01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-06-0388 |
| Title of Abstract | Nitrification in the Indian Ocean and the OMZ of the central Bay of Bengal |
| Authors | Leandro Nazzari, Tina Sanders*, Tim Rixen Gesa |
| Organisation | Institut für Kohlenstoffkreisläufe, Helmholtz-Zentrum Hereon |
| Address | Max-Planck-Str. 1 21502, Hamburg, Germany Pincode: 21502 E-mail: tina.sanders@hereon.de |
| Country | Germany |
| Presentation | Poster |
| Abstract | Oxygen minimum zones (OMZs) account for 20⿿40% of global oceanic nitrogen loss. Despite the presence of a pronounced OMZ in the Bay of Bengal, no significant nitrogen loss has been reported in this area. One proposed explanation is a nitrite limitation, as trace levels of oxygen enables nitrite oxidation to outcompete nitrogen loss for available nitrite. Nitrification, which can occur at very low oxygen levels, adds further complexity to nitrogen cycling in low oxygen environments. However, the oxygen thresholds regulating key nitrogen processes remain highly uncertain. This study provides the first reported nitrification rate measurements from the central Bay of Bengal OMZ, collected during the SO305 BIOCAT-IIOE2 cruise (April - May 2024), alongside comparative data from the equatorial Indican Ocean-an understudied region without a pronounced OMZ-collected during the SO303 BIOGIN-IIOE2 cruise. Using 15N-ammonium tracer incubations, we quantified nitrification rates and examined their spatial and vertical variability in relation to environmental drivers. Preliminary results reveal pronounced spatial and vertical variations in nitrification with significantly higher rates above 100 m. In the BoB, nitrification rates sharply declined within the OMZ and oxygen availability emerged as a key regulator of nitrification, with additional influences from substrate availability, temperature, and salinity. Ultimately, our goal is to provide new insights into the dynamics of nitrification and its role in the nitrogen cycle in the equatorial Indian Ocean and OMZ of the Bay of Bengal, contributing to a better understanding of biogeochemical processes under changing ocean conditions. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Oxygen minimum zones,SO305, BIOCAT-IIOE2 cruise |
| For Awards | no |