The Secret of the Ancient Reservoir Revealed by Diatom Fossils

Find out how the history of the 1000 years old reservoir, Gonggeomji was revealed

Cymbella aspera by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

Diatoms 

Diatoms are organisms that belong to phytoplankton. They make up more than 80% of phytoplankton and have chloroplast which performs photosynthesis. Its cell wall is made of hard glass components.

Diatoms by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

Diatoms are found in wetland sediments, which are very important research materials for understanding past environmental changes or predicting future environmental changes.

Gonggeomji by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

Gonggeomji 

Gonggeomji is an ancient reservoir that is known as one of the three major reservoirs of the Samhan, Korea's ancient kingdom. In the encyclopedia of the Joseon Dynasty, the circumference of Gonggeomji is recorded as 8.6km, slightly longer than the Upo Wetland, the largest wetland in Korea.

Gonggeomji by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

A study on the formation period of the Gonggeomji 

However, there was a question about when Gonggeomji was formed.  NNIBR studied wetland sediments and diatoms of the reservoir to find out the age of Gonggeomji through records of organisms that lived in the past.

The research begins with the drilling of the bottom floor of the reservoir. The dug sediment is transported to the laboratory, where various processing operations such as sedimentary phase analysis, and sampling for age analysis are performed.

Drilling, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Shoot out, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Grab sample, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Sample, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Slide, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Observation, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
Show lessRead more

Process of Research on Wetland Sedimentary Layers and Diatom Fossils: Digging on Targeted Location > Sediment sampling > Sampling for dating > Sampling making for Microscope Slide > Observation by Electron Microscopy

Diatoms by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

Treasure of Gonggeomji, Fossil of diatoms 

Analyzed the sediment, diatoms are found abundantly in the strata that were deposited 500 to 4,000 years ago. A total of 159 diatoms, including Genus Navicula and Genus Cocconeis, which are commonly found in freshwater, were found to have inhabited the reservoir.

Diatoms by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

The 32 species of diatoms are attached algae that mainly live by attaching to bedrock, gravel, and the surface of living organisms in water. Genus Gomphonema, Genus Cymbella, and Unotia were confirmed to have been included. 

Caloneis wardii, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Gomphonema asiaticum, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Gomphonema neoapiculatum, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Pinnularia fusana, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Sellaphora capitata, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
,
Staurosira dimorpha, Nakdonggang National Institute of Biological Resources, From the collection of: Nakdonggang National Institute of Biological Resources
Show lessRead more

 32 species of diatoms that were not reported in Korea was discovered by the research on Gonggeomji

Alteration by Nakdonggang National Institute of Biological ResourcesNakdonggang National Institute of Biological Resources

Revealing the formation period and environmental change

Based on the results, it was revealed that the Gonggeomji was formed as a natural wetland about 10,000 years ago and then reformed as a reservoir about 1300 to 1400 years ago. Moreover, it was seen that the water level was the highest in the late Joseon Dynasty.

Gonggeomji of Sangju city is one of the oldest reservoirs in Korea, which is designated as a protected area. Through this study, it is proofed that Gonggeomji has existed since 1,400 years ago. NNIBR will continue to unveil the historical values of many ancient reservoirs through fossil (paleontological) research.

Credits: Story

Participation: Sang Deuk Lee, Senior Researcher,  Nakdonggang National Institute of Biological Resources

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
Google apps