DISTRIBUTION AND FLUXES OF DISSOLVED FORMS OF CARBON (DOC, DIC) IN SMALL SUB-TROPICAL RIVERS, ESTUARIES, AND COASTAL WATERS OF WEST-CENTRAL FLORIDA (USA)

Small tropical and sub-tropical rivers deliver a significant amount of dissolved material, including carbon (C), to the coastal ocean. However, the fluxes and fate of these materials are poorly quantified, and historical records of land-ocean C delivery are relatively rare in the tropics. Additionally, tropical and sub-tropical estuaries are sites of intense biogeochemical processing and can significantly alter the quantity and character of materials being exported to the coastal ocean. Tampa Bay is one of the largest estuaries in Florida. It is likely a site of intense carbon biogeochemical processing and storage immediately adjacent to the Gulf of Mexico (GoM). To date, most accounts of C flux to the GoM have focused on the Mississippi-Atchafalaya river and estuary system. Therefore, coastal carbon fluxes from large estuaries such as Tampa Bay are under-represented in our understanding of GoM carbon budgets. In this study, the abundance of dissolved forms of organic and inorganic carbon (DOC and DIC, respectively) were measured in riverine, estuarine, and coastal waters along three transects near the mouth of Tampa Bay. Preliminary data indicated that neither form of carbon mixed conservatively along the three transects, and thus biogeochemical alteration is occurring in the estuarine waters of Tampa Bay. DOC concentrations ranged from 1.83 – 16.30 μmol L^-1 and indicated that estuarine waters of Tampa Bay represent a large sink of organic carbon. DIC concentrations ranged from 1985 – 2603 μmol Kg^-1 and indicated that estuarine waters of Tampa Bay contain excess DIC, and therefore represent a source of DIC to the atmosphere. Further study, including isotopic analysis, is necessary to understand the biogeochemical processes that are responsible for the patterns evident in DOC and DIC abundances along each transect.