Glossary - Essential Environment - D-F Flashcards
dam
Any obstruction placed in a river or stream to block the flow of water so that water can be stored in a reservoir. Dams are built to prevent floods, provide drinking water, facilitate irrigation, and generate electricity.
Darwin, Charles (1809-1882)
English naturalist who proposed the concept of natural selection as a mechanism for evolution and as a way to explain the great variety of living things.
data
Information, generally quantitative information.
deciduous
Term describing trees that lose their leaves each fall and remain dormant during winter, when hard freezes would endanger leaves.
decomposer
An organism, such as a fungus or bacterium, that breaks down leaf litter and other nonliving matter into simple constituents that can be taken up and used by plants. Compare detritivore.
Deepwater Horizon
The British Petroleum offshore drilling platform that sank in 2010, creating the largest oil spill in US history.
deep-well injection
A hazardous waste disposal method in which a well is drilled deep beneath an area’s water table into porous rock below an impervious soil layer. Wastes are then injected into the well, so that they will be absorbed into the porous rock and remain deep underground, isolated from groundwater and human contact. Compare surface impoundment.
deforestation
The clearing and loss of forests.
demand
The amount of a product people will buy at a given price if free to do so.
demographer
A scientist who studies human populations.
demographic transition
A theoretical model of economic and cultural change that explains the declining death rates and birth rates that occurred in Western nations as they became industrialized. The model holds that industrialization caused these rates to fall naturally by decreasing mortality and by lessening the need for large families. Parents would thereafter choose to invest in quality of life rather than quantity of children.
demography
A social science that applies the principles of population ecology to the study of statistical change in human populations.
denitrifying bacteria
Bacteria that convert the nitrates in soil or water to gaseous nitrogen and release it back into the atmosphere.
density-dependent factor
A limiting factor whose effects on a population increase or decrease depending on the population density. Compare density-independent factor.
density-independent factor
A limiting factor whose effects on a population are constant regardless of population density. Compare density-dependent factor.
dependent variable
The variable that is affected by manipulation of the independent variable.
deposition
The arrival of eroded soil at a new location. Compare erosion.
desalination (desalinization)
The removal of salt from seawater.
desert
The driest biome on Earth, with an annual precipitation of less than 25 cm. Because deserts have relatively little vegetation to insulate them from temperature extremes, sunlight readily heats them in the daytime, but daytime heat is quickly lost at night, so temperatures vary widely from day to night and in different seasons.
desertification
A form of land degradation in which more than 10% of productivity is lost due to erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion, or other factors. Severe desertification can result in the expansion of desert areas or creation of new ones. Compare soil degradation.
detritivore
An organism, such as a millipede or soil insect, that scavenges the waste products or dead bodies of other community members. Compare decomposer.
dike
A long raised mound of earth erected along a river bank to protect against floods by holding rising water in the main channel.
directional drilling
Modern methods of drilling underground for oil and natural gas in which the drill is bent or curved as it descends, allowing many areas to be reached from single drill pad and thus reducing the environmental impact of drilling on the surface.
distillation
The removal of substances dissolved in water by evaporating the water and condensing its purified vapor.
divergent plate boundary
Area where tectonic plates push apart from one another as magma rises upward to the surface, creating new lithosphere as it cools and spreads. A prime example is the Mid-Atlantic Ridge. Compare convergent plate boundary and transform plate boundary.
DNA (deoxyribonucleic acid)
A double stranded nucleic acid composed of four nucleotides, each of which contains a sugar, a phosphate group, and a nitrogenous base. DNA carries the hereditary information for living organisms and is responsible for passing traits from parents to offspring. Compare RNA.
dose
The amount of toxicant a test animal receives in a dose response test.
dose-response analysis
A set of experiments that measure the response of test animals to different doses of a toxicant. The response is generally quantified by measuring the proportion of animals exhibiting negative effects.
dose-response curve
A curve that plots the response of test animals to different doses of a toxicant, as a result of dose-response analysis.
downwelling
In the ocean, the flow of warm surface water toward the ocean floor. Down welling occurs where surface currents converge. Compare upwelling.
driftnet
Fishing net that spans large expanses of water, arragyed strategically to drift with currents so as to capture passing fish, and held vertical by floats at the top and weights at the bottom. Driftnetting captures substantial bycatch of dolphins, seals, sea turtles, and non target fish.
