| NAAQS
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| National Ambient Air Quality Standard; federal standards specifying the maximum allowable levels (averaged over specific time periods) for regulated pollutants in ambient (outdoor) air.
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| Narrow-spectrum pesticide
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| A chemical agent effective in controlling a small number of pests
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| NASA
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| National Aeronautics and Space Administration
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| Natality
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| The production of new individuals by birth, hatching, germination, or cloning.
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| National Emission Standards for Hazardous Air Pollutants (NESHAPS)
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| The standards for allowable emissions of certain toxic substances.
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| National forests
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| Administered by the National Forest Service, these are public forest and woodlands that have been managed for multiple uses, such as logging, mineral exploitation, livestock grazing, and recreation.
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| National parks
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| Administered by the National Park Service, national parks are lands and coastal areas of great scenic, ecological, or historical importance. They are managed with the dual goals of protection and providing public access.
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| National priorities list (NPL)
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| A list of the chemical waste sites presenting the most immediate and severe threats. Such sites are scheduled for cleanup ahead of other sites.
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| Natural
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| Describes a substance or factor that occurs or is produced as a normal part of mature apart from any activity or intervention of humans. Opposite of artificial, synthetic, human-made, or caused by humans.
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| Natural capital
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| The natural assets and the services they perform are referred to as natural capital; one form of the wealth of a nation is its complement of natural capital.
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| Natural chemical control
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| The rise of one or more natural chemicals such as hormones or pheromones to control a pest.
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| Natural control methods
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| Any of many techniques of controlling a pest population without resorting to the use of synthetic organic or inorganic chemicals. (See biological control, cultural control, genetic control, hormones, and pheromones.)
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| Natural enemies
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| All the predators and/or parasites that may feed on a given organism. Organisms used to control a specific pest
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| Natural erosion
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| Loss of soil occurring at a slow rate but not caused by human activities. A natural event in all terrestrial ecosystems.
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| Natural eutrophication
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| See eutrophication
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| Natural has
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| Gaseous fuel contain 50%-90% methane and lesser amounts of other burnable organic gases such as propane and butane.
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| Natural hazards
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| Dangers that result from normal meteorologic, atmospheric, oceanic, biological, and geological phenomena.
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| Natural history
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| The study of where and how organisms carry out their life cycles.
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| Natural Increase
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| Crude death rate subtracted from crude birthrate.
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| Natural landscaping
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| A landscaping design that uses carefully contrived meadows, forests, and natural-looking ponds and marshes to create an illusion of wild nature.
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| Natural laws
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| Derivations from our observations that matter, energy and certain other phenomena apparently always act (or react) according to certain "rules".
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| Natural rate of change
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| The percent of growth (or decline) of a given population during a year. It is found by subtracting the crude death rate from the crude birth rate and changing the result to a percent. It does not include immigration or emigration.
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| Natural resources
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| Goods and services supplied by the environment.
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| Natural selection
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| The mechanism for evolutionary change in which environmental pressures cause certain genetic combinations in a population to become more abundant; genetic combinations best adapted for present environmental conditions tend to become predominant.
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| Natural services
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| Functions performed free of charge by natural ecosystems such as control of runoff and erosion, absorption of nutrients, and assimilation of air pollutants.
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| Negative feedback
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| Control mechanism present in the ecosystem and in all organisms, Information in the form of chemical, physical, and biological agents influences processes, causing them to shut down or reduce their activity.
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| Neo-classical economics
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| A branch of economics that attempts to apply the principles of modern science to economic analysis in a mathematically rigorous, non-contextual, abstract, predictive manner.
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| Neolithic Revolution
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| The development of agriculture by human societies around 10,000 years ago, leading to more permanent settlement and population increases.
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| Neo-Luddities
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| People who reject technology as the cause of environmental degradation and social disruption. Named after the followers of Ned Ludd who tried to turn back the Industrial Revolution in England.
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| Neo-Malthusian
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| A belief that the world is characterized by scarcity and competition in which too many people fight for too few resources. Named for Thomas Malthus, who predicted a dismal cycle of misery, vice, and starvation as a result of human overpopulation.
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| Net energy
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| See net useful energy production.
