My research focuses on how biology and watershed variables alter the carbon chemistry of streams, rivers and estuaries. Most of this work links into efforts worldwide to gain a better understanding of the carbon cycle due to the linkages between increased atmospheric CO2 and global change. This work entails coupling previously collected stream/river data with digitally available information on climate and land-use, field measurements at various space and time scales, and isotopic studies. Projects which probe the connections between carbon and water and nutrient cycles is an integral component of my research. The transport of riverine organic carbon (OC) to the world’s oceans is a globally significant flux, and connects the terrestrial and oceanic carbon cycles. The age of OC transported from rivers provides key information on the turnover time and recycling of both oceanic and terrestrial OC. My research findings suggest that rivers are variable sources of both old and young terrestrial dissolved organic carbon (DOC), and of very old terrestrial particulate organic carbon (POC) to the North Atlantic Ocean. I have also found that much of the young DOC can be selectively degraded over the residence times of river and coastal waters, leaving an even older and more refractory component for oceanic export. These findings contrasted with limited earlier data that suggested terrestrial organic matter transported by rivers in general might be enriched in bomb 14C, and hence represent organic matter recently fixed by plants.