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Isotopic exchange and complexation of iron, zinc, and manganese in a long-term marine phytoplankton cultureRiedel, Gerhardt Frederick 03 August 1977 (has links)
Graduation date: 1978
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Trace metals in phytoplankton from an area of coastal upwellingPequegnat, John Eugene 18 September 1974 (has links)
Short-term changes in the distribution, surface to 10 meters, of
phytoplankton-associated trace metals (Fe, Mn, Cr, Zn, Co, Ni, and
Cu) were studied in the near-shore waters off Humboldt Bay,
California, through the summer of 1971. The depth distribution of
phytoplankton-associated trace metals was related to local hydrography.
During periods of upwelling higher concentrations of
phytoplankton-associated Fe, Mn, Cr, and Zn were found at depth
(10 meters) than at the surface. During periods of non-upwelling
there was less stratification in their distribution. Phytoplankton-associated
Cu, Go, and Ni showed no significant increase with depth
during either period. The rate of change in trace metal distribution
patterns of Fe, Mn, Cr, and Zn were regulated by surface wind patterns
and hydrographic regimes. Again, Cu, Co, and Ni did not
fluctuate in a significant fashion.
The elements studied tended to fall into three ordered groups
based on their behavior with respect to 1) depth distribution,
2) correlation with other metals studied, and 3) correlation with biomass
indicators. The groupings were Fe, Mn, and Cr; Zn, Co, and
Ni; and finally Cu. This ordering is similar to the Irving- Williams
series and to the elements relative 'hardness" as a Lewis acid where
Fe(III), Cr(III), and Mn(II) are considered hard Lewis acids while
Zn(II), Co(II), Ni(II) and finally Cu(II) are considered borderline hard
to soft Lewis acids. These properties are related to the relative
affinities and selectivities of the elements for organic ligands. There
also appears to be some relation between the physical (dissolved
versus particulate form) and the chemical (oxidation state and ionic
potential) behavior of the elements in sea water and their behavior in
the phytoplankton.
There was a negative correlation between most phytoplankton-associated
trace metal concentrations (Fe, Mn, Cr, Zn, Co, and Ni)
and biomass during non-upwelling periods and a positive correlation
during upwelling periods. Copper, on the other hand, showed a positive
correlation during both periods. This aberrant behavior of copper
may be related to its high affinity for organic ligands and its relative
softness as a Lewis acid. Since no simple negative correlation was
found between phytoplankton biomass and phytoplankton-associated
trace metal concentrations, biological dilution does not appear to be as
important as the hydrographic regime and the chemical activities of
the element in determining the concentrations of trace metals in
near shore phytoplankton populations. / Graduation date: 1975
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The concentration and oxidation state of chromium in sea waterStanford, Harold Milford 13 October 1970 (has links)
Graduation date: 1971
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Development of methods for trace analysis of drinking water /Joehler, Thomas H. January 1980 (has links)
Thesis (M.S.)--Oregon Graduate Center, 1980.
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Topics in the behaviour of atmospheric trace gases /Khalil, Mohammad Aslam Khan. January 1979 (has links)
Thesis (Ph. D.)--Oregon Graduate Center, 1979.
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Effects of trace metal pre-exposure on their bioaccumulation in marine bivalves /Shi, Dalin. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
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Clinical application of trace analysis of carbon monoxide in expired air /Wong, Kung-hin. January 1986 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1987.
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Analysis of trace metals in palm oil.Fung, Ying-sing, January 1977 (has links)
Thesis (M. Phil.)--University of Hong Kong, 1977.
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Trace element incorporation in modern speleothem calcite and implications for paleoclimate reconstructionHatch, Rosemary 02 February 2015 (has links)
Trace element compositions, expressed as ratios relative to Ca (Mg/Ca, Sr/Ca and Ba/Ca), in drip water and modern speleothem calcite were measured at multiple sites within a single cave system (Natural Bridge Caverns) in central Texas. These measurements are used to investigate how water and calcite compositions respond to changes in climate. Drip water trace element ratios respond to changes in climate and in soil, vadose zone and/or in-cave processes, which are in turn influenced by climate. It is commonly assumed that speleothem calcite directly reflects these changes in the drip water composition. To test this assumption, this study quantifies the partitioning of trace elements into speleothem calcite in a natural cave setting. To determine the controls on calcite trace element ratios, empirical partition coefficients (K [subscript D]) for Mg, Sr, and Ba are measured using a unique time series of water and modern calcite geochemistry at two drip sites. One drip site, dominantly supplied by conduit flow, has relatively invariant calcite trace element compositions that reflect correspondingly small variations in drip water chemistry. A second drip site, supplied by a combination of conduit and diffuse flow, exhibits a seasonal change in drip water composition due to changes in cave-air CO₂ concentrations. The drip water seasonality at this site is recorded in the calcite trace element compositions; however the partitioning of Mg/Ca from drip water to calcite is not controlled by the same mechanism(s) that control Sr/Ca and Ba/Ca partitioning. Results of this study indicate that the partitioning of Mg changes with drip water Mg concentration, temperature and location of the calcite relative to the point of drip impact. Calcite Sr/Ca and Ba/Ca ratios are more strongly influenced by changes in cave-air CO₂ that cause changes in CO₂ degassing, affecting calcite precipitation. This element specific partitioning complicates the interpretation of speleothem trace element records, since calcite Mg/Ca and Sr/Ca may not always covary even at drip sites that experience PCP. Although there is a strong correlation between Mg/Ca and Sr/Ca ratios in the drip water at these sites, there is considerable scatter between these two values in calcite. Average K [subscript D] values at both sites fall within the range of previous theoretical and empirical studies and are 0.025, 0.12 and 0.15 for Mg, Sr and Ba respectively. It is important to note that not all trace element partitioning is controlled by the same mechanism, since this has implications for interpretations of hydrologic processes from speleothems. / text
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Analysis of Trace Elements in South African Clinkers using Latent Variable Model and ClusteringAbonyi, J, Tamás, FD, Potgieter, S, Potgieter, H 19 March 2003 (has links)
The trace element content of clinkers (and possibly of cements) can be used to identify the manufacturing factory. The Mg, Sr, Ba,
Mn, Ti, Zr, Zn and V content of clinkers give detailed information for the determination of the origin of clinkers produced in
different factories. However, for the analysis of such complex data there is a need for algorithmic tools for the visualization and
clustering of the samples. This paper proposes a new approach for this purpose. The analytical data are transformed into a twodimensional
latent space by factor analysis (probabilistic principal component analysis) and dendograms are constructed for
cluster formation. The classification of South African clinkers is used as an illustrative example for the approach.
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