Chemical characterization and recent sedimentation rates in sediment cores from Rio Grande reservoir, SP, Brazil

2007 ◽  
Vol 273 (2) ◽  
pp. 451-463 ◽  
Author(s):  
D. I. T. Fávaro ◽  
S. R. Damatto ◽  
E. G. Moreira ◽  
B. P. Mazzilli ◽  
F. Campagnoli
Keyword(s):  
Sediment Cores ◽  
Chemical Characterization ◽  
Rio Grande ◽  
Sedimentation Rates ◽  
Rio Grande Reservoir

scholarly journals CHEMICAL CHARACTERIZATION OF ATMOSPHERIC PARTICLES IN URBAN AREAS OF RIO GRANDE DO SUL, BRAZIL-PRELIMINARY STUDY

2006 ◽  
Vol 14 (14) ◽  
pp. 1-16
Author(s):  
E. Teixeira ◽  
J. Fachel Braga ◽  
J.D. D. Migliavacca ◽  
M.L.L.Fomoso Sanchez
Keyword(s):  
Chemical Composition ◽  
Urban Areas ◽  
Chemical Characterization ◽  
Rio Grande ◽  
Atmospheric Particles ◽  
Rio Grande Do Sul ◽  
Power Stations ◽  
Cluster Data ◽  
Steel Industries

This work reports the determination of the concentration and chemical composition of atmospheric particles in the urban districts of Charqueadas and Sapucaia do Sul, State of Rio Grande do Sul, Brazil. Chemical composition, morphology, and particle size were analyzed using a scanning electron microscope with energy dispersive x=ray microanalysis (SEM-EDS). Cluster analysis showed that there were six types of particles: Fe-Zn, Fe, Si=Al, Si, Ca-S, and Na. Factorial analysis from cluster data showed that particles rich in Fe-Zn, Si-Al, and Ca-S appeared more frequently, indicating anthropogenic influence (vehicles, steel plants, coal-fired power stations). The experimental results and consideration of the wind directions show that the main source of pollution in Charqueadas appears to be due to coal mining and steel industries, while in Sapucaia do Sul due to steel plants and vehicles.

scholarly journals Pollen analysis: state of the art

2010 ◽  
Vol 31 (1-2) ◽  
pp. 151-159 ◽  
Author(s):  
Gordon J. Ogden
Keyword(s):  
North America ◽  
Pollen Analysis ◽  
Sediment Cores ◽  
Data Bank ◽  
Sedimentation Rates ◽  
Data Set ◽  
Radiocarbon Dates ◽  
Surface Pollen ◽  
Pollen Stratigraphy ◽  
Better Than

Although nearly 50 years have passed since P.B. Sears introduced pollen analysis to North America, it remains an occult art. Dramatic improvements in sampling and analytic techniques continue to be limited by intractable problems of differential production, dispersal, ballistics, sedimentation, and preservation. It is a basic tenet of pollen stratigraphy that the data set, consisting primarily of microfossils preserved in sediments, is better than anything we have yet been able to do with it. Basic agreement between late- and postglacial pollen records has been confirmed wherever the method has been applied. Quantitative sampling techniques, sample preparation, and analytic procedures, together with multiple radiocarbon dates, permits calculation of sedimentation rates and absolute pollen influx. Of approximately 300 sediment cores from northeastern North America, fewer than 30 have more than 3 radiocarbon determinations from which least squares power curve regressions can be reliably calculated in the determination of sedimentation rates. Analogy with modern environments represented by surface pollen spectra is limited by an insufficient number of samples of uniform quality to characterize a vegetational mosaic covering 40 degrees of latitude (40-80°N) and longitude (60-100°W). The present surface pollen data bank includes about 700 samples, unevenly spaced and of uneven quality, permitting a grid resolution of no better than 10,000 km2.

