Dose conversion coefficients to marine biota due to natural radionuclides in an oil spill accident using Monte Carlo simulation

Abstract

The crude oil that reached the Brazilian coast in 2019 was the most significant environmental disaster ever recorded in Brazilian marine waters, with severe ecological and economic repercussions not fully dimensioned and understood. One consequence of this kind of oil spill is the absorbed dose delivered to marine organisms. The biota exposure to radiation can introduce consequences that range from fertility decrease to death of exposed population. Therefore, the current study aims to use the ICRP reference organisms (flatfish, crab, and brown seaweed) to assess marine biota exposure due to uranium and thorium series radiation. The oil spill scenario, as well as the reference biota, were simulated in MCNP. Thorium series stood out for presenting a significant contribution to the dose. Furthermore, it was noticed that a remedial action capable of removing Tl-208 would significantly decrease the effects of radiation on marine biota. Finally, dose conversion coefficients for both uranium and thorium series were obtained as oil activity concentration functions. The results obtained here can be used in an oil spill event along with other worldwide recognized models. In addition, the dose coefficients can be used strategically to assess the maximum exposure time for emergency oil control, removal, and mitigation.