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| Abstract Submission No. | ABS-2022-07-0206 |
| Title of Abstract | Dissolved trace gas dynamics in the coastal and open Arabian Sea during winter monsoon |
| Authors | Mohammad Atif Khan*, Siddhartha Sarkar, Himanshu Saxena, Deepika Sahoo, Arvind Singh, Sanjeev Kumar |
| Organisation | Physical Research Laboratory, Ahmedabad |
| Address | Navrangpura Ahmedabad, Gujarat, India Pincode: 380009 Mobile: 8015213155 E-mail: atif@prl.res.in |
| Country | India |
| Presentation | Oral |
| Abstract | The Arabian Sea hosts one of the most intense oxygen minimum zones (OMZs) in the world. These OMZs are known as hotspots for dissolved trace gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), which are the primary agents of atmospheric radiative forcing affecting the climate. Due to natural and human-induced global changes, the OMZ of the Arabian Sea has intensified and expanded in recent decades. In light of these changes, the role of OMZ in the dynamics of these trace gases need a relook in the open Arabian Sea by thoroughly investigating their temporal and spatial variabilities. In the present study, the vertical distribution of dissolved CO2, CH4, and N2O were measured from the surface to 3000 m at fourteen locations along three transects, including 65°E and coastal areas, in the Arabian Sea during winter monsoon (December 2019). Average N2O and CH4 were supersaturated, while CO2 was undersaturated in the surface waters of the Arabian Sea. N2O showed peak concentration in the OMZ, produced mainly from denitrification, while nitrification seemed to be active at the surface and below OMZ. CH4 was supersaturated at all depths with the highest supersaturation at the surface. In general, profiles of CO2 showed undersaturation at all depths. The presence of anticyclonic eddy showed a profound effect with an enhanced surface concentration of all three dissolved gases. In the present study, it was observed that the Arabian Sea acted as a source of N2O and CH4 and a minor sink of CO2 with respect to the atmosphere during the winter monsoon. |