Soil Ecology Wiki - User contributions [en]

Emiliania huxleyi

2021-05-06T22:18:25Z

Leahbarg: /* Scientific interest in Ehux */

''Emiliania huxleyi'' is a species of unicellular, eukaryotic phytoplankton, (also known as a coccolithophore), and is found in nearly all oceanic ecosystems outside of polar regions.[8] Emiliania huxleyi is the most common coccolithophore.[4,5] Named after Thomas Henry Huxley, ''Emiliania huxleyi'', (also abbreviated ''Ehux'') plays an important role in all ecosystems in which it is found.

==Classification==
'''Domain''': Eukaryota

'''(unranked)''': Haptophyta

'''Class''': Prymnesiophyceae

'''Order''': Isochrysidales

'''Family''': Noelaerhabdaceae

'''Genus''': Emiliania

'''Species''': E. huxleyi

==Scientific interest in ''Ehux''==
[[File:Sattelite pic 1.jpg|frame|An E. huxleyi bloom viewed from space. Photo courtesy of NASA.]]
''Emiliania huxleyi'' is tremendously successful at converting inorganic carbon into products used in photosynthesis and biomineralization.[7] ''E. huxleyi'', like many other phytoplankton, is very important to the ecosystems it inhabits. Blooms of Ehux can be seen as large turquoise patches in the water through satellite imagery, covering hundreds of thousands of square meters of ocean.[7] A study of E. huxleyi populations in 2014 discovered a poleward migration path by the phytoplankton.[8] This indicates that, over time, conditions near the poles have become more favorable for Ehux survival.

Some possible explanations for the migration pattern could be decreasing pH near the equator due to ocean acidification and generally rising oceanwater temperature.[3,5] This migration will have effects on both the ecosystems they leave behind and the new ecosystems they settle into at the more northern/southern latitude destination.

Ehux is made up of unique plates that are called coccoliths, consisting of calcium carbonate (Ca CO3). Therefore the formation of Ehux's coccoliths release CO2, acting as a '''[[carbon source]]'''. However, they can also act as a '''[[carbon sink]]''' when they photosynthesize and take away CO2. Because of this, Ehux has can have an effect on the global climate.[2] Ehux blooms can also block out sunlight to the ocean below them. They also affect the [[sulfur cycle]] because they produce DSMP (dimethylsulfonioproprionate) which creates dimethyl sulfide (DMS) clouds.[1]

==E. huxleyi Viruses (EhVs)==
[[File:Coccoliths.jpg|200px|thumb|left|The purple marks the virus on the Ehux's coccoliths.[1]]]

Coccolithoviruses have been affecting Ehux for about 7,000 years now.[1] The virus enters Ehux through the cell membrane by membrane fusion and replicates its RNA polymerase genes in the cytoplasm, alters the lipids of Ehux, and ultimately ruptures the cell and kills it.[4] When Ehux blooms begin to collapse from viruses killing it, calcium carbonate falls to the sediments at the ocean floor. It has also been found that the remaining Ehux skeletons still contain the virus's DNA that can persist for a long time.[1] Some suggest that the coccoliths of the Ehux provides a barrier that can limit virus infection. Loose coccoliths in the water have also prevented infection of viruses in other Ehux populations because the free virion bind to the loose coccolith and stops infection of further hosts.[4]
===Role in cloud formation===
After abundant Ehux blooms die-off from viruses infecting them, they either fall to sediments at the ocean floor or they can be sent into the atmosphere from being swept up by ocean waves. When this happens, Ehux contributes to cloud formation by providing the surface area for water vapor to create droplets that accumulate and produce clouds.[6]

==References==
[1] Ehux: The Little Eukaryote with a Big History. (n.d.). . https://schaechter.asmblog.org/schaechter/2012/08/ehux-the-little-eukaryote-with-a-big-history.html.

