Massive accumulation of plastic particles has been reported for marine ecosystems around the world, posing a risk to the biota. Freshwater ecosystems have received less attention despite most plastic litter being produced onshore and introduced into marine environments by rivers. Some studies not only report the presence of microplastics in freshwater ecosystems, but show that contamination is as severe as in the oceans. In continental waters, microplastics have been observed in both sediments (predominantly lake shores but also riverbanks) and water samples (predominantly surface water of lakes and rivers). This review highlights recent findings and discusses open questions, focussing on the methodology of assessing this contaminant in freshwater ecosystems. In this context, method harmonisation is needed in order to obtain comparable data from different environmental compartments and sites. This includes sampling strategies (at spatial and temporal scales), sample treatment (taking into consideration high levels of organic matter and suspended solids) and reliable analytical methods to identify microplastics.
Emerging contaminants, Freshwater ecosystems, Lakes, Plastic debris, Plastic separation, Polymer identification, Rivers, Sediment, Urban water
Dris, R., Imhof, H., Sanchez, W., Gasperi, J., Galgani, F., Tassin, B., Laforsch, C., 2015b. Beyond the ocean: Contamination of freshwater ecosystems with (micro-)plastic particles. Environmental Chemistry 12(5): 539–550.
Numerous studies on microplastics (MPs; Ø < 5 mm) in the aquatic environment have been published, but knowledge about the occurrence and ecological risks of MPs is limited. This is in part because current data on the distribution of MPs are comparable only to a limited extent, due to the many different methods of investigation. In addition, sample preparation is often difficult such that standard procedures are lacking. The aim of this work was to simplify the preparation of different kinds of MP samples. Our method makes use of the electrostatic behavior of plastic particles to facilitate their separation from sample matter, with up to 99% of the original sample mass removed without any loss of MPs. To determine the efficacy of this approach, four different materials (quartz sand, freshwater suspended particulate matter, freshwater sediment, and beach sand) were spiked with MPs (size: 0.063–5 mm from the seven most common types of plastics, one bioplastic type, polyethylene fibers, and tire wear. A modified electrostatic metal/plastic separator was used to reduce the sample mass and concentrate the plastics based on their physical separation. The recovery achieved with this method was as high as nearly 100% for each type of material. The method was then tested on plastic particles of different shapes and types isolated from the Rhine River. These were successfully electroseparated from the four materials, which demonstrated the utility of this method. Its advantages include the simplified handling and preparation of different field samples as well as a much shorter processing time, because after the last separation step there is hardly any biological material remaining in the sample fraction.
Tire wear, Freshwater suspended particulate matter, Beach sand, Electroseparation, Physical separation, Sediment
Stefanie Felsing, Christian Kochleus, Sebastian Buchinger, Nicole Brennholt, Friederike Stock, Georg Reifferscheid (2018): A new approach in separating microplastics from environmental samples based on their electrostatic behavior. Environmental Pollution Volume 234: 20-28