15 April 2017 11:19:16 IST

Nothing is really as it appears to be...

Nitrogen has been a friend, but we need to be aware of its other face

What comes to your mind when somebody mentions ‘pollution’? Smoke, vehicle exhaust, dust, particulate matter, aerosols, sulphur and so on and so forth. The usual suspects, right?

But, there is one pollutant that I bet you would never have thought of as a trouble maker. Ironically, it is the most abundant element on the planet, making up 78 per cent of the atmospheric gases. Yes, it is the good old Nitrogen.

WHAT!

I can visualise some of you shaking your heads in disbelief. “What! Nitrogen?” The element is so benign that it is responsible for life on this planet — and perhaps, the whole universe.

Over three quarters of the stuff we breathe in every second is this gas. Without nitrogen, and with so much oxygen present here, the planet would have burst into flames, like the sun. So how could nitrogen be a pollutant?

Turns out it is — and it is becoming a menace. Why else do you think the United Nations Environment Programme (UNEP) started a $60 million International Nitrogen Management System, in December 2016?

But first, the problem. Nitogen is a good friend, but only in its pure form, called unreactive nitrogen. There is a ‘reactive nitrogen’, as well — scientists call it Nr.

N(r)ot a joke

Nr refers to a bouquet of nitrogen compounds, including nitrogen oxides, ammonia, nitrous oxide, and ammonium nitrate. A large contributor of Nr is, as you can guess, fertilisers. And we use a lot of nitrogenous fertilisers.

An excess of Nr, which causes nitrogen pollution, is bad for the planet According to UNEP, Nr caused by human beings has increased 10 times in the last 150 years. You don’t need me to tell you that it’s not good news.

Green the water

Nr increases atmospheric ozone levels (again, in the right quantities, ozone is beneficial, as it filters out ultra-violet rays. In excess, it is bad for health). Nr in water creates algal blooms in lakes and rivers. You can tell an algal bloom by the green colour of water. The algae drink up the oxygen and starve the fish of the stuff.

In the Gulf of Mexico, fertiliser run off has created a 5,800 sq mile ‘dead zone’, where fish do not live. Oceanic nitrogen also gets converted to nitrous oxide, a greenhouse gas.

A lot of the fertilisers we apply leaches out and gets into groundwater, and High levels of nitrate contamination in groundwater has been linked to blue baby syndrome.

The problem is so acute that the UNEP, armed with the $60 million funding, has set itself out on developing an evidence base to showcase the need for nitrogen management. In short, it wants to evolve ‘nitrogen science’.

In India...

Now, this is a problem for us Indians. We — much like the rest of the world —do need nitrogenous fertilisers, if we’d rather not starve ourselves to death. But we use the stuff, and over half of it escapes into the ground and the atmosphere, wreaking havoc.

India is the world’s second largest consumer of nitrogenous fertilisers. South Asia (which comprises the SAARC countries and Afghanistan) accounts for a fifth of global nitrogen consumption. Nitrogen fertilisers sustain half the human population today, but few realise the harmful effect on environment, UNEP says.

In the spotlight

Nitrogen pollution, though known to mankind, has not received sufficient attention — until now. Presumably, in the coming years, there will be calls for paradigm shifts in agricultural practices — a move away from chemical fertilisers. Use of compost, for instance, could be promoted; organic farming, which is picking up even now, could perk-up in use.

Nitrogen has been a friend, but the first step is to be aware of the other face of this friend. Goes to show that nothing is truly as it appears to be.