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| Net energy yield
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| Total useful energy produced during the lifetime of an entire energy system minus the energy used, lost, or wasted in making useful energy available.
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| Net migration
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| Number of immigrants minus the number of emigrants. Can be expressed as a rate by determining immigration and emigration rates.
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| Net primary production.
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| The rate at which new organic matter is made available to consumers by primary producers (equals gross primary production minus plant respiration).
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| Net primary productivity
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| Gross primary productivity (the total amount of energy that plants produce) minus the energy plants use during cellular respiration.
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| Net useful energy production
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| Amount of useful energy extracted from an energy system.
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| Neurotoxins
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| Toxic substances, such as lead or mercury that specifically poisons nerve cells.
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| Neutralism
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| A relationship without ties.
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| Neutron
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| A subatomic particle, found in the nucleus of the atom, that has no electromagnetic charge.
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| New Forestry
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| A forestry management strategy that is now part of the Forest Service's management practice, placing priority on protecting the ecological health and diversity of forests rather than maximizing the harvest of logs.
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| New towns
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| Experimental urban environments that seek to combine the best features of the rural village and the modern city.
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| Niche
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| Also called an ecological niche. An organism¡¦s place in the ecosystem: where it lives, what it consumes, what consumes it, and how it interacts with all biotic and biotic factors.
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| Niche (ecological)
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| The total of all the relationships that bear on how an organism copes with both biotic and abiotic factors it faces.
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| Nihilists
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| Those who believe the world has no meaning or purpose other than a dark, cruel, unceasing struggle for power and existence.
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| NIMBY
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| Not In My Backyard: the rallying cry of those opposed to LULUs.
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| NIMTOO. (¡§Not in my term of office¡¨)
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| Refers to the reluctance of office-holders to make unpopular decisions on matters like siting waste facilities.
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| Nitrate (NO2-)
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| Inorganic anion containing two oxygen atoms and one nitrogen atom. Combines with hemoglobin and may cause serious health impairment and death in children.
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| Nitrate (NO3-)
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| Inorganic anion containing three oxygen atoms and one nitrogen atom linked by covalent bonds.
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| Nitrate-forming bacteria
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| Bacteria that convert nitrites into compounds that can be used by green plants to build proteins.
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| Nitric acid (HNO3)
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| One of the acids in acid rain. Formed by reactions between nitrogen oxides and the water vapor in the atmosphere.
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| Nitrite-forming bacteria
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| Bacteria that combine ammonia with oxygen to form nitrites.
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| Nitrogen cycle
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| The circulation and reutilization of nitrogen in both inorganic and organic phases ORThe cycling of nitrogen between organism and the environment..
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| Nitrogen fixation
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| The process of chemically converting nitrogen gas (N2) from the air into compounds such as nitrates (NO3-) or ammonia (NH3) that can be used to plants in building amino acids and other nitrogen-containing organic molecules.
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| Nitrogen oxides (NOx)
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| A group of nitrogen-oxygen compounds formed when some of the nitrogen gas in air combines with oxygen during high-temperature combustion; they are a major category of air pollutants. Along with hydrocarbons, they are a primary factor in the production of ozone and other photochemical oxidants that are the most harmful components of photochemical smog. They also contribute to acid precipitation (see nitric acid). Major nitrogen oxides are nitric oxide, NO; nitrogen dioxide, NO2; and nitrogen tetroxide, N2O2
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| Nitrogen-fixing bacteria
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| Bacteria that convert nitrogen from the atmosphere or soil solution into ammonia that can then be converted to plant nutrients by nitrite- and nitrate-forming bacteria.
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| Nitrous oxide
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| A gas, N2O Nitrous oxide comes from biomass burning, fossil fuel burning, and the use of chemical fertilizers. It is of concern because in the troposphere it is a greenhouse gas and ill the stratosphere it contributes to ozone destruction.
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| NOAA
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| National Oceanic and Atmospheric Administration.
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| Noise
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| An unwanted or unpleasant sound.
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| Nonattainment area
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| Region that violates EPA air pollution standards.
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| Nonbiodegradable.
