User:Lilysandler/sandbox

Article Evaluation:

Evaluating Content:

In general, most of the topics of relevance are present. However, the items need to be fleshed out more thoroughly and written in a more simple, concise way. For example, the relationship between carbonic acid and calcium is not thoroughly described. It is oversimplified and certain things could be explained in more detail. Little is mentioned about coral reef damage. There are blaring missed opportunities for facts, like mentioning the pH change in the ocean specifically. Also, some of the headers could be more effective, such as changing "release of calcium from sedimentary rock" to something more straightforward such as "abiotic calcium cycling" and then a separate category for "biotic calcium cycling".

Evaluating Tone:

The tone of the article is overall neutral. However, the conciseness and clarity of the article could be greatly improved. It is a combination of redundant and not detailed enough. It is quite wordy at parts. I would like to go through each topic and make them easier to understand, hitting the main points to understand about each aspect of the calcium cycle while removing unnecessary information that would be relevant to the average person interested in the calcium cycle. One topic that I would like to expand upon and clarify is the calcium carbonate ocean aspect of the calcium cycle.

Evaluating Sources:

Sources are not as plentiful as they could be. There are several sections that do not appear to have a source. For example, in the " The importance of the calcium cycle and future predictions" section, the entire first paragraph contains no sources. Also, wikilinks are very sparse. There are 4 in the entire article. I would like to make sure that each fact or each section is directly attached to a source. The sources all look reputable, but they do need to be added more frequently in the appropriate places. I plan to do this with the existing sources and also to add (at least 10) new sources to this collection.

Talk Page Analysis:

There is essentially no conversation on the talk page of the Calcium Cycle. The article is rated C, so it definitely warrants some improvement.

Calcium ions cam be released through silicate weathering, the weathering of silica based rocks. These Aqueous calcium ions can react with carbonate (CO32-) to precipitate into carbonate minerals. These cations serve the function of returning carbon dioxide into the solid phase as it precipitates into calcium carbonate.

Draft of New text:

Introduction:

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 marine environments as they react to form insoluble structures such as calcium carbonate and calcium silicate. They 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 production bones and teeth or cellular function. The calcium cycle is a common thread between terrestrial, marine, geological, and biological processes.

Category 1: Calcium in the solid phase

Calcium can be stored in geologic reservoirs most commonly in the form of calcium carbonate or as calcium silicate. Types of rocks containing calcium include calcite, dolomite, phosphate, and gypsum. These rocks can be found globally, anywhere from mountain ranges, such as the Dolomites, to entire landmasses that are primarily Limestone, such as Florida. Physical and chemical erosion of these rocks ultimately causes inputs of calcium ions in aqueous systems. Rain slowly dissolves the rock and carries it down into rivers and oceans. Rivers containing more dissolved calcium are generally considered more alkaline. Calcium-containing minerals are often more easily weathered than magnesium-containing minerals, such as quartz, mica, and zircon, meaning that calcium is often more enriched in waterways than magnesium (Mg2+).

Calcium ions (Ca2+) magnesium ions (Mg2+) are both elements of the same group of Alkali Metals. Thus, they are all have an oxidation state of 2 and are of similar sizes. They react similarly and are sometimes able to substitute for each other in mineral contexts, such as in carbonate structures.

Category 2: Calcium and Aqueous Environments.

** Note: I accidentally put my first draft of the text below in the actual article too. This section existed but was poorly written and not detailed. I added lots of new stuff to it. The most recent version of the article is in this sandbox, not in the article itself**

Calcium is one of the most common elements found in seawater, with an average concentration of 410 ppm in waterways worldwide. Inputs of dissolved calcium (Ca2+) into the ocean include the weathering of calcium sulfate, calcium silicate, and calcium carbonate, basalt-seawater reaction, and dolomitization.

Ca2+ + 2HCO3- → CO2 + H2O + CaCO3

Biogenic calcium carbonate is formed when marine organisms in shallow waterways, such as corals, pteropods, and other mollusks transform calcium ions and bicarbonate into shells and exoskeletons of calcite or aragonite, both forms of calcium carbonate. This is the dominant sink for dissolved calcium in the ocean.

Dead organisms sink to the bottom of the ocean, depositing layers of shell which over time cement to form limestone. This is the origin of both marine and terrestrial limestone, formed over long periods of time.

