Current World Environment

Dear Readers

We are pleased to present before you the Special issue of Current World Environment on Reactive Nitrogen. This special issue pursues to carry an understanding of Nr effects on the environment and contains six research articles on ambient NH₃, NO₂, water soluble inorganic nitrogen species, spatio-temporal variations of Nr species, integrated approach of Azatobacter and N fertilizer for selected crops, and total nitrogen in rain water.

Although nitrogen gas is an inert constituent of the atmosphere which is converted to nitrate through nitrification process in plants via natural route, it is also converted to reactive nitrogen (Nr) species through anthropogenic process during synthesis of fertilizer during Haber-Bosch process. During past century, global production of Nr species has almost doubled.¹ Due to deficiency of nitrogen in Indian soils, the use of synthetic fertilizer provided enough food to the continuously increasing population. N- fertilizer production in India increased from 285 Mt in 1966-67 to 11423 Mt in 2019-20² contributing huge emissions of NH₃ and NO_x. Industrial processes and fossil fuel combustion also contribute the Nr species. Therefore, recently, there has been a tremendous interest of researchers in reactive nitrogen species and their role in changing atmospheric composition. In general, synthetic fertilizer application has changed the budget of nitrogen and N cycle. A detailed report on the Indian Nitrogen Assessment has been published by Abrol and co-workers.³ Reactive nitrogen (Nr) comprises of all active forms of nitrogen in the atmosphere and biosphere e.g., ammonium (NH₄+), ammonia (NH₃), nitric oxide (NO), nitrogen dioxide (NO₂), nitrous oxide (N₂O) nitrate (NO₃-), nitric acid (HNO₃), urea, proteins, amines, and nucleic acids. Nr is essential for proper growth of plants and crops. However, excess Nr may cause detrimental effects on the environment and human health leaving a negative impact on the economy of a country. The anthropogenic sources of Nr such as fossil fuels combustion (industries and transport system), fertilizer production and application have exceeded its natural sources. This  has  damaging effects on air, water and soil systems as well as on  human health. The indoor air quality is affected by high levels of NO_x and NH₃ which may have long term health effects.⁴ In the air, it may lead to the formation of surface ozone causing damage to crops and respiratory problems. It may also get to the surface through atmospheric wet and dry depositions leading to many issues like eutrophication, acidification and corrosion of buildings, creating imbalance of nutrients thereby adversely affecting biodiversity and crop yield. Wet deposition of total inorganic nitrogen (TIN) has been dominated by NH₄ ion over NO₃ ion.^5-6 Both Urban and rural sites show NH₄ iondominated pattern of wet deposition.^7-8

Therefore, comprehensive studies of Nr are needed through monitoring, research with proper assessment at both local and regional levels to understand its effects on environment and human health. Nutrient use efficiency needs to be emphasized for cost saving on agriculture. Comprehensive efforts are needed making policy for integrated action which should bring together all the stakeholders to address this issue towards getting solutions. Programmes such as Global Programme of Nutrient Management (GPNM) and Global Challenges Research Fund (GCRF)- South Asian Nitrogen Hub (SANH) might be useful in strengthening our understanding about N cycle modification and the policy requirement in future. The Berlin Declaration can also be of great help to achieve sustainable management of nitrogenous compounds.

References

1. Sutton M. A., Reis S., Billen G., Cellier P., Erisman J. W.,  Mosier A. R., Nemitz E., et al. 2012. Nitrogen & Global Change. Biogeosciences, 9, 1691–1693. 
   CrossRef
2. FAI, 2021. Fertilizer Association of India. https://www.faidelhi.org/statistics/statistical-database. Retrived on December 20, 2021. 
3. Abrol Y.P., Adhya T. K., Aneja, V.P., Raghuram, N., Pathak H., Kulshrestha U., Sharma C., Singh B.  2017. The Indian Nitrogen Assessment. Elsevier, ISBN-978-0-12-811836-8. 
4. Katoch, A., &Kulshrestha, U. C. 2021. Gaseous and particulate reactive nitrogen species in the indoor air of selected households in New Delhi. Environmental Monitoring and Assessment, 193(4), 1-19. 
   CrossRef
5. Naseem, M and Kulshrestha, U. C. 2021. Wet deposition of atmospheric inorganic reactive nitrogen (Nr) across an urban-industrial-rural transect of Nr emission hotspot (India). Journal of Atmospheric Chemistry, 78, 271–304. 6. 
   CrossRef
6. Kulshrestha, M.J., Kulshrestha, U.C., Parasar, D.C., Vairamani, M.: Estimation of SO4 contribution by dry deposition of SO2 onto the dust particles in India. Atmos. Environ. 37, 3057–3063. 
   CrossRef
7. Kulshrestha, U.C., Granat, L., Engardt, M., and Rodhe, H., 2005. Review of precipitation monitoring studies in India—a search for regional patterns. Atmospheric Environment, v.39, no.38, pp: 7403-7419. 
   CrossRef
8. Kulshrestha, U.C., Kulshrestha, M.J., Satyanarayana, J., Reddy, L.A.K. 2014. Atmospheric deposition of reactive nitrogen in India. In: Nitrogen Deposition, Critical Loads and Biodiversity, 
   pp. 75-82. Springer, Dordrecht.
   CrossRef