Geochemical cycling in the Hooghly estuary, India

Dissolved inorganic carbon (DIC) and its δ13C in the Ganga (Hooghly) River estuary, India: Evidence of DIC generation via organic carbon degradation and carbonate dissolution

“…Although the results of mixing calculations suggest that groundwater can be a potential source of Ca and DIC in the low salinity water of the Hooghly estuary, available data on Ra isotopes (Somayajulu et al, 2002) do not provide evidence of groundwater contributions to the estuary. Additional work employing tracers such as 87 Sr/ 86 Sr needs to be carried out for quantification of groundwater contributions to the Hooghly waters.…”

“…The Hooghly estuary is reasonably well mixed, as evident from the observed strong linear covariation of salinity with the oxygen isotope composition (d 18 O) of water (Somayajulu et al, 2002;Ghosh et al, 2013). The effect of mixing is readily apparent and is manifested in the gradual change of salinity along the mixing zone.…”

“…Submarine groundwater discharge (SGD) has been shown to be important in contributing to the abundance and distribution of selected elements (e.g., Ba) and isotopes (e.g., 226 Ra) at the mouth of the Ganga-Brahmaputra system in Bangladesh (Moore, 1997). In the Hooghly estuary, the observed non-conservative behavior of Ra isotopes has been explained by desorption from the estuary sediments (Somayajulu et al, 2002). In this study, we have sampled and analyzed shallow groundwater collected in areas adjacent to the estuary ( Fig.…”

“…Considering that the Hooghly estuary is relatively well mixed (Somayajulu et al, 2002;Ghosh et al, 2013) and that there is very little stratification in the water column in the estuary (Mukhopadhyay et al, 2006), the Land-Ocean Interaction in Coastal Zone (LOICZ) model (Gordon et al, 1996) was used to estimate the annual and seasonal discharge of DIC from the Hooghly River to the BoB. LOICZ model calculations are based on consideration of the mass balance of water, salts and nutrients in coastal systems.…”

Dissolved silicon and its isotopes in the water column of the Bay of Bengal: Internal cycling versus lateral transport

“…Earlier studies on this topic were focused on the marine budget of dissolved Si, its cycling, and application as a water mass tracer (DeMaster, 1981;Nelson et al, 1995;Tréguer et al, 1995;Dileep Kumar and Li, 1996;You, 2000). Investigations on the budget of Si require knowledge of its sources to, and sinks within the oceans; in this context there have been several studies on its behavior in estuaries and shelf regions (Borole et al, 1977;DeMaster et al, 1991DeMaster et al, , 1996Eyre and Balls, 1999;Somayajulu et al, 2002;Michalopoulos and Aller, 2004). During the last decade, studies on Si marine biogeochemistry took a major leap with the advent of Si isotope measurements in conjunction with its dissolved concentrations; this provided better insights into its various sources, sinks and internal cycling in the open ocean environments Cardinal et al, 2005;Reynolds et al, 2006;Beucher et al, 2011;Cavagna et al, 2011;De La Rocha et al, 2011;Fripiat et al, 2011;de Souza et al, 2012a,b;Grasse et al, 2013).…”