Daylighting A practice in urban design and urban planning, daylighting involves redirecting a stream into an above-ground channel to restore the flow of water to a more natural state. Daylighting improves the riparian environment for a stream that has been diverted into a pipe, culvert or drainage system. The practice has already shown that protecting and restoring natural creek flow and function is possible even within urban environments.
DDT DDT is a synthetic pesticide that became widely used in the 1940's until it was banned by the U.S. in 1973 due to the discovery of how highly toxic it was to fish and water supplies. DDT stands for Dichloro Diphenyl Trichloroethane, which became popular because it effectively controlled diseases such as malaria and typhus among civilians and soldiers during World War II.
Deciduous Forest A type of forest in which the dominant species of trees and other woody vegetation are those species that shed their leaves during the cold months of the year and re-grows new leaves the next spring in time for the growing season. Deciduous forests are found in eastern North America, the British Isles, eastern Europe, New Zealand, eastern Australia, and northeast Asia. These regions though diverse, share some characteristics. They all experience seasonal changes in temperature and precipitation. As a consequence, the trees found in deciduous forests are specially adapted to withstand these environmental changes throughout the year.
Decontamination Procedures that remove foreign substances such as contaminants, pollutants, toxins and radioactivity. Decontamination does not eliminate microorganisms but is a necessary step before disinfection, sterilization or environmental clean up. In public health safety, decontamination involves the use of physical or chemical means to remove, inactivate, or destroy bloodborne or other pathogens on a surface or item, to the point where they are no longer capable of transmitting infectious particles, and the surface or item is rendered safe for handling, use, or disposal.
DEET DEET is a chemical (N,N-diethyl-meta-toluamide) used as the active ingredient in many insect repellent products. Approximately 230 products containing DEET are currently registered with the EPA as the substance can become toxic in certain dosages. It is now widely used, with approximately 30% of the U.S. population using DEET repellents each year. DEET products are currently available in a variety of forms: liquids, lotions, sprays, and even impregnated materials, such as wristbands. Formulations registered for direct application to human skin contain from 4% to 100% DEET.
Deforestation The large-scale destruction of trees in forests which eventually damage the quality of land and soil in the area. Forest trees are cut down usually to make way for agriculture, for logging or to make way for roads and urban sprawl. Deforestation devastates the environment in many ways. Among it's effects: It displaces land animals and plants that live in forests, driving down their populations, and It accelerates climate change since trees play a crucial role in absorbing greenhouse gases.
Desalination The process of treating sea water via reverse osmosis in order to make it suitable for drinking. Desalination is a solution to fresh water shortage typical in tropical as well as off-shore areas. This solution involves determining and combining technologies to optimize water production costs and quality. Desalination can be an environmental concern in some areas where natural habitats are sensitive to brine disposal, which is a consequence of this water treatment process.
Desert A type of biome that is characterized by climactic extremes. Desert lands are usually dry and hot but they are also prone to sudden flash floods and cold nights. Generally, however, deserts are extremely dry areas that get less than 10 inches of rain each year on average. Deserts are known to be sandy landscapes that support very little life, but in reality deserts often have high biodiversity. They are habitat to various cacti and flowers as well as animals that remain hidden during daylight hours to control body temperature or to limit moisture needs. Desert fauna includes the kangaroo rat, coyote, jack rabbit, and many lizards.
Dewatering Removal of water from solid waste and sludge via mechanical or thermal means. Dewatering can remove harmful toxins and chemicals from solid materials such as trash, waste and soil. As the process is becoming popular, more companies are offering dewatering services to treat chemical waste, contaminated water and soil.
Diazinon Diazinon is a chemical pesticide used against cockroaches, ants, fleas and silverfish usually applied in homes and buildings. The pesticide was widely used in the 70s and 80s for indoor pest control and gardening. Starting 2004, the US Environmental Protection Agency (EPA) began phasing out diazinon for household use.
Diesel Particulate Matter or DPM As defined by US EPA regulations and sampling procedures, diesel particulate matter is a complex aggregate of solid and liquid material. Its origin is carbon particles generated in the engine cylinder during combustion, making it an air pollutant and contributor to smog. The primary carbon particles form larger agglomerates and combine with several other, both organic and inorganic, components of diesel exhaust.
