| Daughter nuclei
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| Atomic nuclei that are produced during fission of uranium.
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| DDT (dichloro-diphenyl-trichloroethane)
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| The first and most widely used of the synthetic organic pesticides belonging to the chlorinated hydrocarbon class.
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| Debt crisis
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| Refers to the fact that many less-developed nations are so heavily in debt that they may not be able to meet their financial obligations, e.g., interest payments. Their failure to meet such obligations could have severe economic iml)acts on the entire world.
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| Debt-for-nature swap
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| Forgiveness of international debt in exchange for nature protection in developing countries. Environmental groups and nongovernmental organizations often pay banks to write off uncollectable debts of developing countries at a steep discount in exchange for a promise by the debtor country to establish nature preserves.
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| Decibel (dB)
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| A unit to measure the loudness of sound.
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| Deciduous
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| Trees and shrubs that shed their leaves at the end of the growing season.
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| Decline spiral
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| A catastrophic deterioration of a species, community, or whole ecosystem; accelerates as functions are disrupted or lost in a downward cascade.
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| Declining tax base
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| The loss of tax revenues that occurs when affluent taxpayers and businesses leave an area and property values subsequently decline. Also referred to as eroding tax base.
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| Decommissioning
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| Refers to the inevitable need to take nuclear power plants out of service after 25¡X3 5 years because the effects of radiation will gradually make them inoperable.
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| Decomposers
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| Fungi and bacteria that break complex organic material into smaller molecules.
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| Deep ecology
|
| A philosophy that calls for a profound shift in our attitudes and behavior based on voluntary simplicity; rejection of anthropocentric attitudes; intimate contact with nature; decentralization of power; support for cultural and biological diversity; a belief in the sacredness of nature; and direct personal action to protect nature, improve the environment, and bring about fundamental societal change.
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| Deep-well injection
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| A technique used for the disposal of liquid chemical wastes that involves putting them into deep dry wells where they permeate dry strata.
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| Deforestation
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| The process of removing trees and other vegetation covering the soil, leading to erosion and loss of soil fertility.
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| Degradation (of water resource)
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| Deterioration in water quality due to contamination or pollution; makes water unsuitable for other desirable purposes.
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| Delaney Clause
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| A controversial amendment to the Federal Food, Drug, and Cosmetic Act, added in 1958, prohibiting the addition of any known cancer-causing agent to processed foods, drugs, or cosmetics.
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| Delta
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| Fan-shaped sediment deposit found at the mouth of a river.
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| Demand
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| The amount of a product that consumers are willing and able to buy at various possible prices, assuming they are free to express their preferences.
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| Demographic transition
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| The transition from a condition of high birth rate and high death rate through a period of declining death rate but continuing high birth rate finally to low birth rate and low death rate. This transition may result from economic development.
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| Demography/demographer
|
| The studies of population trends (growth, movement, development, and so on). People who perform such studies and make projections from them.
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| Denitrification
|
| The process of reducing oxidized nitrogen compounds present in soil or water back to nitrogen gas in the atmosphere. It is a natural process conducted by certain bacteria (see text discussion of the nitrogen cycle), and it is now utilized in the treatment of sewage effluents.
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| Denitrifying bacteria
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| Free-living soil bacteria that convert nitrates to gaseous nitrogen and nitrous oxide.
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| Density-dependent
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| Refers to population balancing, factors such as parasitism that increase and decrease in intensity corresponding to population density.
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| Department of Transportation regulations (DOT Regs)
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| Regulations intended to reduce the risk of spills, fires, and poisonous fumes by specifying the kinds of containers and methods of packing to be used in transporting hazardous materials.
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| Dependency ratio
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| The number of nonworking members compared to working members for a given population.
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| Depletion allowance
|
| Tax relief given to extractive industries as they deplete reserves. Intended to allow the companies to invest more in exploration. Gives extraction industries unfair advantage over recycling companies.
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| Desalinization (or desalination)
|
| Removal of salt from water by distillation, freezing, or ultrafiltration.
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| Desert
|
| A type of biome characterized by low moisture levels and infrequent andunpredictable precipitation. Daily and seasonal temperatures fluctuate widely.
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| Desert pavement
|
| A covering of stones and coarse sand protecting desert soils from further wind erosion. The covering results from the differential erosion of finer material.
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| Desertification
|
| The formation of desert in arid and semiarid regions from overgrazing, deforestation, poor agricultural practices, and climate change. Found today in Africa, the Middle East, and the southwestern United States.
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| Desertified
|
| Land for which productivity has been significantly reduced (25% or more) because of human mismanagement. Erosion is the most common cause.
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| Detoxification
|
| Rendering a substance harmless by reacting it with another chemical, chemically modifying it, or destroying the molecule through combustion or thermal decomposition.
