A mixing zone is an area of a lake or river where pollutants from a point source discharge are mixed, usually by natural means, with cleaner water. In the mixing zone, the level of toxic pollutants is allowed to be higher than the acceptable concentration for the general water body. The mixing zone is an area where the higher concentration is diluted to legal limits for water quality. Outside the mixing zone, the pollutant levels must meet water quality standards. A typical mixing zone consists of two parts: the zone of initial dilution (ZID), near the outfall, and the chronic mixing zone from the ZID out to where water quality criteria are met. The discharge into the mixing zone may be effluent from water treatment plants, chemicals, or hot water from cooling towers.
The U.S. Environmental Protection Agency (EPA) is taking steps to ban the use of mixing zones for toxic chemicals. The Great Lakes Initiative (2000) also bans the discharge of twenty-two chemicals considered to be bioaccumulative. Bioaccumulative chemicals (BCCs) are those that become more concentrated as they move up through the food chain, for instance, from aquatic insects to fish to humans. As the release of BCCs into water bodies is phased out, industries will need to treat the discharge at the source.
see also: Bioaccumulation; Dilution; Point Source; Water Pollution.
"Identification of Approved and Disapproved Elements of the Great Lakes Guidance Submissions From the States of Michigan, Ohio, Indiana, and Illinois, and Final Rule." (2000). In Federal Register 65:151.
Great Lakes Initiative Fact Sheet. Available from http://www.epa.gov/ost/GLI/mixingzones/finalfact.html.
"Mixing Zone." Pollution A to Z. . Encyclopedia.com. (April 20, 2019). https://www.encyclopedia.com/environment/educational-magazines/mixing-zone
"Mixing Zone." Pollution A to Z. . Retrieved April 20, 2019 from Encyclopedia.com: https://www.encyclopedia.com/environment/educational-magazines/mixing-zone
Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).
Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.
Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:
Modern Language Association
The Chicago Manual of Style
American Psychological Association
- Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
- In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.