The gaseous envelope surrounding a planet or similar body. (From Random House Unabridged Dictionary, 2d ed)

The sixth planet in order from the sun. It is one of the five outer planets of the solar system. Its twelve natural satellites include Phoebe and Titan.

The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.

Planet that is the third in order from the sun. It is one of the four inner or terrestrial planets of the SOLAR SYSTEM.

The therapeutic intermittent administration of oxygen in a chamber at greater than sea-level atmospheric pressures (three atmospheres). It is considered effective treatment for air and gas embolisms, smoke inhalation, acute carbon monoxide poisoning, caisson disease, clostridial gangrene, etc. (From Segen, Dictionary of Modern Medicine, 1992). The list of treatment modalities includes stroke.

Devices, manned and unmanned, which are designed to be placed into an orbit about the Earth or into a trajectory to another celestial body. (NASA Thesaurus, 1988)

The fourth planet in order from the sun. Its two natural satellites are Deimos and Phobos. It is one of the four inner or terrestrial planets of the solar system.

The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.

A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.

The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned.

Creation and development of bodies within solar systems, includes study of early planetary geology.

The interdisciplinary science that studies evolutionary biology, including the origin and evolution of the major elements required for life, their processing in the interstellar medium and in protostellar systems. This field also includes the study of chemical evolution and the subsequent interactions between evolving biota and planetary evolution as well as the field of biology that deals with the study of extraterrestrial life.

An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.

Chemical and physical transformation of the biogenic elements from their nucleosynthesis in stars to their incorporation and subsequent modification in planetary bodies and terrestrial biochemistry. It includes the mechanism of incorporation of biogenic elements into complex molecules and molecular systems, leading up to the origin of life.

Containers, packaging, and packaging materials for processed and raw foods and beverages. It includes packaging intended to be used for storage and also used for preparation of foods such as microwave food containers versus COOKING AND EATING UTENSILS. Packaging materials may be intended for food contact or designated non-contact, for example, shipping containers. FOOD LABELING is also available.

Experimental devices used in inhalation studies in which a person or animal is either partially or completely immersed in a chemically controlled atmosphere.

Argon. A noble gas with the atomic symbol Ar, atomic number 18, and atomic weight 39.948. It is used in fluorescent tubes and wherever an inert atmosphere is desired and nitrogen cannot be used.

The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)

Celestial bodies orbiting around the sun or other stars.

The presence of bacteria, viruses, and fungi in the air. This term is not restricted to pathogenic organisms.

The origin of life. It includes studies of the potential basis for life in organic compounds but excludes studies of the development of altered forms of life through mutation and natural selection, which is BIOLOGICAL EVOLUTION.

The fifth planet in order from the sun. It is one of the five outer planets of the solar system. Its sixteen natural satellites include Callisto, Europa, Ganymede, and Io.

Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or material. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.

The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

The simplest saturated hydrocarbon. It is a colorless, flammable gas, slightly soluble in water. It is one of the chief constituents of natural gas and is formed in the decomposition of organic matter. (Grant & Hackh's Chemical Dictionary, 5th ed)

The solid substance formed by the FREEZING of water.

The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.

An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.

Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.

The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.

The science concerned with celestial bodies and the observation and interpretation of the radiation received in the vicinity of the earth from the component parts of the universe (McGraw Hill Dictionary of Scientific and Technical Terms, 5th ed)

Acidic water usually pH 2.5 to 4.5, which poisons the ecosystem and adversely affects plants, fishes, and mammals. It is caused by industrial pollutants, mainly sulfur oxides and nitrogen oxides, emitted into the atmosphere and returning to earth in the form of acidic rain water.

The circulation of nitrogen in nature, consisting of a cycle of biochemical reactions in which atmospheric nitrogen is compounded, dissolved in rain, and deposited in the soil, where it is assimilated and metabolized by bacteria and plants, eventually returning to the atmosphere by bacterial decomposition of organic matter.

Life or metabolic reactions occurring in an environment containing oxygen.

Procedures or techniques used to keep food from spoiling.

The longterm manifestations of WEATHER. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Nitric acid (HNO3). A colorless liquid that is used in the manufacture of inorganic and organic nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many different organic chemicals. Continued exposure to vapor may cause chronic bronchitis; chemical pneumonitis may occur. (From Merck Index, 11th ed)

The effect of GLOBAL WARMING and the resulting increase in world temperatures. The predicted health effects of such long-term climatic change include increased incidence of respiratory, water-borne, and vector-borne diseases.

Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.

A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.

A state in which the environs of hospitals, laboratories, domestic and animal housing, work places, spacecraft, and other surroundings are under technological control with regard to air conditioning, heating, lighting, humidity, ventilation, and other ambient features. The concept includes control of atmospheric composition. (From Jane's Aerospace Dictionary, 3d ed)

The ash, dust, gases, and lava released by volcanic explosion. The gases are volatile matter composed principally of about 90% water vapor, and carbon dioxide, sulfur dioxide, hydrogen, carbon monoxide, and nitrogen. The ash or dust is pyroclastic ejecta and lava is molten extrusive material consisting mainly of magnesium silicate. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Organic compounds composed exclusively of carbon and hydrogen where no carbon atoms join to form a ring structure.

Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.

The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.

A measure of the amount of WATER VAPOR in the air.

Any solid objects moving in interplanetary space that are smaller than a planet or asteroid but larger than a molecule. Meteorites are any meteoroid that has fallen to a planetary surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

Frozen water crystals that fall from the ATMOSPHERE.

Any combustible hydrocarbon deposit formed from the remains of prehistoric organisms. Examples are petroleum, coal, and natural gas.

A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).

Compounds consisting of two or more fused ring structures.

A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The motion of air currents.

The natural satellite of the planet Earth. It includes the lunar cycles or phases, the lunar month, lunar landscapes, geography, and soil.

The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.

Inorganic compounds that contain nitrogen as an integral part of the molecule.

Aggregates of matter in outer space, such as stars, planets, comets, etc. and the properties and processes they undergo.

The science of the earth and other celestial bodies and their history as recorded in the rocks. It includes the study of geologic processes of an area such as rock formations, weathering and erosion, and sedimentation. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.

Five-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives.

A space in which the pressure is far below atmospheric pressure so that the remaining gases do not affect processes being carried on in the space.

Inorganic oxides of sulfur.

Water in its gaseous state. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A mixture of smoke and fog polluting the atmosphere. (Dorland, 27th ed)

Hydrogen cyanide (HCN); A toxic liquid or colorless gas. It is found in the smoke of various tobacco products and released by combustion of nitrogen-containing organic materials.

A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form.

The cycle by which the element carbon is exchanged between organic matter and the earth's physical environment.

Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed)

Air pollutants found in the work area. They are usually produced by the specific nature of the occupation.

A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)

Salts or ions of the theoretical carbonic acid, containing the radical CO2(3-). Carbonates are readily decomposed by acids. The carbonates of the alkali metals are water-soluble; all others are insoluble. (From Grant & Hackh's Chemical Dictionary, 5th ed)

One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.

The state of the ATMOSPHERE over minutes to months.

Increase in the temperature of the atmosphere near the Earth's surface and in the troposphere, which can contribute to changes in global climate patterns.

High-energy radiation or particles from extraterrestrial space that strike the earth, its atmosphere, or spacecraft and may create secondary radiation as a result of collisions with the atmosphere or spacecraft.

The study of the structure, preparation, properties, and reactions of carbon compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).

A natural fuel formed by partial decomposition of vegetable matter under certain environmental conditions.

The unstable triatomic form of oxygen, O3. It is a powerful oxidant that is produced for various chemical and industrial uses. Its production is also catalyzed in the ATMOSPHERE by ULTRAVIOLET RAY irradiation of oxygen or other ozone precursors such as VOLATILE ORGANIC COMPOUNDS and NITROGEN OXIDES. About 90% of the ozone in the atmosphere exists in the stratosphere (STRATOSPHERIC OZONE).

The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.

Helium. A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics. (Dorland, 27th ed)

A species of gram-negative bacteria in the genus SERRATIA found in plants and the DIGESTIVE TRACT of rodents. It is the most prevalent Serratia species in the natural environment.

Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)

The inanimate matter of Earth, the structures and properties of this matter, and the processes that affect it.

Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.

Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.

Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.

The nettles plant family of the order Urticales, subclass Hamamelidae, class Magnoliopsida. Many have stinging hairs on stems and leaves. Flowers are small and greenish in leaf axils. The fruit is dry and one-seeded.

Worthless, damaged, defective, superfluous or effluent material from industrial operations.

Techniques used in studying bacteria.

