Spelling suggestions: "subject:"then southern atlantic"" "subject:"then southern tlantic""
1 |
Late Pliocene Ge/Si Record of Marine Biogenic Opal from the Southern AtlanticChen, Cheau-Ju 18 July 2000 (has links)
Abstract
The primary objective for this study is to determine the variations of germanium (Ge) to silicon (Si) ratios in diatom shells from down core sediments off the southwestern coast of the Africa. Because Ge behaves like Si in the ocean and the major source of these two elements is rivers, Ge/Si ratios of the diatom are thus expected to record the intensity of weathering on continents. Two sediment cores (Site 1081 and 1084) were collected during the ODP Leg 175 in August, October 1997 and were analyzed for intervals between 3.1 and 1.9 Ma. Generally, the (Ge/Si)diatom ratios in this study show the similar trend with those reported from the Antarctic Ocean. The decline of Ge/Si ratios after 2.5 Ma is caused by the high opal mass accumulation rate, indicating the increasing rivers input of silica to the ocean. Relatively high Ge/Si ratios of diatom shells during warm periods shown by the depleted benthic foraminiferal £_18O values from the North and Equatorial Atlantic, suggesting a scenario of intensified chemical weathering on continent. Cold periods signified by £_18O-enriched values are associated with lower Ge/Si ratios. Very likely the reduced Ge/Si values reflect the prevailing weathering on continents was less chemical-dissolving due to the dry weather in cold stages.
|
2 |
Detecção e quantificação de alguns elementos químicos inorgânicos em sangue e tecidos de tartarugas-verdes - Chelonia mydas (Linnaeus, 1758) - da costa brasileira: possível correlação com a fibropapilomatose / Detection and quantification of selected inorganic chemical elements in blood and tissue samples from green turtles Chelonia mydas (Linnaeus, 1758) from the Brazilian coast: possible correlation with fibropapillomatosisPrioste, Fabiola Eloisa Setim 30 March 2016 (has links)
A fibropapilomatose é uma doença multifatorial em tartarugas marinhas caracterizada por tumores cutâneos benignos. O surgimento da doença é atribuído à associação do Chelonid herpesvirus 5 (ChHV-5), à genética e à fatores ambientais. A tartaruga-verde (Chelonia mydas) é a espécie mais acometida pela doença, sendo esta uma das maiores ameaças à sua sobrevivência. Este estudo teve por objetivo detectar e mensurar seis elementos químicos inorgânicos: Arsênio (As), Cádmio (Cd), Chumbo (Pb), Selênio (Se), Zinco (Zn) e Mercúrio (Hg) em sangue de tartarugas-verdes (Chelonia mydas) capturadas vivas e tecidos (baço, rins, fígado, glândula de sal, musculatura esquelética e tecido ósseo) de necropsias realizadas em indivíduos encontrados mortos. Quatro localidades da costa brasileira foram amostradas: Almofala CE; Fernando de Noronha PE; Vitória ES e Ubatuba SP. Foram colhidas 233 amostras de sangue e 488 amostras de tecido entre março de 2012 e outubro de 2015. As amostras foram analisadas em um espectrômetro de massas com plasma indutivamente acoplado (ICP-MS). Os resultados das análises de sangue apontaram Fernando de Noronha como um possível grupo controle para estudos desta ordem. As e Se foram encontrados em Fernando de Noronha em níveis séricos muito baixos. Tartarugas-verdes das outras três localidades estudadas apresentaram uma diminuição desses elementos quando com sinais de FP, ao mesmo tempo em que apresentaram concentrações maiores de algum elemento químico tóxico, como Pb e Hg. Quanto aos resultados obtidos com amostras teciduais, as tartarugas-verdes com sinais de FP apresentam menores concentrações de As e Se em todos os órgãos analisados, ao mesmo tempo que apresentam maior concentração de Pb em fígado, rins e ossos / Fibropapillomatosis is a multifactorial disease of sea turtles characterized by benign cutaneous tumors. The development of this disease is attributed to the association of Chelonid herpesvirus 5 (ChHV-5), to genetics and environmental factors. The green turtle (Chelonia mydas) is the species most affected by fibropapillomatosis, one