Managing synthetic N-fertilizer emissions in India: Insights from field surveys across 102 districts.

The use of fixed emission factors (EFs), combined with insufficient temporal distribution, leads to substantial uncertainties in current emission inventories for India, the world's second-largest producer and consumer of synthetic N-fertilizers. Our study aimed to improve the NH3 and N2O emission estimates by utilizing crop-specific district-level activity data and refined EFs tailored to Indian conditions. In this study, a comprehensive NH3 and N2O emission inventory (EI) is methodically developed at 0.1° * 0.1° spatial and monthly temporal resolution for the year 2018-19 considering 52 crops. The data for developing this inventory is aggregated through detailed field surveys, conducted across 102 districts of 14 states, and relevant government databases. EFs have been adjusted for the Indian context by refining them to reflect local conditions through consideration of ambient temperature, application rate, and other factors. Further, upon preparing an EI for FA, a spectrum of mitigation strategies are evaluated to assess their effectiveness in reducing emissions. Yearly total NH3 and N2O emissions amount to 3.15 Tg and 138.53 Gg, with urea fertilizer as the dominant contributor accounting for 93.85% and 96.44% of emissions, respectively. Key crops such as rice, wheat, maize, sugarcane, and cotton collectively represent approximately 82% of the total N consumption. The state of Uttar Pradesh emerges as the largest emitter, contributing 706.5 Gg and 25.31 Gg of NH3 and N2O emissions, respectively. Conversely, PB and HR exhibit the highest NH3 emissions per capita. Temporally, NH3 emissions peak in August, while N2O emissions peak in July, with both pollutants reaching their nadir in February. Among the array of mitigation strategies assessed in this study, 'adhering to recommended fertilizer doses' and 'incorporating urease inhibitors' demonstrated substantial potential for reducing emissions. The current study aids policymaking to mitigate the environmental and health impacts of atmospheric emissions from synthetic N-fertilizers. Future researchers can adopt this study as a benchmark to improve Indian FA emission estimates, which helps in promoting sustainable agricultural practices and contributes to climate change mitigation efforts.

Detection and removal of poly and perfluoroalkyl polluting substances for sustainable environment.

PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not readily biodegrade or neutralize under normal environmental conditions. They have various industrial, commercial, domestic and defence applications. According to the Organization for Economic Co-operation and Development, there are around 4700 PFAs registered to date. They are present in every stream of life, and they are often emerging and are even difficult to be detected by the standard chemical methods. This review aims to focus on the sources of various PFAs and the toxicities they impose on the environment and especially on humankind. Drinking water, food packaging, industrial areas and commercial household products are the primary PFAs sources. Some of the well-known treatment methods for remediation of PFAs presented in the literature are activated carbon, filtration, reverse osmosis, nano filtration, oxidation processes etc. The crucial stage of handling the PFAs occurs in determining and analysing the type of PFA and its remedy. This paper provides a state-of-the-art review of determination & tools, and techniques for remediation of PFAs in the environment. Improving new treatment methodologies that are economical and sustainable are essential for excluding the PFAs from the environment.