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| Not able to be consumed and/or broken donwn by biological organisms. Nonbiodegradable substances include plastics, aluminum, and many chemicals used in industry and agriculture. Particularly dangerous are human-made non-biodegradable chemicals that are also toxic and tend to accumulate in organisms, i.e., nonbiodegradable synthetic organic compounds. (See biodegradable and bioaccumulation.)
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| Nonconsumptive water use.
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| Use of water for such purposes as washing and rinsing where the water, albeit polluted, remains available for further uses. with suitable purification, such water may be recycled indefinitely.
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| Noncriteria pollutants
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| See unconventional pollutants.
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| Nongovernmental organization (NGO).
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| Ally of a number of private organizations involved in studying and/or advocating action on different environmental issues.
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| Noninterference
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| A principle that required us to refrain from interfering with the lives or destinies of other moral agents or moral subjects except to satisfy essential needs.
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| Nonmalfeasance
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| Doing no hard to any being that has goods (values, interests, moral values) of their own.
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| Nonpersistent
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| Refers to chemicals that break down readily to harmless compounds, as, for example, natural organic compounds break down to carbon dioxide and water.
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| Nonpoint sources
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| Scattered, diffuse sources of pollutants such as runoff from farm fields, golf courses, construction sites, etc.
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| Nonrenewable resources
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| Minerals, fossil fuels, and other materials present in essentially fixed amounts (within human time scales) in our environment.
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| North/South division
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| A description of the fact that most of the world¡¦s wealthier countries tend to be in North America, Europe, and Japan while the poorer countries tend to be located closer to the equator.
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| No-till agriculture
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| The farming practice in which weeds are killed with chemicals (or other means) and seeds are planted and grown without resorting to plowing or cultivation. The practice is very effective in reducing soil erosion.
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| NRCS
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| Natural Resources Conservation Service, formerly the SCS (U.S. Soil Conservation Service).
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| Nuclear fall
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| Hypothesis suggestion that the effects on the earth¡¦s climate of dust and smoke released in nuclear explosions would be more temporary and less severe than predicted by the nuclear winter hypothesis. Contrast with nuclear winter.
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| Nuclear fission
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| The radioactive decay process in which isotopes split apart to create two smaller atoms.
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| Nuclear fusion
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| A process in which two smaller atomic nuclei fuse into one larger nucleus and release energy; the sources of power in a hydrogen bomb.
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| Nuclear power
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| Electrical power that is produced by using a nuclear reactor to boil water and produce steam, which, in turn, drives a turbogenerator.
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| Nuclear Regulatory Commission (NRC)
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| The agency within the Department of Energy that sets and enforces safety standards for the operation and maintenance of nuclear power plants.
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| Nuclear water
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| Hypothesis suggesting that dust from nuclear explosions and smoke from burning cities would reduce solar radiation, resulting in a dramatic decrease in global temperature. Contrast with nuclear fall.
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| Nucleic acids
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| Large organic molecules made of nucleotides that function in the transmission of hereditary traits, in protein synthesis, and in control of cellular activities.
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| Nucleus
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| The center of the atom; occupied by protons and neutrons. In cells, the organelle that contains the chromosomes (DNA).
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| Nuees ardentes
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| Deadly, denser-than-air mixtures of hot gases and ash ejected from volcanoes.
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| Numbers pyramid
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| A diagram showing the relative population sized at each trophic level in an ecosystem; usually corresponds to the biomass pyramid.
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| Nutrient
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| Animal: Material such as protein, vitamins, and minerals required for growth, maintenance, and repair of the body and material such as carbohydrates required for energy. Plant: An essential element in a particular ion or molecule that can be absorbed and used by the plant. For example, carbon, hydrogen, nitrogen, and phosphorus are essential elements; carbon dioxide, water, nitrate (NO3-), and phosphate (PO43-) are the respective nutrients.
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| Nutrient cycle
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| The repeated pathway of particular nutrients or elements from the environment through one or more organisms back to the environment. Nutrient cycles include the carbon cycle, the nitrogen cycle, the phosphorus cycle, and so on.
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| Nutrient-holding capacity
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| The capacity of a soil to bind and hold nutrients (fertilizer) against their tendency to be leached from the soil.
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