A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

DAF

Department of Air Force.

DAF

Dilution/Attenuation Factors.

DAF

Dissolved Air Flotation.

dangerously reactive material

a material that can react by itself (e.g., polymerize) or with air or water to produce a hazardous condition. Preventive measures can be taken if you know what conditions may cause the dangerous reactions.

data call-in

a part of the Office of Pesticide Programs (OPT) process of developing key required test data, especially on the long-term, chronic effects of existing pesticides, in advance of scheduled Registration Standard reviews. Data Call-In is an adjunct of the Registration Standards program intended to expedite registration and involves the "calling in" of data from manufacturers.

day tanks

tanks used to hold diluted regenerant chemicals prior to being educted or pumped to the resin bed.

D-18

Coagulant - Cationic Flocculant - Clarification/Settling (ETUS).

DBA

Decibels on A-weighted Scale.

DBMS

Database Management System.

D-CELL

Filter Aid (ETUS).

DCO

Delayed Compliance Order.

DDBSA

Dodecylbenzenesulfonic Acid, acid-type anionic surfactant. Often neutralized and used as an anionic detergent.

DDT

the first chlorinated hydrocarbon insecticide (chemical name: 1,1,1-trichlorous-2, 2-bis (p-chloriphenyl)-ethane.) It has a half-life of 15 years, and can collect in fatty tissues of certain animals. EPA banned registration and interstate sale of DDT for virtually all but emergency uses in the U.S. in 1972 because of its persistence in the environment and accumulation in the food chain.

dealkalization

any process for reducing the alkalinity of water.

Dec, Decomp.

decompose, decomposition. Breakdown of a material (by heat, chemical reaction, electrolysis, decay, or other processes) into parts, elements, or simpler compounds.

decantation

an elutriation process, where the supernatant liquor contains recoverable leaching chemical.

dechlorination

removal of chlorine from a substance by chemically replacing it with hydrogen or hydroxide ions in order to detoxify the substances involved.

decibel (dB)

a unit of sound measurement. In general, a sound doubles in loudness for every increase of ten decibels.

decomposition

the breakdown of matter by bacteria. It changes the chemical make-up and physical appearance of materials.

defoliant

a herbicide that removes leaves from trees and growing plants.

degasifier or deaerator

a system to remove dissolved gas or gases from water.

degradable

that which can be reduced, broken down or chemically separated.

degradation

the process by which a chemical is reduced to a less complex form.

deinking

the process of removing ink from secondary fibers.

deionize

(abbr. DI) - to remove ions from solution by means of ion exchange resins.

deionization

any process removing ions from water, but most commonly an ion exchange process where cations and anions are removed independently of each other.

DEIS

Draft Environmental Impact Statement.

delayed hazard

A hazard with delayed effect(s). The potential to cause an adverse effect which manifests itself after a long period of time. Carcinogenicity, teratogenicity and certain target organ/system effects are examples of delayed hazards.

delegated state

a state (or other governmental entity) which has applied for, and received authority to administer, within its territory, its state regulatory program as the federal program required under a particular federal statute. As used in connection with NPDES, UIC, and PWS programs, the term does not connote any transfer of federal authority to a state.

deliquescent

a term used to characterize water-soluble salts (usually powdered) that tend to absorb moisture from the air and to soften or dissolve as a result. See Hydroscopic; Hydrophilic.

delist

use of the petition process to have a facility's toxic designation rescinded.

demineralization

removal from water of mineral contaminants usually present in ionized form. The methods used include ion exchange techniques, flash distillation or electrolysis.

demulcent

a material capable of soothing or protecting inflamed, irritated mucous membranes.

denitrification

the anaerobic biological reduction of nitrate nitrogen to nitrogen gas.

density

ratio of weight (mass) to volume of a material, usually in grams per cubic centimeter or pounds per gallon. One cc of HàO weighs 1 g. See Specific Gravity.

depletion curve (hydraulics)

a graphical representation of water depletion from storage-stream channels, surface soil, and groundwater. A depletion curve can be drawn for base flow, direct runoff, or total flow.

depressurization

a condition that occurs when the air pressure inside a structure is lower than the air pressure outside.Depressurization can occur when household appliances that consume or exhaust house air, such as fireplaces or furnaces, are not supplied with enough makeup air. Radon-containing soil gas may be drawn into a house more rapidly under depressurized conditions.