[2] Emiliania huxleyi Annotation Consortium, B. A. Read, J. Kegel, M. J. Klute, A. Kuo, S. C. Lefebvre, F. Maumus, C. Mayer, J. Miller, A. Monier, A. Salamov, J. Young, M. Aguilar, J.-M. Claverie, S. Frickenhaus, K. Gonzalez, E. K. Herman, Y.-C. Lin, J. Napier, H. Ogata, A. F. Sarno, J. Shmutz, D. Schroeder, C. de Vargas, F. Verret, P. von Dassow, K. Valentin, Y. Van de Peer, G. Wheeler, J. B. Dacks, C. F. Delwiche, S. T. Dyhrman, G. Glöckner, U. John, T. Richards, A. Z. Worden, X. Zhang, and I. V. Grigoriev. 2013. Pan genome of the phytoplankton Emiliania underpins its global distribution. Nature 499:209–213.

[3] Gerald Langer, G. Nehrke, Ian Probert, J. Ly, P. Ziveri. Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry . Biogeosciences, European Geosciences Union, 2009, 6 (11), pp.2637-2646. <10.5194/bg-6-2637-2009>. <hal-01258266>

[4] Haunost, M., U. Riebesell, and L. T. Bach. 2020. The Calcium Carbonate Shell of Emiliania huxleyi Provides Limited Protection Against Viral Infection. Frontiers in Marine Science 7.

[5] Hay, W.W.; Mohler, H.P.; Roth, P.H.; Schmidt, R.R.; Boudreaux, J.E. (1967), "Calcareous nannoplankton zonation of the Cenozoic of the Gulf Coast and Caribbean-Antillean area, and transoceanic correlation", Transactions of the Gulf Coast Association of Geological Societies, 17: 428–480.

[6] PerkinsAug. 15, S., 2018, and 11:15 Am. 2018, August 15. This alga may be seeding the world’s skies with clouds. https://www.sciencemag.org/news/2018/08/alga-may-be-seeding-world-s-skies-clouds.

[7] Read, Betsy A., et al. “Pan Genome of the Phytoplankton Emiliania Underpins Its Global Distribution.” Nature, vol. 499, no. 7457, Dec. 2013, pp. 209–213., doi:10.1038/nature12221.

[8] Winter, Amos, et al. “Poleward Expansion of the Coccolithophore Emiliania Huxleyi.” Journal of Plankton Research, vol. 36, no. 2, 2013, pp. 316–325., doi:10.1093/plankt/fbt110.

Red wiggler worms

2021-05-06T03:43:17Z

Leahbarg: /* Vermicomposting */

==Overview==
Red wiggler worms, scientifically known as '''''Eisenia fetida''''', are classified as ''[[Annelids]]''. The name ''fetida'' means foul-smelling. This comes from the foul smelling fluid they can exude if disturbed.[3] They go by various other common names such as the manure worm, dung worm, tiger worm, etc. They are widely known for their use in [[compost]] and as fish bait[5]. They are red-brown in color with alternating stripes. Red wiggler worms can range from 26-130 mm long and 2-6 mm wide. Red wiggler worms feed on organic matter and contribute to the [[decomposition]] process.[3]

----
==Classification==
[[File:Eisenia.png|200px|thumb|right|A red wiggler worm[2]]]
'''Domain''': Eukarya

'''Kingdom''': Animalia

'''Phylum''': Annelida

'''Class''': Oligochaeta

'''Order''': Hapliotaxida

'''Family''': Lumbricidae

'''Genus''': Eisenia

'''Species''': Eisenia Fetida

----

==Habitat==

Red wiggler worms are [[Epigeic Earthworms ]], meaning they live on the upper surface of the [[soil]] or in the soil litter[5]. Red wiggler worms prefer moist, organic-rich environments[7]. Manure or compost provides a great environment for them. The species originated from Europe, but because it is a commercial species and used as fish bait and in vermicomposting, it can be found all across the world, excluding Antarctica[3,5]. 

