According to a new report, “Rapid Aggregation of Biofilm-Covered Microplastics with Marine Biogenic Particles,” microplastics are far more ubiquitous in the ocean’s depths than on the surface. While ocean plastics on the surface, such as the Great Pacific Garbage Patch, are visible and get all the attention, the new study shows that there is “substantial accumulation” of microplastics even in “remote habitats such as deep-sea sediments and polar sea ice” that is “believed to pose a threat to ecosystem health.” Microplastics are defined as pieces measuring less than 5 millimeters long.
|Biofilm formed by bacteria and micro-algae on a plastic surface in water from the Kiel Fjord, Germany, is visualized using confocal laser scanning microscopy. Image courtesy Jan Michels/Future Ocean.|
The report from the Proceeding of the Royal Society, Biological Sciences, noted that microplastics on the surface of the ocean are “considerably lower than expected given the ongoing replenishment of microplastics and the tendency of many plastics to float.”
Scientists tested that hypothesis by investigating the interactions of microplastics with marine biogenic particles collected in the southwestern Baltic Sea. “Our laboratory experiments revealed a large potential of microplastics to rapidly coagulate with biogenic particles, which substantiates this hypothesis,” said the study’s authors. “Together with the biogenic particles, the microplastics efficiently formed pronounced aggregates within a few days. The aggregation of microplastics and biogenic particles was significantly accelerated by microbial biofilms that had formed on the plastic surfaces. We assume that the demonstrated aggregation behavior facilitates the export of microplastics from the surface layer of the oceans and plays an important role in the redistribution of microplastics in the oceans.”
So where do all these microplastics come from? In another report by the International Union for Conservation of Nature (IUCN), “Primary Microplastics in the Oceans: A Global Evaluation of Sources,” by Junien Boucher and Damien Friot, it was noted that 35.0% of microplastics in the oceans come from synthetic textiles resulting from washing clothes. Another 28.0% of ocean microplastics come from car-tire particles that eventually get washed from roadways into waterways and eventually into the ocean.
“The global release of primary microplastics into the ocean was estimated at 1.5 million tons per year. The overwhelming majority of the losses of primary microplastics (98%) are generated from land-based activities. Only 2% are generated from activities at sea. The largest proportion of these particles stem from the laundering of synthetic textiles and from the abrasion of tires while driving.”
Cosmos magazine noted in a brief item regarding biofilm-covered micro plastics that “lab simulations performed by a team led by Jan Michaels from GEOMAR Helmholtz Center for Ocean Research Kiel in Germany show that microplastics coated with biofilm such as bacteria and micro-algae create an even stickier surface that clumps to form at a rapid rate, sending even more to the ocean depths.”
Perhaps microplastics—the stuff we can’t see—is a much bigger issue than the plastic stuff we can see!