Decomposition is the process by which organic substances are broken down into simpler organic matter. This process is part of the nutrient cycle and it is important to recycle the material to occupy the physical space in the biosphere. The body of living organisms begins to decay shortly after death. Animals, such as worms, also help to decompose organic materials. The organism that does this is known as the decomposer. Although no two organisms are decomposed in the same way, they all experience the same sequential decomposition stages. The study of decomposition is commonly referred to as taphonomy of the Greek word taphos , which means the tomb.
One can distinguish abiotic from biotic decomposition (biodegradation). The first means "degradation of substances by chemical or physical processes, for example, hydrolysis." The latter means "metabolic breakdown of matter into simpler components by living organisms", usually by microorganisms.
Video Decomposition
Animal decomposition
Decomposition begins at the time of death, caused by two factors: 1.) autolysis, tissue breakdown by the body's internal chemicals and enzymes, and 2.) decay, breakdown of tissue by bacteria. These processes release compounds such as cadaverine and putrescine, which are the main source of the stench of rotting animal tissue.
The main decomposer is bacteria or fungi, although larger scavengers also play an important role in decomposition if the body is accessible to insects, mites and other animals. The most important arthropods involved in this process include carrion beetles, mites, flies (Sarcophagidae) and flies (Calliphoridae), like the green bottle flies seen in summer. In North America, the most important non-insect animals that are usually involved in this process include mammal and bird eaters, such as coyotes, dogs, wolves, foxes, rats, crows and vultures. Some of these scavengers also throw and sprinkle bones, which they swallow at other times. The aquatic and marine environment has a cracking agent that includes bacteria, fish, crustaceans, fly larvae and other scavengers.
Decomposition steps
Five stages are commonly used to describe the decomposition process in vertebrate animals: fresh, bloated, active decay, further decay, and dry/residual. The general stage of decomposition is paired with two stages of chemical decomposition: autolysis and decay. Both stages contribute to the chemical decomposition process, which breaks down the major components of the body. With death, microbiomes from living organisms collapse and are followed by necrobioma that undergoes predictable changes over time.
Fresh
Among the animals that have hearts, the "fresh" stage begins as soon as the heart stops beating. From the moment of death, the body begins to cool or heat up to adjust the ambient temperature, during a phase called mortis algor. Shortly after death, within three to six hours, muscle tissue becomes stiff and unable to relax, during a stage called rigor mortis. Since the blood is no longer pumped through the body, gravity causes it to flow to the dependent parts of the body, creating a whole-blue bluish shade called livor mortis or, more commonly, lividitas.
Once the heart stops, the blood can no longer supply oxygen or remove carbon dioxide from the tissues. Decreased pH and other chemical changes cause the cell to lose its structural integrity, leading to the release of cellular enzymes capable of initiating the breakdown of surrounding cells and tissues. This process is known as autolysis.
The visible changes caused by the decomposition are limited during the fresh stage, although autolysis can cause blisters to appear on the surface of the skin.
The small amounts of oxygen left in the body are quickly depleted by cellular metabolism and aerobic microbes are naturally present in the respiratory and gastrointestinal tracts, creating an ideal environment for the proliferation of anaerobic organisms. It multiplies, consumes carbohydrates, lipids, and body proteins, to produce various substances including propionic acid, lactic acid, methane, hydrogen sulfide, and ammonia. The process of microbial proliferation in the body is referred to as decay and leads to the second stage of decomposition, known as bloat.
Punches and meat flies are the first carcass insects to come in, and they search for the appropriate oviposition site.
Bloat
The bloat stage provides the first clear visual sign that microbial proliferation is underway. At this stage, anaerobic metabolism occurs, leading to accumulation of gases, such as hydrogen sulfide, carbon dioxide, methane, and nitrogen. The accumulation of gas in the body cavity causes abdominal distension and gives the carcass a whole swell appearance. The resulting gas also causes natural liquids and liquefies the tissue to become foaming. As the pressure of the gas in the body increases, the fluid is forced out of the natural hole, such as the nose, mouth, and anus, and enters the surrounding environment. The buildup of pressure combined with loss of skin integrity can also cause the body to rupture.
Intestinal anaerobic bacteria convert hemoglobin into sulfhemoglobin and other colored pigments. The accumulated gases accumulated in the body at this time help in transporting sulfhemoglobin throughout the body through the circulatory and lymphatic system, giving the body an overall marble appearance.
