Aluminum cycle

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A metamorphic rock called emery that is mostly made of corundum which is an aluminum oxide. This is an example of an aluminum deposit. Emery (Naxos Emery Deposits, metamorphism in the Eocene & Miocene, 40-50 Ma & 16-20; Naxos Island, Aegean Sea) 5.jpg
A metamorphic rock called emery that is mostly made of corundum which is an aluminum oxide. This is an example of an aluminum deposit.

Aluminum is the third most abundant element in the lithosphere at 82,000 ppm. It occurs in low levels, 0.9 ppm, in humans. [1] Aluminum is known to be an ecotoxicant and expected to be a health risk to people. Global primary production (GPP) of aluminum was about 52 million tons in 2013 and remains one of the world's most important metals. It is used for infrastructure, vehicles, aviation, energy and more due to its lightweight, ductility, and cheap cost. Aluminum is harvested from gibbsite, boehmite, and diaspore which make up bauxite. [2] The aluminum cycle is the biogeochemical cycle by which aluminum is moved through the environment by natural and anthropogenic processes. The biogeochemical cycle of aluminum is integral with silicon and phosphorus. For example, phosphates store aluminum that has been sedimented and aluminum is found in diatoms (made of silica). Aluminum has been found to prevent growth in organisms by making phosphates less available. The humans/lithosphere ratio (B/L) is very low at 0.000011. This level shows that aluminum is more essential in the lithospheric cycle than in the biotic cycle. [1]

Contents

Natural fluxes

Lithospheric cycle

Aluminum makes up 8% of the Earth’s crust. [2] The majority of aluminum cycling takes place in the lithosphere via sedimentary processes, with 99.999% of aluminum cycled within the lithosphere in the form of primary and secondary minerals as well as colloidal phases. [1] Primary aluminum-rich minerals, such as feldspars, in the Earth's crust are weathered to clay-like materials such as kaolinite. Feldspars are formed when magma cools within Earth’s crust and are weathered away from the parent material. The secondary mineral, kaolinite, forms from carbonic acid weathering. Other secondary minerals include hydroxyaluminosilicates and aluminum hydroxide which are insoluble. They adsorb on mineral and organic surfaces. [1] Clays generally have low solubility and are eventually returned to crust through sedimentation and subduction. [1] Aluminum is then found as an unstable primary mineral. Aluminum goes through several dissolution and precipitation processes when the element is in an aqueous phase, meaning it was dissolved. [1] With further weathering, aluminum is transported as particulates in rivers. [3] Aluminum can also be carried through the atmosphere via dust. [2]

Global aluminum cycle Fluxes are in Gg (gigagrams) Al/yr, and reservoirs are in Gg Al. Most of the aluminum on Earth is located in the mantle and crust of the lithosphere. From various processes, this aluminum is uplifted through the soil and into the biotic cycle. Most notably, humans find mineral deposits of aluminum in the earth and dig it up to use in various products. This process, which includes the production, fabrication, use, and discarding of aluminum, contributes greatly to the cycling of aluminum through our Earth's biogeochemical cycle. Aluminum Cycle Flow 2.png
Global aluminum cycle
Fluxes are in Gg (gigagrams) Al/yr, and reservoirs are in Gg Al. Most of the aluminum on Earth is located in the mantle and crust of the lithosphere. From various processes, this aluminum is uplifted through the soil and into the biotic cycle. Most notably, humans find mineral deposits of aluminum in the earth and dig it up to use in various products. This process, which includes the production, fabrication, use, and discarding of aluminum, contributes greatly to the cycling of aluminum through our Earth's biogeochemical cycle.

