BIOCAN-N (IIOE 2)

BIOCAN-N (IIOE 2): Biogeochemistry of carbon and nitrogen in the Arabian Sea: a contribution to the International Indian Ocean Expedition 2

TP1: Nitrogen Cycle and Coordination (SO 303)

On the research cruise of the research vessel SONNE 303, biogeochemical processes in the Arabian Sea are examined on different time scales.

The Arabian Sea is one of the ocean regions with extremely low oxygen concentrations at intermediate water depths. The southwest and northeast monsoons are responsible for this. During both monsoon phases, primary productivity is enhanced and the degradation of this organic material results in very low oxygen concentrations in medium water depths of approx. 100 to 1000 m. In the upper oxygen minimum zone, denitrification takes place, so that the Arabian Sea is one of the ocean's important nitrogen sinks. These processes are subject to significant changes due to global warming and increased nutrient inputs. The role of the Arabian Sea in the global nitrogen cycle is already being influenced by anthropogenic activities and will increasingly change in the future. The SO 303 research cruise will investigate the variability of the nitrogen cycle and the role of the degradation of organic material on different time scales. Using the stable nitrogen isotope ratios in water and suspended matter samples, nitrogen cycling processes will be quantified. By comparing the new data with archive data, trends in the nitrogen cycle in the recent past are determined. The variability of the nitrogen cycle in the recent geological past will be reconstructed using sediment cores.

The aim of this study is to be able to better assess the consequences of climate change and anthropogenic interference in biogeochemistry and ocean ecosystems. This contributes to a better representation of the region in Earth system models and thus to an improvement of climate forecasts in the monsoon region.

Project partners:

Dr. Samina Kidwai, Director General, National Institute of Oceanography, Karachi, Pakistan

Dr. Tim Rixen, Leibniz Center for Tropical Marine Research (ZMT), Bremen

Dr. Hartmut Schulz, Eberhard Karls University of Tübingen, Department of Geosciences, Micropaleontology

Project duration: 2024-2026

Information about the project: Dr. Birgit Gaye, Dr. Niko Lahajnar, Dr. Thomas Lüdmann, Dr. Gesa Schulz