- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-05-0175 |
| Title of Abstract | Geochemical behaviour of dissolved Rare Earth Elements in the Indian Ocean |
| Authors | Chhaya Yadav*, Sunil Kumar Singh, Tapas Kumar Mishra, Venkatesh Chinni, Robin John |
| Organisation | CSIR National Institute of Oceanography |
| Address | NIO COlony Dona Paula, Goa, India Pincode: 403004 Mobile: 8080597591 E-mail: chhayadav1095@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Rare Earth Elements (REEs) in seawater can be widely used as a tracer of water masses, boundary exchange and oxidative-reductive processes. Factors influencing their distribution in the contemporary ocean and recycling in the water column are vital to understand their application to study paleo-oceanographic processes. Here, we present the vertical profiles of dissolved Yttrium and REE (Rare Earth Element) from the Indian Ocean sampled during the spring inter-monsoon period of 2021 as a part of GEOTRACES-INDIA section cruise to assess the role of riverine, boundary exchange, aeolian input and various waters masses in controlling the distribution of REEs in the basin. Dissolved REE concentrations are significantly high in surface water in the Bay of Bengal which display a strong north-south gradient, being quite high near the mouth of the Ganga-Brahmaputra River System suggesting strong input of REEs from riverine fluxes, particularly sediments which is further evident by their release from slope sediments at higher depths. Similarly, shelf sediments of the Andaman Sea are contributing significantly to the REEs budget through boundary exchange. The PAAS (Post-Archean Australian Shale) normalized pattern REEs in the Indian Ocean show prominent negative Ce anomaly with an incessant increase in MREEs (Middle Rare Earth Elements) and HREEs (Heavy Rare Earth Elements) suggesting removal of Ce and heavy rare earth elements by oxidation and adsorption on sinking particles respectively. Sm/La ratio in the BoB surface water, 0.20-0.18, underscores the role of G-B sediments in contributing to the REEs budget of surface Bay of Bengal which decreases with depth due to mixing with southern sourced water with Sm/Nd as low as 0.11-0.14 corresponding to deep water masses. Y/Ho ratio in the surface waters of the Indian Ocean ranges from 90 to 134 with lower values in BoB and highest in the southernmost stations attributed to high scavenging by particulate matter. REEs distribution in the Indian Ocean is a complex balance among their riverine and water mass inputs and removal by adsorption and oxidation. Seasonal variability in the riverine fluxes, the dominant input, seems to control their residence times and hence could be responsible for their temporal and spatial variabilities. |