Microplastics – tiny particles of plastic less than five millimeters in size – are polluting rivers and ponds along with chemical contaminants. The particles come from cosmetics such as exfoliating body scrubs or are washed out of synthetic fabrics. Until now, scientists have primarily investigated the concentrations and effects of microplastics in seawater.
Professor Christiane Zarfl of the Center for Applied Geosciences (ZAG) of the University of Tübingen has cooperated with Saskia Rehse and Werner Kloas from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin in testing how high concentrations of standardized plastic particles affect water fleas. Their experiments showed that the ubiquitous residents of bodies of freshwater ingest tiny particles of a micrometer, or one thousandth of a millimeter in size. This clearly limited the water fleas’ mobility, and as a result, their intake of nutrients. Larger particles had no measurable effect. The results of the study have been published in the scientific journal, Chemosphere. The scientists see this as the first of further, necessary research into the effects of microplastic pollution of freshwater. One of their further research directions will focus on the interactions of plastics with various chemicals that also end up in the environment. They say the experiments must also be extended to include entire ecosystems.
Research into the presence of microplastics in seawater has shown that they are found almost everywhere – on ocean surfaces, near the mouths of rivers, on coasts and even in deep sea sediments. Only recently have scientists turned their attention to lakes and rivers. Says Christiane Zarfl, “Measurements taken in Europe, South and North America, Africa and Asia show that up to several hundred-thousand particles of microplastic can be found per square kilometer of water.” In addition, concentrations were higher in areas that are densely populated, intensively farmed and where industry is nearby. Sewage treatment plants are not yet filtering out microplastics. Zarfl explains, “Depending on the type of plastic, the particles remain in the water or they are deposited in lake or riverbed sediment.”