If the insect has access, the maggots hatch and start eating body tissues. Maggot activity, usually limited to natural holes, and mass under the skin, causes skin to slip, and hair is released from the skin. Maggot feeding, and accumulation of gas in the body, ultimately lead to skin rupture after death which will further allow the cleaning of gases and liquids into the surrounding environment. Breakage in the skin allows oxygen to reenter the body and provides more surface area for the development of fly larvae and the activity of aerobic microorganisms. Cleaning of gases and liquids produces a distinctive strong odor associated with decay.
Active decay
The active decay is characterized by the period of mass loss. This loss occurs as a result of the feeding of maggots and the cleaning of the decomposition liquid into the surrounding environment. Cleansed fluid accumulates around the body and makes islands of decomposition of carcasses (CDI). The disbursement of tissue and disintegration becomes evident during this time and strong odor persists. The end of active decay is marked by the migration of maggots from the body to the pupa.
Further decay
Decomposition is largely inhibited during advanced decay due to loss of available cadaveric material. Insect activity also decreases during this stage. When the carcass is on the ground, the surrounding area will show evidence of vegetation death. CDI surrounding the carcass will show an increase in soil carbon and nutrients, such as phosphorus, potassium, calcium, and magnesium; pH change; and significant increase in soil nitrogen.
Dry/fixed
During the dry/residual stage, the rise of plant growth around the CDI can occur and is a sign that the nutrients present in the surrounding soil have not returned to normal levels. What remains of the corpse at this stage is dry skin, cartilage, and bone, which will become dry and whitened when exposed to the elements. If all soft tissue is removed from the cadaver, it is called a full frame, but if only part of the bone is open, it is referred to as a partial framework.
Maps Decomposition
Factors affecting body decomposition
Exposure element
Bodies that have been exposed to open elements, such as water and air, will break down more quickly and attract more insect activity than bodies that are buried or confined in a special protector or artifact. This is due, in part, to the limited number of insects that can penetrate the coffin and lower temperatures underground.
The rate and manner of decomposition in the animal body is strongly influenced by several factors. In degrees that are significantly decreased, they are:
- Temperature;
- Availability of oxygen;
- Before embalming;
- The cause of death;
- Funeral, burial depth, and soil type;
- Access by scavengers;
- Trauma, including wounds and devastating blows;
- Humidity, or wetness;
- Rainfall;
- Size and weight;
- Clothing;
- The surface where the body rests;
- Foods/objects in the gastrointestinal tract specimens (meat compared to lettuce).
Decomposition velocity varies greatly. Factors such as temperature, humidity, and season of death all determine how quickly a fresh body will skeletonize or mummy. The basic guidance for environmental effects on decomposition is given as the Law of Casper (or Ratio): if all other factors are equal, then, when there is free access from the air, the body decomposes twice as fast as if immersed in water and eight times faster than if buried on earth. Ultimately, the rate of decomposition of bacteria acting on the tissues will depend on the ambient temperature. Cold temperatures decrease the rate of decomposition while warmer temperatures increase it. The dry body will not break down efficiently. Moisture helps the growth of microorganisms that break down organic matter, but too much moisture can cause anaerobic conditions to slow down the decomposition process.
The most important variable is the body's accessibility to insects, especially flies. On the surface in the tropics, invertebrates alone can easily reduce corpses that are fully inspired to clean bones in less than two weeks. The framework itself is not permanent; Acid in soil can reduce it to an unrecognizable component. This is one of the reasons given for the lack of human remains found in the wreckage of the Titanic ship, even in some parts of the ship deemed inaccessible to the scavengers. New skeletal bones are often called "green" bones and have oily characteristics. Under certain conditions (usually cold, moist soil), the body may experience saponification and develop a waxy substance called adipocere, caused by the action of soil chemicals on protein and body fat. Adipocere formation slows decay by inhibiting bacteria that cause decay.
In very dry or cold conditions, the normal process of decomposition is stopped - by lack of moisture control or temperature on bacterial and enzymatic action - causes the body to be maintained as a mummy. Frozen mummies generally restart the decomposition process when liquefied (see ÃÆ'â € "tzi Iceman), while hot-dried mummies remain so unless exposed to moisture.
The corpse of a newborn who has never swallowed food is an important exception to the normal process of decomposition. They do not have an internal microbial flora that produces much decomposition and is quite common in mummies if kept in rather dry conditions.
