The surface of the marine micro-plastic is formed by bacteria and microalgae. The sample is collected in the Kiel Fjord, Germany. It is imaged by confocal microscope. Sina Technology News Beijing time on October 8th news, according to foreign media reports, the ocean contains a large number of organisms. Particles of the body, including alive or dead plankton, and their excreta. These so-called bio-derived particles interact and often form clumps (academicly called 'polymers'), many of which go straight down. Sinking to the bottom of the sea. In addition to these natural particles, there are a large number of plastic particles (ie, microplastics) less than 5 mm in size. These particles have been in the ocean for a long time.
Despite the constant introduction of new microplastics into the ocean, and the fact that certain plastic types float on the surface due to low density, the microplastics concentration on the ocean surface is often lower than originally expected. In addition, in recent years, deep sea sediments have Microplastic particles have been discovered many times. What have the microplastics on the ocean surface experienced? How have they settled deeper into the water depth? Members of the German Cluster of Excellence 'The Future Ocean', research author Jane M. Jan Michels said: 'Our hypothesis is that microplastics form aggregates with bio-derived particles in seawater, and these polymers are likely to sink deeper into the water layer.' The study was published in the near future. On the Proceedings of the Royal Society B.
To test this hypothesis, the researchers used polystyrene beads with a size of 700 to 900 microns to perform experiments to observe the agglomeration behavior of these beads in the presence or absence of the bioactive particles. The experiment gave clear results. Anja Engel, head of the research team at the Helmholtz Institute for Marine Research (GEOMAR), Germany, describes: 'The presence of bioparticles is critical to the formation of polymers. Although microplastic particles alone will hardly Aggregate, but they can form very distinct and stable aggregates with the virgin particles within a few days.'
'In addition, we assume that biofilms present on the surface of microplastics play a role in the formation of polymers,' Michels explained. Michels led the research during his work at GEOMAR, and now he works for Keele University. The biofilm on the microplastic surface is formed by microorganisms, usually bacteria and unicellular algae, and is relatively viscous. To understand the effects of these microorganisms on the polymer, the researchers conducted a comparative test, a group using clean Plastic beads, the other group uses plastic beads covered with biofilm. Michels said: 'In just a few hours, the microplastic covering the biofilm forms the first polymer together with the bioparticles. At the beginning of the experiment, the microplastics in the clean state were earlier and faster. ' On average, 91% of the microplastics covering the biofilm were wrapped in the polymer after 3 days.
'In the laboratory, if the microplastics are coated with biofilm and there are bio-particles at the same time, the micro-plastics and the bio-derived particles will soon form a stable polymer,' Michels concluded. In many seas The simultaneous presence of a large number of bio-particles and micro-plastic surface biofilms is likely to be a very common situation. Research participants, Ke Weitz, Helmholtz-Zentrum Geesthacht, Helmholtz-Zentrum Geesthacht Professor Kai Wirtz explained: 'This is why the polymerization process we observed in laboratory experiments is also likely to occur in the ocean, which has a great impact on the transport and distribution of microplastics. ' Scientists can These problems are further studied by targeted collection of polymers in the ocean and subsequent systematic analysis of the presence of microplastics.