Reconstruction of seawater 14C from a Porites coral living outside of the Runit Island Dome

After the WWII, Enewetak Atoll was used to test nuclear weapons; the program ran from 1948 to 1958. After an intermittent use from 1958 to 1972 it was decided to return Enewetak Atoll to the Marshallese after the establishment and completion of the clean-up operations. The island of Runit (on Eastern side of Atoll). A cleanup plan was devised to remove all radioactive and non-radioactive debris (equipment, concrete, scrap metal), soil that exceeded 1.48Bq of plutonium per gram of soil and depositing it into the Cactus test crater on Runit Island. Approximately 73,000 cubic meters of surface soil from 6 islands were removed and deposited into the crater.

This project uses a Porites coral collected in 2003 from the lagoon side of Runit Island to reconstruct the radiocarbon history. The coral core covers the years 1982-2003 with radiocarbon measurements every two months. Preliminary results suggest slightly elevated radiocarbon measurements when compared to external coral datasets. At this point it is unknown if the slightly elevated measurements are due to the dome or the much higher inventory of radionuclides in the atoll lagoon sediments.