Delineating the relationship between chromophoric dissolved organic matter (CDOM) variability and biogeochemical parameters in a shallow continental shelf

Absorption coefficient of chromophoric dissolved organic matter (CDOM) at 440 nm [aCDOM (440)], sea surface salinity (SSS), total suspended matter (TSM) and chlorophyll-a (chl-a) were measured during October, 2014 to March, 2015 in the shallow continental shelf waters of the Hugli Estuary, adjacent to West Bengal coast, India. The primary objective of the study was to characterize the relationship between aCDOM (440) and the above mentioned biogeochemical parameters. Upon analyzing the results, we observed that SSS portrayed the best possible relation with aCDOM (440) followed by TSM. Chl-a did not exhibit any statistically significant relationship with aCDOM (440). TSM showed a positive linear relationship with aCDOM (440) (R2 = 0.75) but the relationship did not work at all for the lower end members of TSM values. SSS and aCDOM (440) showed a strong negative relationship throughout the entire data range (R2 = 0.96). In the lower SSS ranges, the relationship showed maximum goodness of fit (R2 = 0.99). Though the goodness of fit between SSS and aCDOM (440) decreased for the higher SSS end members, the relationship was statistically significant all through.