The Tobias lab is part biogeochemistry, part ecosystems science, and all stable isotopes. Current research targets nitrogen, carbon, and oxygen cycling in the coastal zone, specifically addressing several aspects fate and transport along an aquatic continuum from watersheds to the coastal ocean. Hydrologic and stable isotope tracer techniques are the primary tools. Presently funded projects examine these topics in tidal creeks, groundwaters, estuaries, coastal embayments, and salt marshes of the Atlantic and Gulf Coasts, and in the Caribbean.. Much of the work quantifies element processing rates in situ, and examines the interaction among hydrology, geochemistry, and biology.