Dioxin A highly toxic herbicide whose use is regulated at 0.1 parts per million or less. Dioxin in higher levels is considered an environmental contaminant because it can cause severe skin eruptions. In laboratory tests, dioxin causes cancer in animals and damages fetuses of exposed mothers.
Dispersion In the study of air pollution, dispersion is a crucial factor as it is the movement and direction of where air contaminants are spread. Many atmospheric factors influence the way air pollution is dispersed, including wind direction and wind speed, type of terrain and the effects of heat. In unstable conditions, ground level pollution is readily dispersed thereby reducing ground level concentrations. Elevated emissions, however, such as those released from a chimney, are returned more readily to ground level, leading to higher ground level concentrations.
Dissolution The process wherein water-soluble compounds in an oil dissolves into the surrounding water. This depends on the composition and state of the oil, and occurs most quickly when the oil is finely dispersed in the water column. Components that are most soluble in seawater are the light aromatic hydrocarbon compounds, such as benzene and toluene. Dissolution rates are observed and considered during oil spill remediation.
Distillation A water purification process that uses heat to vaporize water and separate it from contaminants and other undesirable elements found in ground and surface water. Distillation heats raw, untreated water until the water reaches its boiling point and begins to vaporize. The heat is then kept at a constant temperature to maintain water vaporization while prohibiting other undesirable elements from vaporizing.
Dominant Species One or a few species that are most numerous in a specific natural environment. Dominant species are usually plant life that reflect the characteristics of a given area--soil type, water type, climactic conditions, etc. Most ecosystems are defined by their dominant species. Mangroves, for example, dominate tropical tidal swamps.
Downcycling Turning waste material or unused products into new materials or new products--but of lesser quality and functionality. Some experts say, technically, all recycling is downcycling. Plastic recycling for instance turns the original plastic into lower grade plastics. The purpose of downcycling is to reduce the use of virgin materials--which in turn reduces energy-consumption, pollution and greenhouse gas emissions.
Dredging A type of excavation fishing where a net is attached to a frame that's dragged along the ocean floor to collect clams, crabs and other edible marine animals. Dredging is destructive to marine ecosystems and has been blamed for coastal erosion.
Dry Mill An ethanol production procedure in which the entire corn kernel is first ground into flour before processing. In addition to ethanol, dry mills also produce distillers grains that are fed to livestock along with carbon dioxide that is used in food processing and bottling. Most new ethanol plants are dry mill facilities.
Drylands Ecosystems characterized by minimal water. Examples include cultivated lands, scrublands, shrublands, grasslands, savannas and semi-deserts. Such areas are especially vulnerable to climate change and environmental degradation. The lack of water constrains the production of crops, forage, wood, and other ecosystem services.
Duckweed Small, free-floating stemless plants that thrive on the surface of still or slow-moving water, looking like a "carpeting" of tiny leaf clusters. Duckweed does not normally grow in rivers, they do tend to appear when there is reduced water flow. These plants are sometimes considered invasive species. If duckweed covers the entire surface of a pond, it will deplete oxygen, killing fishes while preventing other submerged plants from receiving sunlight necessary for them to grow. Duckweeds grow 20 times faster than a corn and is able to cover one acre in just 45 days, if unrestrained.
Dumpster Diving The practice of looking through residential or commercial garbage to find items that can be of use to the dumpster diver. In the UK, this is known as skipping or bin-diving. Most people who resort to dumpster diving are forced to do so out of lack of resources. However, some identify themselves as freegans who live exclusively on dumpster goods to lessen their impact on the environment.
Dust Pollution Airborne particles that contaminate indoor or outdoor environments, affecting healthy breathing and creating dirt wherever they settle. Dust pollution comes mainly from the construction industry and related processes, such as concrete crushing, cement batching and road work. Construction firms are required to minimise dust by adhering to relevant guidance. Processing plants or factories may also be required to make use of industrial dust collectors to minimize materials blowing off an area.
Dustmites House dustmites are a common indoor air pollutant. They are microscopic, spider-like organisms that live in beds, carpets and other soft furnishings. The feces, skin casts and pieces of dead mites contain substances which can trigger asthma attacks, inflammation on the lining of the nose and eczema in sensitive people. Regularly dusting and vacuuming of soft furnishings reduces the incidence of dustmites.