Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Monday, February 12, 2001, Time: 4:30:00 PM

Location: Ruidoso/Pecos

Shull, D, H, Darling Marine Center, University of Maine, Walpole, ME, USA, dshull@maine.edu

Mayer, L, M, Darling Marine Center, University of Maine, Walpole, ME, USA, lmayer@maine.edu

DISSOLUTION OF PARTICLE-REACTIVE RADIONUCLIDES IN DEPOSIT-FEEDER DIGESTIVE FLUIDS

Some particle-reactive radionuclides such as 210Pb are subject to dissolution and diffusive redistribution in sediments. This redistribution can lead to errors in the calculation of sedimentation and particle-mixing rates. Because some radionuclides are isotopes of stable metals that can be dissolved during deposit-feeder digestion, we investigated this dissolution during incubation with the gut fluids of a deposit-feeding polychaete. Algal cells artificially labeled with radionuclides showed measurable dissolution of 210Pb, but not of 234Th. Experiments with unspiked natural sediments indicated little dissolution of the native radionuclides in gut fluid. Experiments conducted with mixtures of labeled algae and natural sediment indicated that Pb-binding sites on mineral phases compete strongly with gut fluids for dissolved 210Pb, so that the gut environment may be an important site for transfer of 210Pb among solid phases. The relative partitioning of 210Pb and 234Th between gut fluid and sediment reflects their chemical bonding preferences - covalent for the former and ionic for the latter.

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Aquatic Sciences Meeting, Albuquerque 2001

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