Microplastics in the Indian Ocean – ScienceDaily

Samples from the tropical Indian Ocean were studied using a new method for extracting and identifying microplastic particles from water samples. The result: the load is clearly measurable.

They may be tiny, but they pose a global problem for humans and the environment: microplastic particles. These are plastic particles with a diameter between one micron and five millimeters. Their accurate analysis is a huge challenge due to high error rates and high time demand of previous methods. The significantly improved analysis of microplastics was performed using a new method, Laser Direct Infrared (LDIR) Chemical Imaging. It has been combined with a new sample preparation protocol that breaks down interfering sample components with fewer working steps through chemical and enzymatic reactions. The protocol was developed in the Department of Inorganic Environmental Chemistry headed by Dr. Daniel Pröfrock. The chemical characterization of microplastic particles is based on their absorption of infrared light.

Dr. Lars Hildebrandt, one of the first two authors, explains: “In this study, the device, which uses a so-called quantum cascade laser, demonstrated its advantages in the analysis of microplastic particles in environmental samples. It is fast and automatable, which is important for a future standard procedure.

In the upper layers of water

An average concentration of 50 microplastic particles and fibers per cubic meter of water has been found in near-surface waters of the tropical Indian Ocean, which is surprisingly high for the open ocean. The most common types of plastic were paint particles (49%), presumably from the abrasion of ship paint, followed by polyethylene terephthalate (PET) with a 25% share. Among other things, PET is used in synthetic clothing in the form of polyester microfibers and for the production of beverage bottles. It potentially enters the environment through washing of clothes. Microplastic particles also form through the fragmentation of PET bottles, for example due to mechanical stress or solar radiation. In recent years, microplastic pollution in the environment has steadily increased. Plastic particles have now been detected in almost all living organisms studied.

Fadi El Gareb, the study’s co-first author, says: “Our results show that many microplastic particles, such as polypropylene, polystyrene and polyethylene, were fragmented on their way from land-based sources to the ocean. open. Thus, they are even more easily ingested by organisms. Through the Sunda Strait, a strait between Sumatra and Java, much of the plastic waste found may have entered the Indian Ocean, making it a hotspot in terms of microplastic pollution. A significant portion of global plastic waste ends up being exported to countries bordering the Indian Ocean. Due to inefficient waste management, approximately five million tonnes of plastic waste are released into the marine environment each year from China and the Indonesian archipelago (estimate based on a 2017 model).

A look into the future

In further investigations, the study authors also want to investigate occurrences of microplastics in other oceans using the new analytical method. Dr Tristan Zimmermann of the Institute for Coastal Environmental Chemistry, who has previously sampled parts of the North Atlantic in another study, says: “We will be sampling arctic waters off the east coast of Greenland in August during of a cruise with the research vessel MARIA. S. MERIAN. Here, the database concerning microplastic particles is still very insufficient. The researchers want to answer the question: How important is microplastic pollution in remote areas and is it worse than expected?

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