of the biggest threats to the survival. The aim of this study was to detect and quantify six inorganic chemical elements: Arsenic (As), Cadmium (Cd), Lead (Pb), Selenium (Se), Zinc (Zn) and Mercury (Hg) in blood samples of green turtles trapped alive, and tissue samples (spleen, kidneys, liver, salt glands, skeletal muscles and bone tissue) collected during necropsies of carcasses. The samples was collected in four different locations of the Brazilian coast: Almofala Ceará; Fernando de Noronha Pernambuco; Vitória Espírito Santo e Ubatuba São Paulo. We collected 233 blood samples and 488 tissue samples between March 2012 and October 2015. Samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS) techniques. The results of the blood analyses indicated Fernando de Noronha as a possible control group for studies of this nature. As and Se were observed in Pernambuco (Fernando de Noronha) in very low blood levels. Green turtles from the three other locations presented decreased levels of the same elements in cases with signs of FP, while presenting higher concentrations of some of the toxic chemical elements, such as Pb and Hg. The results obtained from tissue samples showed that green turtles with signs of FP present lower As and Se in all analysed organs, and higher [Pb] in liver, kidneys and bone tissues
|
3 |
Detecção e quantificação de alguns elementos químicos inorgânicos em sangue e tecidos de tartarugas-verdes - Chelonia mydas (Linnaeus, 1758) - da costa brasileira: possível correlação com a fibropapilomatose / Detection and quantification of selected inorganic chemical elements in blood and tissue samples from green turtles Chelonia mydas (Linnaeus, 1758) from the Brazilian coast: possible correlation with fibropapillomatosisFabiola Eloisa Setim Prioste 30 March 2016 (has links)
A fibropapilomatose é uma doença multifatorial em tartarugas marinhas caracterizada por tumores cutâneos benignos. O surgimento da doença é atribuído à associação do Chelonid herpesvirus 5 (ChHV-5), à genética e à fatores ambientais. A tartaruga-verde (Chelonia mydas) é a espécie mais acometida pela doença, sendo esta uma das maiores ameaças à sua sobrevivência. Este estudo teve por objetivo detectar e mensurar seis elementos químicos inorgânicos: Arsênio (As), Cádmio (Cd), Chumbo (Pb), Selênio (Se), Zinco (Zn) e Mercúrio (Hg) em sangue de tartarugas-verdes (Chelonia mydas) capturadas vivas e tecidos (baço, rins, fígado, glândula de sal, musculatura esquelética e tecido ósseo) de necropsias realizadas em indivíduos encontrados mortos. Quatro localidades da costa brasileira foram amostradas: Almofala CE; Fernando de Noronha PE; Vitória ES e Ubatuba SP. Foram colhidas 233 amostras de sangue e 488 amostras de tecido entre março de 2012 e outubro de 2015. As amostras foram analisadas em um espectrômetro de massas com plasma indutivamente acoplado (ICP-MS). Os resultados das análises de sangue apontaram Fernando de Noronha como um possível grupo controle para estudos desta ordem. As e Se foram encontrados em Fernando de Noronha em níveis séricos muito baixos. Tartarugas-verdes das outras três localidades estudadas apresentaram uma diminuição desses elementos quando com sinais de FP, ao mesmo tempo em que apresentaram concentrações maiores de algum elemento químico tóxico, como Pb e Hg. Quanto aos resultados obtidos com amostras teciduais, as tartarugas-verdes com sinais de FP apresentam menores concentrações de As e Se em todos os órgãos analisados, ao mesmo tempo que apresentam maior concentração de Pb em fígado, rins e ossos / Fibropapillomatosis is a multifactorial disease of sea turtles characterized by benign cutaneous tumors. The development of this disease is attributed to the association of Chelonid herpesvirus 5 (ChHV-5), to genetics and environmental factors. The green turtle (Chelonia mydas) is the species most affected by fibropapillomatosis, one of the biggest threats to the survival. The aim of this study was to detect and quantify six inorganic chemical elements: Arsenic (As), Cadmium (Cd), Lead (Pb), Selenium (Se), Zinc (Zn) and Mercury (Hg) in blood samples of green turtles trapped alive, and tissue samples (spleen, kidneys, liver, salt glands, skeletal muscles and bone tissue) collected during necropsies of carcasses. The samples was collected in four different locations of the Brazilian coast: Almofala Ceará; Fernando de Noronha Pernambuco; Vitória Espírito Santo e Ubatuba São Paulo. We collected 233 blood samples and 488 tissue samples between March 2012 and October 2015. Samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS) techniques. The results of the blood analyses indicated Fernando de Noronha as a possible control group for studies of this nature. As and Se were observed in Pernambuco (Fernando de Noronha) in very low blood levels. Green turtles from the three other locations presented decreased levels of the same elements in cases with signs of FP, while presenting higher concentrations of some of the toxic chemical elements, such as Pb and Hg. The results obtained from tissue samples showed that green turtles with signs of FP present lower As and Se in all analysed organs, and higher [Pb] in liver, kidneys and bone tissues
|
4 |
RESTORATION OF MARITIME FORESTS: EVALUATING LIMITING FACTORS OF QUERCUS VIRGINIANA (LIVE OAK) REGENERATIONEmily C. Thyroff (5930900) 17 January 2019 (has links)
Maritime forests are a critical interface between ocean and terrestrial
ecosystems, providing important ecosystem services and functions. Along the
U.S. southern Atlantic coast, maritime forests are dominated by <i>Quercus virginiana</i>. Maritime forests and
<i>Q. virginiana</i> have been heavily
impacted by conversion to agriculture, residential development, and pine stands.
Southern pine beetle outbreaks have led to salvage
and thinning silvicultural treatments of pine stands which offer an opportunity
to restore more complex maritime forests. This research project is
comprised of two experiments which allowed me to study
the performance of planted <i>Q. virginiana</i>
seedlings in response to (1) animal browse, (2) competing vegetation,
and (3) varying overstory pine canopies. For
both experiments, one-year-old bareroot seedlings were planted as split-plot
experimental designs. The first experiment evaluated control of deer browse
(fenced and not fenced whole plots) and competing vegetation (0, 1, and 2-yr vegetation
control subplots) as independent variables. Overall seedling survival was 60%
after two years. There was a significant interaction between deer browse and
competing vegetation for seedling height, diameter, crown width, and lateral
branches. Seedlings were larger for all response parameters when fenced with
vegetation control. Vegetation control significantly improved seedling
performance only in fenced plots, indicating a shift in pressure from herbivory
to competition when deer were excluded. Foliar nitrogen (N) was significantly
greater in fenced plots than non-fenced plots and in 2-yr vegetation control
subplots than non-weeded subplots. The second experiment evaluated varying pine overstories (clearcut, heavy thin, light thin,
and no thin whole plots) and competing vegetation control (0 and 2-yr vegetation
control subplots). Overall seedling survival
was 78% after one growing season, with clearcut plots at the greatest survival
(83%) and no thin at the lowest (72%). Seedling growth and foliar nitrogen were
significantly greater in clearcut plots followed by the heavy thin, light thin,
and no thin plots. Vegetation control consistently promoted seedling height,
but was only beneficial to diameter and crown width in clearcut/heavy thin
plots. <i>Q. virginiana</i> seedlings
demonstrated plasticity in their ability to acclimate to the varying
microclimates created by silvicultural treatments, as demonstrated by light
response curves, stomatal density, and specific leaf area. These results
highlight the importance of fencing to remove deer browse, introducing light in
the understory, and further improving seedling performance by removing
competing vegetation.
|
Page generated in 0.0826 seconds