Aluwihare, L. I. Woods Hole Oceanographic Institution, laluwihare@whoi.edu
Repeta, D. I. Woods Hole Oceanographic Institution, drepeta@whoi.edu

 
CYCLING AND REACTIVITY OF HIGH MOLECULAR WEIGHT DISSOLVED ORGANIC CARBON IN THE OCEAN
 
Recent work has shown that upto 60% of the high molecular weight (HMW) dissolved organic carbon (DOC) in the surface ocean consists of a ubiquitous family of carbohydrates which appear to be produced during algal photosynthesis. Structural studies further show that the carbohydrate component of deep ocean DOC also closely resembles HMW algal exudates, indicating transport of surface produced DOC to the deep ocean. In addition, bacterial activity and stable DOC concentrations at depth in the ocean indicate close coupling between the production and removal of DOC. This suggests that certain fractions of DOC may turnover rapidly in the deep ocean. Here we use the radiocarbon ages of DOC to evaluate mechanisms for the transport of HMW DOC to the deep ocean, and to determine residence times for the carbohydrate fraction. HMW DOC is isolated via ultrafiltration, and the carbohydrate fraction is separated and purified using various chromatographic methods and submitted for radiocarbon dating by AMS. Preliminary results indicate that the carbohydrate fraction is significantly younger than the total HMW DOC in the deep ocean, suggesting that this fraction is recently produced and has a short residence time in the deep ocean.
 
Day: Tuesday, Feb. 2
Time: 08:30 - 08:45am
Location: Eldorado Hotel
 
Code: SS34TU0830E