| Background radiation
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| Radioactive radiation that comes from natural sources apart from any human activity. We are all exposed to such radiation.
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| Bacterium, pl. bacteria
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| Any of numerous kinds of microscopic organisms that exist as simple single cells that multiply by simple division. Along with fungi, they constitute the decomposer component of ecosystems. A few species cause disease.
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| Balanced herbivory
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| A diversified plant community held in balance by various herbivores specific to each plant species.
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| Barrier islands
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| Small, sandy islands off a coast, separated from the mainland by lagoons or bays.
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| Base
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| Any compound that releases hydroxyl ions (OHs) when dissolved in water. A solution that contains a surplus of hydroxyl ions.
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| Baseload power plant
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| A power plant, usually large and fueled by coal or nuclear energy, that is kept operating continuously to supply electricity.
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| BAT
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| See best available, economically achievable technology.
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| Batesian mimicry
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| Evolution by one species to resemble the coloration, body shape, or behavior of another species that is protected from predators by a venomous stinger, bad taste, or some other defensive adaptation.
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| Beach drift
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| Wave-caused movement of sand along a beach.
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| Bedload
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| The load of coarse sediment, mostly coarse silt and sand, that is gradually moved along the bottom of a riverbed by flowing water rather than being carried in suspension.
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| Bedrock
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| Unbroken, solid rock overlain by sand, gravel, or soil.
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| Benefit-cost analysis
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| See cost-benefit analysis also see cost-benefit-ratio.
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| Benthic plants
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| Plants that grow under water attached to or rooted in the bottom. For photosynthesis, they depend on light penetrating the water.
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| Benthos
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| The bottom of a sea or lake.
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| Best available, economically achievable technology (BAT)
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| The best pollution control available; the Clean Water Act effectively negates this category by stipulating that equipment must be economically feasible.
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| Best management practice
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| Farm management practices that serve best to reduce soil and nutrient runoff and subsequent pollution.
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| Best practical control technology (BPT)
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| The best technology for pollution control available at reasonable cost and operable under normal conditions.
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| Beta particles
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| Negatively charged particles emitted from nuclei of radioactive elements when a neutron is converted to a proton.
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| Big bang
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| Theory of the universe's formation. States that all matter in the universe was infinitely compressed 15 to 20 billion years ago and then exploded, sending energy and matter Out into space. The matter was in the form of subatomic particles which formed atoms as the universe cooled over millions of years.
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| Bill
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| A piece of legislation introduced in Congress and intended to become law.
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| Bioaccumulation
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| The selective absorption and concentration of molecules by cells.
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| Biocentric preservation
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| A philosophy that emphasizes the fundamental right of living organisms to exist and to pursue their own goods.
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| Biocentrism
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| The belief that all creatures have rights and values; being centered on nature rather than humans.
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| Biochemical oxygen demand (BOD)
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| The amount of oxygen that will be absorbed or ¡§demanded¡¨ as wastes are being digested or oxidized in both biological and chemical processes. Potential impacts of wastes are commonly measured in terms of the BOD.
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| Biocide
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| A broad-spectrum poison that kills a wide range of organisms.
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| Bioconcentration
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| Ability of an organism to selectively accumulate certain chemicals, elements, or substances within its body or within certain cells.
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| Bioconversion
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| The use of biomass as fuel. Burning materials such as wood, paper, and plant wastes directly to produce energy, or converting such materials into fuels such as alcohol and methane.
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| Biodegradable
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| Able to be consumed and broken down to natural substances such as carbon dioxide and water by biological organisms, particularly decomposers. Opposite: nonbiodegradable.
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| Biodegradable plastics
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| Plastics that can be decomposed by microorganisms.
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| Biodiversity
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| The genetic, species, and ecological diversity of the organisms in a given area.
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| Biogas
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| A gas containing methane and carbon dioxide. Produced by anaerobic decay of organic matter, especially manure and crop residues.
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| Biogeochemical cycle
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| Complex cyclical transfer of nutrients from the environment to organisms and back to the environment. Examples include the carbon, nitrogen, and phosphorus cycles.
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| Biogeographical area
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| An entire self-contained natural ecosystem and its associated land, water, air, and wildlife resources.
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| Biological community
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| The populations of plants, animals, and microorganisms living and interacting in a certain area at a given time.
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| Biological controls
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| Use of natural predators, pathogens, or competitors to regulate pest populations.
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| Biological extinction
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| Disappearance of a species from part or all of its range.
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| Biological magnification
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| Buildup of chemical elements or sub- stances in organisms in successively higher trophic levels. Also called biomagnification.
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| Biological nutrient removal
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| A process employed in sewage treatment to remove nitrogen and phosphorus from the effluent coming from secondary treatment.
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| Biological or biotic factors
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| Organisms and products of organisms that are part of the environment and potentially affect the life of other organisms.
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| Biological oxygen demand (BOD)
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| A standard test for measuring the amount of dissolved oxygen utilized by aquatic microorganisms.
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| Biological pests
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| Organisms that reduce the availability, quality, or value of resources useful to humans.
