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Distribution of incompatible trace elements in rock-forming and accessory minerals from carbonatites as a tracer of magma evolutionReguir, Ekaterina 22 August 2011 (has links)
Carbonatites are igneous rocks comprising more than 50 modal percent of carbonate minerals and characterized by highly variable modal compositions. The majority of carbonatites are confined to intra-continental rifts, whereas occurrences associated with plate margins and orogenic settings are less common. Petrogenesis of carbonatites has been a matter of intense debate for several decades. The possible genetic models include crystallisation from a primary carbonatite magma, liquid immiscibility and crystal fractionation from carbonate-rich silicate magma. In contrast to the voluminous bulk-rock trace-element data and major-element analyses of minerals from carbonatites available in the literature, there has been no systematic study concerned with the trace-element signatures of the most common constituents of these rocks.
This work is the first comprehensive study of the interrelations between the trace-element chemistry of the most common constituents of carbonatites, the geochemistry of these rocks, and their tectonic setting. The rock samples examined represent 21 different localities worldwide. The extent of major- and trace-element substitutions in amphibole, clinopyroxene, trioctahedral micas, dolomite, magnetite and perovskite is investigated in detail. The silicate minerals from carbonatites exhibit much larger compositional diversity than previously recognized. They can incorporate significant amounts of such petrogenetically important elements as Sr, REE, Zr, Nb and Ta. The majority of studied clino-amphibole- and clinopyroxene-group minerals exhibit previously unrecognized a bimodal distribution patterns of REE, which can be explained in terms of crystal chemistry of these phases. The trace-element signature of phlogopite from carbonatites, particularly Nb, Mn, Ni and Cr, is distinctly different from that of phlogopite from kimberlites, and can be used as a reliable petrogenetic indicator. Compositional variations in dolomite reflect magmatic and subsolidus processes in carbonatites. Magnetite from carbonatites follows a well-defined magmatic and previously unrecognized reaction trend. Contrary to prior studies, this mineral is only a minor host of HFSE in carbonatitic rocks. The U-Pb age data, trace-element and Sr-isotopic composition of perovskite from the Afrikanda carbonatite and clinopyroxenite suggest that the two rocks are not related by crystal fractionation. This study underlines the importance of a systematic approach in petrogenetic studies based on trace-element distribution.
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Meteoric Diagenesis of Plio-Pleistocene Reef Terraces in the Southern Dominican RepublicHernawati, Yulaika 09 December 2011 (has links)
Four prograding reef terraces (6, 15, 30, and 50 m) have been repetitively exposed to marine and freshwater alteration during the Pliocene and Pleistocene periods. Prolonged freshwater alterations have resulted in many diagenetic overprints that obscure early diagenetic products. This study investigates the sequence of the diagenetic processes and products in the terrace deposits using five long cores and 14 short cores taken from these different reef terraces. The lithologic changes in the cores were documented for reconstruction of the original depositional frameworks prior to embarking on a diagenetic study. Both textural and geochemical changes were examined within all four different terraces in order to characterized the diagenetic history. The textural changes observed in the cores and thin sections, provided preliminary evidence of the diagenetic environment. Through the use of X-ray diffractometry, stable isotopes (C and O), and trace element data, the interpretation of the diagenetic environment can be constrained. The reef terraces were deposited as as shallowing upward units following a down-stepping carbonate sequence. The lithology of the cores is dominated by reefal facies, which consist of the back reef, reef crest, front, and fore reef facies. The exposure surfaces, observed at various depths, constrained the interpretation of early diagenetic environments (met. vadose and phreatic). Three major diagenetic environments can be characterized from the cores, these are meteoric vadose, meteoric phreatic, and dolomitizaton. These diagenetis environments produced different geochemical signatures, which can be quantified through analysis of the stable isotopes and trace elements incorporated into the cements. The different reef terraces represent different duration of exposure, with the higher terraces having been exposed longer than the lower ones. This study enables the documentation and comparison of the processes and products of the meteoric diagenesis that occurred within these different terraces. In addition, this study also constrain the early dolomitization observed in sigmoidal reef deposits. In order to further quantify the process of early dolomitization, mineralogy, isotopes C and O, trace elements, and the Sr-isotopes were examined as well.
