Copper (Cu) is required by marine microbes for essential biological processes, including photosynthesis and nitrogen fixation, but can be toxic above a certain threshold. Copper bioavailability in seawater is regulated by complexation with dissolved organic ligands of unknown source and structure. Culturing experiments have demonstrated the production of high-affinity Cu-binding ligands by marine algae in response to metal stress or limitation, suggesting they function either as metal ‘sponges’ to reduce copper toxicity or ‘carriers’ that promote uptake. The goal of my thesis research was to develop methods for the recovery and characterization of Cu ligands from seawater that could then be applied to natural samples to investigate sources and structures of recovered ligands. Using natural seawater spiked with model Cu ligands, I developed an immobilized Cu(II)-ion affinity chromatography (Cu(II)-IMAC) protocol which was shown to be effective in quantifying an operationally defined subset of natural Cu ligands. I then applied Cu(II)-IMAC to seawater collected along transects in the Canadian Arctic and NE Pacific Ocean to assess the abundance of this ligand pool across a diverse set of samples. Ligand distribution profiles and their covariance with other components of seawater (e.g. chlorophyll) were consistent with in situ biological production of some Cu-binding ligands. Model ligands spiked into seawater and recovered by Cu(II)-IMAC were also used to develop protocols for structural characterization of Cu ligands by solid-phase extraction (SPE) and tandem mass spectrometry (MS/MS). This research provides new tools for the isolation and characterization of copper ligands in natural samples, and new insights into the biogeochemical cycling and ecological significance of Cu in the ocean. / Graduate

The green alga, Selenastrum capricornutum Printz, was used in an algal bioassay to determine the toxic properties of copper in various natural lake waters of Oregon. Lake water was collected and brought back to the laboratory where it was treated with various copper concentrations and inoculated with a cell suspension of the test alga. Growth of the alga was determined by direct cell counts. The copper ion activity, pH, and absorbance of the test cultures were also determined. The growth of the alga was ·found to depend upon the water tested and also upon the copper concentration used.

In this thesis, in investigation of various diffusion couple designs is discussed with the aim of enhancing the interaction between the three diffusive flow. Experimental investigation of the theoretical predictions his been carried out for infinite and finite couple boundary conditions. The four independent diffusion coefficients in the copper-rich copper-zinc-tin system have been measured it two temperatures for the dilute composition range. / Thesis / Master of Science (MS)

Copper is a metal that is commonly found in our society's infrastructure, such as cables and wires. In addressing the climate threat, society is facing a major transition towards electrification and digitization, and here copper plays an essential role. Since copper is a main component in the infrastructure, the demand for copper has increased rapidly due to the electrification of, for example, the automotive industry. Even though copper in the earth’s crust is a scarce resource, it can be recycled an infinite number of times without losing its quality. For this reason, meeting future demand partly through secondary copper production is likely to be important. The aim of this study is to investigate what factors influence the secondary refined copper production levels in nine different countries in Europe. Specifically, the study examines how electricity prices, copper scrap prices, primary production of copper, GDP per capita and cost of labor affect the supply of secondary refined copper. The empirical analysis is based on data from nine European countries and over a period of 21 years, 1998 – 2019, thus adopting a panel data approach. The results from the econometric analyses show that all five variables tend to influence the supply of secondary refined copper, some having a more profound effect than the others. For instance, the findings suggest the presence of a low and negative electricity price elasticity of secondary refined supply, while an increase in the copper scrap price appears to have significant deterring impact on secondary refined copper production.

No description available.

The object of this study is to determine the copper and iron intake in food and the output in the urine and feces of women students living in the Home Management House eating a self-selected diet.

Copper exposures of 400 μg/L for 5,10 and 15 days resulted in no significant differences in antibody titers of largemouth bass, Micropterus salmoides injected with Aeromonas hydrophila compared to control-injected bass. Twenty days of exposure did significantly increase titers. The control group had significantly lower antibody titers than either control-injected or copper-exposed.

