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Copper cycle

Main reservoirs and fluxes of the global copper cycle on Earth. Reservoirs are labeled with sizes in μg/g inside parentheses. On Earth, the largest copper reservoirs are metal use (production, fabrication, use, discard), the core, and the crust. Fluxes between reservoirs are shown as arrows with units of Gg Cu/yr. The thickness of the arrows represents the flux size. The anthropogenic fluxes are in red and the natural fluxes are in navy blue. The largest fluxes are from copper metal use and soil, between the crust and mantle, and from the freshwater to oceans.

The copper cycle is the biogeochemical cycle of natural and anthropogenic exchanges between reservoirs in the hydrosphere, atmosphere, biosphere, and lithosphere.

Copper Reservoirs

Natural copper reservoirs include the Earth's core, mantle, and crust. Crustal rocks contain several average copper abundance of hundred parts per million of copper. Other natural reservoirs are terrestrial biomass, sediments, freshwater, oceans, and atmosphere. Anthropogenic reservoirs include copper's manufacturing life cycle (production, fabrication, usage, and discard), fossil fuels, and agricultural biomass. In outer space, there is also copper on the moon and in meteorites.

Copper Fluxes

Natural Fluxes

Copper is exchanged between the mantle and the crust through volcanoes, hydrothermal vents, and subduction zones. Volcanoes and hydrothermal vents degas material from the mantle, which condenses into particulate form. Copper is recycled back to the mantle through subducting ocean crust.

As the Earth's crust weathers, soil and sediment is formed, and some copper is mobilized from freshwater to the ocean. Copper in the soil is taken up by plants and then released back into the soil when the plants decompose. Wildfires or burning of natural biomass releases copper into the atmosphere.

The flux from micrometeorites in space to the atmosphere is difficult to measure, but is relatively constant over time. Also, it is assumed that the rate of cosmic flux does not depend on geographic location and that it is uniform everywhere. There have been many estimates in the past, so the median of all the fluxes post 1980 was used in the figure.

Anthropogenic Fluxes

Copper is present in coal and unrefined crude oil. When fossil fuels are combusted, copper is released into the atmosphere and soils. Copper cycles through agricultural biomass because animals eat plants containing trace amounts of copper. The copper is then returned to the soil when manure is applied as fertilizer. Agricultural burning also releases copper into the atmosphere.

Copper mining contributes significantly to copper emissions into fresh waters. Copper is also introduced into freshwater during metal corrosion, degradation, and abrasion of copper. Scrap copper metal is commonly recycled, but at the end of its manufacturing life cycle, it is discarded to landfills, which can leach significant copper into fresh waters.

Article Evaluations

Hydrogen Cycle

The content is relevant and not out of date. It goes through different sources and sinks for the abiotic cycles and production and consumption sources for the biotic cycles. The section about relevance for the global climate confused me a little bit. It seems like a last minute thought and doesn't explain to what extent hydrogen impacts methane removal from the atmosphere. It just states that it does and then moves on. There are many links to other wikipedia related topics, for example, Jeans escape and serpentinization. The tone is neutral and there are no biased claims. All of the claims are supported with sources, and all of the sources are linked. The sources were mostly research articles published in academic journals or magazines.

There was no figure in this page.

Iron Cycle

The content is relevant. Some of the content may be out of date... It says that "Today, there is approximately double the amount of soluble iron in oceans than pre-industrial times from anthropogenic pollutants and soluble iron combustion sources." and the source is from 2008. Overall, very well explained, very clear and concise. There are plenty of links to other wikipedia related topics. The tone was neutral. However, there is a lot more information about the oceanic portion of the iron cycle compared to the terrestrial portion. There are many sources that are linked. The sources were mostly research articles published in academic journals or magazines. There are many facts mentioned and the article is unbiased.

The figure is very well made and is an accurate representation of the iron cycle. It has arrows along with the flux values in Tg Fe per year. The figure is very easy to read and the caption is well written.

Oxygen Cycle

The content is very relevant. It breaks down each oxygen reservoir before going into the sources and sinks due to biological production, abiotic production, and biological consumption. It also has tables for the capacities and fluxes of oxygen. Lastly, it mentions how the presence of oxygen is related to the ozone. There are plenty of links to other wikipedia articles. The tone is neutral. There is one fact that is missing a citation for the hydrosphere. The sources were mostly research articles published in academic journals or magazines.

The figure is an accurate depiction of the oxygen cycle. It is clear, except for the arrow depicting loss of H2. Everything is labeled and the fluxes are in 10^12 mol/yr. The figure caption is extremely helpful and explains what all the different colors mean.