----

==Life Cycle and Reproduction==
[[File:Life-cycle.jpg|200px|thumb|right|Eisenia fetida life cycle[1]]]
Venter and Reinecke (1988) found that, in favorable conditions, red wiggler worms have a better reproductive ability than other composting worms, so using these worms in vermicomposting will produce a faster working compost. After four days of mating, a cocoon forms where hatchlings will emerge from after an average of 23 days.[6] The cocoon can hold 8-20 embryonic worms[3], although usually 2-3 hatchlings are produced. However this is not always the case and sometimes more emerge. After around 40-60 days hatchlings mature and reproduce[6]. Red wiggler worms, as well as all earthworms, are hermaphroditic, but no self-fertilization has been documented. Juvenile red wiggler worms can be told apart from mature red wigglers because they do not yet have a clitellum which is used in reproduction.[5] When reproducing, mature worms align themselves at the clitella and exchange sperm.[7] Red wigglers' life span is typically 4-5 years.[6]
[[File:red-wiggler.png|200px|thumb|left|The clitellum[4]]]

----
==Vermicomposting==
[[Compost]]ing is a great way to make use out of food and other organic waste. Worms can be used as a compost method called vermicomposting. Vermicomposting bins can be bought, but when homemade, it is important that they are dark in color (earthworms are sensitive to light), have holes for aeration, and a drainage system. Bedding, such as shredded paper or other soft absorbent material, is needed for worms to thrive. The environment needs to be kept moist, but an abundance of water should never be added, or the worms will drown. The compost does not need to be turned like other compost methods, and should be avoided or worms may perish. Eisenia Fetida can consume 25-35% of their body weight per day, so this type of composting works quite fast. Compost bins should begin with about a thousand (1 lb.) red wiggler worms[7]. Other worms can be used for vermicomposting, but red wiggler worms are the most efficient in composting[6]. Bins must have a drainage system because the worms create castings which is the excrement from red wigglers and provides great nutrients to plants.
----


==References==
[1]Edwards, C. A., and N. Q. Arancon. (n.d.). THE SCIENCE OF VERMICULTURE: THE USE OF EARTHWORMS IN ORGANIC WASTE MANAGEMENT:25.

[2]Eisenia andrei specimen during the experiment. Credit: photo courtesy... | Download Scientific Diagram. (n.d.). . https://www.researchgate.net/figure/Eisenia-andrei-specimen-during-the-experiment-Credit-photo-courtesy-of-Elaine-van-Ommen_fig1_265518697.

[3]Going on a worm hunt: Eisenia fetida, a stripy worm. 2016, July 1. . https://www.earthwormwatch.org/blogs/going-worm-hunt-eisenia-fetida-stripy-worm.

[4]Red Wiggler Reproduction. 2013, August 31. . https://www.solanacenter.org/news/blog/red-wiggler-reproduction.

[5]UWL Website. (n.d.). . http://bioweb.uwlax.edu/bio203/2010/yard_jose/habitat.htm.

[6]Venter, J. M., and A. J. Reinecke. 1988. The life-cycle of the compost worm Eisenia fetida (Oligochaeta). South African Journal of Zoology 23:161–165.

[7]Wormy FACTS and Interesting Tidbits (By Rhonda Sherman). (n.d.). . https://composting.ces.ncsu.edu/vermicomposting-2/wormy-facts-and-interesting-tidbits/.

2021-05-04T04:10:46Z

Leahbarg:

2021-04-25T01:48:24Z

Leahbarg: Created page with "==Overview== Red wiggler worms, scientifically known as ''Eisenia fetida'', are classified under the ''Annelida'' phylum."

==Overview==
Red wiggler worms, scientifically known as ''Eisenia fetida'', are classified under the ''[[Annelida]]'' phylum.