The relationship between dissolved calcium and calcium carbonate is affected greatly by the levels of carbon dioxide (CO2) in the atmosphere. Increased carbon dioxide leads to more carbonic acid in the ocean according to the following equation:

CO2 + CO32- + H2O → 2HCO3-

With ocean acidification, inputs of carbon dioxide promote the dissolution of calcium carbonate and harm marine organisms dependent on their protective calcite or aragonite shells.

The dissolution of calcite (CaCO3) into calcium ion (Ca2+) and carbonate ion (CO32-) depends on a number of factors. Solubility of calcite increases with pressure. Deep oceans contain more dissolved calcite than surface waters. The higher pressure inhibits calcium carbonate precipitation, whilst enabling the dissolution of calcium carbonate. As a result, sedimentation of calcium carbonate is more common in shallower oceans, as deep oceans with higher pressure are not conducive to limestone formation. The depth at which dissolution of calcite equals the oceanic input of calcite is known as calcite compensation depth.

Changes in levels of calcium carbonate reflect changes in global climate and the carbon cycle. Ocean acidity due to carbon dioxide has already increased by 25% since the industrial revolution. As carbon dioxide emissions continually increase and accumulate, this will negatively affect the lives of many marine ecosystems. The calcium carbonate used to form many marine organisms' exoskeletons will begin to break down, leaving these animals vulnerable and unable to live in their habitats. This ultimately has a flow on effect to predators, further affecting the function of many food webs globally.

Because calcium is an element so interrelated in many geologic processes, calcium isotopes can be used to understand changes in earth processes over time. For example, one study found that calcium levels have been cut between 25 and 50 percent over a 40 million year timespan, suggesting that dissolved calcium outputs have exceeded its inputs. With calcium isotopes, trends in calcium over time can aid in the understanding of inputs versus outputs of dissolved calcium in marine environments.

With Dr. Glass's Edits:

Introduction:

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 marine 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.

Calcium Weathering and Inputs to Seawater:

** Note: I accidentally put my first draft of the text below in the actual article too. This section existed but was poorly written and not detailed. I added lots of new stuff to it. The most recent version of the article is in this sandbox, not in the article itself**

Calcium is stored in geologic reservoirs, most commonly in the form of calcium carbonate or as calcium silicate. Calcium-containing rocks include calcite, dolomite, phosphate, and gypsum. Rocks are slowly dissolves by physical and chemical processes, carrying calcium ions into rivers and oceans. Calcium ions (Ca2+) and magnesium ions (Mg2+) have the same charge (+2) and similar sizes, so they react similarly and are able to substitute for each other in some minerals, such as carbonates. Ca2+-containing minerals are often more easily weathered than Mg2+minerals, so Ca2+is often more enriched in waterways than Mg2+. Rivers containing more dissolved Ca2+are generally considered more alkaline.

Calcium is one of the most common elements found in seawater, with an average concentration of 410 ppm in waterways worldwide [Insert source, add in both ppm and molar]. Inputs of dissolved calcium (Ca2+) to the ocean include the weathering of calcium sulfate, calcium silicate, and calcium carbonate, basalt-seawater reaction, and dolomitization. Biogenic Calcium Carbonate and the Biological Pump

Biogenic calcium carbonate is formed when marine organisms, such as coccolithophores, corals, pteropods, and other mollusks transform calcium ions and bicarbonate into shells and exoskeletons of calcite or aragonite, both forms of calcium carbonate. This is the dominant sink for dissolved calcium in the ocean. Dead organisms sink to the bottom of the ocean, depositing layers of shell which over time cement to form limestone. This is the origin of both marine and terrestrial limestone.

Calcium precipitates into calcium carbonate according to the following equation:

Ca2+ + 2HCO3- → CO2 + H2O + CaCO3

The solubility of calcium carbonate increases with pressure and carbon dioxide and decreases with temperature. Thus, calcium carbonte is more soluble in deep waters than surface waters due to higher pressure and lower temperature. As a result, precipitation of calcium carbonate is more common in shallower oceans. The depth at which the rate of calcite dissolution equals the rate of calcite precipitation is known as calcite compensation depth.

