The ionic composition of surface waters in the English Lake District, related to bedrock geology, with some singular facts and speculation on the existence of mineral-rich groundwaters
All natural waters are a cocktail of particulate and dissolved substances,including numerous elements that are present in trace amounts, several plant"nutrients" in small to moderate amounts (particularly nitrogen, phosphorusand silicon), and "major ions" or electrolytes (charged solutes) in moderate torelatively large amounts. The major cations are sodium, calcium, magnesiumand potassium, plus hydrogen and aluminium which occur in increasinglygreater amounts in acid waters, especially at pH below ca. 5.0. Major anionsare chloride, sulphate, nitrate and several components representing "alkalinity"- especially bicarbonate and silicates. Although few in number, these ionsdetermine aspects of water quality that are essential for all aquatic organisms.Sodium, potassium and chloride are vital minerals for internal regulation ofblood and tissue cells in animals, and tissues of plants. Calcium, magnesiumand bicarbonate alkalinity are also vital for the biota, and are the principalcomponents of water "softness" and "hardness". Nitrate is an important plantnutrient, together with phosphate (and silicate for diatoms). Sulphate is a majorcomponent of some tissue cells and important in the external environment as aprincipal anion for maintaining charge balance (electroneutrality), especially inproviding a "balance" for hydrogen, calcium and magnesium cations. In thislatter role sulphate is important in acidification processes affecting soils andwaters, although it is frequently present in larger amounts in hard waters