The chemistry of copper sulfate dosing for effective algal kill was investigated in laboratory studies with Selenastrum capricornutum and Microcystis aeruginosa. The goal was to give practical information for water treatment plants operators who often must apply copper sulfate for algae control in impoundments. Research focused on the theoretical relationships involved in copper dosing, with emphasis on the applicability of these relationships to Virginia freshwater. Concentrations of alkalinity and humic acid were varied to study their effect on percentages of ionic copper available. Long-term (2 weeks) growth-rate studies were performed to study the effect of humic acid on the toxicity of ionic copper to algae. Some protection of algae from copper by humic acid was observed. As the humic acid concentration was increased, more ionic copper was complexed and, thus, was unavailable for algal kill. The only case in which humic acid was not demonstrably protective was at a low concentration (4 mg/L TOC). It is possible that in a long-term test, low humic acid levels may not protect algae, because the copper may be released from the humic acid complex. Alkalinity and the humic acid concentration (TOC) both complex ionic copper, however alkalinity appears to be more important in determining available ionic copper in freshwater. At alkalinities greater than 10 mg/L (as CaCO₃) and humic acid less than 8.0 mg/L, alkalinity predominated in determining available ionic copper. A short term (4-hour) procedure involving measurement of oxygen production by algae exposed to copper was also used to determine the effect of humic acid on ionic copper toxicity to algae. The data showed that short-term tests were best used to predict trends shown in the long-term tests. Both Selenastrum capricornutum (a green alga) and Microcystis aeruginosa (a blue-green alga) were protected from ionic copper by humic acid. Oxygen production was found to be best used to approximate toxic concentrations of a suspect compound, as opposed to being used to precisely determine toxic concentrations. / Master of Science

No description available.

Copper and Zn deficiencies of crops have been reported in various parts of the world. To prevent these deficiencies sulfate forms of Cu and Zn are generally used. In addition, Cu and Zn also are contributed to soils by manures, pesticides, and waste materials such as sewage sludge. An insufficient supply of Cu or Zn may reduce crop yield; whereas, excess Cu or Zn may be detrimental to both plant and animals. The field phase of this research was conducted on a Davidson silty clay to evaluate corn response to high levels of CuSO₄ and ZnSO₄ applications up to 338 kg Cu and 830 kg Zn ha⁻¹. The results of this research indicated that corn grain and stalk yields of corn were not affected (α= 0.05) by high levels of CuSO₄ and ZnSO₄ either alone or combined. Copper concentration in neither corn grain nor ear leaves was affected (α = 0.05) by the Cu application. Zinc concentrations in both grain (α = 0.01) and ear leaves (α= 0.001) were increased by ZnS04 application. Application of ZnSO₄ increased the Cu in the labile pool, whereas CuSO₄ fertilization did not affect Zn in the labile pool. A greenhouse experiment was conducted to examine the response of wheat to Cu application on 14 soils. Treatments in this study were a control and 5.35 mg Cu kg⁻¹ as CuSO₄. Dry matter yields were not affected (α = 0. 05) by Cu fertilization whereas tissue cu levels were increased (α = 0.001). Copper uptake was highly correlated with DTPA-Cu (r = 0.80, α = 0.001), but weakly correlated with Mehlich III-Cu (r = 0.28, α = 0.05). The DTPA-Cu showed high correlations with clay content (r = 0.98, α = 0.001) and SA (r = 0.93, α = 0. 001); whereas, Mehlich III-Cu did not correlate with these variables (α = 0.05). A second greenhouse experiment was conducted with 10 Virginia soils to evaluate the response of corn to Cu fertilization. Treatments were a control and 5.35 mg Cu kg⁻¹ as CuS0₄. Dry weights of corn on the 10 soils were not affected (α = 0.05) by Cu application; whereas, tissue Cu levels were increased by the applied Cu (α = 0. 001). Copper uptake by corn plant correlated with DTPA-Cu (r = 0.62, α= 0.001) and with soil pH (r = 0.35, α = 0.05). There was no correlation of organic matter with Cu uptake (α = 0.05). Both DTPA-Cu and Mehlich III-Cu were unrelated to either organic matter or soil pH (α = 0.05). / Ph. D.