Published in Encyclopedia of Inland Waters
This article presents an overview of ground water hydrology. Ground water occurs almost everywhere beneath the land surface and is an integral part of the hydrologic cycle. Basic concepts of the movement of water within porous media and differences in behavior between unconfined and confined aquifers are reviewed. A discussion of natural recharge a...
Published in Encyclopedia of Inland Waters
Submerged vegetation creates a zone of slow flow close to the bed, which may enhance nutrient and sediment retention. The velocity within the canopy is diminished in proportion to the canopy density. Above the canopy, the flow profile is logarithmic. The abrupt change in hydraulic resistance at the top of the canopy creates a region of strong shear...
Published in Encyclopedia of Inland Waters
Phytoplankton are, by definition, photosynthetic, and include cyanobacteria as well as algae. Most of the phytoplankton in inland waters obtain all of their energy from light and their chemical requirements from dissolved inorganic solutes, i.e., they are photolithotrophs. Growth rate limitation by resource supply in photolithotrophic phytoplankton...
Published in Encyclopedia of Inland Waters
Scientists and engineers specialized in geochemistry, chemistry, biology, and ecology of natural waters have collectively contributed thousands of published works dealing with natural organic matter (NOM). That body of scientific information is dispersed across a wide range of disciplinary journals and books, and it ranges in quality from the munda...
Published in Encyclopedia of Inland Waters
Freshwater bodies dominated by dissolved humic substances (HSs) seem to be the major type of inland waters. HSs are natural environmental chemicals and directly interact with organisms. HSs adversely interfere with photosynthesis and suppress cyanobacteria more than eukaryotic algae. Quinones in the HSs appear to be the effective structure. HSs exe...
Published in Encyclopedia of Inland Waters
The occurrence of bacteria attached to surfaces is characteristic of world inland water habitats. Attached bacteria are generally associated with other microorganisms, forming complex microbial consortia living in biofilms, microbial mats, and organic aggregates, or on other organisms as epibiotic communities. In all cases, bacteria largely dominat...
Published in Encyclopedia of Inland Waters
When dissolved or particulate matter of surface waters absorbs solar ultraviolet and short wavelength visible solar radiation (290–500 nm), photochemical reactions may take place. Often the primary absorber of such photolytic solar radiation is chromophoric dissolved organic matter (CDOM). In many lakes, CDOM consists primarily of allochthonous org...
Published in Encyclopedia of Inland Waters
Published in Encyclopedia of Inland Waters
The aquatic Hemiptera include a few inland semiaquatic Homoptera, but overwhelmingly belong to the Heteroptera. The aquatic and semiaquatic Heteroptera, consisting of the infraorders Leptopodomorpha, Gerromorpha, and Nepomorpha, comprise a significant component of the world's aquatic insect biota. Within these three infraorders as a whole there are...
Published in Encyclopedia of Inland Waters
Lakes and reservoirs are found throughout North America. The combination of extensive glaciations and widespread dam building has resulted in a continent that is rich in lakes of all sizes, from the smallest features tens of meters across to the Great Lakes. The number of lakes in the Canadian Shield is very large. The 5 Great Lakes are joined by s...
