| Glossary | Ch01 Ch02 Ch03 Ch04 Ch05 Ch06 Ch07 Ch08 Ch09 Ch10 Ch11 Ch12 Ch13 Ch14 |
| Chapter 12 | |
| abstract expressionism | An American movement in the field of painting that began in the late forties and emphasized a nonrepresentational style. The movement broke into two branches: action painting and color field painting. |
| acid solution | Any water solution that has more hydrogen ions (H+) than hydroxide ions (OH-); any water solution with a pH less than 7. Compare basic solution, neutral solution. |
| advanced sewage treatment | Specialized chemical and physical processes that reduce the amount of specific pollutants left in wastewater after primary and secondary sewage treatment. This type of treatment usually is expensive. See also primary sewage treatment, secondary sewage treatment. |
| aquifer | Porous, water-saturated layers of sand, gravel, or bedrock that can yield an economically significant amount of water. |
| barrier islands | Long, thin, low offshore islands of sediment that generally run parallel to the shore along some coasts. |
| basic solution | Water solution with more hydroxide ions (OH2) than hydrogen ions (H1); water solution with a pH greater than 7. Compare acid solution, neutral solution. |
| biological oxygen demand (BOD) | Amount of dissolved oxygen needed by aerobic decomposers to break down the organic materials in a given volume of water at a certain temperature over a specified time period. See dissolved oxygen content. |
| crude oil | Gooey liquid consisting mostly of hydrocarbon compounds and small amounts of compounds containing oxygen, sulfur, and nitrogen. Extracted from underground accumulations, it is sent to oil refineries, where it is converted to heating oil, diesel fuel, gasoline, tar, and other materials. |
| cultural eutrophication | Overnourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants. See eutrophication. |
| desalination | Purification of salt water or brackish (slightly salty) water by removal of dissolved salts. |
| dissolved oxygen (DO) content | Amount of oxygen gas (O2) dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water. See biological oxygen demand. |
| drainage basin | See watershed. |
| drought | Condition in which an area does not get enough water because of (1) lower-than-normal precipitation or (2) higher-than-normal temperatures that increase evaporation. |
| eutrophication | Physical, chemical, and biological changes that take place after a lake, estuary, or slow-flowing stream receives inputs of plant nutrients--mostly nitrates and phosphates--from natural erosion and runoff from the surrounding land basin. See cultural eutrophication. |
| floodplain | Flat valley floor next to a stream channel. For legal purposes, the term often applies to any low area that has the potential for flooding, including certain coastal areas. |
| groundwater | Water that sinks into the soil and is stored in slowly flowing and slowly renewed underground reservoirs called aquifers; underground water in the zone of saturation, below the water table. Compare runoff, surface water. |
| high-waste society | See high-throughput economy. |
| hydrologic cycle | Biogeochemical cycle that collects, purifies, and distributes the earth's fixed supply of water from the environment to living organisms and then back to the environment. |
| indicator species | Species that serve as early warnings that a community or ecosystem is being degraded. Compare keystone species, native species, nonnative species. |
| natural recharge | Natural replenishment of an aquifer by precipitation, which percolates downward through soil and rock. See recharge area. |
| nekton | Strongly swimming organisms found in aquatic systems. Compare benthos, plankton. |
| neutral solution | Water solution containing an equal number of hydrogen ions (H+) and hydroxide ions (OH-); water solution with a pH of 7. Compare acid solution, basic solution. |
| nonpoint source | Large or dispersed land areas such as cropfields, streets, and lawns that discharge pollutants into the environment over a large area. Compare point source. |
| oxygen-demanding wastes | Organic materials that are usually biodegraded by aerobic (oxygen-consuming) bacteria if there is enough dissolved oxygen in the water. See also biological oxygen demand. |
| parts per billion (ppb) | Number of parts of a chemical found in 1 billion parts of a particular gas, liquid, or solid. |
| parts per million (ppm) | Number of parts of a chemical found in 1 million parts of a particular gas, liquid, or solid. |
| parts per trillion (ppt) | Number of parts of a chemical found in 1 trillion parts of a particular gas, liquid, or solid. |
| point source | Single identifiable source that discharges pollutants into the environment. Examples are the (1) smokestack of a power plant or an industrial plant, (2) drainpipe of a meatpacking plant, (3) chimney of a house, or (4) exhaust pipe of an automobile. Compare nonpoint source. |
| ppb | See parts per billion. |
| ppm | See parts per million. |
| ppt | See parts per trillion. |
| primary sewage treatment | Mechanical sewage treatment in which large solids are filtered out by screens and suspended solids settle out as sludge in a sedimentation tank. Compare advanced sewage treatment, secondary sewage treatment. |
| prior appropriation | Legal principle by which the first user of water from a stream establishes a legal right to continued use of the amount originally withdrawn. Compare riparian rights. |
| rain shadow effect | Low precipitation on the far side (leeward side) of a mountain when prevailing winds flow up and over a high mountain or range of high mountains. This creates semiarid and arid conditions on the leeward side of a high mountain range. |
| recharge area | Any area of land allowing water to pass through it and into an aquifer. See aquifer, natural recharge. |
| reliable runoff | Surface runoff of water that generally can be counted on as a stable source of water from year to year. See runoff. |
| riparian rights | System of water law that gives anyone whose land adjoins a flowing stream the right to use water from the stream, as long as some is left for downstream users. Compare prior appropriation. |
| saltwater intrusion | Movement of salt water into freshwater aquifers in coastal and inland areas as groundwater is withdrawn faster than it is recharged by precipitation. |
| secondary sewage treatment | Second step in most waste treatment systems in which aerobic bacteria break down up to 90% of degradable, oxygen-demanding organic wastes in wastewater. This usually involves bringing sewage and bacteria together in trickling filters or in the activated sludge process. Compare advanced sewage treatment, primary sewage treatment. |
| septic tank | Underground tank for treating wastewater from a home in rural and suburban areas. Bacteria in the tank decompose organic wastes, and the sludge settles to the bottom of the tank. The effluent flows out of the tank into the ground through a field of drainpipes. |
| sludge | Gooey mixture of toxic chemicals, infectious agents, and settled solids removed from wastewater at a sewage treatment plant. |
| stream | Flowing body of surface water. Examples are creeks and rivers. |
| surface runoff | Water flowing off the land into bodies of surface water. See reliable runoff. |
| tertiary sewage treatment | See advanced sewage treatment. |
| thermocline | Zone of gradual temperature decrease between warm surface water and colder deep water in a lake, reservoir, or ocean. |
| transpiration | Process in which water (1) is absorbed by the root systems of plants, (2) moves up through the plants, (3) passes through pores (stomata) in their leaves or other parts, and (4) evaporates into the atmosphere as water vapor. |
| upwelling | Movement of nutrient-rich bottom water to the ocean's surface. This can occur far from shore but usually occurs along certain steep coastal areas where the surface layer of ocean water is pushed away from shore and replaced by cold, nutrient-rich bottom water. |
| water pollution | Any physical or chemical change in surface water or groundwater that can harm living organisms or make water unfit for certain uses. |
| water table | Upper surface of the zone of saturation, in which all available pores in the soil and rock in the earth's crust are filled with water. |
| watershed | Land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river). |
| wetland | Land covered all or part of the time with salt water or fresh water, excluding streams, lakes, and the open ocean. See coastal wetland, inland wetland. |
| zone of aeration | Zone in soil that is not saturated with water and lies above the water table. See water table, zone of saturation. |
| zone of saturation | Area where all available pores in soil and rock in the earth's crust are filled by water. See water table, zone of aeration. |