[Report] Battling Anxiety Over Contaminated Water... "Daily Radiation Tests on Seawater and Seafood"

Daily Cesium Concentration Checks Before Seafood Auctions
Monthly Emergency Radiation Inspections at 75 Marine Sites

"First, we will sample mackerel and Spanish mackerel, and once the unloading work is finished, we will proceed with hairtail."

At 3 a.m. on the 15th at Busan Cooperative Fish Market, Lee Dae-wook, an inspector from the Korea Fisheries Disease Control Association, quickly crossed the fish market holding a white plastic bag. This was to collect samples of the fish species caught that day for rapid radioactive safety testing of seafood. Since the auction can only proceed after completing the radiation test before 6 a.m., rapid sample collection is crucial.

The inspector randomly selected and collected mackerel and Spanish mackerel that had finished unloading into collection bags. The seafood samples weighed 3 kg per species. Since 1 kg of edible parts, called 'gasikbu,' is required for testing, they collected a generous amount. Rapid testing of caught fish and shellfish began on July 24, following Japan's Fukushima contaminated water discharge. So far, rapid tests have been conducted on about 80 species and over 1,100 cases.

In the early morning of the 15th, seafood is being organized before the auction at the Busan Cooperative Fish Market.

Separately from rapid testing, since the Fukushima nuclear accident in 2011, 80,000 radiation tests on seafood have been conducted. Domestic food radiation standards are set at 100 becquerels (Bq/kg) for cesium. This is more than 10 times stricter than the international standard of 1,000 becquerels and higher than the U.S. standard of 1,200 Bq/kg. Yoon Ki-jun, a manager at the Ministry of Oceans and Fisheries' Distribution Policy Division, emphasized, "There has never been a single case of non-compliance in seafood radiation tests." The Ministry plans to test all varieties of Korean fish and shellfish at 29 of the 43 nationwide fish markets, considering seasonal differences in species.

The collected samples are transferred to the Seafood Quality Management Service, where radioactive concentrations of isotopes such as iodine, cesium-134, and cesium-137 are measured. For testing, the edible parts of the fish are cut and made into a paste. The samples are homogenized to improve testing accuracy. Then, they are placed in a gamma isotope analyzer to measure radiation levels and obtain results. No radiation was detected in the samples tested that day, allowing the auction to proceed normally.

Radiation safety tests are conducted not only on seafood but also in marine areas. This is a measure to ensure seawater safety. On the 14th, at the Namdong marine area about 13 km from Busan Port Coastal Passenger Terminal, an investigator from the Korea Marine Environment Management Corporation conducted seawater radiation testing using a sampling device called a 'Rosette sampler.' The cylindrical Rosette sampler was lowered into the sea to collect surface water, after which hydrochloric acid was added. A corporation official explained, "Maintaining the seawater's pH at an acidic level prevents radioactive materials from adhering to the storage container."

On the 14th, a Korea Marine Environment Management Corporation official is collecting seawater from a sample collection device (Rosette sampler) that was submerged in the sea for sample collection.

The collected seawater is transported to the Marine Environment Research Institute's radiation analysis laboratory for radioactive concentration investigation. The researchers adsorb radioactive cesium present in the seawater onto reagents, precipitate it, and analyze cesium concentration from the final sample. Since 2015, the Ministry of Oceans and Fisheries has been conducting marine radiation surveys and plans to increase survey points from 200 this year to 243 next year. In particular, 75 emergency survey points are tested monthly. Considering the direction and range of ocean currents entering Korea, the marine areas are divided into five zones: Southwest, South-Southwest, South-Central, South-East, and Jeju. Each zone collects five samples three times a month. Han Ki-jun, director of the Korea Marine Environment Management Corporation, stated, "Through emergency marine radiation surveys, we will closely monitor the safety status of our marine areas related to Japan's nuclear wastewater discharge."