carbon content were determined. The content of 62 major and trace elements was studied using atomic emission spectrometry (AES-MS) и inductively coupled plasma spectrometry (ICP-MS). It was revealed that the dust has an alkaline reaction pH = 7.4 - 10.2, low organic carbon content (0.07 - 2.9%). The particle size distribution is dominated by particles PM = 100-250. The content of small particles (PM <2 and PM2-10) representing the greatest environmental hazard is minimal on roads with an average traffic intensity. Studies have shown that the main road dust pollutants in Tyumen are Ni, Sb, Cr, Zn, Co. The average geoaccumulation index (Igeo) values ​​are ranked as Ni (2.2) > Sb (1.5) > Cr (1.3) > Zn (0.4) > Co (0.4) > Cu (0.2). The contamination evaluation through enrichment factor (EF) calculation showed that road dust is highly enriched in Ni and significantly in Cr and Sb. More than 80% of Zn, Co, Cu and more than 90% of Ni, Sb, Cr come from anthropogenic sources. By the content of Ni and Cr, Tyumen surpasses all cities of the Earth where similar studies were carried out. The high Ni content is associated with the composition of local soils and roadways, increased content in vehicle exhaust gases, and abrasion of metal parts. Calculations of the total pollution indices (IPI and Zc) showed that the level of road dust pollution in most of Tyumen's territory is average, moderately hazardous.

scholarly journals Mercury in Sediment Core Samples From Deep Siberian Ice-Rich Permafrost

2021 ◽  
Vol 9 ◽  
Author(s):  
Clara Rutkowski ◽  
Josefine Lenz ◽  
Andreas Lang ◽  
Juliane Wolter ◽  
Sibylle Mothes ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Total Nitrogen ◽  
The Arctic ◽  
Specific Magnetic Susceptibility ◽  
Shallow Soils

We determine Hg concentrations of various deposits in Siberia’s deep permafrost and link sediment properties and Hg enrichment to establish a first Hg inventory of late Pleistocene permafrost down to a depth of 36 m below surface. As Arctic warming is transforming the ice-rich permafrost of Siberia, sediment is released and increases the flux of particulates to the Arctic shelf seas through thawing coasts, lakeshores, and river floodplains. Heavy metals within soils and sediments are also released and may increasingly enter Arctic waters and the biological food chain. High levels of mercury (Hg) have been reported from shallow soils across the Arctic. Rapid thawing is now mobilizing sediment from deeper strata, but so far little is known about Hg concentrations in deep permafrost. Here, forty-one samples from sediment successions at seven sites and of different states of permafrost degradation on Bykovsky Peninsula (northern Yakutian coast) and in the Yukechi Alas region (Central Yakutia) were analyzed for Hg, total carbon, total nitrogen, and total organic carbon as well as grain-size distribution, bulk density, and mass specific magnetic susceptibility. We show average Hg concentrations of 9.72 ± 9.28 μg kg−1 in the deep sediments, an amount comparable to the few previous Arctic studies existing, and a significant correlation of Hg content with total organic carbon, total nitrogen, grain-size distribution, and mass specific magnetic susceptibility. Hg concentrations are higher in the generally sandier sediments of the Bykovsky Peninsula than in the siltier sediments of the Yukechi Alas. The ratio of Hg to total organic carbon in this study is 2.57 g kg−1, including samples with very low carbon content. We conclude that many deep permafrost sediments, some of which have been frozen for millennia, contain elevated concentrations of Hg and the stock of Hg ready to be released by erosion is of significance for the Arctic ecosystem. The Hg mobilized may accumulate on the way to or in the shallow sea, and where it enters into active biogeochemical cycles of aquatic systems it may concentrate in food webs. Our study highlights the need for better understanding Hg stocks and Hg release from permafrost.

scholarly journals Carbon and nitrogen ratio and δ13С values ​​in polygonal landscapes on the coast of the Gulf of Oneman, Chukotka

2021 ◽  
pp. 47-64
Author(s):  
Alla Constantinovna Vasil'chuk ◽  
Nadine Arkad'evna Budantseva ◽  
Yurij Kirillovich Vasil'chuk ◽  
Jessica Yur'evna Vasil'chuk ◽  
Lyubov' Bakhtiyarovna Bludushkina
Keyword(s):  
Organic Carbon ◽  
Carbon Content ◽  
Isotope Composition ◽  
C3 Plants ◽  
Organic Carbon Content ◽  
Peat Accumulation ◽  
Carbon And Nitrogen ◽  
Nitrogen Ratio ◽  
The Subject ◽  
In The Beginning

The subject of the study is the analysis of the ratio of carbon (C) and nitrogen(N) and &delta;13C values in polygonal landscapes on the coast of Onemen Bay, near the Anadyr city. The maximum values of carbon (59.09%) and nitrogen (2.18%) in peatlands were obtained at a depth of 1.1 m in a narrow peat vein. The values of &delta;13C in the peatlands on the coast of Onemen Bay vary from -24.1% to -28.6%, the N content varies from 0.37% to 3.24%, the C content varies from 3.1% to 59.09%, the C/N value varies from 8.3 to 34.4.The values of &delta;13C and C/N values in the 1.5-m peat correspond to C3 plants, the values of &delta;13C and C/N values for a 2.5&ndash;m peat suggest the presence of algae along with plants C3. Fluctuations in the nitrogen and organic carbon content in the section of a 1.5-meter peatland to a depth of 0.8 m are synchronous, which suggests an autochthonous mechanism of peat accumulation, below depth of 0.8-1.2 m, there is a lightening of the carbon isotope composition, which suggests the participation of reworked organic matter in the beginning of peat accumulation. Fluctuations in the nitrogen and organic carbon content in the section of a 2.5-meter peat bog are synchronous, which suggests an autochthonous mechanism of peat accumulation.

Quantification of dioxin in the sieved fraction of river sediment

2005 ◽  
Vol 52 (9) ◽  
pp. 225-233 ◽  
Author(s):  
H. Ozaki ◽  
S. Taniguchi ◽  
R. Takanami ◽  
N. Shimomukai ◽  
T. Hamasaki ◽  
...  
Keyword(s):  
Grain Size ◽  
Organic Carbon ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
River Sediment ◽  
Contaminated Sediments ◽  
Total Carbon ◽  
Ignition Loss ◽  
Environment Agency ◽  
Nitrogen Contents

Dioxin pollution of aquatic sediments has been one of the important environmental problems in Japan. Grain size distribution and organic constituents may play important roles in dioxins contents in sediments, which have not been well investigated. This paper aims to quantify dioxins (PCDDs/Fs and co-PCBs) in sieved surface sediment fractions obtained from Kizu and Sumiyoshi Rivers in Osaka, Japan. The samples were prepared and analyzed following the ‘Manual of the Survey and Measurement of Dioxins in Sediment’ (Environment Agency of Japan, 2000). The results showed that TEQ concentrations of dioxins increased with decreasing grain size in sediment fractions. Sediment fractions with less than 20μm grain size showed the highest dioxin contents. Dioxins with five and six chlorine atoms dominated other congeners in less than 20μm fractions. The dioxin TEQ concentrations increased with total organic carbon (TOC), total carbon (TC), ignition loss (IL), total sulphur and nitrogen contents in the sediment fractions. Thus, reporting dioxin contents in sediments without considering grain size distribution may be erroneous, and conventional sedimentation and separation techniques might not be useful for treating contaminated sediments. This information can be useful for effective remediation of dioxin-contaminated sediments.

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