Biotic cycle

Aluminum enters the biosphere through water and food as soluble aluminum, Al3+ or AlF2+. It is then cycled through the food chain. [1] Aluminum has a low abundance in the biosphere but can be found in all organisms. [1] Humans, animals, and plants accumulate aluminum throughout their lives as it cycled throughout the food chain. There is no evidence to support aluminum being essential to humans or in any other forms of life. [1] It causes no harm or good unless over-consumed. [1] The low abundance of aluminum in biology may be due to Al3+ being held in the lithosphere and/or organisms have evolved to lose Al3+. [2]

Aluminum can be toxic to plants when the soil is acidic with a pH of 5 or below. Half of the world’s agricultural lands experience this acidity so aluminum is a limiting factor of a crop’s success. Plants can become resistant to Al by methods such as internal detoxification with carboxylate ligands or sequestration of Aluminum complexes. [4]

The Calhoun Experimental Forest where aluminum accumulation in biomass was studied. The Calhoun Experimental Forest (IA CAT10507256).pdf
The Calhoun Experimental Forest where aluminum accumulation in biomass was studied.

In a study on the translocation and transformation of Aluminum in the Calhoun Experimental Forest in South Carolina, an average annual uptake of Al was 2.28 kg/ha/year while the average annual accumulation in biomass off the ground was 0.48 kg/ha/year. Aluminum was found to not leach through the soil so the only method of removal was in the biomass. [5]

Anthropogenic influence

Acid rain

Human activity has influenced the aluminum cycle through the acidification of the environment. Acid rain increases weathering of the lithosphere through sulfuric acid weathering instead of the usual carbonic acid weathering. This alters the aluminum cycle by reducing the availability of silicic acid and lowering the pH of the environment. [1] The depletion of silicic acid causes the solubility of aluminum to switch from being dependent on relatively stable hydroxyaluminosilicates to much more unstable solubility controls, such as amorphous aluminum hydroxide and organoaluminum complexes. These complexes are more able to move around in the environment which causes an increase in the dissolution of aluminum into the water ways. [6] Aluminum is usually physically weathered and remains in a stable state, acid rain chemically weathers aluminum deposits. This creates a toxic form of aluminum while also increasing the total amount of aluminum being weathered. [1]

A bauxite mine in Weipa, Australia. Mining equipment at the Comalco bauxite mine; Weipa.jpg
A bauxite mine in Weipa, Australia.

Mining and industrial use

Mining for aluminum and the subsequent industrial usage disrupts the natural burial processes of the aluminum cycle. By the year 2050 the need for aluminum is expected to increase by 200-300%. [7] Aluminum is mined in the form of bauxite ore. Bauxite is only 40-60% aluminum oxide. [8] The elements that make up the rest of bauxite are also very useful. [9] Globally, 68 million tons of aluminum were mined in 2021. This aluminum is mostly used in vehicle production, construction, and packaging like cans and foil. The two largest bauxite producers are China and Australia. [8] Bauxite is mined with traditional strip mining techniques. This harms the environment by removing top soil, disturbing the ecosystem, and increasing erosion. [10] Aluminum mined from the earth is transported from its original location to all over the world through international trade. It is mainly shipped from the southern hemisphere to the northern hemisphere. This means that most of the environmental impacts from mining are suffered by the southern hemisphere. [11] Aluminum is able to be recycled an infinite amount of times. [8]

Oceanic cycling

Aluminum primarily enters oceans by the process of mineral dust deposition. Dust deposition mainly occurs in the Atlantic Ocean, and in the Indian Ocean to a lesser extent, with dust mainly originating from Western Africa and Southern Asia, respectively. [12] From here, some aluminum dust dissolves into the oceans' water columns. Aluminum may also enter or re-enter the cycle from sedimentary sources from oceanic basins. [12]

Recent research suggests that dissolved aluminum is transported by ocean currents through advection. Because of advection, dissolved aluminum is present in a greater area within the ocean's surface. Dissolved aluminum is especially dispersed over the greater Atlantic ocean, first towards Central America and eventually as far as Iceland. [12]

The process of particle scavenging is the main source of dissolved aluminum removal, with dissolved aluminum accumulating on sinking particulates. [12] However, some particulate aluminum is released during sinking, as a result of this scavenging being reversible. The reversibility of this scavenging allows for the distribution of aluminum across depth, with dissolved aluminum becoming more common at greater depths, albeit in lesser concentrations than that of the surface. [12]

Phytoplankton may contribute to the removal of aluminum within the scavenging process. At the ocean's surface, dissolved aluminum is incorporated into phytoplankton, primarily within the cell walls of diatoms. [12] [13] Particulate aluminum—whether adsorbed onto mineral or biotic particulates—eventually sinks to the ocean floor, where it is buried. [12] [13]

Related Research Articles

<span class="mw-page-title-main">Weathering</span> Deterioration of rocks and minerals through exposure to the elements

Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs in situ, and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity.

