Nitrogen — the main component of the atmosphere of our planet (78 per cent by volume) — is a double-edged sword! Its conversion to other chemically reactive forms could be indispensable for some life processes while for others it could wreak havoc in the form of nitrogen pollution. This growing menace has been driven by industrialisation, urbanisation and increased usage of fertilisers in the agricultural fields and it has become one of the most challenging pollution issues which people across the world have been facing for years. However, the enormity of this human-induced threat remains unknown to many — unlike some other forms of pollution. Whether it is the deteriorating quality of air and water or increasing greenhouse gases emission and disturbing our ecosystems and biodiversities — nitrogen pollution could be attributed to all of these problems.
Nitrous oxide (N2O), a greenhouse gas, which is known to be 300 times more potent than carbon dioxide in heating our atmosphere, occurs naturally as a result of nitrification and denitrification by microbes in soil and water bodies. However, in recent years, we have seen a surge in its release which has been primarily driven by agricultural activities and manufacturing of nylon and acids. The growing population has been increasing the demand for food and this has put a strain on farmers who want to increase the productivity of their farms by adding fertilisers which mainly comprise of nitrogen and its compounds. It is estimated that these fertilised fields, manures and other agricultural sources can emit as much as 60 per cent of total nitrous oxide into the atmosphere, which has been accelerating the greenhouse effects.
Further, as the implications of climate change become more visible in the form of frequent drought and floods, the run-offs from these agricultural fields often end up in water bodies. This leads to nutrient enrichment of rivers, lakes and oceans resulting in an overgrowth of phytoplankton and algae, also known as eutrophication. The algal blooms not only pollute water and deplete oxygen in the aquatic world, but they also release greenhouse gases which could further contribute to climate change and global warming.
The combustion of fossil fuels also adds nitrogen dioxide and nitric oxide (collectively known as NOx) into the atmosphere; ammonia emission from agricultural activities further promotes the emission of nitrous oxide and on reacting with NOx creates harmful suspended particulate matter (SPM) which can worsen cardiovascular and respiratory issues in living beings. Nitrogen pollution is also threatening our forests which help in sequestering carbon in soil and its biomass. The mycorrhizal fungi which live symbiotically with the roots of the trees help in absorbing more carbon from the atmosphere. However, these fungi are quite sensitive to nitrogen pollution and the forests exposed to nitrogen pollution have been found with fewer mycorrhizal fungi in their roots. This, in turn, has reduced the carbon-absorbing capacity of these forests and now more carbon is being added in the atmosphere. To effectively combat the ongoing climate change, we need more awareness among masses and stricter policies for nitrogen management which can play a crucial role in the mitigation of climate change challenges.