A thick mass of ICE formed over large regions of land; RIVERS; LAKES; ponds; or SEAWATER.

Small solar system planetary bodies including asteroids. Most asteroids are found within the gap lying between the orbits of Mars and Jupiter.

A liquid that functions as a strong oxidizing agent. It has an acrid odor and is used as a disinfectant.

A solid form of carbon dioxide used as a refrigerant.

The eighth planet in order from the sun. It is one of the five outer planets of the solar system. Its two natural satellites are Nereid and Triton.

A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)

Characteristic events occurring in the ATMOSPHERE during the interactions and transformation of various atmospheric components and conditions.

The presence of contaminants or pollutant substances in the air (AIR POLLUTANTS) that interfere with human health or welfare, or produce other harmful environmental effects. The substances may include GASES; PARTICULATE MATTER; or volatile ORGANIC CHEMICALS.

Areas of the earth where hydrocarbon deposits of PETROLEUM and/or NATURAL GAS are located.

A phase transition from liquid state to gas state, which is affected by Raoult's law. It can be accomplished by fractional distillation.

The process of producing a form or impression made of metal or plaster using a mold.

Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.

The motion of air relative to the earth's surface.

A highly toxic, colorless, nonflammable gas. It is used as a pharmaceutical aid and antioxidant. It is also an environmental air pollutant.

Relating to the size of solids.

The fusion of ceramics (porcelain) to an alloy of two or more metals for use in restorative and prosthodontic dentistry. Examples of metal alloys employed include cobalt-chromium, gold-palladium, gold-platinum-palladium, and nickel-based alloys.

Chemical reactions effected by light.

A genus of zygomycetous fungi of the family Mucoraceae, order Mucorales. It is primarily saprophytic, but may cause MUCORMYCOSIS in man from spores germinating in the lungs.

A dark powdery deposit of unburned fuel residues, composed mainly of amorphous CARBON and some HYDROCARBONS, that accumulates in chimneys, automobile mufflers and other surfaces exposed to smoke. It is the product of incomplete combustion of carbon-rich organic fuels in low oxygen conditions. It is sometimes called lampblack or carbon black and is used in INK, in rubber tires, and to prepare CARBON NANOTUBES.

A complex sulfated polymer of galactose units, extracted from Gelidium cartilagineum, Gracilaria confervoides, and related red algae. It is used as a gel in the preparation of solid culture media for microorganisms, as a bulk laxative, in making emulsions, and as a supporting medium for immunodiffusion and immunoelectrophoresis.

The atmospheric properties, characteristics and other atmospheric phenomena especially pertaining to WEATHER or CLIMATE.

A genus of gram-positive, anaerobic bacteria whose organisms divide in three perpendicular planes and occur in packets of eight or more cells. It has been isolated from soil, grains, and clinical specimens.

The fertilizing element of plants that contains the male GAMETOPHYTES.

The mechanical process of cooling.

A genus of gram-positive bacteria in the family CARNOBACTERIACEAE. They are tolerant to freezing/thawing and high pressure and able to grow at low temperatures.

Keeping food for later consumption.

Insulated enclosures in which temperature, humidity, and other environmental conditions can be regulated at levels optimal for growth, hatching, reproduction, or metabolic reactions.

Derived proteins or mixtures of cleavage products produced by the partial hydrolysis of a native protein either by an acid or by an enzyme. Peptones are readily soluble in water, and are not precipitable by heat, by alkalis, or by saturation with ammonium sulfate. (Dorland, 28th ed)

A species of bacteria present in man and many kinds of animals and birds, often causing infertility and/or abortion.

Elements of limited time intervals, contributing to particular results or situations.

A vertical distance measured from a known level on the surface of a planet or other celestial body.

Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)

A mitosporic Trichocomaceae fungal genus that develops fruiting organs resembling a broom. When identified, teleomorphs include EUPENICILLIUM and TALAROMYCES. Several species (but especially PENICILLIUM CHRYSOGENUM) are sources of the antibiotic penicillin.

Stable sulfur atoms that have the same atomic number as the element sulfur, but differ in atomic weight. S-33, 34, and 36 are stable sulfur isotopes.

Units that convert some other form of energy into electrical energy.

Inorganic compounds that contain carbon as an integral part of the molecule but are not derived from hydrocarbons.