DERA

Defense Environmental Restoration Account.

dermal

used on or applied to the skin.

dermal toxicity

the ability of a pesticide or toxic chemical to poison people or animals by touching the skin.

dermatitis

inflammation of the skin.

DERP

Defense Environmental Restoration Program.

DES (Diethylstilbestrol)

a synthetic estrogen used as a growth stimulant in food animals. Residues in neat are thought to be carcinogenic.

designated area

an area of (or device within) a lab to be used for work with "select carcinogens", reproductive toxins, and other materials which have a high degree of acute toxicity. An engineering control intended to minimize the potential for employee exposure to hazardous chemicals.

desalination

removing salt from ocean or brackish water.

desalting

the removal of salt from crude oil.

desiccant

a chemical agent that dries out plants or insects causing death.

designated pollutant

an air pollutant which is neither a criteria nor hazardous pollutant, as described in the Clean Air Act, but for which new sources performance standards exist.The Clean Air Act does require states to control these pollutants, which include acid mist, total reduced sulfur (TRS), and fluorides.

designated uses

those water uses identified in state water quality standards which must be achieved and maintained as required under the Clean Water Act. Uses can include cold water fisheries, public water supply, agriculture, etc.

designer bugs

popular term for microbes developed through biotechnology that can degrade specific toxic chemicals at their source in toxic waste dumps or in ground water.

desulfurization

removal of sulfur from fossil fuels to cut pollution.

detackify

treatment of solids from a paint spray booth to eliminate their sticky properties.

detection limit

the lowest amount that can be distinguished from the normal electronic noise of an analytical instrument.

detergent

synthetic washing agent that helps water to remove dirt and oil. Most contain large amounts of phosphorus compounds which may kill useful bacteria and encourage algae growth in the receiving water.

developer

a person, government unit, or company that proposes to build a hazardous waste treatment, storage, or disposal facility.

developmental RfD

an estimate (with uncertainty spanning perhaps an order of magnitude or greater) of an exposure level for the human population, including sensitive subpopulations, that is likely to be without an appreciable risks of developmental effects. Developmental RfDs are used to evaluate the effects of a single event (generally 1 day) exposure.

dewater

to separate water from sludge to produce a cake that can be handled as a solid.

dewatering (sludge processing)

removing water from sludge.

DFA

Department of Food and Agriculture.

DFM

Diesel Fuel Marine.

DHS

Department of Health Services (California).

DI

Diagnostic Inspection.

dialysis

a separation process that depends on differences in diffusion rates of solutes across a permeable membrane.

diaphoresis

perspiration, especially profuse.

diatomaceous earth (diatomite)

a chalk-like material (fossilized diatoms) used to filter out solid wastes in waste water treatment plants, also found in powdered pesticides.

diatomaceous earth filtration

means a process resulting in substantial particulate removal in which (1) a precoat cake of diatomaceous earth filter media is deposited on a support membrane (septum), and (2) while the water is filtered by passing through the cake on the septum, additional filter media known as body feed is continuously added to the feed water to maintain the permeability of the filter cake.

diatoms

organisms related to algae, having a brown pigmentation and siliceous skeleton.

diazinon

an insecticide. In 1986, EPA banned its use on open areas such as sod farms and golf courses because is posed a danger to migratory birds who gathered on them in large numbers. The ban did not apply to it use in agriculture, or on lawns of homes and commercial establishments.

dicofol

a pesticide used on citrus fruits.

dielectric material

means a material that does not conduct direct electrical current. Dielectric coatings are used to electrically isolate UST systems from the surrounding soils. Dielectric bushings are used to electrically isolate portions of the UST system (e.g., tank from piping).

differentiation

the process by which single cells grow into particular forms of specialized tissue, e.g., root, stem, leaf.

diffused air

a type of aeration that forces oxygen into sewage by pumping air through perforated pipes inside a holding tank.

digester

in wastewater treatment a closed tank, sometimes heated to 90 degrees F, where sludge is subjected to intensified bacterial action.

digestion

the biochemical decomposition of organic matter.Digestion of sewage sludge occurs in tanks where it breaks down into gas, liquid, and mineral matter.

dike

a low wall that can act as a barrier to prevent a spill from spreading.