Root hairs

2021-04-23T02:38:51Z

Leahbarg: /* Overview */

==Overview==
Root hairs provide an interface between the primary [[plant roots]] and the [[soil]]. Aside from the larger more commonly known system, root hairs are smaller cylindrical extensions of larger roots that are important for nutrient acquisition, microbial interactions below-ground, and for plant anchorage in the soil. Root hairs are able to be beneficial to the health of a plant and its root systems because it effectively increases the surface area and diameter of the roots [1]. Root hairs can be 10μm in diameter or up to 1mm in diameter. The study of root hairs is important for [[ecology]], cell biology, and plant physiology because of their unique cell makeup and cell growth. Root hairs are often players in the formation of root nodules on legume plants; these facilitate symbiotic mycorrhizal interactions. Root hairs are usually visible to the naked eye but are better seen with a compound microscope or electron microscope. [[File:Root_hair_diagram.jpg|200px|thumb|right|Diagram of different zones of the root [9]]]

==Growth and Development==
Root hairs are excellent specimens to study in the field of cell biology. Root hairs are tip growing extensions from specialized root epidermal cell (trichoblasts); in most [[angiosperms]] root hairs develop on epidermal cells in the differentiation zones of younger roots [2]. In most eudicots, the first sign of root hair development is a bulge on the outer radial wall (periclinal wall) of the epidermal cell [2]. Cells of the plant epidermis in the differentiation zone can either become a root hair or non root hair cell. After the basic understanding that the root epidermis consists of root hair cells and non root hair cells, it is important to understand that there are three different types patterns of differentiation that have been seen to occur in the development of root hairs [3].[[File:Root_hair_cells.jpg|200px|thumb|left|Diagram of root hair cells and non root hair cells.[1]]]]
====Type 1:====
Root hairs can emerge from any kind of cell and can be considered a random type.

====Type 2:====
Root hairs develop from a specific population of root epidermal cells composed of vertically alternating short and long cells; root hairs will
emerge from the short cells.

====Type 3:====
Root hairs grow from cells that are localized between two cortical cells (cell in the cortex) in which non hair cells contact only one
cortical cell. This makes for adequate spacing between root hair growths.

Auxin, a signaling hormone used for regulating the growth of almost all plant development was previously studied mainly in the aboveground development of plant leaves and shoots. Recently, genetic and physiological evidence has shown that auxin is also a key player in the growth of both lateral roots and root hairs below-ground [4].

==Root Hair Surface Area==
Recent developments in technology used in studies to show the below-ground biomass of the root systems of plants has aided in studying the mass and surface area of tiny root hairs that were previously uncountable or immeasurable. In grassland plants such as ''Secale Cereale'' (Winter Rye), preliminary studies done on the counting of root hairs shows that root hairs alone can amount to up to 11, 483, 271 compared to around 2 million larger roots [5]. It was shown in this study that root hairs from just one rye plant can account for 4,322 square feet below ground. This remarkable discovery not only shows how much root hairs contribute to below-ground biomass, but points to root hair's importance in nutrient acquisition and water uptake.

==Nutrient Acquisition==
Previously mentioned, root hairs play a significant role in nutrient acquisition because of their small size and role in increasing the surface area of the below-ground root system. Root hairs are especially important for the uptake of phosphorus (P) and potassium (K) for the health and growth of the shoots above ground [3]. Not only do root hairs increase nutrient acquisition through their extension of root surface area into soil spaces that could not otherwise be reached, root hairs also increase the preferential expression of enzymes involved in the mobilization of and uptake of multiple nutrients that are vital to plant growth [6]. These extensions of the root systems contribute to increased surface area as discussed above which improves soil contact, and can account for up to 80% of P intake [7]. Improving P uptake in particularly P deficient soil lays in the hands of root hairs. Certain root morphological and architectural adaptations can increase total soil exploration by altering the size, angle, and length of the root hairs. It has also been shown that even in P deficient environments, root hair growth increases in order to locate sparse sources of P in the soil. This has been seen with other vital nutrients as well such as Pi, K, N, and C [7].

==Water Uptake and Hydraulics==
Root hairs also play significant roles in water uptake, similar to nutrient acquisition. Roots consist of many zones. Lateral roots and root caps sometimes exist in regions that have low water permeability due to immature water conduit and root suberization [8]. It has been shown that the root hair zone tends to be the most permeable zone which suggests the root hair's contributions to a plant's water uptake ability. Root water uptake is increased not only because of increased surface area of roots in small crevices of soil, but also because these small root hairs increase water potential which physically makes water uptake easier and more possible [8].