Particles of any solid substance, generally under 30 microns in size, often noted as PM30. There is special concern with PM1 which can get down to PULMONARY ALVEOLI and induce MACROPHAGE ACTIVATION and PHAGOCYTOSIS leading to FOREIGN BODY REACTION and LUNG DISEASES.

A major group of unsaturated cyclic hydrocarbons containing two or more rings. The vast number of compounds of this important group, derived chiefly from petroleum and coal tar, are rather highly reactive and chemically versatile. The name is due to the strong and not unpleasant odor characteristic of most substances of this nature. (From Hawley's Condensed Chemical Dictionary, 12th ed, p96)

Any of several processes for the permanent or long-term artificial or natural capture or removal and storage of carbon dioxide and other forms of carbon, through biological, chemical or physical processes, in a manner that prevents it from being released into the atmosphere.

Substances or mixtures that are added to the soil to supply nutrients or to make available nutrients already present in the soil, in order to increase plant growth and productivity.

Closable openings in the epidermis of plants on the underside of leaves. They allow the exchange of gases between the internal tissues of the plant and the outside atmosphere.

The five-carbon building blocks of TERPENES that derive from MEVALONIC ACID or deoxyxylulose phosphate.

A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Inorganic oxides that contain nitrogen.

A process facilitated by specialized bacteria involving the oxidation of ammonium to nitrite and nitrate.

Removal of ENVIRONMENTAL POLLUTANTS or contaminants for the general protection of the environment. This is accomplished by various chemical, biological, and bulk movement methods, in conjunction with ENVIRONMENTAL MONITORING.

A metallic element that has the atomic number 13, atomic symbol Al, and atomic weight 26.98.

The presence of bacteria, viruses, and fungi in food and food products. This term is not restricted to pathogenic organisms: the presence of various non-pathogenic bacteria and fungi in cheeses and wines, for example, is included in this concept.

A plant genus of the family BETULACEAE. The tree has smooth, resinous, varicolored or white bark, marked by horizontal pores (lenticels), which usually peels horizontally in thin sheets.

Discarded electronic devices containing valuable and sometimes hazardous materials such as LEAD, NICKEL, CADMIUM, and MERCURY. (from http://www.epa.gov/osw/conserve/materials/ecycling/faq.htm#impact accessed 4/25/2010)

Supplying a building or house, their rooms and corridors, with fresh air. The controlling of the environment thus may be in public or domestic sites and in medical or non-medical locales. (From Dorland, 28th ed)

Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.

A large group of rod-shaped bacteria that retains the crystal violet stain when treated by Gram's method.

Sulfur compounds in which the sulfur atom is attached to three organic radicals and an electronegative element or radical.

A genus of gram-positive, spherical bacteria found in soils and fresh water, and frequently on the skin of man and other animals.

A climate which is typical of equatorial and tropical regions, i.e., one with continually high temperatures with considerable precipitation, at least during part of the year. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

Environments or habitats at the interface between truly terrestrial ecosystems and truly aquatic systems making them different from each yet highly dependent on both. Adaptations to low soil oxygen characterize many wetland species.

The application of smoke, vapor, or gas for the purpose of disinfecting or destroying pests or microorganisms.

A large and heterogenous group of fungi whose common characteristic is the absence of a sexual state. Many of the pathogenic fungi in humans belong to this group.

The Arctic Ocean and the lands in it and adjacent to it. It includes Point Barrow, Alaska, most of the Franklin District in Canada, two thirds of Greenland, Svalbard, Franz Josef Land, Lapland, Novaya Zemlya, and Northern Siberia. (Webster's New Geographical Dictionary, 1988, p66)

The exposure to potentially harmful chemical, physical, or biological agents by inhaling them.

Organic and inorganic compounds that contain iron as an integral part of the molecule.

A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.

The destroying of all forms of life, especially microorganisms, by heat, chemical, or other means.

An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.

Inorganic salts of sulfuric acid.

The enrichment of a terrestrial or aquatic ECOSYSTEM by the addition of nutrients, especially nitrogen and phosphorus, that results in a superabundant growth of plants, ALGAE, or other primary producers. It can be a natural process or result from human activity such as agriculture runoff or sewage pollution. In aquatic ecosystems, an increase in the algae population is termed an algal bloom.

Nitrate reduction process generally mediated by anaerobic bacteria by which nitrogen available to plants is converted to a gaseous form and lost from the soil or water column. It is a part of the nitrogen cycle.

