- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-05-0225 |
| Title of Abstract | PARTICLE FLUXES ALONG CENTRAL WESTERN MARGIN OF INDIA |
| Authors | Paropkari A.L.*, Joao H. M.., Fernando, V., Afzulpurkar, S., Kodagali V. N., Marathe P., Khedekar V., Sardar A., Nampoothiri G. E., Borole D. V. |
| Organisation | Retired Scientist, CSIR-NIO, Dona Paula, Goa - 403004 |
| Address | 2 B, Palmanova II, Behind Post Office, Eugenio Waddo Caranzalem,, Goa, India Pincode: 403002 Mobile: 9422847222 E-mail: parop1951@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Western margin of India (WMI) is one of the highly productive regions in the eastern Arabian Sea (EAS). Characteristically, this margin is intercepted by over 1000 m thick intense "Oxygen Minimum Zone (OMZ)" between the water depths of 120 to 1200 m. The sediments juxtaposed with the OMZ are highly enriched with the organic matter contents. Hence, this area is an ideal location to investigate the biogeochemical cycle of carbon in the oceanic realm. Considering the unique biogeochemical nature of the region, we decided to understand the influence of the reducing environment of OMZ on the settling particle fluxes, particularly organic fluxes. For this, we deployed two bottom moored sediment traps on the slope off Goa in such a way that the shallow trap (SMT) was located at a depth of ~150 m coinciding upper boundary of the OMZ and the deep trap (DMT) was located at a depth of ~1150 m coinciding with the lower boundary of OMZ. These traps collected the particle fluxes from December 2000 to February 2003. The moorings also consisted the current meters to understand the influence of currents on settling particles. Results show that the average annual total particulate flux is 160 g m-2 in SMT and is 136 g m-2 in DMT. Generally, the SMT shows higher particle flux throughout than the DMT. These annual total particulate fluxes are 3-5 times higher than the open ocean traps close by in the EAS signifying the importance of WMI as an important repository of particulates. Biogenic material dominates and constitute 60-70% of the total flux. Carbonate is the major biogenic component (40-45%) of the total flux. Calcium carbonate flux dominates over the siliceous flux implying that this region is a carbonate ocean. Average annual organic matter (OM) fluxes are 24 g m-2 in the case of SMT and are 17 g m-2 in the case of DMT. Similar to the total flux, OM fluxes are higher by a factor of 3-7 that the open EAS underlying the importance of this coastal zone in biogeochemical cycling of organic C. The C/N values of about 5-8 indicate dominance of productivity oriented OM in both the traps. Lower organic carbon fluxes and high C/N in the DMT (6-8) comared to SMT (5-7) is attributed to the mineralization of OM during sinking through the OMZ, The clay mineralogical data (smectite and illite) reveals no significant response to the seasonal changes except that both the clay minerals show enhanced content during the SW monsoon and followed by the inter-monsoon in 2001 compared to the same seasons during 2002. The current meter data shows that the currents associated with the SMT are much stronger (20 cm/sec and sometimes exceeding 30 cm/sec) as compared to that of DMT (5-10 cm/sec). There seems to be a positive correlation between current patterns and the particle flux with northerly component is usually responsible for higher particle flux. In general, the above findings suggest that this is an area which needs to be thoroughly investigated for biogeochemical cycling of organic carbon in context with the climate change. |