Figure 1: SeaWiFS image of chlorophyll concentrations in the Mid and South Atlantic Bights from 9 Oct. 1999. A fresh water plume is seen as a jet of high chlorophyll extending from the Outer Banks. click here for more information

As part of its mission to fund scientific research that will provide a global census of various forms and quantities of carbon and the natural and manmade factors that regulate carbon, NASA recently announced a $671 thousand grant to Dr. Ajit Subramaniam, a Doherty Associate Research Scientists with the Lamont-Doherty Earth Observatory, part of the Earth Institute at Columbia University.

Subramaniam’s research will map dissolved organic carbon in Eastern United States coastal waters using ocean color satellite data. Each year, rivers transport roughly .25 gigatons of dissolved organic carbon from the continents to the oceans, playing a major role in global carbon cycling. Under anomalous meteorological events, such as flooding or hurricanes, the amount of organic carbon reaching the coastal environment from rivers can significantly increase, and even double.

Figure 1: SeaWiFS image of chlorophyll concentrations in the Mid and South Atlantic Bights from 9 Oct. 1999. A fresh water plume is seen as a jet of high chlorophyll extending from the Outer Banks. click here for more information

The amount of dissolved organic carbon in the ocean is about the same as the amount of CO2 in the atmosphere . Because a certain fraction of dissolved organic carbon contains matter that can absorb visible light, satellite sensors can detect it. Through this NASA research grant, Subramaniam will develop an algorithm to map the dissolved organic carbon using satellite ocean color sensors. The research goal is to develop yearly time-series of dissolved organic carbon maps for the east coast, thus allowing researchers to explore location and time variability as well as long-term changes, if any. A major component of this research will be to determine the processes driving the distribution, transformation, and transport of dissolved organic carbon.

“We are interested in understanding the carbon cycle—the forms of carbon present in the environment—and how these various forms are transformed,” said Subramaniam. “This is crucial to know because CO2 is thought to be an important greenhouse gas that plays a key role in climate change. Apart from human activities that increase the amount of CO2 in the atmosphere, the way we use land —converting forests to agricultural land or converting agricultural land to suburban housing and parking lots—also has an impact on the carbon cycle.

“Scientists and policy makers are interested in following carbon pathways, from the atmosphere to plant matter through photosynthesis. When plants die, some of the cellulose is buried while the rest is released back into the atmosphere as CO2 by bacterial decomposition or released via rivers into coastal waters as dissolved organic carbon. We’re trying to study how much carbon is coming out in the dissolved form and how it changes over a 10-to-15-year period,” said Subramaniam.