Essential properties of water

• Water is one of the main agents in Pedogenesis (soil formation). • It is the medium for several different ecosystems. • It is present as moisture in the atmosphere and the outer layers of the lithosphere and is uneven in distribution on the earth. • Water is heavier than air and imparts greater buoyancy to the aquatic medium.

This enables organism to float at variable levels. • Water has high heat capacity and latent heat, due to which it can withhold large amounts of heat. Thus, oceans and lakes tend to maintain a relatively constant temperature, and the biosphere is relatively thermostable. • Water is physically unique because it is less dense as a solid (ice) than as a liquid.

• When water freezes ( ⁰ C), it contracts. The maximum density of liquid water occurs at 4ºC. Below that, it expands markedly. This enables ice to float on the top of water bodies.

Hence, only the surface of water bodies will freeze, while below the surface, water will be in liquid form, sustaining life ( Fig. . ). • Water is considered as the Universal solvent.

It is the main medium by which chemical constituents are transported from abiotic components to the living components of an ecosystem. • Water has high surface tension. This allows pollen, dust, and even water striders to remain at the surface of a water body even though they are denser than the water.