Spatial Variability and Sources of Atmospheric Ammonia in India: A Review

Recent studies suggest that human activities have accelerated the production and emissions of atmospheric ammonia (NH3) and other reactive nitrogen on a global scale. The increase in reactive nitrogen emissions may lead to environmental impacts including photochemical air pollution, reduced visibility, formation of fine particulates, changes in biodiversity, and climate change. The global NH3 emissions have increased many folds due to anthropogenic activities and rapid growth in population. The extensive research has been conducted around the globe to estimate the global NH3 emissions to mitigate the anthropogenic sources of NH3; however, a limited effort has been done over the Indian sub-continents. NH3 emissions are primarily contributed from the agriculture sector of India. However, the influence of atmospheric NH3 from urban area has been attributed to vehicles, drainage and fertilizer industries. This review summarizes the sources and distributions of atmospheric NH3 over the urban, sub-urban, Himalayan and oceanic regions of India. The review also summarizes the NH3 emission factors and emission estimates from the agriculture sector of India.