Research icebreaker Xuelong 2 has returned from its 208-day, 40,000-nautical mile journey, marking China's longest single-ship Antarctic voyage.

The scientific breakthroughs made during the trip have provided effective scientific support for the country's more proactive engagement in Antarctic marine ecological conservation, expedition team members said on Thursday.

The domestically built Xuelong 2, or Snow Dragon 2, which took part in China's 41st Antarctic expedition, initially departed from Guangzhou, Guangdong province, on Nov 1 last year and returned to Haikou, Hainan province, on Wednesday having completed all its assigned tasks.

Amid the breakthroughs achieved during the expedition, China launched its first multinational joint cruise in the Antarctic autumn focusing on research on the Ross Sea ecosystem, and extended traditional Antarctic research from summer to the harsher conditions of autumn and winter, Wang Jinhui, the expedition's leader and chief scientist, said during a news conference in Haikou.

"By studying the over 5,000 samples collected, including water, membrane, sediment, biological and sea ice, new discoveries have been made on the water structure as well as low-nutrient-level and high-nutrient-level organisms in the Ross Sea," the scientist said.

Furthermore, for the first time, Xuelong 2 collected long gravity cores with an accumulated length of 8 meters in the Amundsen Sea, Wang said.

"The samples collected will be used to study the evolution of the ancient Amundsen Sea, which will help people better understand climate change," he said.

During the vessel's expedition in the Amundsen Sea and Ross Sea, other tasks such as studying the nutrient level structure of key species in the upper layers of the ocean as well as deploying and retrieving moored buoys were completed, he added.

"The expedition explored new approaches and methods for conducting international and interdisciplinary surveys across seasons. What's more, it has deepened global understanding of ecosystem adaptations and survival strategies of key biological groups in the weak light-dark environments of the Antarctic autumn," Wang said.

The expedition by Xuelong 2 helped further promote international cooperation in polar scientific research and logistical support, He Jianfeng, deputy expedition leader said.

The research on the Ross Sea, which took place between March 21 and April 26, was joined by 12 scientists from eight countries including the United States, the United Kingdom and Australia, taking a solid step towards better understanding and protecting the polar regions internationally, He said.

"It's also the first time that Xuelong 2 carried out research in an extreme environment, with the average temperature of — 20 C and the lowest temperature of-26 C," He added.

On May 23, Xuelong 2 wrapped up a five-day visit to Thailand, offering public tours and highlighting the growing scientific and technological ties between the two countries. The visit also served to honor the 50th anniversary of diplomatic relations between China and Thailand this year, Xiao Zhimin, capital of the vessel said.

Xuelong 2 is 122.5 meters long and can continuously break through ice as thick as 1.5 meters at a speed of 2 to 3 knots. After entering service in 2019, it now serves both as a supply vessel for China's research facilities in the Arctic and Antarctic regions and as a research vessel, with capabilities for geological and biological experimentation and surveying. The vessel will be open to the public from June 2 to 7 in Haikou.

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