Dissolved materials and ions occur naturally in water because of mineral dissolution from weathered rocks and soils. The most common positively charged chemicals found in natural waters are calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+). Several other chemicals are present and essential to sustaining life in aquatic systems. Nutrients such as nitrogen (N) and phosphorus (P) are needed by aquatic organisms, but at high concentrations can degrade ecosystems through eutrophication. Metal ions, similarly, are essential to biological processes at low concentrations but can be toxic at higher concentrations.
The most important negatively charged ions, called anions, found in natural waters are chloride (Cl–), sulphate (SO42–), bicarbonate (HCO3–) and carbonate (CO32–), which also originate from dissolution of rock and soil minerals. These anions play an important role in buffering water and also impact the solubility of many cations. The ability to neutralise acids is termed alkalinity and is mainly due to the presence of bicarbonate and carbonate.
Industrial discharge from base metal mines (copper, lead and zinc) and other industrial activities can impair the chemical water characteristics if they are not regulated.
Discharges from base metal mines can drastically alter chemical water quality characteristics.
Source: Vogel 2002
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Chemical parameters of water quality are further explored through the following subjects:
