Summary of Abstract Submission

Abstract Submission No. IO50-08-0020PresentationPoster

FLUORESCENCE AS A TOOL TO DISTINGUISH DOM INPUTS OF DIFFERENT RIVERS IN THE WESTERN COASTAL WATERS OF THE BAY OF BENGAL

N.V.Harikrishnachari*1, P Sudarsana Rao1, R Kiran1, G. Chiranjeevulu1, Nittala S Sarma1

1 Andhra University, Visakhapatnam, India

ABSTRACT :

The Coloured Dissolved Organic Matter (CDOM) and its fluorescence were measured at 8 stations each up to 1000 meters isobath in 9 transects i.e., at a total of 72 stations. The transects were off major estuaries on the east coast of India (Bay of Bengal) and off Visakhapatnam at the centre during July-August 2010. Grossly, two distinct geographic regions were identified by statistical analysis: (i) southern water consisting of the coastal region off Visakhapatnam and the rivers Godavari and Krishna, and (ii) northern water consisting of transects off Mahanadi and Haldiar. The CDOM (absorption coefficient, aCDOM(350)) was higher in northern region. Parallel factor (PARAFAC) analysis of Excitation Emission Matrix (EEM) spectra extracted two humic-like (Marine humic-like, M and UV humic-like, A) and two protein-like (Tryptophan, T and Tyrosine, B) fluorophores. The B and T are the most abundant fluorophores particularly in the northern region where the B fluorophore shows a significant correlation coefficient with chlorophyll. This is despite the fact that the humic fluorophores should be expected as major due to monsoon water flux from rivers. The origin of both T and B is by in situ production, the former from phytoplankton exudates (extracellular metabolism) and the latter by bacterial action of the in situ produced proteinous DOM. Thus in the northern transects, not only is the production of phytoplankton high but their bacterial decay also is high. Within the southern region, the influx from Godavari and Krishna are also distinguished by CDOM and FDOM.