==References==
[1] Grierson, C., E. Nielsen, T. Ketelaarc, and J. Schiefelbein. 2014. Root Hairs. The Arabidopsis Book / American Society of Plant Biologists 12.

[2] Datta, S., C. M. Kim, M. Pernas, N. D. Pires, H. Proust, T. Tam, P. Vijayakumar, and L. Dolan. 2011. Root hairs: development, growth and evolution at the plant-soil interface. Plant and Soil 346:1–14.

[3] Crespi, M. 2012. Root Genomics and Soil Interactions. John Wiley & Sons, Incorporated, Somerset, UNITED STATES.

[4] Santelia, D., V. Vincenzetti, E. Azzarello, L. Bovet, Y. Fukao, P. Düchtig, S. Mancuso, E. Martinoia, and M. Geisler. 2005. MDR-like ABC transporter AtPGP4 is involved in auxin-mediated lateral root and root hair development. FEBS Letters 579:5399–5406.

[5] Dittmer, Howard J. A Quantitative Study of the Roots and Root Hairs of a Winter Rye Plant (Secale Cereale). American Journal of Botany, vol. 24, no. 7, 1937, pp. 417–420. JSTOR, www.jstor.org/stable/2436424.

[6] Salazar-Henao, J. E., and W. Schmidt. 2016. An Inventory of Nutrient-Responsive Genes in Arabidopsis Root Hairs. Frontiers in Plant Science 7.

[7] Haling, R. E., L. K. Brown, A. G. Bengough, I. M. Young, P. D. Hallett, P. J. White, and T. S. George. 2013. Root hairs improve root penetration, root–soil contact, and phosphorus acquisition in soils of different strength. Journal of Experimental Botany 64:3711–3721.

[8] Segal, E., T. Kushnir, Y. Mualem, and U. Shani. 2008. Water uptake and hydraulics of the root hair rhizosphere. Vadose Zone Journal 7:1027–1034.

[9] Caring for Plant Roots: What You Need to Know. 2017, March 18. . https://www.finegardening.com/article/caring-for-plant-roots-what-you-need-to-know.

Nitrogen cycle

2021-04-23T02:34:26Z

Leahbarg: /* Processes */

The nitrogen cycle is a repeating circulation of the element nitrogen in various chemical forms throughout living and non-living things on Earth. By changing forms nitrogen is able to move from the atmosphere, as a gas, to a form that is usable by plant life. The nitrogen cycle can be divided into several processes including: nitrogen fixation, assimilation, ammonification, nitrification, and denitrification. Other processes have been considered in this cycle as scientific research continues.[1][[File:1024px-Nitrogen Cycle.svg.png |thumb|The Nitrogen Cycle. [12]]]

The nitrogen cycle allows for the continued maintenance of healthy productive ecosystems. The alteration of nitrogen levels can greatly affect plant production and biomass in our environment. The nitrogen cycle allows us to understand how to better grow crops in agriculture to maintain a food supply for the human population but also limit fertilizer pollution in soils that can lead to eutrophication.

== Nitrogen ==

Nitrogen is a critical nutrient in the survival and success of all organisms [2]. Around 78% of the Earth’s atmosphere is made up of nitrogen. This nitrogen in the atmosphere occurs as dinitrogen gas (N2) and is unable to be used directly by living organisms such as plants which can limit nitrogen availability ecosystems [3]. The nitrogen cycle is a key component in many ecosystem processes such as decomposition and primary production. Nitrogen availability can alter the rate of these processes. Nitrogen has several forms including dinitrogen gas (N2), nitrogen oxide (NO), nitrogen dioxide (NO2), ammonia (NH3), ammonium (NH4 +), and ammonium nitrate (NH4NO3).
== Processes ==

Through a series of processes nitrogen can be converted by microbial activities through fixation, assimilation, ammonification, nitrification, and denitrification.[4] These processes make up the nitrogen cycle and play an important role for all living organisms on Earth.

