Current World Environment

The unprecedented increase in Nr is causing several environmental problems such as eutrophication, ozone depletion and climate change etc. Excessive Nr creation is also responsible for poor plant and human health, soil acidification, groundwater contamination etc. Inhabiting ~ one-fourth population of the world and sharing only 4.9% of land of the total global landmass, the South Asian region consumes 60% of the total global fertilizer nutrient. India is the largest consumer of synthetically produced fertilizer in South Asia. According to estimates, India consumes ~ 17 million tonnes Nr/yr, making South Asia and India a hot spot for the deposition of N species. In India, the fertilizer N consumption is increased 314 folds from 1950-51 to 2013-14. In 1951-52 per hectare fertilizer N consumption was 0.44 kgha^-1while it was 86.2 kgha^-1in 2013-14. Since rains are limited to a few months, most of the time the weather is hot and dry. And hence, the dry deposition is the key mechanism of pollutant removal in the region. Wet deposition predominantly occurs during the monsoon period. The wet deposition of NH₃-N observed to be the highest in the Indo-Gangetic plains. The annual NO₃-N deposition at the urban, suburban, rural and industrial site found to be 4.48, 2.10, 4.06 and 3.92 kgha^-1respectively, and the annual deposition of NH₄-N at the urban, suburban, rural and industrial site found to be 2.38, 2.10, 2.38 and 5.05 kgha^-1respectively. The average total wet deposition of NO₃-N and NH₄-N in India is estimated to be 6.01kgha^-1which is equivalent to 1.97 Tg N/yr_.The average total dry deposition of NH₄-N and NO₃-N through dust fall found to be 0.37 kg ha^-1and 0.84 kg ha^-1respectively. The average total dry deposition of NH₄-N and NO₃- n以气溶胶的形式发现0.28和1。65 kg ha^-1while through gaseous dry deposition it was 4.72 kg ha^-1and 0.28 kg ha^-1for NH₄-N and NO₃-N respectively. This study highlights the need for integrated nitrogen monitoring and assessment in South Asia.

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