Lake Towuti Sediments Reveals the Earth's Secrets
Danau Towuti (Sumber Google Maps)
BANDUNG, itb.ac.id—Indonesia is considered to have the same climate and environmental conditions from time to time due to its position in the equator. However, this assumption is incorrect. Indonesia has its own charm to be a study of ancient climate.
Indonesia is located in the Indo Pacific Warm Pool (IPWP), an ocean with high temperatures that affect rainfall patterns in the world. Geologically, Indonesia has many active volcanoes too. The eruption of these mountains can cause global climate change.
Lake Towuti, located in East Luwu Regency, South Sulawesi Province, is one of the locations that can become an ancient climate study area. With a surface of 560 km2 or about the size of ??DKI Jakarta, this lake is the second largest lake in Indonesia.
Research Trip
In 2005, Prof. Dr. Satria Bijaksana, professor of the Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering (FTTM), Institut Teknologi Bandung (ITB), and his partner, Prof. James from Brown University, United States, discussed with the intention of doing a small study on Lake Towuti. The study was conducted to determine its feasibility as an ancient climate study or paleoclimate by utilizing sediment from the 200-meter depth lake.
In 2007, Prof. Satria and Prof. James surveyed Lake Towuti in person. They mapped the presence of lake sediment with the Compressed High-Imensiry Radimed Pulse (CHIRP). Sediment samples were also taken from the surface of Lake Towuti.
A more extensive survey was conducted in 2010. Prof. Satria and Prof. James used a seismic airgun to map the sediments beneath the lake's surface. They also used the piston core to collect sediment samples with a deeper position in Lake Towuti.
In 2012, they held an international workshop in Bandung to discuss the feasibility of drilling into Lake Towuti sediments. The Regent of East Luwu Regency, researchers from LIPI and various universities, and PT Vale Indonesia Tbk representatives were also present at the workshop. As a result, the participants agreed to continue with the plan to drill into Lake Towuti sediments.
In 2015, the Towuti Drilling Project (TDP) was successfully carried out with logistical support from PT Vale Indonesia Tbk. Researchers from ITB, Hasanuddin University, Halu Oleo University, Sam Ratulangi University, and foreign research partners (from the United States, Germany, and Switzerland) worked for three months. They succeeded in removing sediment from three locations of Lake Towuti with a depth of up to 170 meters.
Research result
"Sedimentological studies show that Lake Towuti was formed about 1 million years ago. Initially, the area was a swamp. Then there was a rapid tectonic activity that lowered the land surface," said Prof. Wise Knight.
Studies of the youngest 10 meters of sediment show that 31 to 17 thousand years ago, the area around the lake had a dry climate and was a savanna, which is a grassy area. This condition is different from now, which is a tropical rainforest. This finding proves that environmental conditions are not always the same around the lake.
The geochemical conditions of the sediment and water of Lake Towuti are unique. This condition provides information that, at a depth of more than 130 meters in the lake, it is free of dissolved oxygen but very rich in dissolved iron.
Three billion years ago, during the faint young sun paradox phenomenon, the earth was rich in greenhouse gases to avoid freezing the earth. This study of sediment provides clues to the origin of these greenhouse gases. It turns out that microbes in the sediments of Lake Towuti produce a greenhouse gas, namely methane gas. The findings have been published in the scientific journal named Nature Communication.
Lake Towuti sediment research is still ongoing. Time and hard work are needed to uncover more information from this lake. More young Indonesian scientists are expected to study this country's lakes and ways to preserve them.
This community service program was published in Media Indonesia's Rekacipta ITB rubric on August 24, 2021. The full link of the article can be seen on the https://research.lppm.itb.ac.id/information/menuak_sejarah_bumi_dari_dasar_danau_towuti page.
Reporter: Amalia Wahyu Utami (Engineering Physics 2020)
Translator: Zahra Annisa Fitri (Urban and Regional Planning, 2019)
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