Increased carbon dioxide leads to more bicarbonate in the ocean according to the following equation:

CO2 + CO32- + H2O → 2HCO3-

With ocean acidification, inputs of carbon dioxide promote the dissolution of calcium carbonate and harm marine organisms dependent on their protective calcite or aragonite shells.

Changes in calcium concentrations over geologic time

Calcium stable isotopes have been used to study inputs and outputs of dissolved calcium in marine environments. For example, one study found that calcium levels have decreased between 25 and 50 percent over a 40 million year timespan, suggesting that dissolved Ca2+outputs have exceeded its inputs. The isotope Calcium-44 can help to indicate variations in calcium carbonate over long timespans and help explain variants in global temperature. Declines in the isotope Calcium-44 usually correlate with periods of cooling, as dissolution of calcium carbonate typically means a decrease in temperature. Thus, Calcium isotopes can correlate with changes in temperature. For Peer Edit: Things that have been addressed have been crossed out

1) Lead Section: Concerning the Lead Section references, this new lead section is excellently cited compared to the current Wikipedia entry. Great job!  I found a couple of things that might help references 5 and 6. Reference 5 links to a book about Calcium in humans, perhaps this could be replaced with a review article on Biological Calcium Use that is more general biologically and more easily accessible.  We could also link this sentence to the Wikipedia page for "Calcium in biology. " Reference 6 links to a corrigendum to figure 11 of the original article. Perhaps we should fix this to link to the original instead.

Concerning the Lead Section content, I think it is a good summary of the page content and it reflects the most important points of the article evenly, but I had a few thoughts/questions as I read it. Many Wikipedia elemental cycle pages start with the spheres of Earth that the element cycles through. Does calcium travel through the atmosphere or only the pedosphere, hydrosphere, and geosphere? The second sentence mentions the flow of calcium ions into waterways. Does calcium travel from water back to land? After reading this, I have a good idea about where calcium is, and it makes me want to read more about it in the rest of the article which is great, but I am not clear on the path or flow of the cycle. I think a non-science reader might get the idea that the flow of calcium is unidirectional rather than cyclical. Perhaps we could link the sentences together or add a sentence to the end that makes it feel more like a cycle? Lastly, it looks like there is a small typo in sentence four that ends with reference 5. "such as production bones and teeth" looks like it should read, "such as the production of bones and teeth."

2) Clear Structure: I am not completely certain which portion(s) of the current Wikipedia article will be updated with this sandbox draft. It looks like it will replace sections 1 and 2 of the current Wikipedia page. I like the structure of the draft text compared to the current text. When reading about Calcium weathering and inputs to seawater, I found myself wondering where the calcium carbonate or other calcium-containing rocks come from and where they are found. Perhaps we could include a sentence to discuss this? Or maybe another section that explains this could be positioned first?

3) Balanced Coverage: The draft text seems well balanced to me. I consider all sections and content to be necessary and on topic. I am only briefly familiar with calcium cycle. Based on what little I know, the draft text appears to represent the published literature. Searching for calcium biogeochemistry or the calcium cycle on NCBI’s PubMed yields primarily research concerning calcium’s role in biological processes. Judging by a quick scan, I didn't notice any significant viewpoints that were left out or missing. I did not feel that the article drew conclusions or tried to convince me of anything.

4) Neutral Content: The perspective of the author is neutral. I did not find any phrases that indicated otherwise. Everything was consistently on-topic and seems to reflect our current scientific understanding of the subject. However, I am not aware of any juicy debates between calcium cycle scientists. I did not notice any negative or positive phrases. The information is stated very matter of factly. I believe this draft to be a clear reflection of various aspects of the topic.

5) Reliable Sources: The sources are all reliable academic textbooks or peer-reviewed articles. Reference 7 currently does not link to the article or have DOI number. Here is the link: https://doi.org/10.1016/S0074-6142(08)62689-3 . The same for Reference 8: https://doi.org/10.1016/0022-0248(76)90240-2 . Nearly all statements in this article have a reference at the end of the sentence. If not the same sentence, they look to be covered by the reference in the sentence before or after. No references are from blogs or self-published authors. Some sources are reused multiple times, but there are also plenty of other sources included throughout the text. I think all statements are represented accurately by the sources.

One last comment is that I think there are many words in the draft text that can be linked to other Wikipedia pages such coccolithophores, exoskeletons, ocean acidification ect.