Seasonal POC fluxes at BATS estimated from 210Po deficits

• Published in: Deep-sea research. Part I, Oceanographic research papers Vol. 57; no. 1; pp. 113 - 124
• Main Authors: Stewart, Gillian M., Bradley Moran, S., Lomas, Michael W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 2010; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; BATS; Biological and medical sciences; Carbon; Deep sea; Earth, ocean, space; Exact sciences and technology; Exports; External geophysics; Fluxes; Fundamental and applied biological sciences. Psychology; International trade; Marine; Oligotrophic ocean; Physical and chemical properties of sea water; Physics of the oceans; Polonium; Sea water ecosystems; Seasonal POC export; Springs; Synecology; Bermuda; North Atlantic; Atlantic Ocean Islands; Atlantic Ocean; ANW, Atlantic, Bermuda; BATS; Polonium; Oligotrophic ocean; Seasonal POC export; biogeochemical cycle; sediment traps; Particulate carbon; carbon cycle; marine environment; Measurement technique; Polonium 210; Oligotrophy; organic carbon; radioactive tracers
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2009.09.007

In this study at the Bermuda Atlantic Time-series Study (BATS) site we demonstrate that the polonium–lead disequilibrium system may perform better as a tracer of organic carbon export under low-flux conditions (in this case, <2.5 mmol C m −2 d −1) than under bloom conditions in an oligotrophic setting. With very few exceptions, the POC flux predictions calculated from the water-column 210Po deficit were within a factor of 2 of the POC flux caught in surface-tethered sediment traps. However, we found higher correlation between size-fractionated particulate 210Po activity and POC concentration in November 2006 ( r=0.93) than in January ( r=0.79) and during the spring bloom in March 2007 ( r=0.80). We suggest that this is due to the ability of polonium to distinguish between bulk mass flux and organic carbon export under oligotrophic and lithogenic-driven flux regimes. Further, we found that the POC/Po ratio on particles was largely independent of size class between 10 and 100 μm ( P=0.13) during each season, supporting the notion that export in this oligotrophic system is driven by sinking aggregates of smaller cells and not by large, individual cells.