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| Abstract Submission No. | ABS-2022-05-0149 |
| Title of Abstract | Biogeochemistry of Ni in the Arabian Sea |
| Authors | Nirmalya Malla*, Prof. Sunil Kumar Singh, Arvind Shukla |
| Organisation | CSIR-National Institute of Oceanography |
| Address | CSIR-NIO, DONA PAULA Panaji, Goa, India Pincode: 403004 Mobile: 8917209885 E-mail: nirmalyamalla@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Life in the ocean requires a variety of bio-essential trace metals that act as a vital part of their metabolic pathways, being the reactive centres in the metalloenzymes making their study very crucial. To understand the control of biogeochemical processes on the distribution of Nickel (Ni), the present study details the distribution of some of the bio-essential trace elements (micro-nutrients) such as dissolved Ni (dNi) from16 complete vertical profiles in the Arabian Sea encompassing an area between the latitudes 9° - 17.4°N and longitudes 75.5° - 61.9ºE as a part of the GEOTRACES-India program. The Arabian Sea is distinctive due to dual monsoon activity, high dust flux from nearby arid landmasses, upwelling, intense Oxygen Minimum Zone (OMZ), and shelf input from the continental margins controlling the biogeochemical cycling of micronutrients. dNi concentration ranges from 2-2.5nM in the surface waters to 10.2-11nM in the deeper waters of the Arabian Sea. A relatively high concentration of dNi than the other micronutrients may be due to the incomplete drawdown of Ni, which may be due to the bio-unavailability of some Ni. The distribution of dNi features a kink (increase in slope) in the Ni-PO4 relationship. This study suggests a significant deficit of dNi with respect to the PO4 in the intense OMZ compared to waters outside OMZ. Ni depletion up to 4.0 nmol kg-1 is observed in 100-1000m depth of intense OMZ, whereas in deeper waters, the deficit was less than 1.0 nmol kg-1. OMZ waters seem to act as a sink for dNi, unlike dFe and dMn, possibly due to its precipitation as sulphides or its differential biological uptake/release. |