DILUTE HF

Electrode Maintenance Reagent (ETUS).

dilution ratio

the relationship between the volume of water in a stream and the volume of incoming waste. It can affect the ability of the stream to assimilate water.

dilution ventilation

see General Ventilation.

dinocap

a fungicide used primarily by apple growers to control summer diseases. EPA, in 1986, proposed restrictions on its use when laboratory tests found it caused birth defects in rabbits.

dinoseb

a herbicide that is also used as a fungicide and insecticide. It was banned by EPA in 1986 because it posed the risk of birth defects and sterility.

dioxin

any of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity and contaminants in commercial products. Tests on laboratory animals indicate that it is one of the more toxic man-made chemicals known.

DIR

Department of Industrial Relations.

direct discharger

a municipal or industrial facility which introduces pollution through a defined conveyance or system; a point source.

direct filtration

means a series of processes including coagulation and filtration but excluding sedimentation resulting in substantial particulate removal.

discharge

as defined by section 311(a)(2) of the CWA, includes, but is not limited to, any spilling, leaking, pumping, pouring, emitting, emptying, or dumping of oil, but excludes discharges in compliance with a permit under section 402 of the CWA, discharges resulting from circumstances identified and reviewed and made a part of the public record with respect to a permit issued or modified under section 402 of the CWA, and subject to a condition in such permit, or continuous or anticipated intermittent discharges from a point source, identified in a permit or permit application under section 402 of the CWA, that are caused by events occurring within the scope of relevant operating or treatment systems. For purposes of the NCP, discharge also means threat of discharge.

disinfectant

a chemical or physical process that kills pathogenic organisms in water. Chlorine is often used to disinfect sewage treatment effluent, water supplies, wells and swimming pools.

disinfectant contact time ("T" in CT calculations)

means the time in minutes that it takes for water to move from the point of disinfectant application or the previous point of disinfectant residual measurement to a point before or at the point where residual disinfectant concentration ("C") is measured. Where only one "C" is measured, "T" is the time in minutes that it takes for water to move from the point of disinfectant application to a point before or at the point where residual disinfectant concentration ("C") is measured. Where more than one "C" is measured, "T" is (a) for the first measurement of "C", the time in minutes that it takes for water to move from the first or only point of disinfectant application to a point before or at the point where the first "C" is measured and (b) for subsequent measurements of "C", the time in minutes that it takes for water to move from the previous "C" measurement point to the "C" measurement point for which the particular "T" is being calculated. Disinfectant contact time in pipelines must be calculated based on "plug flow" by dividing the internal volume of the pipe by the maximum hourly flow rate through that pipe. Disinfectant contact time within mixing basins and storage reservoirs must be determined by tracer studies or an equivalent demonstration.

disinfection

application of energy or chemical to kill or inactivate pathogenic organisms.

dispersant

a chemical which causes particulates in a water system to remain in suspension. Those chemical agents that emulsify, disperse, or solubilize oil into the water column or promote the surface spreading of oil slicks to facilitate dispersal of the oil into the water column.

DISPERSE

Boiler Water Treatment (ETUS).

disposal

final placement or destruction of toxic, radioactive, or other wastes; surplus or banned pesticides or other chemicals; polluted soils; and drums containing hazardous materials from removal actions or accidental releases.Disposal may be accomplished through use of approved secure landfills, surface impoundments, land farming, deep well injection, ocean dumping, or incineration.

dissociate

the process of ionization of an electrolyte or a salt upon being dissolved in water, forming ions of cation and anion.

dissolved oxygen (DO)

the oxygen freely available in water.Dissolved oxygen is vital to fish and other aquatic life and for the prevention of odors. Traditionally, this level of dissolved oxygen has been accepted as the single most important indicator of a water body's ability to support desirable aquatic life. Secondary and advanced waste treatment are generally designed to protect DO in waste-receiving waters.

dissolved solids

the total of disintegrated organic and inorganic material contained in water. Excesses can make water unfit to drink or use in industrial processes.

distillation

purifying liquids through boiling. The steam condenses to pure water and pollutants remain in a concentrated residue. The process in which a liquid, such as water, is converted into its vapor state by heating, and the vapor cooled and condensed to the liquid state and collected; used to remove solids and other impurities from water. Multiple distillations are required for extreme purity.

divinylbenzene

(abbr. DVB) - a difunctional monomer used to cross-link polymers.