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Biomarkers of Cadmium, Lead and Selenium Toxicity in the Marine Bivalve Molluscs Tellina deltoidalis and Anadara trapezia: Linking Exposure, Dose and ResponseTaylor, Anne Marie, n/a January 2009 (has links)
The relationships between metal exposure, dose and response were investigated in two
sediment dwelling marine bivalves: a deposit feeder Tellina deltoidalis and a filter feeder
Anadara trapezia. The bivalves were exposed in the laboratory to individual metal spiked
sediments: Cadmium 10 and 50 Ag/g; lead 100 and 300 Ag/g; selenium 5 and 20 Ag/g dry
mass, T. deltoidalis for 28 days A. trapezia for 56 days. A. trapezia was also exposed in the
laboratory for 56 days to sediments from three sites along a metal contamination gradient of
cadmium, lead, selenium, zinc and copper from Lake Macquarie, NSW. Metal total tissue
dose was measured in whole tissue of T. deltoidalis over 28 days and in gill, hepatopancreas
and haemolymph tissues in A. trapezia over 56 days. Subcellular metal distribution,
biologically active metal (BAM) versus biologically detoxified metal (BDM) was measured
in whole tissues of T. deltoidalis at day 28 and in gill and hepatopancreas tissues of
A. trapezia at day 56. Biomarkers of response measured in spiked sediment exposed, at day
28 T. deltoidalis and day 56 A. trapezia were: total antioxidant capacity (TAOC); glutathione
peroxidase enzyme activity (GPx); total glutathione concentration (GSH+2GSSG); reduced to
oxidised glutathione ratio (GSH:GSSG); lipid peroxidation (TBARS); lysosomal membrane
stability and micronuclei frequency. Response indices measured in A. trapezia exposed to
Lake Macquarie sediments were: TAOC, TBARS, lysosomal membrane stability,
micronucleus frequency and condition index. Native A. trapezia and sediments were also
collected from Lake Macquarie and measured for sediment and tissue metal concentrations,
TAOC, TBARS, lysosomal membrane stability and condition index to allow comparison
between chronically exposed and previously unexposed organisms.
T. deltoidalis and A. trapezia accumulated metal over time in all sediment metal exposures
with most reaching equilibrium tissue metal concentrations by the end of the exposure period.
T. deltoidalis generally reached equilibrium with the exposure concentration for cadmium and
lead but had significantly higher selenium tissue concentrations than the sediment metal at the
5 Ag/g exposure. A. trapezia tissue lead was below the sediment concentration for all
exposures including in the native organisms. A high proportion of accumulated lead and
copper in A. trapezia was in the haemolymph, probably associated with haemoglobin which
has a high affinity for these metals`. A. trapezia cadmium tissue concentrations were higher
than the sediment metal in the 10 Ag/g spiked sediment exposure and between half and one
eighth the sediment concentrations in other treatments, including in native organisms.
A. trapezia including the native organisms exposed to selenium sediment concentrations at or
below 5 Ag/g in the Lake Macquarie mixed metal sediments accumulated significantly higher
than ambient selenium tissue concentrations while those exposed to 5 and 20 Ag/g selenium
spiked sediments had lower than ambient selenium tissue concentrations. The majority of
accumulated cadmium, selenium and zinc was associated with the gill/mantle tissues.
A. trapezia hepatopancreas contributed significant selenium concentrations in the later part of
the exposure period indicating and increased contribution from dietary derived selenium.
Native A. trapezia had significantly lower tissue concentrations of selenium, copper and zinc,
higher cadmium and approximately equal lead compared to organisms exposed to similar
sediment metal concentrations in the laboratory.
T. deltoidalis detoxified around 50 % of accumulated cadmium and 70 % of lead while
A. trapezia detoxified around 70 % of accumulated cadmium and 60 % of lead. Much of
T. deltoidalis BDM cadmium was converted to metal rich granules (MRG), while A. trapezia
had most in the metallothionein like proteins (MTLP) fraction. The conversion of lead to
MRG was 75 % of the total BDM in T. deltoidalis while A. trapezia had an even distribution
between MRG and MTLP. The majority of recovered selenium in both species was
associated with the nuclei+cellular debris fraction, probably as protein bound selenium
associated with plasma and selenium bound directly to cell walls. Selenium exposed
organisms had increased BDM selenium burdens which were associated with both MRG and
MTLP fractions, indicating selenium detoxification. The majority of BAM cadmium, lead
and selenium was associated with the mitochondrial fraction in both species with increases in
cadmium burden in this organelle of T. deltoidalis up to 7200 fold; lead 154 fold; and
selenium 7 fold and in A. trapezia up to 84 fold cadmium, 50 fold lead and selenium 7 fold in
exposed organisms compared to controls. The subcellular distribution of all three metals in
T. deltoidalis and A. trapezia indicates active metal detoxification processes which at these
exposure concentrations were unable to prevent significant metal burdens from accumulating
in sensitive organelles.
