Environmental Science and Engineering Seminar

Dissolved organic carbon is the largest reservoir of reduced carbon in the ocean. Though it originates mainly from primary production in the surface ocean using modern carbon, its ¹⁴C age is thousands of years old. In this seminar I will give an overview of this paradox, and show you new ¹⁴C data from the Pacific and Atlantic Oceans. I will show that ¹⁴C ages of DOC from the deep South Pacific are equal to those from the deep north central Pacific, which is contrary to the dissolved inorganic carbon ¹⁴C patterns. Apparently, DOC ¹⁴C values in the deep Pacific are not controlled by aging during northward transport of deep waters. We hypothesize that DOC in the South Pacific is influenced by input of ancient DOC from hydrothermal flanks and ridges of the East Pacific Rise. We also have found bomb ¹⁴C in DOC in the deep North Atlantic, making the age of DOC ~5000 years, not 4000 years as had been previously estimated. I will address why the deep oceanic carbon cycle needs reassessment.