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Oxic
Hypoxia (''hypo'': 'below', ''oxia'': 'oxygenated') refers to low oxygen conditions. Hypoxia is problematic for air-breathing organisms, yet it is essential for many anaerobic organisms. Hypoxia applies to many situations, but usually refers to the atmosphere and natural waters. Atmospheric hypoxia Atmospheric hypoxia occurs naturally at high altitudes. Total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen, which is defined as hypobaric hypoxia. Oxygen remains at 20.9% of the total gas mixture, differing from hypoxic hypoxia, where the percentage of oxygen in the air (or blood) is decreased. This is common in the sealed burrows of some subterranean animals, such as blesmols. Atmospheric hypoxia is also the basis of altitude training, which is a standard part of training for elite athletes. Several companies mimic hypoxia using normobaric artificial atmosphere. Aquatic hypoxia An aquatic system lacking dissolved oxygen (0% ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocrine Disruptor
Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause numerous adverse human health outcomes, including alterations in sperm quality and fertility; abnormalities in sex organs‚ endometriosis‚ early puberty‚ altered nervous system or immune function; certain cancers; respiratory problems; metabolic issues; diabetes, obesity, or cardiovascular problems; growth, neurological and learning disabilities, and more. Found in many household and industrial products, endocrine disruptors "interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for development, behavior, fertility, and maintenance of homeostasis (normal cell metabolism)." Any system in the body controlled by hormones can be derailed by hormone disrupt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anoxic Waters
Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. Anoxic waters can be contrasted with hypoxic waters, which are low (but not lacking) in dissolved oxygen. Often, hypoxia is defined as waters that have less than 2 milligrams per litre of dissolved oxygen. This condition is generally found in areas that have restricted water exchange. In most cases, oxygen is prevented from reaching the deeper levels by a physical barrier, as well as by a pronounced density stratification, in which, for instance, denser, colder or hypersaline waters rest at the bottom of a basin. Anoxic conditions will occur if the rate of oxidation of organic matter by bacteria is greater than the supply of dissolved oxygen. Anoxic waters are a natural phenomenon, and have occurred throughout geological history. The Permia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eutrophication
Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the surface of a river, lake, etc., often because chemicals that are used to help crops grow have been carried there by rain. Eutrophication may occur naturally or as a result of human actions. Manmade, or cultural, eutrophication occurs when sewage, Industrial wastewater treatment, industrial wastewater, fertilizer runoff, and other nutrient sources are released into the environment. Such nutrient pollution usually causes algal blooms and bacterial growth, resulting in the depletion of dissolved oxygen in water and causing substantial environmental degradation. Many policies have been introduced to combat eutrophication, including the United Nations Development Program (UNDP)'s sustainability development goals. Approaches for prevention and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algal Bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in fresh water or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. ''Algal bloom'' commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest. Algal blooms are the result of a nutrient, like nitrogen or phosphorus from various sources (for example fertilizer runoff or other forms of nutrient pollution), entering the aquatic system and causing excessive growth of algae. An algal bloom affects the whole ecosystem. Consequences range from benign effects, such as feeding of higher trophic levels, to more harmful effects like blocking sunlight from reaching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other chemical compound, compounds. Oxygen is abundance of elements in Earth's crust, the most abundant element in Earth's crust, making up almost half of the Earth's crust in the form of various oxides such as water, carbon dioxide, iron oxides and silicates.Atkins, P.; Jones, L.; Laverman, L. (2016).''Chemical Principles'', 7th edition. Freeman. It is abundance of chemical elements, the third-most abundant element in the universe after hydrogen and helium. At standard temperature and pressure, two oxygen atoms will chemical bond, bind covalent bond, covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pollution
Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Although environmental pollution can be caused by natural events, the word pollution generally implies that the contaminants Human impact on the environment, have a human source, such as manufacturing, Extractivism, extractive industries, poor waste management, transportation or Agricultural pollution, agriculture. Pollution is often classed as point source pollution, point source (coming from a highly concentrated specific site, such as a factory, Environmental effects of mining, mine, construction site), or nonpoint source pollution (coming from a widespread distributed sources, such as microplastics or agricultural runoff). Many sources of po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Kill
The term fish kill, known also as fish die-off, refers to a localized mass mortality event, mass die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005)"Fish kill." ''Plant Management in Florida's Waters.'' The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought, harmful algal bloom, overpopulation (biology), overpopulation, or a sustained increase in water temperature. Fish diseases and parasites, Infectious diseases and parasites can also lead to fish kill. Toxicity is a real but far less common cause of fish kill, and is often associated with man-made water pollution. Fish kills are often the first visible signs of environmental stress and are usually investigated as a matter of urgency by environmental agencies to determine the cause of the kill. Many fish species have a relatively low tolerance of variations in environmental conditi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altitude Training
Altitude training is the practice by some endurance athletes of training for several weeks at high altitude, preferably over above sea level, though more commonly at intermediate altitudes due to the shortage of suitable high-altitude locations. At intermediate altitudes, the air still contains approximately 20.9% oxygen, but the barometric pressure and thus the partial pressure of oxygen is reduced. Depending on the protocols used, the body may acclimate to the relative lack of oxygen in one or more ways such as increasing the mass of red blood cells and hemoglobin, or altering muscle metabolism. Proponents claim that when such athletes travel to competitions at lower altitudes they will still have a higher concentration of red blood cells for 10–14 days, and this gives them a competitive advantage. Some athletes live permanently at high altitude, only returning to sea level to compete, but their training may suffer due to less available oxygen for workouts. Altitude training ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxic Hypoxia
Generalized hypoxia is a medical condition in which the tissues of the body are deprived of the necessary levels of oxygen due to an insufficient supply of oxygen, which may be due to the composition or pressure of the breathing gas, decreased lung ventilation, or respiratory disease, any of which may cause a lower than normal oxygen content in the arterial blood, and consequently a reduced supply of oxygen to all tissues perfused by the arterial blood. This usage is distinct from localized hypoxia, in which only an associated group of tissues, usually with a common blood supply, are affected, usually due to an insufficient or reduced blood supply to those tissues. Generalized hypoxia is also used as a synonym for hypoxic hypoxia This is not to be confused with hypoxemia, which refers to low levels of oxygen in the blood, although the two conditions often occur simultaneously, since a decrease in blood oxygen typically corresponds to a decrease in oxygen in the surrounding tissue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypolimnion
The hypolimnion or under lake is the dense, bottom layer of water in a thermally- stratified lake. The word " hypolimnion" is derived from . It is the layer that lies below the thermocline. Typically the hypolimnion is the coldest layer of a lake in summer, and the warmest layer during winter. In deep, temperate lakes, the bottom-most waters of the hypolimnion are typically close to 4 °C throughout the year. The hypolimnion may be much warmer in lakes at warmer latitudes. Being at depth, it is isolated from surface wind-mixing during summer, and usually receives insufficient irradiance (light) for photosynthesis to occur. Oxygen dynamics The deepest portions of the hypolimnion often have lower oxygen concentrations than the surface waters (i.e., epilimnion). While oxygen can typically exchange between surface waters and the atmosphere (i.e., in the absence of ice cover), bottom waters are comparatively isolated from atmospheric replenishment of oxygen. In particular, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaerobic Organism
An anaerobic organism or anaerobe is any organism that does not require oxygen, molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular (e.g. protozoans, bacteria) or multicellular. Most fungi are obligate aerobes, requiring oxygen to survive. However, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen will disrupt their metabolism or kill them. The sea floor is possibly one of the largest accumulation of anaerobic organisms on Earth, where microbes are primarily concentrated around Hydrothermal_vent, hydrothermal vents. These microbes produce energy in absence of sunlight or oxygen through a process called chemosynthesis, whereby inorganic compounds such as hydrogen gas, hydrogen sulfide or ferrous ions are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
