User:Compost Camel/sandbox

Article Evaluation
EAS 4220

Hydrogen cycle

content: The content is relevant to the topic of the hydrogen cycle. An accompanying figure would have been helpful to understanding the various sources and sinks. More wiki links could also be used in the main body to define scientific jargon such as serpentinization, however there are sufficient links to other related various wiki pages at the bottom of the page.

tone: The tone of this article is neutral.

sources: Sources are generally accessible via provided links and appropriately used to support claims. Citations should be used more frequently to support nearly every sentence.

Calcium cycle

content: The content is generally relevant to the topic of the calcium cycle. There are a few typos. Better figures could be created to cover the global biogeochemical cycle more thoroughly in a visual format.

tone: This article does display some bias. A significant portion of the article is devoted to the function of calcium in the human body, which may not be the best focus for the overall biogeochemical cycle. Additionally, it mentions dairy as a main source of calcium which is not cited with any supporting articles.

sources: Sources are generally accessible via provided links and appropriately used to support some of the claims. Citations should be used more frequently to support all claims (large paragraphs of text contain no citations).

Iron cycle

content: The content is relevant to the topic of the iron cycle. A visually appealing and easy to understand figure displays the global biogeochemical cycle and includes fluxes and reservoir values. Some chemical interactions (such as Fe with S and P) may benefit from chemical equations to better understand the reactants and subsequent product formation. Wiki links are used frequently, but more could be added.

tone: This article does not have any apparent bias in content or supporting sources.

sources: Citations are frequently used to support claims in this article, although some sentences are still left uncited. Sources are generally accessible using the links provided, although a few sources do not have functional links to articles.

EAS 4602

Mercury cycle

Everything in this article is relevant to the topic and the information is up to date, with several cited papers published just within the last 4 years. While the article gives an overview of the processes involved in the mercury cycle, it could benefit from the addition of more details that describe the specifics of processes. There are several linked related Wikipedia articles throughout the article. The article is in a neutral tone that does not bias toward any position. The facts stated in this article are properly cited with working links; these unbiased references support the claims made in the article and come from reliable research journals. The article could also benefit from the addition of a figure showing the biogeochemical cycle.

Phosphorus cycle

The article contains only relevant information, but not all of the facts in this article are cited, especially in the first half. This article could also benefit from an increase in the use of linked related Wikipedia articles, such as when it mentions the Canadian Experimental Lakes Area. The article only mentions the reservoirs of phosphorous briefly and could expand on that topic further. The article is in a neutral tone and uses unbiased references from reputable organizations (journals and regulatory environmental government organizations) to support its claims. The figure in this article does provide a scientifically accurate depiction of the phosphorous cycle and has good resolution. Its arrows are well organized and easy to follow throughout the figure. The labels are accurate and the legend is present. The figure is missing the quantities and units for the sizes of reservoirs and fluxes.

Oxygen cycle

This article focuses on relevant information, but not all of the scientific information is correct. A “clarify” comment notes that the abiotic production of O2 does not actually free N as the article claims and adds that the N atoms will recombine to form N2. There are several instances where facts have no citations, such as the percentages listed under biosphere, hydrosphere, and lithosphere subsections. When facts are cited, they have reputable, unbiased sources with functioning links. The article is also written in a neutral tone. The figure provides accurate scientific information on the oxygen cycle. It has excellent resolution and is neat and easy to follow. The labels are accurate and units and quantities for reservoirs and fluxes are noted.

Draft Article


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

K Functions
Along with nitrogen and phosphorous, potassium is one of the three major nutrients that plants require in large quantities. Potassium is essential to stomata control in plants and is also essential for muscles contraction in humans.

Lithosphere and Soil
By weight, K totals to 2.6% of the Earth’s crust. Stored in primary minerals (feldspar, biotite, and muscovite), chemical weathering releases potassium into the soil to account for up to 11% of plant demand. Some plants and bacteria also release organic acids into the soil that make K accessible for their use. Potassium exists in its highest concentrations in the upper most layers of soil, stored in three pools: fixed K, exchangeable K, and solution K. Fixed K accounts for 96-99% of soil K and is stored in the feldspar, mica, and illite, which also compromise some of the lithospheric reserves. Exchangeable K is potassium adsorbed onto clay particles and organic matter and accounts for 1-2% of total soil K. Potassium in soil solution is the most readily available form of K for plants to absorb, but only amounts to 0.1-0.2% of total soil K.

Reserves of potassium exist in ores and evaporites of potassium chloride (KCl) found in Germany, France, Canada, the United States, and Dead Sea brine. An estimated 32 x 106 tonnes (32 Tg) of potassium are mined from the Earth each year, of which 28 x 106 tonnes (28 Tg) are applied to crop fields annually. Potassium is most commonly applied as potassium chloride (KCl), but also referred to as potash and K2O. Application of potassium is necessary in agriculture because the removal of potassium from the soil through plant uptake and crop removal occurs at a faster rate than the replacement through rock weathering. At the current consumption rate, K2O reserves are expected to last 100 years. Potassium depletion in soils can be minimized by leaving crop residues on soils, allowing the plant matter to decay and release their stored potassium back into the soil.

Biosphere
The most abundant ion in plant cells is the potassium ion. Plants take up potassium for plant growth and function. A portion of potassium uptake in plants can be attributed to weathering of primary minerals, but plants can also ‘pump’ potassium from deeper soil layers to increase levels of surface K. Potassium stored in plant matter can be returned to the soil during decomposition, especially in areas of higher rainfall that experience higher leaching rates. Potassium leaching occurs at higher rates than nitrogen and phosphorous, likely because it only exists in the soluble ion form (K+) in the plant. Nitrogen and phosphorous are typically incorporated into large, complex molecules that are more difficult to leach through cell membranes than the small K+ ion. Deciduous plants that lose their leaves will relocate 10-32% of potassium for use in other areas of the plant before abscission.

Atmosphere
Some potassium is exchanged between plants and the atmosphere through organic aerosols released from plant leaves. Atmospheric potassium deposition varies from 0.7 to greater than 100 kg ha-1 yr-1 depending on geographic location and climate. Additionally, marine aerosols can evaporate into the atmosphere and return via precipitation.

Hydrosphere
The hydrosphere is the largest reservoir for potassium, holding an estimated 552.7x106 Tg. Leaching and erosion carry 1400 Tg yr-1 of potassium in soil solution into groundwater, rivers, and oceans. Some potassium in the atmosphere also enters the hydrosphere through precipitation. Potassium in sediment pore fluids is removed from solution by the authigenic formation of clay, which is then subducted, along with potassium deposits and ocean basalt, to return to the lithosphere.