DLA

Defense Logistics Agency.

DMR

Discharge Monitoring Report.

DMS

Data Management System.

DN

Department of Navy.

DNA

deoxyribonucleic acid, the molecule in which the genetic information for most living cells is encoded. Viruses, too, can contain DNA.

DNA hybridization

use of a segment of DNA, called a DNA probe, to identify its complementary DNA; used to detect specific genes. This process takes advantage of the ability of a single strand of DNA to combine with a complimentary strand.

DNR

Department of Natural Resources.

DOC

Department of Commerce.

DOCKET

Consolidated Docket of Civil Enforcement Actions.

DOD

U.S. Department of Defense; responsible for administering military programs to protect the nation from external aggression; manages arsenals and other facilities containing toxic and hazardous materials and wastes.

DOE

U.S. Department of Energy; responsible for research and development of energy technology, marketing of federal power, the nuclear weapons program, and energy regulation.

DOE

Department of Ecology.

DOI

U.S. Department of the Interior.

DOJ

U.S. Department of Justice.

DOL

U.S. Department of Labor.

donnan effect

the rejection of diffusion of external ions by a semipermeable membrane because of a high internal concentration of ions of the same charge.

DOS

U.S. Department of State.

DOS

Disk Operating System.

dose

the amount of a substance penetrating the exchange boundaries of an organism after contact. Dose is calculated from the intake and the absorption efficiency, and it usually is expressed as mass of a substance absorbed into the body per unit body weight per unit time (e.g., mg/kg-day). Also, in radiology, the quantity of energy or radiation absorbed.

dose-response evaluation

the process of quantitatively evaluation the toxicity information and characterizing the relationship between the dose of the contaminant administered or received and the incidence of adverse health effects in the exposed population. From the quantitative dose-response relationship, toxicity values are derived that are use in the risk characterization step to estimate the likelihood of adverse effects occurring in humans at different exposure levels.

dosimeter

an instrument that measures exposure to radiation.

DOT

U.S. Department of Transportation, enforces regulations governing the transport of hazardous and non-hazardous materials.

DOT identification numbers

four-digit numbers [preceded by UN (United Nations) or NA (North America] used to identify particular materials for regulation of their transportation.See DOT publications that describe the regulations (49 CFR 172.102). These numbers are called product identification numbers (PINs) under the Canadian Transportation of Dangerous Goods Regulation.

DPA

Deepwater Ports Act.

DQO

Data Quality Objectives.

DRE

Destruction and Removal Efficiency.

dredging

removal of mud from the bottom of water bodies using a scooping machine. This disturbs the ecosystem and causes silting that can kill aquatic life. Dredging of contaminated muds can expose aquatic life to heavy metals and other toxics. Dredging activities may be subject to regulation under Section 404 of the Clean Water Act.

DREW

Drew Industrial Division, Ashland Chemical Co.

drift

entrained water in the stack discharge of a cooling tower.

drinking water supply

as defined by section 101(7) of CERCLA, means any raw or finished water source that is or may be used by a public water system (as defined in the Safe Drinking Water Act) or as drinking water by one or more individuals.

dry limestone process

an air pollution control method that uses limestone to absorb the sulfur oxides in furnaces and stack gases.

DSCF

Dry Standard Cubic Feet.

DSCM

Dry Standard Cubic Meter.

DSL

Domestic Substances List (Environment Canada).

DTC

Sodium Dimethyldithiocarbamate, a biocide.

DTC-40

Restricted Precipitant - Chelate Breaker - Heavy Metal (ETUS).

DTMF

Dual Tone Multi-Frequency telephone dialing.

dump

a site used to dispose of solid wastes without environmental controls.

dust

solid particles suspended in air produced by some mechanical process such as crushing, grinding, abrading, or blasting. Dusts may be inhalation, fire, or dust-explosion hazards.

dustfall jar

an open container used to collect large particles from air for measurement and analysis.

DWR

Department of Water Resources.

DWS

Drinking Water Standard.

dynamic

an ion exchange reaction taking place as the water moves past ion exchange resins.

dysplasia

Malformation; abnormal development of an organ or tissue.

dyspnea

a sense of difficulty in breathing; shortness of breath.

dystrophic lakes

shallow bodies of water that contain much organic matter. They contain many plants but few fish and are almost eutrophic.

dyspnea

 

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z