=== Nitrogen fixation: ===
Nitrogen fixation is the process by which nitrogen gas (N2), is transformed into ammonium (NH4-), a form of nitrogen that can be used by plants. Through this process nitrogen is moved from the atmosphere into the soil where plants can absorb it through their root system. A small percentage of fixation can occur via abiotic activities such as lightening. A majority of nitrogen fixation occurs naturally in [[File:1104px-Nitrogen_fixation_Fabaceae_en.svg.png|thumb|Nitrogen Fixation. [13]]] soils by bacteria that have a symbiotic relationship with the plants [5]. In exchange for energy from photosynthesis the bacteria will fix nitrogen into a usable form for the plant by using the enzyme nitrogenase. Nitrogen fixation by bacteria can also produce forms of nitrogen that can be utilized by various [[organisms]]. This fixation process requires a great deal of energy and therefore uses a lot of ATP.

A common symbiont, nitrogen fixing bacteria, fix the most nitrogen. The two most common of these symbiotic bacteria are ''Rhizobium'' and ''Bradyrhizobium''. Both of these bacteria are able to invade the roots of legume plants. These bacteria provide plants with usable nitrogen to assist with protein production and the plants provide energy in the form of carbon for the symbiont bacteria. this process is beneficial to [[agriculture]] as leguminous plants can assist with returning nitrogen into the soil to promote plant growth. Many farmers will use a crop rotation system where legumes will be grown and then plowed back into the [[soil]] to increase nitrogen availability for crops the following year.



=== Assimilation: ===
Assimilation of inorganic nitrogen is the process by which organic nitrogen compounds form from inorganic nitrogen compounds in an ecosystem. Plants use these ions to make proteins and nucleic acids [6]. Nitrogen assimilation requires ATP and reduced ferredoxin from photosynthesizing cells in plants [7]. The assimilation process occurs when nitrates enter a cell and are reduced to ammonia. [[File:1920px-Glutamine synthetase reaction.svg.png|thumb|glutamine synthetase- glutamate synthase pathway. [14]]] This ammonia is then incorporated into organic compounds through the glutamine synthetase- glutamate synthase pathway (see figure 3). Through this pathway ammonia and glutamate are catalyzed by glutamine synthase into glutamine. Glutamine is then catalyzed by glutamate synthase into two glutamate molecules. One of these molecules will go back into the pathway, the other goes into transamination reactions to form other amino acids.

=== Ammonification/ Mineralization: ===
Soil nitrogen can be derived from dead organic materials. Ammonification or mineralization is the process where bacteria incorporate nitrogen into amino acids and release the excess nitrogen as ammonium ions into the soil. These ammonium ions are then readily available for uptake by plants for protein synthesis and microorganisms that require it for growth [8].



=== Nitrification: ===
Nitrification is a two-part oxidation process of ammonium ions into nitrates and nitrites moderated by many microbial communities in the ecosystem [9]. This process provides extra available nitrogen for plants to take in via their roots. Through the process of nitrification, ammonium, produced by ammonification, found in soils is transformed into nitrites (NO2-) and nitrates (NO3-). Nitrates are able to be used by plants and plant consuming animals and are formed by ammonia-oxidizing bacteria. Nitrites are not readily available to plants and animal but can be converted to nitrates by bacteria. These nitrite-oxidizing bacteria, nitrobacter, receive energy in exchange for this process [10]. Nitrate is the form most living plants use to absorb nitrogen.



=== Denitrification: ===
Denitrification follows the process of nitrification and is where nitrates are returned to the atmosphere as nitrogen gas by denitrifying bacteria in soils [6]. Denitrification generally occurs in anoxic environments with exhausted oxygen levels. This process can lead to a loss in soil nitrogen content which needs to be replaced. Denitrification can also occur during the process of harvesting crops, [[soil erosion]], burning, and leaching.





