Executive Summary : | Dinitrogen is an inert gas that constitutes the largest N pool & reactive nitrogen (Nr) broadly envelops all photochemically, biologically reactive, & radiative N species that includes inorganic forms (NH₃, NOx (NO+NO₂), N₂O, NH₄+, NO₂−, NO₃−) & organic forms (nucleic acid, amines, proteins, urea, N in soil humus). Nitrogen cycle intricately balances the reactive & inert N species. A special characteristic in it, is the existence of various Nr species, either in oxidized or reduced state, which undergo chemical & biological transformations before ultimately transforming into dinitrogen & adding back to atmosphere. Anthropogenic activities are key aspects that alter the global N cycle through unregulated Nr inputs to the ecosystems, which is accountable for excess Nr emissions in the form of NO (80% or more), NH₃ emissions (70%), & N₂O (40%), globally. Three most important Nr species (NO₂, N₂O & NH₃) “Triple Trouble” require immediate attention as they adversely impact all living forms. There exists a gap in understanding of Nr dynamics in lentic & lotic ecosystems also how the environmental conditions or biotic communities play a major role in N dynamics within lentic ecosystems. Study hypothesis are; 1. Abiotic factors directly influence N transformation as compared to biotic factors in lentic ecosystems. 2. Freshwater lakes have higher denitrification potential as compared to inland saline lakes of semi-arid region. 3. Organic matter reduces the denitrification losses by promoting mineralization-immobilization in lentic ecosystems. The main experiments involve reactive N transformation rates highlighting sediment nitrification, amended denitrification & N₂O production rates along with denitrifier abundance and diversity in the lentic ecosystem. The data obtained will be used for process-based modeling to infer the pathways & fluxes of Nr within lentic ecosystems with different sets of environmental & geophysical conditions. Considering complexity of N dynamics, this work would enrich the present understanding of N dynamics and its management in freshwater & hypersaline inland lentic ecosystems through the application of the experimental techniques, quantitative estimations, predictive mathematical model on an ecosystem scale. The work will shed some spotlight on the inception of sustainable approaches to mitigate the future impacts of nutrient pollution & would contribute to the Nr database and raise awareness on the issue of “nutrients turning into pollutants,” and help decision-makers in drafting policies. The data generated during the study would act as baseline information for generating wetland health cards to pursue rapid assessment of wetlands condition. The project outcome could address the prevailing wetlands’ biodiversity & ecosystem services, values, & current and future threats, thus creating a Wetland Integrated Management Plan under National Plan for Conservation of Aquatic Ecosystems (NPCA). |