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General Session 2: Marine & estuarine biogeochemistry |
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Multiple sources and dynamic cycling of
ocean dissolved organic carbon revealed by carbon isotopes
GS2-52
Li Xu* , Woods hole Oceanographic Institution, Woods Hole, MA, USA
Prosper K Zigah, Woods hole Oceanographic Institution, Woods Hole, MA, USA
Ann P McNichol, Woods hole Oceanographic Institution, Woods Hole, MA, USA
Carl Johnson, Woods hole Oceanographic Institution, Woods Hole, MA, USA
Chiara Santinelli, Consiglio Nazionale delle Ricerche, Istituto di Biofisica, Pisa, Italy
David Karl, Inouye Center for Microbial Oceanography, Research and Education, University of Hawaii, Honolulu, Haiwai, USA
Daniel J Repeta, Woods hole Oceanographic Institution, Woods Hole, MA, USA
Presenter Email: lxu@whoi.edu
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We present concentration and isotopic profiles of total, size (high molecular weight (HMW) and low molecular weight (LMW)), and polarity (hydrophobic and hydrophilic) fractionated dissolved organic carbon (DOC) fromStation ALOHA, an oligotrophic site in the North Pacific Ocean. The data show that between the surface and 3500m, LMW hydrophilic DOC, LMW hydrophobic DOC, and HMW DOC constitute 20-29%, 45-52% and 23-35% of DOC respectively. LMW hydrophilic DOC is more isotopically depleted (δ13C of -23.9‰ to -31.5‰ and Δ14C of -304‰ to -795‰; 2850 to 15000 14C years) than the LMW hydrophobic DOC (δ13C of -22‰ to -23‰ and Δ14C of -270‰ to -568‰; 2470 to 668014C years) and HMW DOC (δ13C of -21‰ and Δ14C of -24‰ to -294‰; 135-2700 14C years). The isotope value of LMW hydrophilic DOC suggests that this fraction may be derived from allochthonous source.
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