Page 84 - e-Book

Acidity

As stated above acidic water means when the pH lies below neutral (7). The acidic nature of
water is mainly due to dissolved carbon dioxide in water, hydrolysed salts etc. As enzymes

are pH dependent therefore acidity can alter many biological process [13].
Alkalinity

Any pH above neutral (7) makes the alkaline in nature. The alkaline nature of water is mainly
−
2−
due to the presence of hydroxide ions (OH ), carbonate ions (CO3 ) , bicarbonate ions
3−
(HCO ) or a mix of them [18].
Chloride
It is naturally present in water but the presence of chlorine in relatively high concentration in

fresh water (about 250 mg/L or more) may point out towards water pollution. It may enter

water resources due to various activities in agricultural sector, industrial sector rocks etc.
Chloride ions in water do not pose any harmful affect on human health but may taste

unpleasant.chloride in small amount. Chloride ion in small amount is necessary for normal
cellular functions [22-23]. Public drinking water as a standard requires chloride level to not

exceed than 250 mg/l [13].
Nitrogen

There are mainly four different forms of nitrogen present in water a) organic nitrogen,

b) ammonia nitrogen, c) nitrite nitrogen, and d) nitrate nitrogen. Nitrate is a form of nitrogen
whose presence in water represents the chemical pollution. If its daily inake limit is higher

than 45 mg/lit than it may cause blue baby syndrome and in adults it may be a reason for
causing cancer [24]., Nitrates are the basic requirement for the growth of plants. Nitrate

enters the ground water mainly because of the usage of chemical fertilizers in agricultural
fields. Nitrate concentration in drinking water in excess to 10 mg/l may lead to blue baby or

methemoglobinemia that result when nitrate ions reacts with haemoglobin of blood severely

hampering the oxygen carrying capacity of blood [13, 16, 18].
Arsenic

The daily intake limit of arsenic is 0.05 mg/lit, exceeding which results in the arsenicosis

disease. Government has taken a number of steps for preventing arsenic consumption [24].
Iron

The presence of iron in drinking water does not cause any serious disease, but any amount
greater than 0.3 mg/lit will leave red stains over the cloths and utensils and also alters the

taste of water. The concentration of iron can be lowered by keeping the water stagnant for
around 12-14 hours [24].

74