Initial findings from a TÜBITAK 1001 project aimed at revealing the pollution history of the Sea of Marmara show that microplastic pollution in the sea has increased significantly since the 2000s, in some areas rising up to three times.

The pollution history of the Sea of Marmara is being investigated through a TÜBITAK 1001 project carried out in partnership by the Middle East Technical University (METU) Institute of Marine Sciences, Akdeniz University, Ege University and Recep Tayyip Erdoğan University.

According to the interim report of the project, initial analyses of sediment cores taken from 14 critical points in the Sea of Marmara have yielded results. The examined samples include early findings on microplastic distribution, pollutant load and radiometric dating.

In the next phase of the study, polymer characterization and metal pollution analyses will continue.

Since its launch last year under the leadership of associate professor Olgaç Güven from the Faculty of Fisheries at Akdeniz University, the project has collected 40-50 cm-long (16-20 inches) sediment samples from the seabed using a core device called an "octopus” aboard the METU research vessel Bilim-2.

Striking findings

Güven told Anadolu Agency (AA) that the Sea of Marmara, being under the administration of a single country, offers a more controlled and unique research area compared to many other seas in the world for monitoring the effects of human activities.

Explaining that the first phase of the project involved sampling areas representing regions under different pressures in the Sea of Marmara, Güven said:

"We examined the vertical distribution and characterization of microplastics in sediment cores taken from the Gulf of İzmit, the Gulf of Gemlik, the Çınarcık Trough - the deepest point of the Marmara Sea - the İmralı Basin and the central Marmara region. We obtained notable findings, particularly in the Gulf of Izmit, which is affected by heavy industry, population and freshwater inputs and in the Çınarcık Trough, where currents from the Black Sea accumulate transported loads.”

Güven noted that dating studies conducted on sediment samples are being carried out at the Nuclear Sciences Institute of Ege University, adding:

"A clear increasing trend in plastic pollution from the past to the present is observed at all stations. We see a marked increase in plastic pollution starting from the early 2000s. Depending on the station, there is about a threefold increase in some areas.”

Traces of 1999 Gölcük earthquake

Güven also stated that traces of the 1999 Gölcük Earthquake were found during the studies:

"In the Izmit Gulf and Çınarcık Basin, we detected a significant increase in plastic amounts in layers corresponding to the earthquake period. We believe this increase is related to the transport of pollutant loads from land to the marine environment after the earthquake. Major events on land can be recorded in marine sediments through transported material.”

She added that meaningful microplastic pollution dating back to the 1960s was identified in sediment layers and even older layers contained isolated plastic particles.

After completion of polymer analyses, the relationship between plastic types used in specific periods and industrial and consumption habits will be more clearly revealed. The aim is to understand the reflection of policy changes or production habits in the marine environment over time.

Fiber microplastics

Güven also stated:

"About 94% of the microplastics we have detected so far are in fiber form. These are thin, hair-like plastic particles.”

She noted that one of the main sources of these fibers is synthetic textile products, explaining that fibers released during washing machines pass through wastewater treatment plants - due to the lack of microfiltration systems - and reach the sea.

Güven also reported that microbeads used especially in cosmetic products were found in the Gulf of İzmit.

Plastic movement in Marmara

Professor Mustafa Yücel, deputy director of METU Institute of Marine Sciences, stated that the project aims not only to detect the presence of plastics but also to understand how they are transported in the Marmara Sea and where they accumulate.

He emphasized that deep basins in the Marmara Sea act as natural reservoirs that collect incoming particles, noting that areas such as the Çınarcık Trough, İzmit Gulf and Gemlik Gulf are important regions for understanding the sea’s plastic history.

Yücel also pointed out that earthquakes not only cause physical destruction but also transport pollutant loads and debris from coastal areas into deeper parts of the Marmara Sea, adding:

"This shows that seismic activity is not only a geophysical event, but also a factor that affects marine ecosystems and pollution cycles.”