David Griffith sampling for dissolved and particulate organic carbon (DOC and POC) on the Hudson River

The Age and Processing of Organic Carbon in Rivers

There are two main forms of carbon: organic (such as the biomass within a tree), and inorganic (carbon dioxide in the atmosphere, for example). These forms are intimately coupled through photosynthesis in plants, which creates organic carbon from inorganic carbon and decomposition, which returns plant-produced carbon to its inorganic form. In rivers, organic and inorganic carbon exist in approximately equal proportions, and originate mainly when rainfall hits continental surfaces and either dissolves plant carbon, or carries it to rivers in particulate form. A single river can drain a landscape with a wide array of plant species, land uses, soils and climatic zones. This complexity has made it difficult to pin down exactly where most river carbon originates, how long it was on land before being carried to a river, and how reactive it might be once in a river and, later, the coastal ocean. Most of the carbon found in rivers ultimately comes from atmospheric CO₂ and therefore represents mobile 'greenhouse carbon' that either cycles back to the atmosphere and contributes to global warming, or enters a storage compartment that is not in contact with the atmosphere. The goal of this research is to determine how old carbon is in rivers and therefore gain information on how long it resided on land, and how much of this carbon is processed during its journey to the coastal ocean.

Collaborators: Jim Bauer (VIMS), Jon Cole/Nina Caraco (IES), Steve Petsch (Amherst), PARTNERS program, Rob Striegl and George Aiken (USGS)

Funding:

• NSF, Collaborative Research: Assessing the Variability and Modification of Age, Character and Reactivity of Organic Carbon Delivered by Rivers and Estuaries to an Ocean Margin
• NSF, Collaborative Research: Delivery and Fate of Old Terrestrial Organic Matter in a Riverine Ecosystem