British researchers have shown the highest yet-recorded levels of microplastics on the seafloor. The new count reveals 1.9 million pieces of the pollutant in a thin layer covering only one square meter.
Microplastics are formed through the breakdown of larger plastics, which have been discarded into the environment. Over time plastics are subject to weathering, like wind abrasion or exposure to ultraviolet radiation from sunlight.
The significance of microplastics in relation to human health arises from the various toxic and carcinogenic chemicals that are introduced into the processes used to manufacture the plastics and what they carry. It also stands that some microplastics serve as vector for pathogens.
Microplastics and the marine environment
Today plastic is the most prevalent type of marine debris found in our ocean and Great Lakes. Researchers are concerned about the extent of the pollution and the impact upon marine life, as well as the risks of microplastics entering the food chain and thus presenting a risk to human health. Several studies have revealed how microplastics damage aquatic creatures, plus turtles and birds. In particularly, these plastic fragments can block digestive tracts and alter feeding behavior. In other cases, when sea birds end up with their stomachs stuffed with plastic, some species starve and die.
The research, which was led by the University of Manchester (U.K.) and where the Tyrrhenian Sea(part of the Mediterranean Sea off the western coast of Italy) was studied, focused on the phenomenon of deep-sea currents. These currents function act as types of aquatic conveyor belts, moving tiny plastic particles and fibers across the seafloor.
The effect of the powerful, and very turbulent currents is to concentrate microplastics within large sediment accumulations (or ‘microplastic hotspots’). This was revealed using flume experiments, where specialist tanks where turbid water flow can be controlled are used. These studies reveal how turbidity currents transport microplastics, and their role in differential burial of microplastic fragments and fibers. The majority of the plastics recovered in relation to the new study were found to be formed of fibers from textiles and clothing, which had been passed through wastewater systems. This was confirmed using infra-red spectroscopy. According to principal scientist, Dr Ian Kane: “Almost everybody has heard of the infamous ocean ‘garbage patches’ of floating plastic, but we were shocked at the high concentrations of microplastics we found in the deep-seafloor.”
The typical numbers of microplastic particles, at close to 2 million per square meter, was confirmed through direct microscopic counting.
The new study into microplastics has been published in the journal Science. The research paper is tilted “Seafloor Microplastic Hotspots Controlled by Deep-Sea Circulation.”