Evaluation of the Extent of Contaminated Sediments in the West Branch of the Grand Calumet River, Indiana-Illinois, USA

1993 ◽  
Vol 28 (8-9) ◽  
pp. 53-58 ◽  
Author(s):  
R. A. Cahill ◽  
M. T. Unger
Keyword(s):  
Trace Elements ◽  
Organic Carbon ◽  
Sediment Cores ◽  
River Sediments ◽  
Organic Carbon Content ◽  
Sedimentation Rates ◽  
The West ◽  
Surface Samples ◽  
Rate Information ◽  
The Mean

The extent of contamination in river sediments is often not rigorously evaluated. In many cases, only surface sediment samples are taken. In other cases, entire sediment cores are composited for analysis, an approach that limits the ability to identify discrete zones of contamination. In addition, few studies include information on the rate of sedimentation. Composited sediment cores, subsamples of cores made at discrete intervals, and surface samples were obtained from locations in the West Branch of the Grand Calumet River. The organic carbon content and concentrations of up to 26 major, minor, and trace elements were determined. Sedimentation rates at the ten locations were estimated using 137Cs. The mean concentrations of metals in the surface samples were considerably higher than concentrations in samples obtained by the two coring approaches. Only by analyzing discrete subsamples was it possible to plot the concentrations by depth and location. This approach was used to demonstrate that high levels of organic carbon and trace elements are confined between river miles 5 and 7.5. Sedimentation rate information combined with chemical analyses of the same cores indicate that contamination of this part of the river began in the 1930s.

scholarly journals Glacial-Marine Sedimentation, Canadian Polar Margin, North of Axel Heiberg Island

2007 ◽  
Vol 45 (2) ◽  
pp. 213-227 ◽  
Author(s):  
Frances J. Hein ◽  
Peta J. Mudie
Keyword(s):  
Sediment Cores ◽  
Open Water ◽  
Silty Clay ◽  
Sedimentation Rates ◽  
The Core ◽  
Marine Sedimentation ◽  
Northwestern Shelf ◽  
History Of ◽  
Axel Heiberg Island ◽  
High Sediment

ABSTRACT Sediment cores, taken at depths of 140 to 300 m across the northwestern shelf of Axel Heiberg Island (82° N), record the deposition of sediments under perennial sea ice. Five sedimentary fades are recognized: (A) soft pebbly-sandy-mud with dropstone structures; (B) bioturbated silty muds; (C) wispy-laminated silty clay/clay; (D) laminated sands/silts and mud; (E) firm pebbly-sandy-mud with chaotic pebble fabrics. Other sediments include terrestrial bedrock of Paleogene Eureka Sound Group, and a younger Tertiary deposit, possibly the Beaufort Formation. Ages range from 1530 ± 60 BP (Fades A) to 9950 ± 80 BP (Fades D). Sedimentation rates vary as follows: - 0.8 cm ka-1, Fades B; 4 cm ka"\ Fades A; 90 cm ka-1, Fades C; 134 cm ka~', Fades D. The sedimentation history, as interpreted from the sedimentology, palynology and foraminiferal results, suggests intervals of more continuous ice cover, with a reduced influx of coarse ice-rafted detritus, alternating with more open water conditions, and high sediment input from meltwater and/or floating icebergs. Only marine sediments overlie Neogene bedrock in the cores. The absence of diamictons at the core sites suggests that grounded ice perhaps never occupied this part of the Axel Heiberg Island shelf. The interpreted history of sedimentation generally corresponds to the land-based record from Ellesmere Island, but differs significantly from marine-based studies in more southern latitudes.

Determining tributary sources of increased sedimentation in East-African Rift Lakes using a combination of sediment tracing and radioactive dating.

2020 ◽  
Author(s):  
Maarten Wynants ◽  
Geoffrey Millward ◽  
Aloyce Patrick ◽  
Alex Taylor ◽  
Linus Munishi ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Sediment Cores ◽  
East African Rift ◽  
Sediment Dynamics ◽  
Sedimentation Rates ◽  
East African ◽  
Sediment Delivery ◽  
Sediment Tracing ◽  
Lake Sedimentation ◽  
African Rift

