Of river communities are wonderfully varied - from single-celled plants and animals, aquatic insects, and other small residents, up through large fishes and waterfowl. It profoundly affects, and is affected by, aquatic organisms. In the absence of human influence, the water chemistry is determined by the soils and rocks in the watershed, the chemistry of the precipitation, and interaction with plants and animals on land and in the water. These are the water's oxygen content (dissolved oxygen or DO), acidity (pH), ability to neutralize acid (alkalinity), nutrients, metals, and other constituents. The river's chemical characteristicsĪre the basic building blocks for river life. ![]() ![]() Shallow rapids where water flows over submerged rocks or riffles, calm gentle glides, deep slow pools, and stagnant waters along the river margin or backwaters, provide a variety of habitats for fish, waterfowl, and aquatic invertebrates. In turn, the river influences the land by cutting its channel through rock and soil, and carrying the eroded material downstream. It is a physical process, as runoff flowing over land and groundwater flowing underground replenish the river with water, sediment, and nutrients. It's water rushing through a gorge, or flowing lazily through a farm meadow. We can think of river communities as having physical, chemical, and biological attributes: The physical layoutĪnd foundation for a river community is flowing water and its relationship to the land area that drains into the river - its watershed. Once we begin to consider the river as a web of living organisms bound together by water, we should begin to wonder how river users affect how that biological community functions. Yet, many of the uses we make of rivers have tremendous impacts on natural communities, making the health of rivers our responsibility. They are "home" to an interconnected web of creatures, many of which we never see and rarely think about. But they are more than their sum of human uses. Pyykkö, personal communication, 1998, 204, 2008, 2010.Rivers offer areas for swimming, boating, fishing, or waste disposal, and sources of water for generating energy, drinking, snowmaking, irrigating crops or fighting fires. Lide, (ed.), CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998. I am grateful to Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data in this and the following two references. Where given, data for certain radioactive nuclei are from this reference. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. I am grateful to Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC, adapted from his contribution contained within this reference. ![]() 5, John Wiley & Sons, Chichester, UK, 1996. Harris in Encyclopedia of Nuclear Magnetic Resonance, D.M. ![]() Magnetogyric ratio, γ (10 7 rad T ‑1 s -1) Table of NMR-active nucleus propeties of boron Ĭommon reference compound: BF 3.OEt 2/CDCl 3. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988.
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