Japan concluded its fourth round of release of the nuclear-contaminated wastewater from the crippled Fukushima Daiichi Nuclear Power Plant into the Pacific Ocean on Sunday, the plant's operator said.

Despite raging concerns and opposition both at home and abroad, Tokyo Electric Power Company (TEPCO) released about 7,800 tonnes of wastewater in the latest round, a similar amount to the previous three rounds.

"The Fukushima Daiichi Nuclear Power Plant is located in the northern part of the Pacific Ocean, and the discharge of nuclear-contaminated water into the sea will directly affect the fishing grounds of the North Pacific, and then affect the world through the water cycle, the atmospheric cycle and the food chain, subsequently affecting the global marine and freshwater aquaculture industry, but the timing and extent of the impact have yet to be verified," Yu Hong, a senior research fellow of the East Asian Institute, National University of Singapore, wrote in an article published by CGTN recently.

"The negative impact of the Japanese government's plan to discharge nuclear-contaminated water into the sea is long-term and irreversible, ignoring a series of basic rights such as the safety of human life and health," the expert noted.

Residents have taken to the streets to oppose the ocean release many times. They have also voiced concerns over the recent leakage of contaminated water from the Fukushima plant pipes and potential safety hazards for the disaster-prone country in light of the Noto Peninsula Earthquake.

Domestic opposition and distrust were rekindled after TEPCO admitted that on February 7, about 5.5 tonnes of water containing radioactive materials were discovered to have leaked from the outlet of a device used to purify nuclear-contaminated water at the Fukushima plant and that the water may contain 22 billion becquerels of radioactive materials, such as cesium and strontium.

According to TEPCO, human error was deemed as the cause of the incident, as 10 out of the 16 valves of the device that should have been closed were open.

In October last year, five workers were directly exposed to liquid waste containing radioactive materials in the crippled plant.

In February, a group of plaintiffs in Indonesia filed a lawsuit against Japan at the Central Jakarta District Court, demanding an end to the ocean release.

Marthin Hadiwinata, a member of the local environmental organization Ekomarin and one of the plaintiffs, said the release "will directly impact Indonesia's ecosystem," Japan's national news agency Kyodo reported.

Hit by a 9.0-magnitude earthquake and an ensuing tsunami on March 11, 2011, the Fukushima nuclear plant suffered core meltdowns that released radiation, resulting in a level-7 nuclear accident, the highest on the International Nuclear and Radiological Event Scale.

The plant has been generating a massive amount of water tainted with radioactive substances from cooling down the nuclear fuel in the reactor buildings, which are now being stored in tanks at the nuclear plant.

In August 2023, Japan started to discharge the Fukushima wastewater into the Pacific Ocean, despite repeated objections from governments and communities, environmental groups, non-governmental organizations, and anti-nuclear movements in Japan and the Pacific region.