A contamination gradient of zinc, lead, copper, cadmium and selenium was established in
Lake Macquarie sediments which emanated from the same source. A. trapezia accumulated
all metals in each sediment exposure. Accumulation and tissue distribution patterns of
cadmium, lead and selenium were similar to those of the single metal spiked sediment
exposures. Cadmium and lead BAM burdens increased at all exposures while selenium, zinc
and copper did not.
T. deltoidalis and A. trapezia in the spiked sediment metal exposures generally had reduced
GPx activity. This resulted in an increase in total glutathione concentrations which the
reduced GSH:GSSG ratios indicated was due to a build up of oxidised glutathione.
T. deltoidalis and A. trapezia had reduced TAOC in all laboratory sediment metal exposures
which corresponded with increased TBARS concentrations, lysosomal destabilisation and
micronucleus frequency. A. trapezia exposed to Lake Macquarie metal contaminated
sediments also had a reduction in physiological condition, indicated by the reduced condition
index, after 56 days at the higher metal exposures.
Clear exposure - dose - response relationships have been demonstrated for T. deltoidalis and
A. trapezia exposed to single cadmium, lead and selenium spiked sediments and for
A. trapezia exposed to Lake Macquarie mixed metal contaminated sediments. Detoxification
of all metals was evident in both T. deltoidalis and A. trapezia but detoxification capacity was
exceeded for cadmium, lead and selenium leading to significant accumulation of these metals
in sensitive organelles. The significant relationships, in the laboratory exposed T. deltoidalis
and A. trapezia, between TAOC reduction with increased TBARS, lysosomal destabilisation
and micronuclei frequency and between increased TBARS with lysosomal destabilisation and
micronuclei frequency indicates that increased tissue metal dose and BAM burdens caused
significant impairment of the antioxidant reduction capacity which resulted in a cascade of
effects from lipid peroxidation to cellular perturbation and genotoxic damage. The reduction
in physiological condition in the organisms with the highest tissue metal doses suggests the
response goes beyond subcellular perturbations to whole organism and potentially population
effects.
Chronically metal exposed native Lake Macquarie A. trapezia did not show a clear metal
exposure - dose - response relationship. Accumulation of the essential elements zinc, copper
and selenium appeared to be regulated while cadmium and lead were not. TAOC was
significantly reduced and TBARS significantly increased compared to reference organisms
but lysosomal stability and condition were not significantly affected.
The suite of interrelated biomarkers used offers a weight of evidence approach for
demonstrating adverse effects of metal tissue accumulation in T. deltoidalis and A. trapezia
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Genetic studies on the tolerance of wheat to high concentrations of boron / by Yodsaporn Chantachume.Yodsaporn Chantachume January 1995 (has links)
Bibliography: leaves 213-245. / iv, 246, [59] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Genetic control of tolerance to boron was investigated between a moderately tolerant variety, Halberd, a tolerant line G61450 and the moderately sensitive varieties Schomburgk and Condor. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996
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Genetics of boron tolerance in durum wheat / by Sansanee Jamjod.Jamjod, Sansanee January 1996 (has links)
Bibliography: leaves 234-256. / ix, 257 leaves, [12] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Genetic studies of tolerance of durum wheat (Triticum turgidum L. var durum) to high concentrations of boron (B) were undertaken to identify genetic variation in response to B, the mode of gene action, number of genes and chromosomal locations of genes controlling tolerance. Results demonstrated that tolerance to B is under simple genetic control as observed in bread wheat. High levels of tolerance can be transferred into sensitive commercial varieties via backcrossing and selection can be performed during seedling growth at early generations. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996
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Peat Deposits of Moreton Bay:Natural Archives of Environmental PollutionJiajia Zheng Unknown Date (has links)
