Determination of dissolved oxygen free CO2, total alkalinity, total hardness, calcium, magnesium, ammonia, nitrate and phosphorus

DISSOLVED GASES The major gases dissolving - Nitrogen, Oxygen and Carbon dioxide and minor gases such as Helium and the inert gases-Neon, Argon, Krypton and Xenon Gases present in water enters from the atmosphere; very rare gases come from radio active decay processes with in the sediment in the ocean Dissolution of gases depends on Temperature of the gas and the solution Atmospheric partial pressure of the gas Salt content of the solution Biological activity

DISSOLVED OXYGEN Oxygen - one of the most significant chemical substances in natural waters Significant for metabolic processes as a regulator of both community and organisms Oxygen acts as an indicator of water quality The solubility of oxygen in water is increased by lowering of the temperature The solubility increases by more than 40% as fresh water cools from 250 to 00 C The oxygen saturation values at various temperatures are represented in nomogram

The solubility of each gas is independent of other gases in the mixture Under standard conditions of pressure and temperature, the solubility of oxygen in water is over twice that of nitrogen and about 1/3 that of carbon dioxide The solubility of oxygen decreases as the dissolved salts increases At O0C, fresh water at saturation and salts contains slightly over 2.0 mg/l than the average sea water salty (35%) at 150C the difference is about 1.5 mg/l

The amount of dissolved oxygen in sea water varied between 0 and 12 The amount of dissolved oxygen in sea water varied between 0 and 12.6 mg/l Oxygen in neutral waters may also be derived from photosynthetic activity by plants. 6C2 + 12 H20  C6H1206 + 602 + 6H20 + energy Maximum production of oxygen during afternoon on clear day and minimum after dawn Major sources of oxygen in water The atmosphere The Biological

FACTORS INFLUENCE THE CONCENTRATION OF OXYGEN The volume percent of oxygen in the atmosphere i.e. 20.99% value of 210 cc. of oxygen/l.0 gm. air. This is some 25 times the conc. oxygen in he same volume, fresh water The rate of atmospheric oxygen passes across the air-water surface i) Wave action - more dissolution at higher wave action ii) Partial pressure between air and water-At greater partial pressure greater dissolution iii) Moritecatent of the gas (Less rapid dissolve)

Transport of by currents Major consumer of oxygen is animals and plants for respiratory and decomposition of organic materials Oxidation process is the addition of oxygen to a substance Reduction is the processes of removal of oxygen from the substance

CARBON DIOXIDE It helps to buffer the environment –Important agent for acidity and alkalinity Helps in biological productivity through photosynthesis Help the seed germination in some plants and growth Carbon dioxide readily reacts with document groups of elements to produce many compounds Carbon dioxide has very high solubility in natural water Carbon dioxide is locked up in various combined forms especially in marine water – Bivales, corabonate etc.,

SOURCE OF CO2 IN NATURAL WATERS: Bacterial decomposition of organic matter. Respiration by animals and plants. Rain water Chemical reactions Ground water Atmospheric direct supply CO2 in natural water is 35 – 40 atom; reaches 200 ppm or more. Calcium and magnesium carbonate precipitated as Marl highly saline lakes carbonate conc. may be 8500 ppm The pH of sea water usually ranged between 8.00 and 8.3 due to bicarbonate system

OTHER GASES Methane (CH4) Methane is an organic gas widely called Marsh Gas common in many alkaline lakes, ponds and swamps especially during summer season Chemically CH4 gas produced due to decomposition of organic substances It occurs in aquatic environments under anaerobic conditions