Behavior of /sup 226/Ra in the Mississippi River mixing zone

Journal Article · Mon Dec 15 00:00:00 EST 1986 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JC091iC12p14317· OSTI ID:6860445

Moore, D G; Scott, M R

The behavior of /sup 226/Ra in the Mississippi River mixing zone is strongy nonconservative and includes desorption similar to that for the Hudson, Pee Dee, and Amazon rivers. However, dissolved and desorbed /sup 226/Ra concentrations in the Mississippi are 2 to 5 times greater than in the other rivers at the same salinity. Radium concentrations vary inversely with the water discharge rate. The /sup 226/Ra desorption maximum occurs at a salinity of 5.0, much lower than the 18 to 28 salinity values for the maxima of the other three rivers. High concentrations of dissolved /sup 226/Ra (up to 82 dpm per 100 L) and the low salinity values for the desorption maximum in the Mississippi River result from three major factors. Suspended sediments include a large fraction of montmorillonite, which gives the sediment a high cation exchange capacity. 0.54 meq/g. The average suspended sediment load is large, about 510 mg/L, and contains 1.9 dpm g desorbable /sup 226/Ra. The dissolved /sup 226/Ra river water end-member (9.6 dpm per 100 L) is higher than in surface seawater. The annual contribution of /sup 226/Ra to the ocean from the Mississippi River is 3.7 x 10/sup 14/ dmp/yr based on data from three cruises. Evidence of flux of /sup 226/Ra from estuarine and shelf sediments is common in vertical profile sampling of the deltaic waters but is not reflected in calculations made with an ''apparent'' river water Ra value extrapolated to zero salinity.

• Research Organization: Department of Oceanography, Texas AandM University, College Station
• OSTI ID: 6860445
• Journal Information: J. Geophys. Res.; (United States), Vol. 91:C12
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
MISSISSIPPI RIVER
RADIOCHEMISTRY
RADIUM 226
DESORPTION
DISSOLUTION
GEOCHEMISTRY
ION EXCHANGE
MIXING
MONTMORILLONITE
SALINITY
SEAWATER
SEDIMENTS
SUSPENSIONS
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
CHEMISTRY
CLAYS
DISPERSIONS
EVEN-EVEN NUCLEI
HEAVY NUCLEI
HYDROGEN COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOTOPES
MATERIALS
NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
RADIUM ISOTOPES
RIVERS
STREAMS
SURFACE WATERS
WATER
YEARS LIVING RADIOISOTOPES
520300* - Environment
Aquatic- Radioactive Materials Monitoring & Transport- (1989)