Anaerobic vs Aerobics
Aerobic decomposition occurs in the presence of oxygen. This is most common in nature. Living organisms that use oxygen to survive feed on the body. Anaerobic decomposition occurs in the absence of oxygen. This can be a place where the body is buried in organic matter and oxygen can not reach it. This decomposition process has a bad odor accompanied by it because of hydrogen sulfide and organic material containing sulfur.
Artificial preservation
Embalming is the practice of delaying the decay of human and animal remains. Embal decelerates decomposition, but does not prevent it indefinitely. Embalmers are usually very concerned about the body parts seen by mourners, such as the face and hands. The chemicals used in embalming drive most insects, and slow the decay of bacteria by killing bacteria inside or in the body alone or by "fixing" cellular proteins, meaning that they can not act as a source of nutrients for subsequent bacterial infections. In a fairly dry environment, the embalmed body can end up with a mummy and it is not uncommon for the body to remain conserved to levels seen after decades. Visible bodies that look visible include:
- Eva PerÃÆ'³n from Argentina, whose body was injected with paraffin was stored perfectly for years, and still as far as is known (his body is no longer displayed in public).
- Vladimir Lenin of the Soviet Union, whose body was submerged in a special fluid tank for decades and publicly displayed in the Lenin Mausoleum.
- Other Communist leaders with prominent personality cults like Mao Zedong, Kim Il-sung, Ho Chi Minh, Kim Jong-il and most recently Hugo ChÃÆ'¡vez also have their corpses preserved in Lenin preservation mode and now displayed in each mausoleum.
- Pope John XXIII, whose body is preserved can be seen in St. Peter's Basilica.
- Padre Pio, whose body was injected with formaldehyde before being buried in a dry vault which was then discarded and placed in public at San Giovanni Rotondo.
Environmental preservation
Bodies buried in a fairly dry environment can be well preserved for decades. This is observed in the case for civil rights activists who murdered Medgar Evers, who was found almost perfectly maintained for 30 years after his death, allowing an accurate autopsy when his murder case reopened in the 1990s.
The body submerged in peat swamps can become "embalmed" naturally, withholds decomposition and produces preserved specimens known as swamp bodies. The time for the embalmed body to be reduced to the skeleton varies greatly. Even when the body decays, embalming treatment can still be done (the artery system decays slower) but will not restore its natural appearance without extensive reconstruction and cosmetics, and is mostly used to control foul odor due to decomposition.
An animal can be preserved almost perfectly, for millions of years in a resin like amber.
There are instances where bodies are inexplicably preserved (without human intervention) for decades or centuries and appear almost as they did when they died. In some religious groups, this is known as not corrupt. It is not known whether or for how long the body can remain free from decay without artificial preservation.
The importance of forensic science
Various sciences study the body decomposition under the general rubric of forensic science because the usual motive for such studies is to determine the timing and causes of death for legal purposes:
- Typical forensic taphonomy studies the decomposition process to apply biological and chemical principles to forensic cases to determine post-mortem interval (PMI), post-burial intervals and to find clandestine graves.
- The forensic pathology studies the causes of death found in the corpse as a medical phenomenon.
- forensic entomology studies insects and other pests found in corpses; the order in which they appear, the type of insect, and where they are found in their life cycle are clues that can explain the time of death, the length of the corpse's exposure, and whether the body was removed.
- Forensic anthropology is a medico-legal branch of physical anthropology studying skeletons and human remains, usually for clues about the identity, age, gender, height and ethnicity of previous owners.
Anthropology Research Facilities University of Tennessee (better known as Body Farm) in Knoxville, Tennessee has a number of corpses laid out in various situations in a fenced plot near the medical center. Scientists at Body Farm are studying how the human body decays in different circumstances to gain a better understanding of decomposition.
Crop decomposition
The decomposition of plant matter occurs in many stages. It begins with washing by water; the most readily dissolved and soluble carbon compounds are released in this process. Another preliminary process is the physical breaking or fragmentation of plant material into small pieces that have larger surface area for colonization and microbial attack. In smaller dead plants, this process is mostly done by soil invertebrate fauna, whereas in larger plants, life forms such as insects and fungi play a major role in solving and are not assisted by many species of detritivora.
After this, plant detritus (consisting of cellulose, hemicellulose, microbial products, and lignin) undergoes
chemical changes by microbes. Different types of compounds decompose at different levels. It depends on the chemical structure.
