A researcher from the Geology Study Program, Faculty of Mathematics and Natural Sciences (FMIPA), Universitas Indonesia (UI), Asri Oktavioni Indraswari, S.T., M.Sc., took part in an international scientific expedition in the southern waters of Sumba Island, East Nusa Tenggara. The expedition was part of a collaborative research effort between the Second Institute of Oceanography (SIO), China, and researchers from BRIN, UI, Universitas Gadjah Mada (UGM), and Institut Teknologi Bandung (ITB), supported by the Research and Innovation for Advanced Indonesia (RIIM) program under the Indonesian Endowment Fund for Education (LPDP).

The 16-day research, conducted from August 10 to 26, 2025, utilized the research vessel R/V Tan Kah Kee owned by Xiamen University, China. The expedition involved 30 researchers, consisting of 23 from China and 7 from Indonesia. Its main focus was to explore the collision zone between the Australian and Eurasian continental plates, known for its tectonic activity, while also examining potential geological hazards such as earthquakes and tsunamis, as well as the biodiversity of the deep sea.

“This expedition marks an important milestone in advancing marine geological research in Indonesia,” said Asri. “I feel fortunate to be directly involved in this international mission and to learn from both Chinese and Indonesian researchers, particularly regarding research methods and instruments that I had previously only studied through literature.”

In this research, Asri focused on studying the distribution and behavior of mercury (Hg) in deep-sea sediments, particularly in tropical trench zones where data remain scarce. To date, studies on heavy metals such as mercury have been more commonly conducted in high- and mid-latitude regions, such as the Mariana Trench and the Bougainville Trench.

“This research fills a knowledge gap in equatorial regions, such as the Java Trench. This is important for understanding the mercury cycle in tropical areas, which are strongly influenced by submarine volcanic activity and deep ocean currents,” she explained.

The issue of mercury content in marine sediments has become increasingly relevant, given the growing global concern over heavy metal pollution in the marine environment. Such content can serve as an important indicator for monitoring both natural geochemical activities and the influence of human activities, including their impacts on the marine food chain and human health.

Beyond the environmental aspect, this expedition also makes an important contribution to strengthening disaster mitigation systems in Indonesia. As an archipelagic country located within the Pacific Ring of Fire, Indonesia is in great need of accurate marine geological data. The plate collision zone south of Sumba is known as one of the areas with significant potential for major earthquakes and tsunamis.

During the expedition, Asri was also involved in the core sampling process and participated in technical training on the use of various deep-sea geophysical instruments, such as the Ocean Bottom Seismometer (OBS), Ocean Bottom Electromagnetic Meter (OBEM), and Controlled-Source Electromagnetic (CSEM). Sediment sampling was carried out at a depth of 2,000 meters using the gravity sediment coring method, which allows for precise collection of seabed material for further analysis. This training expanded her understanding of seismic and electromagnetic data acquisition from the ocean floor.

“This training not only enriched my technical skills but also provided firsthand experience in the dynamics of international research work, ranging from scientific aspects to bureaucratic coordination,” she said.

All data were collected through gravity sediment coring, active–passive seismic measurements, and subsurface mapping using OBEM and CSEM instruments. The sediment samples obtained will subsequently be analyzed using a range of equipment, including the LUMEX Mercury Analyzer, thermal desorption profiling, Rock-Eval, and Elemental Analyzer, to measure chemical and physical parameters.

However, this expedition also presented its own challenges. Rough seas caused many team members, including Asri, to experience severe seasickness.

“Those conditions greatly disrupted the fieldwork process, especially during the deployment of instruments to the seafloor,” she recalled.

Asri emphasized the importance of such expeditions in strengthening the national marine research ecosystem. She also highlighted the existing gap between Indonesia and China in the field of marine geological research.

“This serves as a reminder that we must promptly catch up, both in terms of technology and human resources,” she said.

Asri expressed her hope that more Indonesian students and young researchers would actively engage in collaborative research, both at the national and international levels. She emphasized the importance of building networks and cross-institutional cooperation to uncover the many potentials and mysteries that remain hidden in the field of marine geology.

“Do not hesitate to collaborate with research institutions such as BRIN, as well as with other universities both at home and abroad. The world of marine geology still holds many mysteries waiting to be uncovered together,” she said.