Hydrogen Ion concentration are given by pH values which range from 1 to 14, with pH 1 being very acidic, pH7, neutral , and pH 14, very alkaline.
The pH of mist soils ranges from strongly acidic (pH 4: 5) to fairly alkaline (pH 8:3). In aquatic habitats, pH varies with the salinity of the water. Fresh water is usually neutral, while sea water tends to be fairy alkaline (pH 8:5). In aquatic habitats, pH varies with the salinity of the water. Fresh water is usually neutral, while sea water tends to be fairly alkaline (pH 8:5).
Living organisms are highly sensitive to pH changes. For example, fresh water molluscs (mytilus) are usually absent in water with pH less than 6. Most plants thrive well in neutral PR slightly alkaline soils. Acidic soils support very little vegetation.
