A radiotracer study of cerium and manganese uptake onto suspended particles in Chesapeake Bay

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90499-5· OSTI ID:5242071

Moffett, J W ^[1]

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1. Woods Hole Oceanographic Institution, MA (United States)

The oxidation kinetics of Ce(III) and Mn(II) were studied in Chesapeake Bay in March and July 1990 to establish the role of water column redox processes in contributing to Ce anomalies observed in this estuary (SHOLKOVITZ and ELDERFIELD, 1988; SHOLKOVITZ et al., 1992). Oxidation was measured by adding Mn(II) and Ce(III) to freshly collected water samples as radiotracers and measuring their uptake onto the ambient suspended particle assemblage. Mn(II) oxidation was measured by following the uptake of [sup 54]Mn(II) onto suspended particles and utilizing protocols established by other workers to distinguish oxidation from Mn(II) adsorption. The same protocols were applicable to Ce(III), using [sup 139]Ce(III), and were supported by the use of [sup 152]Eu(III) as a nonredox reactive control. Specific rates of Ce(III) and MN(II) oxidation measured at a station in the North Bay (depth = 4 m) in July were 2016% per day and 4032% per day, respectively. In March, at the same station, the specific rate of Mn(II) of oxidation was only 1-% per day, and Ce(III) oxidation was undetectable. Both Ce(III) and Mn(II) oxidation processes were inhibited by azide, indicating that they were microbially mediated. The seasonal differences probably reflect strong seasonal variation in the abundance of Mn oxidizing bacteria. No Ce(III) oxidation occured in samples collected below the oxic/anoxic interface in July. The specific rates of oxidation for both elements were over 1000 times higher than those measured in the Sargasso Sea. However, the specific rates for Ce(III) and Mn(II) were very similar to each other. This fact, coupled with similar spatial and temporal trends for specific oxidation rates, suggests a common mechanism of oxidation of both elements which may be significant in a wide range of marine environments.

• OSTI ID: 5242071
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 58:2; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CERIUM
OXIDATION
CHESAPEAKE BAY
WATER CHEMISTRY
MANGANESE
CERIUM 139
EUROPIUM 152
MANGANESE 54
TRACER TECHNIQUES
ATLANTIC OCEAN
BAYS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CERIUM ISOTOPES
CHEMICAL REACTIONS
CHEMISTRY
COASTAL WATERS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EUROPIUM ISOTOPES
EVEN-ODD NUCLEI
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MAS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MANGANESE ISOTOPES
METALS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
RADIOISOTOPES
RARE EARTH ISOTOPES
RARE EARTH NUCLEI
RARE EARTHS
SEAS
SURFACE WATERS
TRANSITION ELEMENTS
540311* - Environment
Aquatic- Basic Studies- Radiometric Techniques- (1990-)