The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere, biosphere, lithosphere and the hydrosphere. The pedosphere is the foundation of terrestrial life on Earth.

<span class="mw-page-title-main">Iron cycle</span>

The iron cycle (Fe) is the biogeochemical cycle of iron through the atmosphere, hydrosphere, biosphere and lithosphere. While Fe is highly abundant in the Earth's crust, it is less common in oxygenated surface waters. Iron is a key micronutrient in primary productivity, and a limiting nutrient in the Southern ocean, eastern equatorial Pacific, and the subarctic Pacific referred to as High-Nutrient, Low-Chlorophyll (HNLC) regions of the ocean.

Lithogenic silica (LSi) is silica (SiO2) derived from terrigenous rock (Igneous, metamorphic, and sedimentary), lithogenic sediments composed of the detritus of pre-existing rock, volcanic ejecta, extraterrestrial material, and minerals such silicate. Silica is the most abundant compound in the earth's crust (59%) and the main component of almost every rock (>95%).

<span class="mw-page-title-main">Phosphorus cycle</span> Biogeochemical movement

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth. The production of phosphine gas occurs in only specialized, local conditions. Therefore, the phosphorus cycle should be viewed from whole Earth system and then specifically focused on the cycle in terrestrial and aquatic systems.

<span class="mw-page-title-main">Laterite</span> Product of rock weathering in wet tropical climate rich in iron and aluminium

Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by intensive and prolonged weathering of the underlying parent rock, usually when there are conditions of high temperatures and heavy rainfall with alternate wet and dry periods. Tropical weathering (laterization) is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils. The majority of the land area containing laterites is between the tropics of Cancer and Capricorn.

<span class="mw-page-title-main">Oceanic carbon cycle</span> Ocean/atmosphere carbon exchange process

The oceanic carbon cycle is composed of processes that exchange carbon between various pools within the ocean as well as between the atmosphere, Earth interior, and the seafloor. The carbon cycle is a result of many interacting forces across multiple time and space scales that circulates carbon around the planet, ensuring that carbon is available globally. The Oceanic carbon cycle is a central process to the global carbon cycle and contains both inorganic carbon and organic carbon. Part of the marine carbon cycle transforms carbon between non-living and living matter.

<span class="mw-page-title-main">Marine biogeochemical cycles</span>

Marine biogeochemical cycles are biogeochemical cycles that occur within marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. These biogeochemical cycles are the pathways chemical substances and elements move through within the marine environment. In addition, substances and elements can be imported into or exported from the marine environment. These imports and exports can occur as exchanges with the atmosphere above, the ocean floor below, or as runoff from the land.

<span class="mw-page-title-main">Calcium cycle</span>

The calcium cycle is a transfer of calcium between dissolved and solid phases. There is a continuous supply of calcium ions into waterways from rocks, organisms, and soils. Calcium ions are consumed and removed from aqueous environments as they react to form insoluble structures such as calcium carbonate and calcium silicate, which can deposit to form sediments or the exoskeletons of organisms. Calcium ions can also be utilized biologically, as calcium is essential to biological functions such as the production of bones and teeth or cellular function. The calcium cycle is a common thread between terrestrial, marine, geological, and biological processes. Calcium moves through these different media as it cycles throughout the Earth. The marine calcium cycle is affected by changing atmospheric carbon dioxide due to ocean acidification.

