<p>N₂O production and consumption processes in coastal sediments contribute significantly to the global N₂O budget. Rate measurements, however, have largely remained restricted to high latitude ecosystems. To bridge this gap, N₂O fluxes at the sediment-water interface were measured along the inlet regions of a tropical, shallow coastal lagoon (Pulicat lagoon) on the East coast of India. Pulicat is connected to the coastal waters of the Bay of Bengal through three such inlets. Intact core incubation experiments were conducted using sediment cores sampled during the wet season (December) of the years 2020 and 2022.</p> <p>Negative N₂O fluxes at the sediment-water interface were observed in both years, indicating sediment uptake of N₂O during the wet season. Water column salinity and temperature conditions prevalent during the wet season played an influential role in sediment N₂O uptake. Furthermore, the sediment-water incubators were treated with inhibitors in a parallel experimental set-up to understand the role of nitrification and denitrification in driving N₂O uptake at the sediment-water interface. Allylthiourea was used as a nitrification inhibitor, and acetylene was used as a denitrification inhibitor. A framework of benthic N₂O cycling in the ecosystem has been illustrated based on an understanding of the controls and pathways of N₂O consumption in Pulicat sediments revealed by the experiments.</p> <p>N₂O consumption in Pulicat sediments is an important finding in terms of the global N₂O budget and climate change.</p>

Primary Presenter: Tanisha Nag, National Centre for Coastal Research (tanisha.nag@gmail.com)

Authors:

Tanisha Nag, National Centre for Coastal Research  (tanisha@nccr.gov.in)

Damodara Valavala, National Centre for Coastal Research  (vdrao@nccr.gov.in)

Anitha Gera, National Centre for Coastal Research  (anitha@nccr.gov.in)

M. V. Ramana Murthy, National Centre for Coastal Research  (mvr@nccr.gov.in)