Jennifer L. Morey
Bioengineers at the University of Washington are using laser-scattering spectroscopy to determine whether carbon-based molecules in the ocean could play a role in the carbon cycle and, by extension, in moderating the greenhouse effect.
Pedro Verdugo, a professor of bioengineering at the university, said that with the amount of carbon dioxide that humans produce, the greenhouse effect should be much more apparent than it is. This discrepancy suggests that something is suppressing some of that carbon dioxide.
The researchers are examining the assembly of marine biopolymers that form networks of microgels. Using a Brookhaven laser spectrometer, they focus an argon-ion beam onto the target sample and collect the scattering information with a photomultiplier. The spectral structure of the fluctuations in scattering reveals the mobility of molecules and particles in the sample. The researchers can determine the size and shape of these particles by the way they move. The rest is simply a matter of analysis, Verdugo said.
Once formed, the polymer gels could be colonized by bacteria. This mechanism could provide a means for dissolved organic matter to re-enter the carbon cycle, thereby adding carbon dioxide to the atmosphere.
However, additional research indicates that the microgels exhibit a negative electrostatic charge and thus accumulate calcium carbonate from seawater and crystallize. Once crystallized, they eventually can sink to the ocean floor as sediment.
The researchers also discovered that the microgels can undergo a phase transition in which they release water and collapse into dense particles that also could fall to the ocean floor.
Both processes would remove carbon from the marine life cycle and could provide a new approach to investigating the disappearance of carbon dioxide from the atmosphere.
Verdugo added that researchers have used laser-scattering spectroscopy for years to study the polymer networks that comprise the matrix of gels. Although he acknowledges that his research is only in its preliminary stages, he said it is an important first step in linking polymer gels to effects on the carbon cycle. "The time will come when we establish how much of this is taking place. Then we'll really know the significance."