Pb-210 and Pu-239,240 in nearshore Gulf of Mexico sediments
Pb-210, Ra-226, and Pu-239,240 activities were measured in nearshore Gulf of Mexico sediments. Sediment cores were collected from the Mississippi delta, and the western Gulf of Mexico shelf. Mississippi delta cores which exhibit significantly higher sedimentation rates show larger inventories of Pb-210. The measured Pu levels from the western shelf are lower than from the delta at comparable depths. In three of the western shelf cores, the observed Pu inventory is considerably less than predicted from atmospheric flux. Therefore, Pu is not being removed to the sediment, or is being released following deposition. A key difference between these isotopes is that Pu exists in a less particle-reactive state. The ratio of excess Pb-210 to Pu levels increases with water depth in the delta and the western shelf. Water depth acts as an integrator of depth-sensitive processes. Pu scavenging is more sensitive to these processes. A sub-surface Pu maximum has been observed. Excess Pb-210 and Pu levels correlate well with sedimentation rates. This suggests that particle flux is important in removal of Pb-210 and Pu to the sediment. The flux of Mn out of the sediment is correlated with inventory data, suggesting that redox cycling of Mn may play a role in increasing Pb-210 and Pu sediment inventories. It is unclear whether the effects of increased sedimentation rates and increased Mn fluxes can be evaluated independently. Mixing of surface sediment correlates with inventory data. Increased sediment mixing allows for additional scavenging of Pb-210 and Pu from overlying waters. Mixing of sediment at depths below the mixed surface layer may play a role in increasing sediment inventories of Pb-210 and Pu.
- Research Organization:
- Texas A and M Univ., College Station (USA). Dept. of Oceanography
- DOE Contract Number:
- AS05-76EV03852
- OSTI ID:
- 6101744
- Report Number(s):
- DOE/EV/03852-56; ORO-3852-56; ON: DE85007269
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Aquatic-- Radioactive Materials Monitoring & Transport-- (1989)
54 ENVIRONMENTAL SCIENCES
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
ATLANTIC OCEAN
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARIBBEAN SEA
CHEMICAL REACTIONS
COASTAL WATERS
DATA
ECOLOGICAL CONCENTRATION
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
GULF OF MEXICO
HEAVY NUCLEI
INFORMATION
ISOTOPES
LEAD 210
LEAD ISOTOPES
MINERAL CYCLING
NUCLEI
NUMERICAL DATA
PLUTONIUM 239
PLUTONIUM 240
PLUTONIUM ISOTOPES
RADIOECOLOGICAL CONCENTRATION
RADIOISOTOPES
RADIUM 226
RADIUM ISOTOPES
REDOX REACTIONS
SEAS
SEDIMENTS
SURFACE WATERS
YEARS LIVING RADIOISOTOPES