Wednesday, 4 September 2013

The nitrate effect

Earlier posts had dwelt on the presence of chemicals in the ground water of Bangalore and the need to take remedial steps.
This post will deal with the presence of nitrates and the best and easiest way to tackle its presence in ground water.
Nitrate, which affects the blood cells, varies from 16 to 554 mg against a permissible level of 50 mg per litre in many areas of Bangalore. One of the main reasons for the presence of nitrates in ground water is the inefficient garbage disposal system. This has led to people dumping garbage in open areas. This is aggravated by the fact that  the landfills where Bangalore’s domestic waste is dumped is not scientific.
The nitrates in garbage seeps into the groundwater when it rains. A report published by the Geological Society of India has shed light  on the ground water and its nitrate, fluoride and chromium content, all of which is dangerous.
It says the permissible limit is 45mg of nitrates per litre of water. But the reading for underground water in Sanjay Gandhi Nagar is 335mg/ litre and in Old Yelahanka, 335mg/ litre. Even more shocking is the 554mg/ litre in Nayandahalli on Mysore Road.
Excess nitrate is also found in:
Nayandahalli------------------------554 mg/l
Sanjay Gandhi Nagar---------------375 mg/l
Old Yelahanka-----------------------335 mg/l
Anjananagar-------------------------298 mg/l
Santhammanahalli------------------294 mg/l
Permissible limit: 45mg/l
The nitrates in the water react with the haemoglobin in the blood to produce methemoglobin, which impairs the capacity of the red blood cells to carry oxygen to different parts of the body.
It also causes methemoglobinemia, or blue baby syndrome, a condition in which newborn babies die due to lack of oxygen supply.
Another recent study conducted by Department of Environmental Science, Bangalore University and the Bhabha Atomic Research Centre, Mumbai, says groundwater in Bangalore has a high concentration of nitrate.
This study was conducted by Jiban Singh M., Somashekar R.K., Prakash K.L., and Shivanna K., and  81 samples were collected for the study between January 29 and February 3, 2013.
This study too found the nitrate values in the groundwater from the central core of the city ranged from 10 to 400 mg/L.
Another study on ground water is by  M A Farooqi, scientist at Central Groundwater Board. He was conferred a doctorate by Bangalore University for his work on “Municipal waste disposal practices and their impact on groundwater quality in Bangalore Metropolitan Region”.
The study said 50 per cent of the ground water has high Nitrate levels. It says North, North-East and Southern parts of Bangalore have levels of nitrate that is ten times more than permissible limits.. 
The high nitrate content can also cause cancer, when it reacts with protein compounds in the body to form nitrosamine, a cancer-causing agent. It can also cause cyanosis among infants and also gastric cancer when present in high quantity. Nitrite is absorbed in the blood and hemoglobin gets converted to methemoglobin. Methemoglobin does not carry oxygen efficiently, resulting in a reduced oxygen supply to vital tissues such as the brain. Methemoglobin in infant blood cannot change back to hemoglobin, which normally occurs in adults. Severe methemoglobinemia can result in brain damage and even death.
Pregnant women, adults with reduced stomach acidity, and people deficient in the enzyme that changes methemoglobin back to normal hemoglobin are all susceptible to nitrite-induced methemoglobinemia or blue baby syndrome. The most obvious symptom of methemoglobinemia is a bluish color of the skin, particularly around the eyes and mouth.
Other symptoms of nitrate consumption include headache, dizziness, weakness or difficulty in breathing. Generally, healthy adults consume fairly large amounts of nitrate with few known health effects. In fact, most of the nitrate we consume is from our diets, particularly from raw or cooked vegetables. This nitrate is readily absorbed and excreted in the urine. However, prolonged intake of high levels of nitrate and that too taken in liquid form are linked to gastric problems due to the formations of nitrosamines. N-nitrosamine compounds have been shown to cause cancer in test animals.
Although there is no enforceable drinking water standard for livestock, animals too should not be allowed to drink water with more than 100 mg/l NO3-N or Nitrate. This is especially true of young animals. They are affected by nitrates the same way as human babies. Older animals may tolerate higher levels.
However, it is difficult to determine the toxicity of nitrate in animals because it depends on the rate at which the substance is consumed. A few hundred milligrams of nitrate may cause poisoning if consumed in a few hours. But spread over a whole day, 1,000 mg nitrate may cause no signs of toxicity.
Common symptoms include abdominal pain, diarrhea, muscular weakness or poor coordination. Affected animals will have blood that is a chocolate-brown color.
Nitrate also exists in animal feeds and fodder. Drought-stressed forage plants commonly have high nitrate levels. These feeds can have an additive effect when consumed with high nitrate drinking water.
Nitrate is listed as the second greatest chemical threat to surface and groundwater after pesticides. Another fact is that increasing nitrate levels in water is a potential source of several environmental stresses to aquatic organisms, because nitrate is known to be toxic to crustaceans, insects, amphibians and fish.
Today, it is acknowledged that human and animal wastes, industrial effluents, use of agrochemicals and seepage of sewage through drainage system are the main sources of nitrate contamination of ground water.
Thus Nitrates cannot be washed away or wished away. Nor will boiling the water rid it of nitrate content. If you boil water, the nitrates hardens and solidifies and this is more dangerous. Then what is the solution?.
The traditional three pot method can be implemented at the house level to get rid of the nitrates. It involves placing a pot containing sand on the top. Beneath it comes a pot containing charcoal and the last pot will be empty and this collects the filtered water.
Another way would be to dilute the nitrate-polluted water by mixing it with water from another source with low nitrate concentration. Though blended water is not safe for infants it is frequently used for livestock.

The best way is the natural way. Let water seep in to the soil and more the water that enters the ground, more will the nitrate dissolve. Studies have shown that both rainwater harvesting and modifies drain systems can dilute nitrates substantially. Beside, recharging of ground water can not only raise the water table but also dissolve to different extents all chemicals, including nitrates. 

No comments:

Post a Comment