a zone of decline in a water course (falling level of dissolved oxygen)
1environment — environmental, adj. environmentally, adv. /en vuy reuhn meuhnt, vuy euhrn /, n. 1. the aggregate of surrounding things, conditions, or influences; surroundings; milieu. 2. Ecol. the air, water, minerals, organisms, and all other external factors… …
2chemical element — Introduction also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. This article considers the… …
3hydrologic sciences — Introduction the fields of study concerned with the waters of the Earth. Included are the sciences of hydrology, oceanography, limnology, and glaciology. In its widest sense hydrology encompasses the study of the occurrence, the… …
4nervous system disease — Introduction any of the diseases or disorders that affect the functioning of the human nervous system (nervous system, human). Everything that humans sense, consider, and effect and all the unlearned reflexes of the body depend on the… …
5Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …
6river — river1 riverless, adj. riverlike, adj. /riv euhr/, n. 1. a natural stream of water of fairly large size flowing in a definite course or channel or series of diverging and converging channels. 2. a similar stream of something other than water: a… …
7Life Sciences — ▪ 2009 Introduction Zoology In 2008 several zoological studies provided new insights into how species life history traits (such as the timing of reproduction or the length of life of adult individuals) are derived in part as responses to… …
8literature — /lit euhr euh cheuhr, choor , li treuh /, n. 1. writings in which expression and form, in connection with ideas of permanent and universal interest, are characteristic or essential features, as poetry, novels, history, biography, and essays. 2.… …
9international relations — a branch of political science dealing with the relations between nations. [1970 75] * * * Study of the relations of states with each other and with international organizations and certain subnational entities (e.g., bureaucracies and political… …
10Egypt — /ee jipt/, n. 1. Arab Republic of. a republic in NE Africa. 64,791,891; 386,198 sq. mi. (1,000,252 sq. km). Cap.: Cairo. Arabic, Misr. Formerly (1958 71), United Arab Republic. 2. an ancient kingdom in NE Africa: divided into the Nile Delta… …
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