Bauer, J. E.
Raymond, P. R.
Wolgast, D. M.
Hopkinson, C. S.
14C AND 13C EVIDENCE FOR UTILIZATION OF TERRIGENOUS DOC IN ESTUARIES
Delta 14C and del 13C of dissolved organic carbon (DOC) were measured along the salinity gradient of the York river estuary (Virginia), and the Parker Estuary (Massachusetts) in order to better understand the cycling of DOC in estuarine systems. Initial data indicate that terrestrial DOC is being preferentially utilized during transit through these estaurine systems. In both systems the freshwater entering the estuary contained significant terrestrial derived DO14C, while the high salinity end-member DO14C reflected a older marine source.
Mixing curves were generated to investigate the fate of DO14C during its transit through the York and Parker estuaries. Ten of the 12 mid-estuarine points were depleted relative to calculated conservative mixing curves. The two possible explanations for this non-conservative behavior are that there is either an input of phytoplankton or salt marsh doc in the mid estuary with a depleted mean 14C signature, or a selective removal of 14C-enriched terrestrial DOC. Several independent lines of evidence support the latter explanation including incubation experiments, which also indicate preferential degradation of bomb 14C-enriched terrestrial DOC.
Day: Tuesday, Feb. 2
Location: Sweeney Center