<span class="mw-page-title-main">Silica cycle</span> Biogeochemical cycle

The silica cycle is the biogeochemical cycle in which biogenic silica is transported between the Earth's systems. Silicon is considered a bioessential element and is one of the most abundant elements on Earth. The silica cycle has significant overlap with the carbon cycle and plays an important role in the sequestration of carbon through continental weathering, biogenic export and burial as oozes on geologic timescales.

<span class="mw-page-title-main">Lithium cycle</span>

The lithium cycle (Li) is the biogeochemical cycle of lithium through the lithosphere and hydrosphere.

<span class="mw-page-title-main">Boron cycle</span> The biogeochemical cycle of boron

The boron cycle is the biogeochemical cycle of boron through the atmosphere, lithosphere, biosphere, and hydrosphere.

<span class="mw-page-title-main">Arsenic cycle</span>

The arsenic (As) cycle is the biogeochemical cycle of natural and anthropogenic exchanges of arsenic terms through the atmosphere, lithosphere, pedosphere, hydrosphere, and biosphere. Although arsenic is naturally abundant in the Earth's crust, long-term exposure and high concentrations of arsenic can be detrimental to human health.

<span class="mw-page-title-main">Chromium cycle</span> Biogeochemical cycle

The chromium cycle is the biogeochemical cycle of chromium through the atmosphere, hydrosphere, biosphere and lithosphere.

<span class="mw-page-title-main">Gold cycle</span>

The gold cycle is the biogeochemical cycling of gold through the lithosphere, hydrosphere, atmosphere, and biosphere. Gold is a noble transition metal that is highly mobile in the environment and subject to biogeochemical cycling, driven largely by microorganisms. Gold undergoes processes of solubilization, stabilization, bioreduction, biomineralization, aggregation, and ligand utilization throughout its cycle. These processes are influenced by various microbial populations and cycling of other elements such as carbon, nitrogen, and sulfur. Gold exists in several forms in the Earth's surface environment including Au(I/III)-complexes, nanoparticles, and placer gold particles. The gold biogeochemical cycle is highly complex and strongly intertwined with cycling of other metals including silver, copper, iron, manganese, arsenic, and mercury. Gold is important in the biotech field for applications such as mineral exploration, processing and remediation, development of biosensors and drug delivery systems, industrial catalysts, and for recovery of gold from electronic waste.

<span class="mw-page-title-main">Lead cycle</span>

The lead cycle is the biogeochemical cycle of lead through the atmosphere, lithosphere, biosphere, and hydrosphere, which has been influenced by anthropogenic activities.

<span class="mw-page-title-main">Potassium cycle</span>

The potassium (K) cycle is the biogeochemical cycle that describes the movement of potassium throughout the Earth’s lithosphere, biosphere, atmosphere, and hydrosphere.

<span class="mw-page-title-main">Fluorine cycle</span> Biogeochemical cycle

The fluorine cycle is the series of biogeochemical processes through which fluorine moves through the lithosphere, hydrosphere, atmosphere, and biosphere. Fluorine originates from the Earth’s crust, and its cycling between various sources and sinks is modulated by a variety of natural and anthropogenic processes.

<span class="mw-page-title-main">Zinc cycle</span>

The zinc cycle is a biogeochemical cycle that transports zinc through the lithosphere, hydrosphere, and biosphere.

