Carbon-nitrogen-phosphorus cycling in Tomales Bay, California

Tomales Bay, California, has been the site of long-term study of carbon-nit rogen-phosphorus fluxes in the coastal zone. It has also one of several coa stal sites being used for comparison of C-N-P biogeochemical fluxes. The si te releases phosphorus and consumes dissolved nitrogen. It also produces di ssolved inorganic carbon, mostly as elevated alkalinity. The overall interp retation placed on the biogeochemical fluxes is as follows. The system is n et heterotrophic; that is, it consumes more organic matter than it produces . A pathway of consumption that is of particular importance to the nitrogen cycle is denitrification. The combination of net heterotrophy and denitrif ication is the simultaneous release of dissolved inorganic phosphorus and t he uptake of dissolved inorganic nitrogen. Much of the dissolved inorganic carbon released during the net heterotrophy is bound in alkalinity, apparen tly the result of sulfate reduction. Because this work can be traced by to the training that one of the authors (SVS) received from Keith Chave, it is appropriate to present a summary of the Tomales Bay research in memory of Keith.