== References ==

1. Stein, L. Y., and M. G. Klotz. 2016. The nitrogen cycle. Current Biology 26:R94–R98.

2. LeBauer, D. S., and K. K. Treseder. 2008. Nitrogen Limitation of Net Primary Productivity in Terrestrial Ecosystems Is Globally Distributed. Ecology 89:371–379.

3. Ollivier, J., S. Töwe, A. Bannert, B. Hai, E.-M. Kastl, A. Meyer, M. X. Su, K. Kleineidam, and M. Schloter. 2011. Nitrogen turnover in soil and global change: Key players of soil nitrogen cycle. FEMS Microbiology Ecology 78:3–16.

4. Meng, L., W. Li, S. Zhang, C. Wu, and L. Lv. 2017. Feasibility of co-composting of sewage sludge, spent mushroom substrate and wheat straw. Bioresource Technology 226:39–45.

5. Peoples, M. B., D. F. Herridge, and J. K. Ladha. 1995. Biological nitrogen fixation: An efficient source of nitrogen for sustainable agricultural production? Plant and Soil 174:3–28.

6. Mader, Sylvia S., and Michael Windelspecht. Essentials of Biology. 11th ed., McGraw-Hill Education, 2017.

7. Raven, Peter H., Ray Franklin Evert, and Susan E. Eichhorn. Biology of Plants. New York: W.H. Freeman and Co, 2005.

8. Fath, B. D. 2018. Encyclopedia of Ecology. Elsevier, San Diego, NETHERLANDS, THE.

9. Sims, J. T., and D. C. Wolf. 1994. Poultry Waste Management: Agricultural and Environmental Issues. Pages 1–83 in D. L. Sparks, editor. Advances in Agronomy. Academic Press.

10. Cáceres, R., K. Malińska, and O. Marfà. 2018. Nitrification within composting: A review. Waste Management 72:119–137.

11. Gu, B., Y. Ge, Y. Ren, B. Xu, W. Luo, H. Jiang, B. Gu, and J. Chang. 2012. Atmospheric Reactive Nitrogen in China: Sources, Recent Trends, and Damage Costs. Environmental Science & Technology 46:9420–9427.

12. Nitrogen_Cycle.jpg: Environmental Protection Agency[https://upload.wikimedia.org/wikipedia/commons/d/de/Nitrogen_Cycle.jpg]

13. https://en.wikipedia.org/wiki/File:Nitrogen_fixation_Fabaceae_en.svg [https://en.wikipedia.org/wiki/File:Nitrogen_fixation_Fabaceae_en.svg]

14. https://commons.wikimedia.org/wiki/File:Glutamine_synthetase_reaction.svg#/media/File:Glutamine_synthetase_reaction.svg

Sand

2021-04-23T01:08:17Z

Leahbarg:

[[File:beachSand.jpg|right|thumb]]

==Overview==
Sand is a combination of broken-down grains of rock and minerals that forms from weathering. It may also contain shells, coral, seaweed, or other biogenic material. Grains smaller than sand are [[silt]] and grains larger are [[gravel]]. The word sand comes from the Proto-Germanic word sandam. [2]

==Formation==
Sand is the result of the breakdown of a variety of inorganic and organic materials. It is broken down via physical and chemical weathering. Physical processes can be driven by water, air, or other sand grains. Sand can be weathered chemically by minerals reacting with water, or other substances. Physical and chemical weathering tend to be a bit indistinguishable from each other when it comes to the formation of sand. [1] They support each other and occur at the same time.  The older the grains, the smoother they are, young grains typically have sharper edges. [4]

==Composition==
[[File:uniqueSands.jpg|right|thumb|Unique Sands: From Mongolia, Estonia, Hawaii, and Mainland US]]
Sand ranges in size from 1/16th to 2mm. [1] One of the most common possible materials is Quartz, although it can be composed of a large variety of minerals and materials. The most common tan beach sand is composed of quartz, some form of iron oxide (which reacts with oxygen to form red/tan material), feldspar, and other assorted rocks, minerals, or organic materials. [3]