<span class="mw-page-title-main">Manganese cycle</span> Biogeochemical cycle

The manganese cycle is the biogeochemical cycle of manganese through the atmosphere, hydrosphere, biosphere and lithosphere. There are bacteria that oxidise manganese to insoluble oxides, and others that reduce it to Mn2+ in order to use it.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Exley, C (2003). "A biogeochemical cycle for aluminium?". Journal of Inorganic Biochemistry. 97 (1): 1–7. doi:10.1016/s0162-0134(03)00274-5. ISSN   0162-0134. PMID   14507454.
  2. 1 2 3 4 Pogue, Aileen I.; Lukiw, Walter J. (2014). "The Mobilization of Aluminum into the Biosphere". Frontiers in Neurology. 5: 262. doi: 10.3389/fneur.2014.00262 . ISSN   1664-2295. PMC   4259105 . PMID   25538680.
  3. 1 2 3 Rauch, Jason N.; Pacyna, Jozef M. (2009). "Earth's global Ag, Al, Cr, Cu, Fe, Ni, Pb, and Zn cycles". Global Biogeochemical Cycles. 23 (2): n/a. Bibcode:2009GBioC..23.2001R. doi:10.1029/2008gb003376. ISSN   0886-6236.
  4. ↑ Kochian, Leon V.; Piñeros, Miguel A.; Hoekenga, Owen A. (2005-07-01). "The Physiology, Genetics and Molecular Biology of Plant Aluminum Resistance and Toxicity". Plant and Soil. 274 (1): 175–195. doi:10.1007/s11104-004-1158-7. ISSN   1573-5036. S2CID   9966512.
  5. ↑ Markewitz, Daniel; Richter, Daniel D. (1998-08-01). "The Bio in Aluminum and Silicon Geochemistry". Biogeochemistry. 42 (1): 235–252. doi:10.1023/A:1005901417165. ISSN   1573-515X.
  6. ↑ Martin, R. Bruce (1994). "Aluminum: A Neurotoxic Product of Acid Rain". Chemistry Department, University of Virginia. 27 (7): 204–210. doi:10.1021/ar00043a004.
  7. ↑ Haraldsson, Joakim; Johansson, Maria T. (2018-10-01). "Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling". Renewable and Sustainable Energy Reviews. 93: 525–548. doi:10.1016/j.rser.2018.05.043. ISSN   1364-0321. S2CID   49427140.
  8. 1 2 3 Canada, Natural Resources (2018-01-19). "Aluminum facts". natural-resources.canada.ca. Retrieved 2023-04-21.
  9. ↑ Chen, Yang; Zhang, Ting-an; Lv, Guozhi; Chao, Xi; Yang, Xuewei (2022-07-01). "Extraction and Utilization of Valuable Elements from Bauxite and Bauxite Residue: A Review". Bulletin of Environmental Contamination and Toxicology. 109 (1): 228–237. doi:10.1007/s00128-022-03502-w. ISSN   1432-0800. PMID   35445293. S2CID   248270181.
  10. ↑ Lad, R.J.; Samant, J.S. (2015). "Impact of Bauxite Mining on Soil: A Case Study of Bauxite Mines at Udgiri, Dist-Kolhapur, Maharashtra State, India" (PDF). International Research Journal of Environment Sciences. 4 (2): 77–83.
  11. ↑ Liu, Gang; Müller, Daniel B. (2013-10-15). "Mapping the Global Journey of Anthropogenic Aluminum: A Trade-Linked Multilevel Material Flow Analysis". Environmental Science & Technology. 47 (20): 11873–11881. Bibcode:2013EnST...4711873L. doi:10.1021/es4024404. ISSN   0013-936X. PMID   24025046.
  12. 1 2 3 4 5 6 7 Van Hulten, M.M.P.; Sterl, A.; Tagliabue, A.; Dutay, J.-C.; Gehlen, M.; De Baar, H.J.W.; Middag, R. (2013-10-01). "Aluminium in an ocean general circulation model compared with the West Atlantic Geotraces cruises". Journal of Marine Systems. 126: 3–23. arXiv: 1202.4679 . Bibcode:2013JMS...126....3V. doi:10.1016/j.jmarsys.2012.05.005. ISSN   0924-7963. S2CID   18518681.
  13. 1 2 Gehlen, M.; Heinze, C.; Maier-Reimer, E.; Measures, C. I. (2003-03-19). "Coupled Al-Si geochemistry in an ocean general circulation model: A tool for the validation of oceanic dust deposition fields?: COUPLING Al-Si GEOCHEMICAL CYCLES IN AN OGCM". Global Biogeochemical Cycles. 17 (1). doi:10.1029/2001GB001549. S2CID   59422808 – via American Geophysical Union.
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