As part of the radioactive exercises taking place around the world anthropogenic
radionuclides were introduce to Puerto Rico’s terrestrial and aquatic environments
beginning in 1962. Two major projects took place in the island, the Rain Forest Project
and the construction of a Boiling Superheat Nuclear Power Plant (BONUS). While in
operation several accidental shutdowns occurred at the BONUS facility. One of these
accidental shutdowns released 582 MBq into the nearby environment. Vieques an island
located few miles east of the main island has received anthropogenic inputs of heavy
metals resulting from military practices conducted by the US Navy. Due to the potential
presence of Cs-137 in soils and sediments in Puerto Rico a radiological assessment was
performed.
Downcore soil and sediment analysis as well as surface samples analysis was
conduct in these three sites indicating the presence of Cs-137. Activity range varies
among site from below detection limit to 12 dpm/g at Vieques, 15 dpm/g at Espiritu
Santo Estuary and 12 dpm/g at the BONUS Facility. ICP-OES analysis indicates the
existence of an oxic environment at the sedimentary system of the island. Cs-137
retention is strongly influenced by particle grain size and at the study sites clay was
present in less than 20% for most sites. An X-ray diffraction analysis show that kaolinite
and smectite are present at all sampling sites and illite is absent.
To further analysis the ability of soil and sediments to retain adsorption and
desorption was conducted using clay reference material and samples from the island. All
samples, reference and natural, used in the study were placed in an aqueous solution that
contained MES buffer (5.0 micromol, pKa of 6.1), ammonium nitrate (0.010 M) and the
five metals (individual concentrations ranged from 0.48 micromol to 1.6 micromol).
Solution pH was adjusted by titration with acid or base, depending on the nature of the
sample. Results were quantified as distribution coefficients. These results indicate that
the absorption and retention of Cs-137 in the sediments in Puerto Rico is driven by the
mineralogy of the site.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-4791 |
| Date | 14 July 2010 |
| Creators | Ithier-Guzman, Warner |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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