Fluorine cycle
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Fluorine Cycle
The fluorine (F) cycle is the series of biogeochemical processes through which fluorine moves through the lithosphere, hydrosphere, atmosphere, and biosphere.
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Fluorine distribution
Fluorine is the thirteenth most abundant element on Earth and the 24th most abundant element in the universe. It the most electronegative element and it is highly reactive. Thus, it is rarely found in its elemental state (although elemental fluorine has been identified in certain geochemical contexts)[3]. Instead, it is most frequently found in ionic compounds (e.g. HF, CaF2). Additionally, fluorine is a component in chlorofluorocarbon gases, which were mass-produced throughout the 20th century until the detrimental effects associated with their breakdown into highly reactive chlorine and chlorine oxide species were better understood[4].
The vast majority of the Earth's fluorine is found in the crust, where it is primarily found in hydroxysilicate minerals[3]. However, other details concerning the exact mineralogy and distribution of fluorine in the crust are poorly understood, particularly fluorine's abundance in metamorphic rocks and in the mantle.
Fluorine Cycling
Fluorine can be liberated from its crustal reservoirs via natural processes (such as weathering, erosion, and volcanic activity) or anthropogenic processes, such as phosphate rock processing, coal combustion, and brick-making. Anthropogenic contributions to the fluorine cycle are highly prominent, with anthropogenic emissions contributing about 55% of total F inputs[1]. Fluorine's transfer between surface waters and crustal rocks is not well-constrained[5].
Anthropogenic Influences
References
- ^ a b Schlesinger, William H.; Klein, Emily M.; Vengosh, Avner (2020). "Global Biogeochemical Cycle of Fluorine". Global Biogeochemical Cycles. 34 (12). doi:10.1029/2020gb006722. ISSN 0886-6236.
- ^ Rudnick, R.L.; Gao, S. (2003), "Composition of the Continental Crust", Treatise on Geochemistry, Elsevier, pp. 1–64, doi:10.1016/b0-08-043751-6/03016-4, ISBN 978-0-08-043751-4
- ^ a b Fuge, Ron (2019). "Fluorine in the environment, a review of its sources and geochemistry". Applied Geochemistry. 100: 393–406. doi:10.1016/j.apgeochem.2018.12.016. ISSN 0883-2927.
- ^ Crutzen, Paul J. (2006), Tressaud, Alain (ed.), "Introduction to "Fluorine and the Environment"", Advances in Fluorine Science, Fluorine and the Environment, vol. 1, Elsevier, pp. xv–xvii
- ^ Koga, Kenneth T.; Rose-Koga, Estelle F. (2018). "Fluorine in the Earth and the solar system, where does it come from and can it be found?". Comptes Rendus Chimie. 21 (8): 749–756. doi:10.1016/j.crci.2018.02.002.
Article Evaluation
Oxygen Cycle
Content
Overall, this article contains lots of useful information about the oxygen cycle, and is corroborated by many references. The majority of the sources were published within the last 20 years, and the important information generally appears up to date. Complex concepts are explained well. A wide variety of related topics are linked to their respective Wikipedia articles (e.g. biogeochemical transitions, silicate minerals, and the Great Oxygenation Event). This article could be improved by adding more general details: for example, the relationship between atmospheric oxygen and ozone is briefly mentioned, but more discussion of the impacts of ozone depletion could be interesting. Additionally, there are some instances of poor sentence structure, grammatical errors, and run-on sentences, which sometimes impact readability.
Tone
Overall, the article has a neutral, unbiased tone. However, there is a claim in the "Capacities and fluxes" section that many organizations misrepresent the level of oceanic oxygen production. The only information supporting this claim comes from a single source that is over 40 years old.
Sources
The checked citations all worked, and the sources generally support the claims made in the article. However, there are many instances where facts are not backed up by referenced sources (notably the sections on sources/sinks and ozone). Most of the cited sources are from reputable scientific journals, so the articles have been subjected to peer-review processes and are presumably reasonably neutral and well-founded. However, this also means that most of these pieces are behind paywalls, so readers without subscription services or institutional access will not be able to access the full texts of many of these sources.
Figure
The figure is visually interesting, well-designed, and high resolution. The arrows portray the flow of oxygen between the atmosphere and the the terrestrial biosphere, marine biosphere, and lithosphere. However, the depiction of the loss of hydrogen gas from space and its relevance to the oxygen cycle is confusing.
Selenium Cycle
Content
Everything included in this article is relevant to the selenium cycle; however, there are many areas that could use additional development. For example, the introduction states that selenium can be metabolized by a wide variety of bacteria, fungi, and plant species, and an example of a terrestrial plant is provided. However, the only sub-topic of the article focuses on selenium cycling in aquatic systems. The article only cites 3 sources, the newest of which was published in 1999. More sources overall, and more recent sources, should be incorporated into this article. Complex ideas are generally explained well, but there are some instances of jargon (e.g. seleniferous soils, valence, benthic invertebrates) that would benefit from further explanation. Additionally, the article does link to some other Wikipedia articles, but there are definitely other topics that could be linked to their respective articles.
Tone
The tone of the article is neutral, and no heavily biased claims are made. Viewpoints from the environmental sustainability community are missing, which is especially conspicuous because two of the three cited sources focus on the detrimental role of selenium as a bioaccumulating contaminant, which is not mentioned in the article.
Sources
All of the links work, and the cited facts generally do appear in the original sources. The sources come from scientific journals and government reports, so are likely reliable. However, more sources and more up-to-date information would benefit this article. Additionally, many stated facts are not linked to sources.
Mercury Cycle
Content
Everything in this article is relevant to the topic of mercury cycling, and related articles are linked throughout the piece. A lot of complicated jargon is used, but these topics are generally explained or linked to an explanatory article. The primary and secondary sources of mercury are discussed in detail, and an overview of its sinks is also given. Mercury's ecological and health impacts are touched on, and well-documented within the references section, but a more detailed discussion within the article itself would be valid. The information is generally up-to-date, with most sources being less than 10 years old and all sources being less than 20 years old.
Tone
The tone of the article is neutral and well-balanced, including primarily perspectives in Earth systems science, and some perspectives from ecology, sustainability, and health (although more discussion of mercury's relevance to these topics would be useful).
Sources
This article cites sources from a wide variety of origins, including scientific publications, the World Health Organization, and ecological and sustainability organizations. Facts are linked to relevant references, with some facts even being linked to multiple references. All of the checked sources link to the correct article, and the claims that they back up are valid.