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| Biological resources
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| The earth¡¦s organisms.
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| Biological species concept
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| The concept that defines species as a group of interbreeding natural populations that does not breed with other groups because of various barriers.
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| Biological wealth
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| The life-sustaining combination of commercial, scientific, and aesthetic values imparted to a region by its biota.
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| Biomagnification
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| Bioaccumulation occurring through several levels of a food chain.
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| Biomass
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| Mass of biological material. Usually the total mass of a particular group or category; for example, biomass of producers.
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| Biomass fuel
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| Organic material produced by plants, animals, or microorganisms that can be burned directly as a heat source or converted into a gaseous or liquid fuel.
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| Biomass energy/Biomass fuels
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| Energy or fuels, such as alcohol and methane, produced from current photosynthetic production of biological materials; also, firewood. (See bioconversion.)
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| Biomass pyramid
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| A metaphor or diagram that explains the relationship between the amounts of biomass at different trophic levels.
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| Biome
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| A broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions.
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| Bioregionalism
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| Organization of human activities according to natural geographic or ecological boundaries and associations. This philosophy emphasizes a sense of place and living within the resources of one¡¦s local ecosystem.
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| Bioremediation
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| Refers to the use of microorganisms for the decontamination of soil or groundwater. Usually involves injecting organisms and/or oxygen into contaminated zones.
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| Biosolids
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| Organic material removed from sewage effluents in the course of treahnent. Formerly referred to as sludge.
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| Biosphere
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| All the life-supporting regions (ecosystems) of the earth and all the interactions that occur between organisms and between organisms and the environment.
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| Biosphere reserves
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| World heritage sites identified by the IUCN as worthy for national park or wildlife refuge status because of high biological diversity or unique ecological features.
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| Biota
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| All organisms in a given area.
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| Biotechnology
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| The use of genetic-engineering techniques, enabling researchers to introduce new genes into food crops and domestic animals to produce valuable products and more nutritious crops.
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| Biotic
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| Pertaining to life; environmental factors created by living organisms.
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| Biotic
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| Living or derived from living things.
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| Biotic (reproductive) potential
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| Maximum reproductive potential of a species.
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| Biotic community
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| All the living organisms (plants, animals, and microorganisms) that live in a particular area.
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| Biotic factor
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| The biological component of the ecosystem, consisting of populations of plants, animals, and microorganisms in complex communities.
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| Biotic potential
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| The maximum reproductive rate of an organism, given unlimited resources and ideal environmental conditions. Compare with environmental resistance.
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| Biotic structure
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| The organization of living organisms in an ecosystem into groups such as producers, consumers, detritus feeders, and decomposers.
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| Birth control
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| Any method used to reduce births, including celibacy, delayed marriage, contraception; devices or medication that prevent implantation of fertilized zygotes, and induced abortions.
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| Black lung disease
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| Inflammation and fibrosis caused by accumulation of coal dust in the lungs or airways. See respiratory fibrotic agents.
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| Blue revolution
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| New techniques of fish farming that may contribute as much to human nutrition as miracle cereal grains but also may create social and environmental problems.
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| BOD
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| See biochemical oxygen demand.
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| Bog
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| An area of waterlogged soil that tends to be peaty; fed mainly by precipitation; low productivity; some bogs are acidic.
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| Boreal forest
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| A broad band of mixed coniferous and deciduous trees that stretches across northern North America (and also Europe and Asia); its northernmost edge, the taiga, intergrades with the arctic tundra.
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| Bottle law (Bottle Bill)
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| A law that provides for the recycling or reuse of beverage containers, usually by requiring a returnable deposit at the purchase of the item.
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| BPT
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| See Best Practical Control technology.
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| Breeder reactor
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| A nuclear reactor that in the course of producing energy also converts nonfissionable uranium-23S into fissionable plutonium-2 39, which can be used as fuel. Hence, a reactor that produces as much nuclear fuel as it consumes or more.
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| Broad-spectrum pesticides
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| Chemical pesticides that kill a wide range of pests. They also kill a wide range of nonpest and beneficial species; therefore, they may lead to environmental upsets and resurgences. ihe opposite of narrow-spectrum pesticides and biorational pesticides.
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| Bronchitis
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| Persistent inflammation of the bronchi caused by smoking and air pollutants. Symptoms include mucus buildup, chronic cough, and throat irritation.
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| Brown-air cities
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| Newer, relatively nonindustrialized cities whose polluted skies contain photochemical oxidants (especially ozone) and nitrogen oxides, largely from automobiles and power plants. Tend to have dry, sunny climates. Contrast with gray-air cities.
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| Brownfields
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| Abandoned or underused urban areas in which redevelopment is blocked by liablilty or financing issues related to toxic contamination.
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| BTU (British thermal unit)
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| A fundamental unit of energy in the English system. The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
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| Buffer
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| A substance that will maintain the pH of a solution by reacting with the excess acid. Limestone is a natural buffer that helps to maintain water and soil at a pH near neutral.
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| Buffering capacity
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| Refers to the amount of acid that may be neutralized by a given amount of buffer.
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