<p>Temporal and spatial sediment dynamics in an East-African Rift Lake (Lake Manyara, Tanzania), and its river inputs, have been evaluated via a combination of sediment tracing and radioactive dating. Changes in sedimentation rate were assessed using radioactive dating of sediment cores in combination with geochemical profile analysis of allogenic and autogenic elements. Geochemical fingerprinting of riverine and lake sediment was integrated within a Bayesian mixing model framework, including spatial factors, to establish which tributary sources were the main contributors to recent lake sedimentation. The novel application of Bayesian source attribution on sediment cores and subsequent integration with sedimentation data permitted the coupling of changes in the rate of lake sedimentation with variations in sediment delivery from the tributaries. These complimentary evidence bases demonstrated that Lake Manyara has experienced an overall upward trajectory in sedimentation rates over the last 120 years with distinct maxima in the 1960s and in 2010. Sedimentation rates are largely a result of a complex interaction between increased upstream sediment delivery following changes in land cover and natural rainfall fluctuations. Modelling results identified two specific tributaries as responsible for elevated sedimentation rates, contributing 58% and 38% of the recently deposited lake sediment. However, the effects of sedimentation were shown to be spatially distinct given the domination of different tributaries in various areas of Lake Manyara. The application of source-tracing techniques constrained sedimentation problems in Lake Manyara to specific tributary sources and established a link between upstream land degradation and downstream ecosystem health. This novel application provides a solid foundation for targeted land and water management strategies to safeguard water security and environmental health in Lake Manyara and has potential application to fill knowledge gaps on sediment dynamics in other East-African Rift Lakes.</p>

Time averaging and stratigraphic unmixing: reconstructing ecological decline in molluscan production (Holocene, Brijuni, NE Adriatic)

2020 ◽  
Author(s):  
Adam Tomašových ◽  
Martin Zuschin ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Coralline Algae ◽  
Time Averaging ◽  
Sedimentation Rates ◽  
Amino Acid Racemization ◽  
Ecological History ◽  
Shell Bed ◽  
Warm Temperate

<p>The northeastern Adriatic seafloor is formed by warm-temperate bioclastic carbonates with coralline algae, bryozoans and mollusks. These sediments represent a mixture of past and present-day production owing to low sedimentation rates and bioturbation. Although low sedimentation rates do not allow resolution of ecological history at centennial or even millennial scales on the basis of raw stratigraphic data, age unmixing based on radiocarbon-calibrated amino acid racemization shows that one of the major molluscan sediment producers – the infaunal suspension-feeder Timoclea ovata  – markedly peaked in production ~5,000 years during the maximum flooding and earliest highstand phase and significantly diminished in abundance during the late highstand phase at Brijuni, with a large proportion of dead shells now present in surface sediments representing shells that are several centuries old. This species still occurs in living assemblages but our analyses indicate that its former production was by several orders of magnitude higher. In contrast, stratigraphic trends in absolute and proportional abundance of this species in ~1.5 m-thick sediment cores show a gradual or a very mild upcore decline, indicating that raw stratigraphic data do not efficiently detect millennial-scale ecological dynamic. The temporal decline in production of Timoclea ovata is associated with an increase in water depth and an increase in sediment-accumulation rate, and led to a transition from molluscan oyster-scallop shell bed to late highstand bryomol sediments.</p>

AMS-14C Ages Measured in Deep Sea Cores from the Southern Ocean: Implications for Sedimentation Rates during Isotope Stage 2

1989 ◽  
Vol 31 (2) ◽  
pp. 309-317 ◽  
Author(s):  
Edouard Bard ◽  
Laurent Labeyrie ◽  
Maurice Arnold ◽  
Monique Labracherie ◽  
Jean-Jacques Pichon ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sedimentation Rate ◽  
Deep Sea ◽  
Sediment Cores ◽  
Sea Surface ◽  
Sedimentation Rates ◽  
Deep Sea Sediment ◽  
The Difference ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract14C dates obtained by accelerator mass spectrometry (AMS) on monospecific foraminiferal samples from two deep-sea sediment cores raised in the Indian sector of the Southern Ocean have been corrected for the difference in 14C composition between atmosphere and sea surface by using a reconstruction of the latitudinal 14C gradient which existed in the Southern Ocean prior to 1962. The corrected AMS-14C data show a reduced sedimentation rate in core MD 84-527 between 25,000 and 10,000 yr BP. For core MD 84-551 the available data suggest that the sedimentation rate was higher during the Holocene than during the glacial period. These changes in sedimentation rates may be attributed to an increased opal dissolution during the last glacial maximum.

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