Many different locations around the world are known for their distinctly colored sand, like pink sand from Utah, black sand from volcanic areas, green sand from Hawaii, etc. These unique sands all have compositional reasons for their specific color. For example, white sands often are largely composed of shells or skeletons of marine animals. Pink sands are often from single-celled organisms ''Homotrema rubrum'', which possesses red/pink shells. Green sands are often composed of Olivine, and black sands are often composed of volcanic rock. There are many other specific sands that have a very specific composition unique to them. [5] 

==Soil Texture==
[[File:USDA_Soil_Texture.png|right|thumb|Soil Texture Triangle]]
[[File:Texture by Feel.png|right|thumb|Texture by Feel Flowchart]]
Sand is an important component in many soils. It's one of the 3 base components for soil according to the [[Soil Textures]] triangle, the others being [[silt]] and [[clay]]. These 3 combine in distinct ratios to make different soil types, like loam, silt loam, sandy clay, etc. The soil classification can be determined by feel, via flowchart, or by the hydrometer method. [6]

==Ecology==
Sand can form dunes, which are mounds of sand piled up from the wind. They migrate with the prevailing wind, sand grains picked up on the windward side and deposited on the leeward side. They are often in a state of flux and do not remain in the same location. This makes it difficult for any vegetation to take root and grow. Especially since water drains so easily through sand and sandy soil mixtures. Even if there are sufficient rains, the sand/soil may not hold water for long. Some sandy locations have especially arid environments, like the Sahara desert or the Gobi desert. Other locations have a much more moderate climate; these places are more likely to develop vegetation. When vegetation does manage to take root, it begins to foster a small ecosystem. 

Some arid desert dune plant types include perennial grasses like ''Pleuraphis rigida'', some perenial herbs like ''Artemisia filifolia'' or shrubs like ''Ephedra trifurca'' and ''Eriogonum deserticola''. In more humid areas, sand dunes can be populated by species of dune-grasses, like ''Ammophila breviligulata'', ''Uniola paniculata'', ''Calamovilfa longifolia''. As dune vegetation stabilizes, it may form successional ecosystems like prairies, with occasional shrubs and trees, which may eventually form more forested communities. [7] The Sleeping Bear Dunes of Michigan support populations of cottonwood trees, which have a fast growth rate and a very connected root network that helps hold sand in place. [8] Older Great lake dunes support species of trees like''Acer rubrum'', ''Betula alleghaniensis'', etc. [9] 

==References==
[1] Sepp, Siim. "What is Sand" SandAtlas.org, Retrieved April 10, 2021, from https://www.sandatlas.org/sand/

[2] Harper, Douglas. “Sand.” Online Etymology Library, Etymonline.com, Retrieved April 10, 2021, from www.etymonline.com/word/sand.

[3] NOAA. "How does sand form?" National Ocean Service, oceanservice.noaa.gov, Retrieved April 10, 2021, from https://oceanservice.noaa.gov/facts/sand.html

[4] Adams, Dennis. "Beach Sand: What Is It, Where It Comes and How It Gets Here" Beaufort County Library, Retrieved April 10, 2021, from https://web.archive.org/web/20091201183346/http://www.beaufortcountylibrary.org/htdocs-sirsi/beachsan.htm

[5] "Seaweed also plays a role in the formation of sand" Ocean Watch, Retrieved April 10, 2021, from http://www.susanscott.net/Oceanwatch2002/mar1-02.html

[6] "Estimating Soil Texture" University of Colorado Boulder, Retrieved April 10, 2021, from https://culter.colorado.edu/~kittel/SoilTriangle&Tests_handout.pdf

[7] "Sand Dune Ecology" Encyclopedia.com, Retrieved April 10, 2021, https://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/sand-dune-ecology

[8] "Dune Ecology" National Park Service, nps.gov, Retrieved April 10, 2021, https://www.nps.gov/slbe/planyourvisit/psduneecology.htm

[9] "Great Lakes Dunes" New York Natural Heritage Program, nynhp.org, Retrieved April 10, 2021, https://guides.nynhp.org/great-lakes-dunes/

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