China announced a blanket ban on seafood and other aquatic products from Japan on Thursday as Tokyo began dumping treated radioactive wastewater from the ruined Fukushima nuclear plant into the Pacific Ocean. China said it is “highly concerned about the risk of radioactive contamination brought by ... Japan’s food and agricultural products” in a statement released by its customs bureau. The plan to release the water had been approved by the UN’s nuclear watchdog and is regarded by Japan as an important step in decommissioning the plant destroyed by the 2011 tsunami. But neighboring countries, and China in particular, have vociferously opposed the move, claiming Japanese authorities had failed to prove it was safe. Elsewhere on Thursday, at least 16 protesters were arrested as they entered the Japanese embassy in South Korea, while North Korea’s foreign ministry blasted the water release as a “crime against humanity,” according to state media.