International Journal of Current Trends in Science

International Journal of Current Trends in Science and Technology Online ISSN: 0976-9730 Print ISSN: 0976- 9498

Different Aspects of Chloride In Freshwater: A Review Supratim Pal1* and Kaushik Chakraborty2 Ph. D. Student, Department of Zoology, University of Gour Banga, Mokdumpur, Malda, West Bengal, India, 7321031 Associate Professor, Department of Zoology, University of Gour Banga, Mokdumpur, Malda, West Bengal, India, 7321032 Correspondence Author * Accepted 2017-07-31; Published 2017-08-12

Abstract: Chloride is a natural component and is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is in its dissolved form. Chloride is widely distributed in nature as salts. Though it is most prevalent in sea water, it permits rivers, lakes, and other freshwater systems also. Some common chloride compounds found in natural water are sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2) and magnesium chloride (MgCl2). For its essentiality as an electrolyte to the animals, it is sometimes referred as the “queen of electrolytes”. But, higher concentration of chloride in water is reported to be an indication of pollution and affects physiological processes of the organisms. Chloride increases the electrical conductivity and corrosiveness of water. The relationship with water temperature, bicarbonate and calcium is positive with this anion, but inverse correlations exist with pH and total alkalinity. There are several techniques for chloride estimation, but removal processes of chloride from water are expensive and energy-intensive. Key words: Chloride, freshwater, pollution, anion. chloride are often very soluble in water (Green and Sadru, 2001). The chloride ion is highly Chloride is widely distributed in nature, generally mobile and is eventually transported into closed as the sodium (NaCl) and potassium (KCl) salts; it basins or to the oceans (NRCC, 1977). The ion is constitutes approximately 0.05% of the colourless and diamagnetic. In aqueous solution, it lithosphere (National Research Council of is highly soluble in most cases. In aqueous Canada, 1977). Chloride is one of the major solution, chloride is bound by the protic end of the inorganic anion in water. Chloride in anionic form water molecules. It is an when present in natural waters, generally results essential electrolyte located in all body fluids from the dissociation of salts, such as sodium responsible for maintaining acid-base balance, chloride or calcium chloride (Ito, 1997). In transmitting nerve impulses and regulating fluid in potable water, the salty taste is produced by the and out of cells. Chloride is a common component chloride concentrations. Chlorides are present in of most waters and is useful to fish in maintaining both fresh and salt water, and are essential their osmotic balance. elements of life (Hunt et al., 2012). Chloride is Chloride is a ubiquitous aqueous anion in all formed when the element chlorine (a halogen) natural waters, the concentrations varying very gains an electron or when a compound such as widely and reaching a maximum in sea water. hydrogen chloride is dissolved in water or other Natural levels in rivers and other fresh waters are polar solvents. Chloride salts such as sodium usually in the range 15 - 35 mg/L. Chlorides are International Journal of Current Trends in Science and Technology, Vol. 7, Issue. 8, Page no: 20295-20303 Page | 20295 Introduction:

Supratim Pal et al. Different Aspects Of Chloride In Freshwater: A Review

also found in water as mineral solvents. Chloride is widely distributed in nature as salts of sodium chloride (NaCl), potassium chloride (KCl) and calcium chloride (CaCl2). Chlorides are leached from various rocks into soil and water by weathering. The chloride ions are highly mobile and are easily transported to closed basin and oceans (Shyamala et al., 2008). Chloride in surface and ground water originates from both natural and anthropogenic sources such as the use of inorganic fertilizers, landfill, septic tank effluents, animal feed, industrial effluents, etc. Chloride levels in unpolluted waters are often below 10 mg/L (Department of National Health and Welfare, 1978). The chloride concentrations in excess of about 250 mg/L can give rise to detectable taste in water, depending on associated cations. Chlorine is known as a toxic element but when combined with a metal such as sodium, it becomes essential to life forms. All natural environments contain chloride in varying degrees with content increasing as mineral content increases. There is no known evidence that chlorides constitute any human health hazard. For this reason, chlorides are generally limited to 250 mg/l in supplies intended for public use (WHO, 2003). But, it is said that huge ingestion of chlorides may results in several health effects. So, this crucial natural element bears a number of qualities, range, features, roles and effects. There are also a number of techniques for the estimation and removal of chloride. Henceforth, present study focuses on the various aspects of chloride. Different Aspects Of Chloride  Some physicochemical properties of chloride (Sconce, 1962; NIOSH., 1976): Systemic IUPAC name - Chloride Property Value Chemical formula clMolar mass 35.45g/mol Boiling point -34.6 °C Melting point -101 °C Density 3.214 g/litre at 0°C and 101.3 kPa Vapour pressure 480 Pa at 0°C Water solubility 14.6 g/litre at 0°C 

Normal range of Chloride in freshwater bodies: Chlorides constitute approximately 0.05% of the earth’s crust. Chloride, the ionized form of chlorine, is one of the most abundant inorganic ions in natural water and wastewater. Though

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most prevalent in sea water at concentration averaging 35000 ppm, chloride permits rivers, lakes, and other freshwater systems. Chloride levels in unpolluted waters are often below 10 mg/L (Department of National Health and Welfare, 1978). The permissible drinking water standard of chloride is