Dust Bowl
An area that loses huge amounts of topsoil to wind erosion as a result of drought and/or human impact; first used to name the region in the North American Great Plains severely affected by drought and topsoil loss in the 1930s. The term is now also used to describe that historical event and others like it.
Earthquake
A release of energy occurring as Earth relieves accumulated pressure between masses of lithosphere, and which results in shaking at the surface.
ecocentrism
A philosophy that considers actions in terms of their damage or benefit to the integrity of whole ecological systems, including both biotic and abiotic elements.
ecofeminism
A philosophy holding that the patriarchal (male-dominated) structure of society is a root cause of both social and environmental problems. Ecofeminists hold that a worldview traditionally associated with women, which interprets the world in terms of interrelationships and cooperation, is more in tune with nature than a worldview traditionally associated with men, which interprets the world in terms of hierarchies and competition.
ecolabeling
The practice of designating on a product’s label how the product was grown harvested, or manufactured so that consumers buying it are aware of the processes involved and can differentiate between brands that use processes believed to be environmentally beneficial (or less harmful than others) and those that do not.
ecological economics
A developing school of economics that applies the principles of ecology and systems thinking to the description and analysis of economies. Compare environmental economics; neoclassical economics.
ecological footprint
The cumulative amount of land and water required to provide the raw materials a person or population consumes and to dispose of or recycle the waste that is produced.
ecological modeling
The practice of constructing and testing models that aim to explain and predict how ecological systems function.
ecological restoration
Efforts to reverse the effects of human disruption of ecological systems and to restore communities to their condition before the disruption. The practice that applies to principles of restoration ecology.
ecology
The science that deals with the distribution and abundance of organisms, the interactions among them, and the interactions between organisms and their abiotic environments.
economically recoverable
Extractable such that income from a resource’s sale exceeds the costs of extracting it. Applied to fossil fuel deposits.
economics
The study of how we decide to use scarce resources to satisfy the demand for goods and services.
economy
A social system that converts resources into goods and services
ecosystem
All organisms and nonliving entities that occur and interact in a particular area at the same time.
ecosystem-based management
The attempt to manage the harvesting of resources in ways that minimize impact on the ecosystems and ecological processes that provide the resources.
ecosystem diversity
The number and variety of ecosystems in a particular area. One way to express biodiversity. Related concepts consider the geographic arrangement of habitats, communities, or ecosystems at the landscape level, including the sizes, shapes, and interconnectedness of patches of these entities.
ecosystem service
An essential service an ecosystem provides that supports life and makes economic activity possible. For example, ecosystems naturally purify air and water, cycle nutrients, provide for plants to be pollinated by animals, and serve as receptacles and recycling systems for the waste generated by our economic activity.
ecotone
A transitional zone where ecosystems meet.
ecotourism
Visitation of natural areas for tourism and recreation. Most often involves tourism by affluent people, which may generate economic benefits for less-affluent communities near natural areas and thus provide economic incentives for conservation of natural areas.
effective dose 50%
The amount of a toxicant it takes to affect 50% of a population of test animals. Compare threshold dose.
edge effect
An impact on organisms, populations, or communities that results because conditions along the edge of a habitat fragment differ from conditions in the interior.
effluent
Water that flows out of a facility such as a wastewater treatment plant or power plant
E horizon
The layer of soil that lies below the A horizon and above the B horizon. The letter “E” stands for “eluviation,” meaning “loss”, and the E horizon is characterized by the loss of certain minerals through leaching. It is sometimes called the “zone of leaching.” Compare C horizon; O horizon; R horizon.
electricity
A secondary form of energy that can be transferred over long distances and applied for a variety of uses.
electrolysis
A process in which electrical current is passed through a compound to release ions. Electrolysis offers one way to produce hydrogen for use as fuel: Electrical current is passed through water, splitting the water molecules into hydrogen and oxygen atoms.
