环境英语证书考试（PEC）-核心词汇解释AAbiotic environment The part of an ecosystem that includes the nonliving surroundings.Activated sludge An active population of microorganisms used to treat wastewater, or the process in which the organisms are employed.Adsorption A surface phenomena in which a solute (soluble material) concentrates or collects at a surface (the adsorbent).Advanced wastewater treatment The removal of any dissolved or suspended contaminants beyond secondary treatment, often this is the removal of the nutrients nitrogen and/or phosphorus.Aeration Intimate contact of the atmosphere and water to add air (oxygen) to the water. The term is also applied to gas stripping where an undesirable gas is removed from the water. See gas stripping.Aerobes Organisms which require molecular oxygen as an electron acceptor for energy production. See anaerobes.Aerobic process A process which requires molecular oxygen.Alcohol An organic compound with one or more hydroxyl -OH groups.Aldehyde An organic compound with a carbonyl at one end of a hydrocarbon group.Alkalinity The capacity of a water to neutralize acids.Amine A functional group consisting of -NH2.Amino acid A functional group which consists of a carbon with a carboxylic acid, -COOH and an amine, -NH2. These compounds are the building blocks for proteins.Anabolism Biosynthesis, the production of new cellular materials from other organic or inorganic chemicals.Anaerobes A group of organisms that do not require molecular oxygen. These organisms, as well as all known life forms, require oxygen. These organisms obtain their oxygen from inorganic ions such as nitrate or sulfate or from protein.Anaerobic process A process which only occurs in the absence of molecular oxygen.Anoxic process A process which occurs only at very low levels of molecular oxygen or in the absence of molecular oxygen.Anthropogenic Of, made, or caused by human activity or actions.Aromatic A form of bonding in which ring compounds share electrons over more than two atoms. The electrons are delocalized. This leads to unusual ring stability.Attached growth reactor A reactor in which the microorganisms are attached to engineered surfaces within the reactor. Examples of attached growth reactors are the trickling filter and the rotating biological contactor. Seesuspended growth reactor.Autotrophic Organisms which utilize inorganic carbon for synthesis of protoplasm. Ecologists narrow the definition further by requiring that autotrophs obtain their energy from the sun. In microbiologist parlance, this would be a photoautotroph. See photoautotrophic and chemoautotrophic.Autotrophs A group of organisms capable of obtaining carbon for synthesis from inorganic carbon sources such as carbon dioxide and its dissolved species (the carbonates). This group includes plants and algae.BBacteria One celled microorganisms which do not have a nuclear membrane.Baghouse filter A fabric filter device used to remove particulate air pollutants.Biochemical oxygen demand (BOD) The amount of oxygen required to oxidize any organic matter present in a water during a specified period of time, usually 5 days. It is an indirect measure of the amount of organic matter present in a water.Biofilm A film of microorganisms attached to a surface, such as that on a trickling filter, rotating biological contactor, or rocks in natural streams.Biogeochemical cycle The cycle of elements through the biotic and abiotic environment.Biosynthesis Catabolism, the production of new cellular materials from other organic or inorganic chemicals.BOD See biochemical oxygen demand.CCarbonaceous biochemical oxygen demand (CBOD) The amount of oxygen required to oxidize any carbon containing matter present in a water.Carbonyl A functional group with an oxygen atom double bonded to a carbon atom.Catabolism The production of energy by the degradation of organic compounds.Cell A unit of varying dimensions in a landfill which is isolated from the environment by 6 to 12 inches of soil cover. A cell is one days waste or less. A cell is covered with soil at the end of each day.CFCs Chlorofluorocarbons, chemicals which result in a depletion of the ozone layer in the upper atmosphere.Chemical fixation (or stabilization/solidification) A term for several different methods of chemically immobilizing hazardous materials into a cement, plastic, or other matrix.Chemical oxygen demand (COD) The amount of oxygen required to oxidize any organic matter in the water using harsh chemical conditions.Chemoautotrophic Organisms which utilize inorganic carbon (carbon dioxide or carbonates) for synthesis and inorganic chemicals for energy. See autotrophic and photoautotrophic.Chemotroph Organisms which obtain energy from the metabolism of chemicals, either organic or inorganic.Chlorofluorocarbons Synthetic organic compounds used for refrigerants, aerosol propellants (prohibited in the U.S.), and blowing agents in plastic foams. CFCs migrate to the upper atmosphere destro