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Others may breathe atmospheric air while remaining submerged, via breathing tubes or trapped air bubbles, though some aquatic insects may remain submerged indefinitely and respire using a plastron. A number of insects have an aquatic juvenile phase and an adult phase on land. In these case adaptions for life in water are lost at the final ecdysis.
Breathing air is primarily of use to fish that inhabit shallow, seasonally variable waters where the water's oxygen concentration may seasonally decline. Fish dependent solely on dissolved oxygen, such as perch and cichlids , quickly suffocate, while air-breathers survive for much longer, in some cases in water that is little more than wet mud.
The concentration of oxygen in water is lower than air and it diffuses more slowly. In a litre of freshwater the oxygen content is 8 cm 3 per litre compared to 210 in the same volume of air. [7] Water is 777 times more dense than air and is 100 times more viscous. [7] Oxygen has a diffusion rate in air 10,000 times greater than in water. [7 ...
Fresh water hold less than 1/25th the oxygen content of air, the dissolved oxygen content being approximately 8 cm 3 /L compared to that of air which is 210 cm 3 /L. [4] Water is 777 times more dense than air and is 100 times more viscous. [4] Oxygen has a diffusion rate in air 10,000 times greater than in water. [4]
Assimilative capacity in hydrology is defined as the maximum amount of contaminating pollutants that a body of water can naturally absorb without exceeding the water quality guidelines and criteria. This determines the concentration of pollutants that can cause detrimental effects on aquatic life and humans that use it.
Sea spray is largely responsible for corrosion of metallic objects near the coastline, as the salts accelerate the corrosion process in the presence of abundant atmospheric oxygen and moisture. [9] Salts do not dissolve in air directly, but are suspended as fine particulates, or dissolved in microscopic airborne water droplets. [35]
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated.
in the condensation of the water-vapour of the air on the cold surface of a glass; in the capillarity of hair, wool, cotton, wood shavings, etc.; in the imbibition of water from the air by gelatine; in the deliquescence of common salt; in the absorption of water from the air by concentrated sulphuric acid; in the behaviour of quicklime". [4]