For example, lignin is a wood component, which is relatively resistant to decomposition and can in fact only be decomposed by certain fungi, such as black fungus. Wood decomposition is a complex process involving mushrooms that transport nutrients to rare woods of nutrients from the outside environment. Because of the enrichment of these nutrients, the saproxylic insect fauna can develop and in turn affect dead wood, contributing to wood decomposition and nutrient cycles on the forest floor. Lignin is one of the remaining products of decomposing plants with very complicated chemical structures that cause the rate of microbial damage to slow down. Warmth determines the speed of decomposition of plants, with the rate of decay increases when heat increases, ie plants in warm environments will decompose over a shorter period of time.
In most grassland ecosystems, natural damage from fire, insects that feed on decomposing matter, termites, grazing mammals, and physical movement of animals through the grass are the main agents of nutritional breakdown and cycles, while bacteria and fungi play a major role in further decomposition. The natural damage to organic carbon accounts for more than 90 percent of the annual carbon dioxide released. therefore all leaves fall, their decay helps scientists flow global carbon dioxide. although one leaf can produce a different decay than say the various types of leaves.
The chemical aspects of plant decomposition always involve the release of carbon dioxide.
Food decomposition
The decomposition of food, plants or animals, called decay in this context, is an important field of study in food science. Decomposition of food can be slowed by conservation. Meat damage occurs, if meat is not treated, within hours or days and produces meat to be unappetizing, toxic or contagious. Decay is caused by inevitable infections and the decomposition of meat by bacteria and fungi, which are borne by the animals themselves, by the people handling the meat, and with their equipment. Meat can continue to be eaten for longer periods - though not without limits - if good hygiene is observed during production and processing, and if food safety is appropriate, food preservation and food storage procedures are applied.
Food decay is associated with contamination of microorganisms such as bacteria, fungi, and yeast, along with the natural decay of food. This decomposition bacterium reproduces at a rapid rate under preferred moisture and temperature conditions. When proper conditions lack bacteria can form spores that lurk until the appropriate conditions appear to continue reproduction.
Decomposition value
The degree of decomposition is governed by three sets of factors - the physical environment (temperature, humidity and soil properties), the quantity and quality of the dead material available for the decomposer, and the nature of the microbial community itself.
Low decomposition rate under very wet or very dry conditions. The highest decomposition rate in wet, humid conditions with adequate oxygen levels. Wetlands tend to be oxygen deprived (this is especially true in wetlands), which slows microbial growth. In dry soil, decomposition also slows down, but bacteria continue to grow (albeit at a slower rate) even after the soil becomes too dry to support plant growth. When it rains back and the soil becomes wet, the osmotic gradient between bacterial cells and groundwater causes the cells to get water quickly. Under these conditions, many bacterial cells explode, releasing nutrient pulses. Decomposition rates also tend to be slower in acid soils. Soils rich in clay minerals tend to have lower decomposition rates, and thus, higher levels of organic matter. Smaller particles of clay produce a larger surface area that can hold water. The higher the water content of a soil, the lower the oxygen content and consequently, the lower the rate of decomposition. Clay minerals also bind particles of organic material to the surface, making them less accessible to microbes. Soil disturbances such as tilling increase decomposition by increasing the amount of oxygen in the soil and by exposing new organic matter to soil microbes.
The quality and quantity of materials available for decomposers is another major factor affecting the rate of decomposition. Substances such as sugars and amino acids readily decompose and are considered labile. Cellulose and hemicellulose, which are broken down more slowly, are "quite volatile". Compounds that are more resistant to decay, such as lignin or cutin, are considered stubborn. Litter with a higher proportion of the unstable compound decomposes much faster than the waste with a higher proportion of recalcitrant materials. As a result, the dead animals decompose faster than the dead leaves, which in themselves decompose faster than the falling branches. As an organic material in the age of the soil, its quality decreases. The more volatile compounds decompose rapidly, leaving the proportion of recalcitrant materials increasing. Microbial cell walls also contain recalcitrant materials such as chitin, and this also accumulates when the microbes die, further reducing the quality of older soil organic matter.
See also
- Kadaverine
- Ecosystem
- Humus
- Leachate
- Decomposition microbiology
- Peat (grass)
- Putrescine
- Staling
References
External links
- Media related to Decomposition in Wikimedia Commons
- 1Lecture.com - Food decomposition (Flash animation)
Source of the article : Wikipedia
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