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| Detritivore
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| Organisms that consume organic litter, debris, and dung.
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| Detritus
|
| The dead organic matter, such as fallen leaves, twigs, and other plant and animal wastes, that exists in any ecosystem.
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| Detritus feeders
|
| Organisms such as termites, fungi, and bacteria that obtain their nutrients and energy mainly by feeding on dead organic matter.
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| Deuterium (2H)
|
| A stable, naturally occurring isotope of hydrogen. It contains one neutron in addition to the single proton normally in the nucleus.
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| Developed countries
|
| Industrialized countries¡XUnited States, Canada, Western European nations, Japan, Australia, and New Zealand¡Xin which the gross domestic product exceeds $8200 per capita.
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| Developing countries
|
| All free-market countries in which the gross domestic product is less than $8200 per capita. Includes nations of Latin America, Africa, and Asia, except Japan.
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| Dew point
|
| The temperature at which condensation occurs for a given concentration of water vapor in the air.
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| Dieback
|
| A sudden population decline; also called a population crash.
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| Differential reproduction
|
| Refers to the fact that within a population, certain individuals reproduce more successfully than others.
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| Diminishing returns
|
| A condition in which unrestrained population growth causes the standard of living to decrease to a subsistence level where poverty, misery, vice, and starvation makes life permanently drab and miserable. This dreary prophecy has led economics to be called ¡§the dismal science."
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| Dioxin
|
| A synthetic organic chemical of the chlorinated hydrocarbon class. It is one of the most toxic compounds known to humans, having many harmful effects, including induction of cancer and birth defects, even in extremely minute concentrations. It has become a widespread environmental pollutant because of the use of certain herbicides that contain dioxin as a contaminant.
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| Direct action
|
| Civil disobedience, guerrilla street theater, picketing, protest marches, road blockades, demonstrations, and other techniques borrowed from the civil rights movement and applied to environmental protection.
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| Discharge
|
| The amount of water that passes a fixed point in a given amount of time; usually expressed as liters or cubic feet of water per second.
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| Discharge permit
|
| (Technically called NPDES permit.) A permit that allows a company to legally discharge certain amounts or levels of pollutants into air or water.
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| Disclimax community
|
| See equilibrium community.
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| Discount rate
|
| The amount we discount or reduce the value of a future payment. When you borrow money from the bank at 10 percent annual interest, you are in effect saying that having the money now is worth 10 percent more to you than having the same amount one year from now.
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| Disease
|
| A deleterious change in the body¡¦s condition in response to destabilizing factors, such as nutrition, chemicals, or biological agents.
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| Disinfection
|
| The killing (as opposed to removal) of microorganisms in water or other media where they might otherwise pose a health threat. For example, chlorine is commonly used to disinfect water supplies.
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| Dissolved oxygen (DO)
|
| Oxygen gas molecules (02) dissolved in water. Fish and other aquatic organisms depend on dissolved oxygen for respiration. Therefore, concentration of dissolved oxygen is a measure of water quality.
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| Distillation
|
| A process of purifying water or other liquids by boiling the liquid and recondensing the vapor. Contaminants remain behind in the boiler.
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| Distributive justice
|
| The ethical process of making certain that all parties receive equal rights regardless of their economic status.
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| Disturbance
|
| A natural or human-induced event or process that interrupts ecological succession and creates new conditions on a site (for example, forest fire).
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| Diversity (species diversity, biological diversity)
|
| The number of species present in community (species richness), as well as the relative abundance of each species.
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| DNA (deoxyribonucleic acid)
|
| The natural organic macromolecule that carries the genetic or hereditary information for virtually all organisms.
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| Dominant plants
|
| Those plant species in a community that provide a food base for most of the community; they usually take up the most space and have the largest biomass.
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| Domination
|
| To rule or dominate. Some religions and moral philosophies regard humans as superior to nature and hold that we are justified in controlling and using other organisms in any way we choose.
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| Dose
|
| A consideration of the concentration of a hazardous material times the length of exposure to it. For any given material or radiation, effects correspond to the product of these two factors.
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| Doubling time
|
| The time it will take a population to double in size, assuming the continuation of current rate of growth.
|
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| Drift-netting
|
| The practice of harvesting marine fish and squid by laying down miles of gill nets across the open seas. The nets collapse around larger organisms and kill many whales, dolphins, seals, marine birds, and turtles.
|
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| Drip irrigation
|
| Supplying irrigation water through tubes that literally drip water onto the soil at the base of each plant.
|
|
| Drought
|
| A local or regional lack of precipitation such that the ability to raise crops and water animals is seriously impaired.
|
|
| Dry alkali injection
|
| Spraying dry sodium bicarbonate into flue gas to absorb and neutralize acidic sulfur compounds.
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