Two ombrotrophic peat bogs (NC2 and BL2) from North Stradbroke Island, Australia, were precisely dated using 210Pb and analyzed by scanning electron microscopy. Sub-samples were total digested and sequentially leached for trace and major elements concentrations using ICP-MS and ICP-OES. Total Pb concentrations in both profiles increased with the time. PAAS normalized REE patterns were characterized by relatively flat patterns, with slight enrichment in LREE, and a significant negative Eu anomaly. The temporal changes in metal concentrations, 206Pb/207Pb ratios, REEs, and ash content observed in the two profiles suggest three different periods with distinct conditions in terms of dust provenance and atmospheric pollution: (1) Pre-anthropogenic (pre-1842); (2) Early industrial (from 1840s to 1920s); (3) Industrial (post-1930s). Ombrotrophic peat bogs may be reliable archives of environmental pollution, but also shows that adjacent sites may provide contrasting evidence. Despite their close proximity, the two sites show different trends in metal deposition. Metals in NC appear to be largely bound to minerals and inorganic materials, while in BL they are mainly organic-related. Indeed the peculiar behaviour of Pb in the BL profile suggests that biological process may cause Pb isotopic fractionation. Ash contents, texture, Pb isotopic compositions, Sb/Pb values, patterns of selected trace elements (Pb, Cu, Zn, Cd, Cr, Co, Sb, Ni, Se, As, Be and Mo), and their leaching behaviours suggests that NC and BL are chemically different types of peat bogs. NC peat bog is an open sink for elements, and can be used to define regional anthropogenic impacts. In contrast, the BL site appears to be influenced by local natural and anthropogenic processes and activities, such as changes in land use. Furthermore, it demonstrated that only some of the environmental-related trace elements preserve their original depositional record. Arsenic, Be, Co, and Zn are highly mobile under weak acid conditions, and are therefore not suitable for assessing temporal trends of pollution. Cadmium, Ni, and V may also be highly mobile under certain conditions. In contrast, Pb, Cu, Cr, Mo, and Sb are not subject to vertical migration, and are useful for establishing the pollution record of ombrotrophic peat bogs.
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Peat Deposits of Moreton Bay:Natural Archives of Environmental PollutionJiajia Zheng Unknown Date (has links)
Two ombrotrophic peat bogs (NC2 and BL2) from North Stradbroke Island, Australia, were precisely dated using 210Pb and analyzed by scanning electron microscopy. Sub-samples were total digested and sequentially leached for trace and major elements concentrations using ICP-MS and ICP-OES. Total Pb concentrations in both profiles increased with the time. PAAS normalized REE patterns were characterized by relatively flat patterns, with slight enrichment in LREE, and a significant negative Eu anomaly. The temporal changes in metal concentrations, 206Pb/207Pb ratios, REEs, and ash content observed in the two profiles suggest three different periods with distinct conditions in terms of dust provenance and atmospheric pollution: (1) Pre-anthropogenic (pre-1842); (2) Early industrial (from 1840s to 1920s); (3) Industrial (post-1930s). Ombrotrophic peat bogs may be reliable archives of environmental pollution, but also shows that adjacent sites may provide contrasting evidence. Despite their close proximity, the two sites show different trends in metal deposition. Metals in NC appear to be largely bound to minerals and inorganic materials, while in BL they are mainly organic-related. Indeed the peculiar behaviour of Pb in the BL profile suggests that biological process may cause Pb isotopic fractionation. Ash contents, texture, Pb isotopic compositions, Sb/Pb values, patterns of selected trace elements (Pb, Cu, Zn, Cd, Cr, Co, Sb, Ni, Se, As, Be and Mo), and their leaching behaviours suggests that NC and BL are chemically different types of peat bogs. NC peat bog is an open sink for elements, and can be used to define regional anthropogenic impacts. In contrast, the BL site appears to be influenced by local natural and anthropogenic processes and activities, such as changes in land use. Furthermore, it demonstrated that only some of the environmental-related trace elements preserve their original depositional record. Arsenic, Be, Co, and Zn are highly mobile under weak acid conditions, and are therefore not suitable for assessing temporal trends of pollution. Cadmium, Ni, and V may also be highly mobile under certain conditions. In contrast, Pb, Cu, Cr, Mo, and Sb are not subject to vertical migration, and are useful for establishing the pollution record of ombrotrophic peat bogs.
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Cadmium in newborns : bioavailability from infant food studied in a rat pup, a piglet and a human intestinal cell line model /Eklund, Gunilla, January 2003 (has links) (PDF)
Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.
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Organic vs. inorganic selenium in farm animal nutrition with special reference to supplementation of cattle /Ortman, Kerstin, January 1900 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.
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Nutrition and immune response in periparturient dairy cows : with emphasis on micronutrients /Meglia, Guillermo Esteban, January 2004 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 4 uppsatser.
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