Re ECF Project: 2011-13

Project Title: Radiocesium accumulation and risk in marine shellfish and fish

Applicant: Prof. Wen-Xiong WANG of The Hong Kong University of Science & Technology

Total Approved Grant: $495,120

Duration: 1/2/ 2012 to 31/1/2013

Project Status/Remarks: Completed

Scope:
The objectives of the project are

  • to study the routes and potentials of radiocesium accumulation in important shellfish and fish in Hong Kong; and
  • to study the potential bioaccessibility of this radioactive substance to humans.

Summary of the Findings/Outcomes:
Our study demonstrated that the bioconcentration factors and dissolved uptake constants of 137Cs were low in shellfish and fish when compared to most other trace metals. Temperature, salinity, and K+ concentration significantly affected the influx rate of 137Cs into shellfish and fish. Assimilation efficiencies of 137Cs were low for shellfish but high for fish. The depuration rates of 137Cs were slower in shellfish than in fish. Scallops had the fastest loss rate of 137Cs than other studied marine organisms. Our modeling indicated that dissolved pathway was more important for the accumulation of 137Cs in shellfish and fish under most circumstances. Dietary pathway may contribute significantly when the concentration factors of ingested food are high. Biomagnification of 137Cs was more likely at the top of food chain than at the base of the food chain. Cooking methods and duration had significant effects on the loss of 137Cs in seafood, with boiling was the most effective way to reduce 137Cs in seafood compared to steaming, grilling, and frying. The 137Cs bioaccessibility was high in seafood.