Environmental Fate of Copper

Copper has long been used by humans for a variety of reasons. The name copper derives from the Latin for the metal, cuprum, which is named for the Roman source, the island of Cyprus. Copper has been used in a variety of alloys; of particular importance among copper alloys is bronze, which comprised most of the tools and weapons of the age that bears its name. Brass, a copper–zinc alloy, is also highly used, for example, in brass musical instruments. Copper has also long been used as a building material, and owing to the metal’s malleability, as well as high thermal and electric conductivity, continues to find new uses. 

Copper and its compounds are naturally present in the earth’s crust. Natural discharges to air and water may be significant. Therefore, it is important to consider the background levels that are commonly found and distinguish these from high levels that may be found as a result of anthropogenic activity. Copper is emitted into the air naturally from windblown dust, volcanoes, and anthropogenic sources, the largest of which are being primary copper smelters and ore processing facilities. It is associated with particulate matter. The mean concentration of copper in the atmosphere is 5–200 ng m^-3.

Uses

Copper is an essential trace element. Adequate daily requirements are 2–3 mg day¹. It is widely distributed in nature and extensively used in industry. It is used as an electrical conductor, as a component in a variety of alloys (including gold and silver alloys), and as a constituent in paints and ceramic glazes. Because it corrodes at a very slow rate, it is used extensively for water pipes. In addition, copper sulfate mixed with lime is used as a fungicide.
Medicinally, copper sulfate is used as an emetic. It has also been used as an antihelminthic (antiparasitic agent) based on its astringent and caustic actions.

Environmental Fate

The largest release of copper by far is to land, and the major sources of release are mining and milling operations, agriculture, solid waste, and sludge from publicly owned treatment works. Sediment is an important sink and reservoir for copper.  In relatively clean sediment, the copper concentration is<50 ppm; polluted sediment may contain several thousand ppm of copper. 

Copper is released to water as a result of natural weathering of soil and discharges from industries and sewage treatment plants. Copper compounds may also be intentionally applied to water to kill algae. Of special concern is copper that gets into drinking water from the water distribution system. 

The major species of soluble copper found in freshwater, seawater, and a combination of the two over a range of pHs is Cu2+, Cu(HCO3)+, and Cu(OH)2. At the pH values and carbonate concentrations characteristic of natural waters, most dissolved Cu(II) exists as carbonate complexes rather than as free (hydrated) cupric ions.
The transport of copper is largely dependent on source characteristics as well as particle size; however, it can bind to many inorganic ligands. Some copper compounds are water soluble, and this can increase transport distance, as well as likelihood the metal will be taken up by organisms or adsorb to organic residues.

Mechanism

Copper reduces glutathione, which is necessary for normal cell viability. The amino acid transferases are inhibited in the presence of excess copper; lipid peroxidation also occurs. Copper combines with thiol groups, which reduces the oxidation state II to I in copper and oxidizes the thiol groups to disulfides, especially in the cell membrane.

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