Inorganic or organic compounds that contain sulfur as an integral part of the molecule.

The generic term for salts derived from silica or the silicic acids. They contain silicon, oxygen, and one or more metals, and may contain hydrogen. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Ed)

Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.

A series of hydrocarbons containing both chlorine and fluorine. These have been used as refrigerants, blowing agents, cleaning fluids, solvents, and as fire extinguishing agents. They have been shown to cause stratospheric ozone depletion and have been banned for many uses.

A species of gram-positive, coccoid bacteria commensal in the respiratory tract.

A carboxy-lyase that plays a key role in photosynthetic carbon assimilation in the CALVIN-BENSON CYCLE by catalyzing the formation of 3-phosphoglycerate from ribulose 1,5-biphosphate and CARBON DIOXIDE. It can also utilize OXYGEN as a substrate to catalyze the synthesis of 2-phosphoglycolate and 3-phosphoglycerate in a process referred to as photorespiration.

A plant genus of the family POLYGONACEAE that contains patientosides and other naphthalene glycosides.

Gases, fumes, vapors, and odors escaping from the cylinders of a gasoline or diesel internal-combustion engine. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Random House Unabridged Dictionary, 2d ed)

The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.

Contamination of the air, bodies of water, or land with substances that are harmful to human health and the environment.

The use of chemical agents in TERRORISM. This includes the malevolent use of nerve agents, blood agents, blister agents, and choking agents (NOXAE).

Chemical bond cleavage reactions resulting from absorption of radiant energy.

A high-molecular-weight polymeric elastomer derived from the milk juice (LATEX) of HEVEA brasiliensis and other trees and plants. It is a substance that can be stretched at room temperature to at least twice its original length and after releasing the stress, retract rapidly, and recover its original dimensions fully.

A polyvinyl resin used extensively in the manufacture of plastics, including medical devices, tubing, and other packaging. It is also used as a rubber substitute.

An element that is a member of the chalcogen family. It has an atomic symbol S, atomic number 16, and atomic weight [32.059; 32.076]. It is found in the amino acids cysteine and methionine.

Travel beyond the earth's atmosphere.

Decompression external to the body, most often the slow lessening of external pressure on the whole body (especially in caisson workers, deep sea divers, and persons who ascend to great heights) to prevent DECOMPRESSION SICKNESS. It includes also sudden accidental decompression, but not surgical (local) decompression or decompression applied through body openings.

A plant division of GYMNOSPERMS consisting of cone-bearing trees and shrubs.

The reproductive elements of lower organisms, such as BACTERIA; FUNGI; and cryptogamic plants.

Substances which pollute the soil. Use for soil pollutants in general or for which there is no specific heading.

Product of the oxidation of ethanol and of the destructive distillation of wood. It is used locally, occasionally internally, as a counterirritant and also as a reagent. (Stedman, 26th ed)

The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

The period of history before 500 of the common era.

A family of gram-negative bacteria found primarily in the intestinal tracts and mucous membranes of warm-blooded animals. Its organisms are sometimes pathogenic.

Any of a group of plants formed by a symbiotic combination of a fungus with an algae or CYANOBACTERIA, and sometimes both. The fungal component makes up the bulk of the lichen and forms the basis for its name.

Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.

A large or important municipality of a country, usually a major metropolitan center.

The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.

An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.

Earth or other matter in fine, dry particles. (Random House Unabridged Dictionary, 2d ed)

Free-floating minute organisms that are photosynthetic. The term is non-taxonomic and refers to a lifestyle (energy utilization and motility), rather than a particular type of organism. Most, but not all, are unicellular algae. Important groups include DIATOMS; DINOFLAGELLATES; CYANOBACTERIA; CHLOROPHYTA; HAPTOPHYTA; CRYPTOMONADS; and silicoflagellates.

Uncontrolled release of a chemical from its containment that either threatens to, or does, cause exposure to a chemical hazard. Such an incident may occur accidentally or deliberately.

Atomic species differing in mass number but having the same atomic number. (Grant & Hackh's Chemical Dictionary, 5th ed)

The science, art or practice of cultivating soil, producing crops, and raising livestock.

Myoglobin which is in the oxidized ferric or hemin form. The oxidation causes a change in color from red to brown.

Water particles that fall from the ATMOSPHERE.

A genus of bacteria found in the reproductive organs, intestinal tract, and oral cavity of animals and man. Some species are pathogenic.