Copper ions, toxicity

An interesting effect is sometimes observed when cupronickels are galvanically coupled to less noble materials. The corrosion rate of the active metal is increased and the corrosion rate of the cupronickel is diminished, as expected. The diminished corrosion rate of the cupronickel can, however, diminish its fouling resistance since reduced production of copper ions lowers toxicity to copper-ion-sensitive organisms. 

Trace metals can serve as essential nutrients and as toxic substances (Sunda et al, 1991 Frausto da Silva and Williams, 1991). For example, cobalt is a component of vitamin B-12. This vitamin is essential for nitrogen fixing algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and... 

In the past, copper was believed to be toxic to most microbiological species. Although this may be true in a test tube under laboratory conditions, it is not generally true in the real world. In this real world, microbial communities excrete slime layers which tend to sequester the copper ions and prevent their contact with the actual microbial cells, Aus preventing the copper from killing the microbes. Many cases of MIC in copper and copper alloys have been documented, especially of heat-exchange tubes, potable water, and fire protection system piping. 

An important harmful effect of metals at the cellular level is the alteration of the plasma membrane permeability, leading to leakage of ions like potassium and other solutes (Passow and Rothstein, 1960 Wainwright and Woolhouse, 1978 De Filippis, 1979 De Vos et al., 1988, 1991). After supply of copper ions Ohsumi et al. (1988) demonstrated for yeast cells and De Vos et al. (1989) for root cells of Silene cucubalus that the permeability barrier (controlled by means of potassium leakage) of the plasma membrane was almost immediately lost. Oshumi et al. (1988) also reported a quick release of amino acids, especially glutamate and aspartate. After McBrien and Hassall (1965) and Overnell (1975), who studied potassium release from algal cells, the increased permeability of the plasma membrane may be considered to constitute the primary toxic effect of copper. 

Metal ion toxicity copper Local water quality... 

Excess copper is toxic to cells. On one hand, copper ions can avidly bind to biomolecules by ligand interaction with cysteines or by binding to histidine-rich regions. Copper ions could also be incorporated into proteins instead of zinc or other metal ions during biosynthesis. On the other hand, copper ions can form radicals by a Fenton-type reaction as shown in Eq. (1) ... 

Under conditions where copper is in excess in the surrounding medium, the yeast cell s perspective shifts from one of active acquisition of copper ion to one of protecting the cytoplasm from its toxic effects. To... 

Copper Hemocyanrn/Tyrosinase Models Copper Proteins with Dinuclear Active Sites Copper Proteins with Type 1 Sites Copper Proteins with Type 2 Sites Cytochrome Oxidase Electron Transfer Reactions Theory Long-range Electron Transfer in Biology Metal Ion Toxicity Metal-related Diseases of Genetic Origin Metallochaperones Metal Ion Homeostasis Nutritional Aspects of Metals Trace Elements. 

If the numbers were accepted at face value, the data indicate that the species involved account for S0-S % of the toxicity, the carbonato complexes do not contribute to toxicity, the anionic hydroxo copper complexes contribute 13-18 to the total toxicity, and the free copper ion and/or the neutral and cationic hydroxo complexes of copper are responsible for 60-70 of the toxicity of copper to aquatic life. 

Since copper is toxic to plants, it must be used at low levels or in the insoluble form. For this reason, the relatively insoluble or fixed copper salts are used. These compounds release copper ions at very low rates that are adequate for fungicidal activity but not at concentrations that would harm or kill the host plant. 

In the early 1970s, Zitko et al. (1973) noted that HAs reduced the activity of the free Cu " ion, as measured by the copper ion-selective electrode, and that this effect was quite well correlated with the observed toxicity of Cu(II) to salmon. Soon thereafter, Pagenkopf et al. (1974) also reported on the effect of complexation on the toxicity of copper to fishes. Sunda and Guillard (1976) demonstrated that the activity of the free Cu " ion in synthetic growth media containing the metal complexing agent TRIS (2-amino-2-hydroxy-methyl-1,3-propanediol) was an excellent... 

Copper intrauterine devices are widely used and highly effective (> 99% at one year) for 5 and some for 10 years. They are especially useful in the over-40s in whom oral contraceptives may become progressively contraindicated and for whom one lUD will last into the menopause. The lUD prevents implantation of the fertilised ovum, and has an additional antifertilisation effect enhanced by the toxic effect of copper ions on the gametes. 

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